[ty] Use CompactStr for StringLiteralType values

This PR implements "go to definition" and "go to declaration"
functionality for name nodes only. Future PRs will add support for
attributes, module names in import statements, keyword argument names,
etc.

This PR:
* Registers a declaration and definition request handler for the
language server.
* Splits out the `goto_type_definition` into its own module. The `goto`
module contains functionality that is common to `goto_type_definition`,
`goto_declaration` and `goto_definition`.
* Roughs in a new module `stub_mapping` that is not yet implemented. It
will be responsible for mapping a definition in a stub file to its
corresponding definition(s) in an implementation (source) file.
* Adds a new IDE support function `definitions_for_name` that collects
all of the definitions associated with a name and resolves any imports
(recursively) to find the original definitions associated with that
name.
* Adds a new `VisibleAncestorsIter` stuct that iterates up the scope
hierarchy but skips scopes that are not visible to starting scope.

---------

Co-authored-by: UnboundVariable <unbound@gmail.com>

.github/workflows/ci.yaml

@@ -214,7 +214,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         run: |
           rustup component add clippy
@@ -234,17 +234,17 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
         uses: rui314/setup-mold@85c79d00377f0d32cdbae595a46de6f7c2fa6599 # v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
+        uses: taiki-e/install-action@c07504cae06f832dc8de08911c9a9c5cddb0d2d3 # v2.56.13
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
+        uses: taiki-e/install-action@c07504cae06f832dc8de08911c9a9c5cddb0d2d3 # v2.56.13
         with:
           tool: cargo-insta
       - name: ty mdtests (GitHub annotations)
@@ -292,17 +292,17 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
         uses: rui314/setup-mold@85c79d00377f0d32cdbae595a46de6f7c2fa6599 # v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
+        uses: taiki-e/install-action@c07504cae06f832dc8de08911c9a9c5cddb0d2d3 # v2.56.13
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
+        uses: taiki-e/install-action@c07504cae06f832dc8de08911c9a9c5cddb0d2d3 # v2.56.13
         with:
           tool: cargo-insta
       - name: "Run tests"
@@ -321,11 +321,11 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
+        uses: taiki-e/install-action@c07504cae06f832dc8de08911c9a9c5cddb0d2d3 # v2.56.13
         with:
           tool: cargo-nextest
       - name: "Run tests"
@@ -348,7 +348,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
       - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
@@ -377,7 +377,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
@@ -400,27 +400,18 @@ jobs:
         with:
           file: "Cargo.toml"
           field: "workspace.package.rust-version"
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         env:
           MSRV: ${{ steps.msrv.outputs.value }}
         run: rustup default "${MSRV}"
       - name: "Install mold"
         uses: rui314/setup-mold@85c79d00377f0d32cdbae595a46de6f7c2fa6599 # v1
-      - name: "Install cargo nextest"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
-        with:
-          tool: cargo-nextest
-      - name: "Install cargo insta"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
-        with:
-          tool: cargo-insta
-      - name: "Run tests"
+      - name: "Build tests"
         shell: bash
         env:
-          NEXTEST_PROFILE: "ci"
           MSRV: ${{ steps.msrv.outputs.value }}
-        run: cargo "+${MSRV}" insta test --all-features --unreferenced reject --test-runner nextest
+        run: cargo "+${MSRV}" test --no-run --all-features
 
   cargo-fuzz-build:
     name: "cargo fuzz build"
@@ -432,7 +423,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
         with:
           workspaces: "fuzz -> target"
       - name: "Install Rust toolchain"
@@ -494,7 +485,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         run: rustup component add rustfmt
       # Run all code generation scripts, and verify that the current output is
@@ -708,7 +699,7 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           architecture: x64
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels"
@@ -732,7 +723,7 @@ jobs:
         with:
           persist-credentials: false
       - uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 22
@@ -765,7 +756,7 @@ jobs:
       - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
         with:
           python-version: "3.13"
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Add SSH key"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
         uses: webfactory/ssh-agent@a6f90b1f127823b31d4d4a8d96047790581349bd # v0.9.1
@@ -804,7 +795,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Run checks"
@@ -874,7 +865,7 @@ jobs:
           persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 22
@@ -905,14 +896,14 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
 
       - name: "Install Rust toolchain"
         run: rustup show
 
       - name: "Install codspeed"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
+        uses: taiki-e/install-action@c07504cae06f832dc8de08911c9a9c5cddb0d2d3 # v2.56.13
         with:
           tool: cargo-codspeed
 
@@ -920,7 +911,7 @@ jobs:
         run: cargo codspeed build --features "codspeed,instrumented" --no-default-features -p ruff_benchmark
 
       - name: "Run benchmarks"
-        uses: CodSpeedHQ/action@0010eb0ca6e89b80c88e8edaaa07cfe5f3e6664d # v3.5.0
+        uses: CodSpeedHQ/action@c28fe9fbe7d57a3da1b7834ae3761c1d8217612d # v3.7.0
         with:
           run: cargo codspeed run
           token: ${{ secrets.CODSPEED_TOKEN }}
@@ -938,14 +929,14 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
 
       - name: "Install Rust toolchain"
         run: rustup show
 
       - name: "Install codspeed"
-        uses: taiki-e/install-action@d12e869b89167df346dd0ff65da342d1fb1202fb # v2.53.2
+        uses: taiki-e/install-action@c07504cae06f832dc8de08911c9a9c5cddb0d2d3 # v2.56.13
         with:
           tool: cargo-codspeed
 
@@ -953,7 +944,7 @@ jobs:
         run: cargo codspeed build --features "codspeed,walltime" --no-default-features -p ruff_benchmark
 
       - name: "Run benchmarks"
-        uses: CodSpeedHQ/action@0010eb0ca6e89b80c88e8edaaa07cfe5f3e6664d # v3.5.0
+        uses: CodSpeedHQ/action@c28fe9fbe7d57a3da1b7834ae3761c1d8217612d # v3.7.0
         with:
           run: cargo codspeed run
           token: ${{ secrets.CODSPEED_TOKEN }}

.github/workflows/daily_fuzz.yaml

@@ -39,7 +39,7 @@ jobs:
         run: rustup show
       - name: "Install mold"
         uses: rui314/setup-mold@85c79d00377f0d32cdbae595a46de6f7c2fa6599 # v1
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
       - name: Build ruff
         # A debug build means the script runs slower once it gets started,
         # but this is outweighed by the fact that a release build takes *much* longer to compile in CI

.github/workflows/mypy_primer.yaml

@@ -12,6 +12,7 @@ on:
       - ".github/workflows/mypy_primer.yaml"
       - ".github/workflows/mypy_primer_comment.yaml"
       - "Cargo.lock"
+      - "!**.md"
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.sha }}
@@ -39,7 +40,7 @@ jobs:
       - name: Install the latest version of uv
         uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
 
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
         with:
           workspaces: "ruff"
 
@@ -49,46 +50,12 @@ jobs:
       - name: Run mypy_primer
         shell: bash
         env:
-          TY_MEMORY_REPORT: mypy_primer
+          PRIMER_SELECTOR: crates/ty_python_semantic/resources/primer/good.txt
+          DIFF_FILE: mypy_primer.diff
         run: |
           cd ruff
-
-          echo "Enabling mypy primer specific configuration overloads (see .github/mypy-primer-ty.toml)"
-          mkdir -p ~/.config/ty
-          cp .github/mypy-primer-ty.toml ~/.config/ty/ty.toml
-
-          PRIMER_SELECTOR="$(paste -s -d'|' crates/ty_python_semantic/resources/primer/good.txt)"
-
-          echo "new commit"
-          git rev-list --format=%s --max-count=1 "$GITHUB_SHA"
-
-          MERGE_BASE="$(git merge-base "$GITHUB_SHA" "origin/$GITHUB_BASE_REF")"
-          git checkout -b base_commit "$MERGE_BASE"
-          echo "base commit"
-          git rev-list --format=%s --max-count=1 base_commit
-
-          cd ..
-
-          echo "Project selector: $PRIMER_SELECTOR"
-          # Allow the exit code to be 0 or 1, only fail for actual mypy_primer crashes/bugs
-          uvx \
-            --from="git+https://github.com/hauntsaninja/mypy_primer@e5f55447969d33ae3c7ccdb183e2a37101867270" \
-            mypy_primer \
-            --repo ruff \
-            --type-checker ty \
-            --old base_commit \
-            --new "$GITHUB_SHA" \
-            --project-selector "/($PRIMER_SELECTOR)\$" \
-            --output concise \
-            --debug > mypy_primer.diff || [ $? -eq 1 ]
-
-          # Output diff with ANSI color codes
-          cat mypy_primer.diff
-
-          # Remove ANSI color codes before uploading
-          sed -ie 's/\x1b\[[0-9;]*m//g' mypy_primer.diff
-
-          echo ${{ github.event.number }} > pr-number
+          scripts/mypy_primer.sh
+          echo ${{ github.event.number }} > ../pr-number
 
       - name: Upload diff
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
@@ -101,3 +68,41 @@ jobs:
         with:
           name: pr-number
           path: pr-number
+
+  memory_usage:
+    name: Run memory statistics
+    runs-on: depot-ubuntu-22.04-32
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          path: ruff
+          fetch-depth: 0
+          persist-credentials: false
+
+      - name: Install the latest version of uv
+        uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
+
+      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+        with:
+          workspaces: "ruff"
+
+      - name: Install Rust toolchain
+        run: rustup show
+
+      - name: Run mypy_primer
+        shell: bash
+        env:
+          TY_MAX_PARALLELISM: 1 # for deterministic memory numbers
+          TY_MEMORY_REPORT: mypy_primer
+          PRIMER_SELECTOR: crates/ty_python_semantic/resources/primer/memory.txt
+          DIFF_FILE: mypy_primer_memory.diff
+        run: |
+          cd ruff
+          scripts/mypy_primer.sh
+
+      - name: Upload diff
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: mypy_primer_memory_diff
+          path: mypy_primer_memory.diff

.github/workflows/mypy_primer_comment.yaml

@@ -45,15 +45,28 @@ jobs:
           if_no_artifact_found: ignore
           allow_forks: true
 
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
+        name: "Download mypy_primer memory results"
+        id: download-mypy_primer_memory_diff
+        if: steps.pr-number.outputs.pr-number
+        with:
+          name: mypy_primer_memory_diff
+          workflow: mypy_primer.yaml
+          pr: ${{ steps.pr-number.outputs.pr-number }}
+          path: pr/mypy_primer_memory_diff
+          workflow_conclusion: completed
+          if_no_artifact_found: ignore
+          allow_forks: true
+
       - name: Generate comment content
         id: generate-comment
-        if: steps.download-mypy_primer_diff.outputs.found_artifact == 'true'
+        if: ${{ steps.download-mypy_primer_diff.outputs.found_artifact == 'true' && steps.download-mypy_primer_memory_diff.outputs.found_artifact == 'true' }}
         run: |
           # Guard against malicious mypy_primer results that symlink to a secret
           # file on this runner
-          if [[ -L pr/mypy_primer_diff/mypy_primer.diff ]]
+          if [[ -L pr/mypy_primer_diff/mypy_primer.diff ]] || [[ -L pr/mypy_primer_memory_diff/mypy_primer_memory.diff ]]
           then
-              echo "Error: mypy_primer.diff cannot be a symlink"
+              echo "Error: mypy_primer.diff and mypy_primer_memory.diff cannot be a symlink"
               exit 1
           fi
 
@@ -74,6 +87,18 @@ jobs:
             echo 'No ecosystem changes detected ✅' >> comment.txt
           fi
 
+          if [ -s "pr/mypy_primer_memory_diff/mypy_primer_memory.diff" ]; then
+            echo '<details>' >> comment.txt
+            echo '<summary>Memory usage changes were detected when running on open source projects</summary>' >> comment.txt
+            echo '' >> comment.txt
+            echo '```diff' >> comment.txt
+            cat pr/mypy_primer_memory_diff/mypy_primer_memory.diff >> comment.txt
+            echo '```' >> comment.txt
+            echo '</details>' >> comment.txt
+          else
+            echo 'No memory usage changes detected ✅' >> comment.txt
+          fi
+
           echo 'comment<<EOF' >> "$GITHUB_OUTPUT"
           cat comment.txt >> "$GITHUB_OUTPUT"
           echo 'EOF' >> "$GITHUB_OUTPUT"

.github/workflows/publish-docs.yml

@@ -68,7 +68,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
 
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
 
       - name: "Install Insiders dependencies"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}

.github/workflows/sync_typeshed.yaml

@@ -1,5 +1,25 @@
 name: Sync typeshed
 
+# How this works:
+#
+# 1. A Linux worker:
+#    a. Checks out Ruff and typeshed
+#    b. Deletes the vendored typeshed stdlib stubs from Ruff
+#    c. Copies the latest versions of the stubs from typeshed
+#    d. Uses docstring-adder to sync all docstrings available on Linux
+#    e. Creates a new branch on the upstream astral-sh/ruff repository
+#    f. Commits the changes it's made and pushes them to the new upstream branch
+# 2. Once the Linux worker is done, a Windows worker:
+#    a. Checks out the branch created by the Linux worker
+#    b. Syncs all docstrings available on Windows that are not available on Linux
+#    c. Commits the changes and pushes them to the same upstream branch
+# 3. Once the Windows worker is done, a MacOS worker:
+#    a. Checks out the branch created by the Linux worker
+#    b. Syncs all docstrings available on MacOS that are not available on Linux or Windows
+#    c. Commits the changes and pushes them to the same upstream branch
+#    d. Creates a PR against the `main` branch using the branch all three workers have pushed to
+# 4. If any of steps 1-3 failed, an issue is created in the `astral-sh/ruff` repository
+
 on:
   workflow_dispatch:
   schedule:
@@ -10,7 +30,13 @@ env:
   FORCE_COLOR: 1
   GH_TOKEN: ${{ github.token }}
 
+  # The name of the upstream branch that the first worker creates,
+  # and which all three workers push to.
+  UPSTREAM_BRANCH: typeshedbot/sync-typeshed
+
 jobs:
+  # Sync typeshed stubs, and sync all docstrings available on Linux.
+  # Push the changes to a new branch on the upstream repository.
   sync:
     name: Sync typeshed
     runs-on: ubuntu-latest
@@ -19,7 +45,6 @@ jobs:
     if: ${{ github.repository == 'astral-sh/ruff' || github.event_name != 'schedule' }}
     permissions:
       contents: write
-      pull-requests: write
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         name: Checkout Ruff
@@ -36,37 +61,130 @@ jobs:
         run: |
           git config --global user.name typeshedbot
           git config --global user.email '<>'
-      - name: Sync typeshed
-        id: sync
+      - uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
+      - name: Sync typeshed stubs
         run: |
           rm -rf ruff/crates/ty_vendored/vendor/typeshed
           mkdir ruff/crates/ty_vendored/vendor/typeshed
           cp typeshed/README.md ruff/crates/ty_vendored/vendor/typeshed
           cp typeshed/LICENSE ruff/crates/ty_vendored/vendor/typeshed
+
+          # The pyproject.toml file is needed by a later job for the black configuration.
+          # It's deleted before creating the PR.
+          cp typeshed/pyproject.toml ruff/crates/ty_vendored/vendor/typeshed
+
           cp -r typeshed/stdlib ruff/crates/ty_vendored/vendor/typeshed/stdlib
           rm -rf ruff/crates/ty_vendored/vendor/typeshed/stdlib/@tests
           git -C typeshed rev-parse HEAD > ruff/crates/ty_vendored/vendor/typeshed/source_commit.txt
-      - name: Commit the changes
-        id: commit
-        if: ${{ steps.sync.outcome == 'success' }}
-        run: |
           cd ruff
           git checkout -b typeshedbot/sync-typeshed
           git add .
-          git diff --staged --quiet || git commit -m "Sync typeshed. Source commit: https://github.com/python/typeshed/commit/$(git -C ../typeshed rev-parse HEAD)"
-      - name: Create a PR
-        if: ${{ steps.sync.outcome == 'success' && steps.commit.outcome == 'success' }}
+          git commit -m "Sync typeshed. Source commit: https://github.com/python/typeshed/commit/$(git -C ../typeshed rev-parse HEAD)" --allow-empty
+      - name: Sync Linux docstrings
+        if: ${{ success() }}
         run: |
           cd ruff
-          git push --force origin typeshedbot/sync-typeshed
+          ./scripts/codemod_docstrings.sh
+          git commit -am "Sync Linux docstrings" --allow-empty
+      - name: Push the changes
+        id: commit
+        if: ${{ success() }}
+        run: git -C ruff push --force --set-upstream origin "${UPSTREAM_BRANCH}"
+
+  # Checkout the branch created by the sync job,
+  # and sync all docstrings available on Windows that are not available on Linux.
+  # Commit the changes and push them to the same branch.
+  docstrings-windows:
+    runs-on: windows-latest
+    timeout-minutes: 20
+    needs: [sync]
+
+    # Don't run the cron job on forks.
+    # The job will also be skipped if the sync job failed, because it's specified in `needs` above,
+    # and we haven't used `always()` in the `if` condition here
+    # (https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#example-requiring-successful-dependent-jobs)
+    if: ${{ github.repository == 'astral-sh/ruff' || github.event_name != 'schedule' }}
+
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        name: Checkout Ruff
+        with:
+          persist-credentials: true
+          ref: ${{ env.UPSTREAM_BRANCH}}
+      - uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
+      - name: Setup git
+        run: |
+          git config --global user.name typeshedbot
+          git config --global user.email '<>'
+      - name: Sync Windows docstrings
+        id: docstrings
+        shell: bash
+        run: ./scripts/codemod_docstrings.sh
+      - name: Commit the changes
+        if: ${{ steps.docstrings.outcome == 'success' }}
+        run: |
+          git commit -am "Sync Windows docstrings" --allow-empty
+          git push
+
+  # Checkout the branch created by the sync job,
+  # and sync all docstrings available on macOS that are not available on Linux or Windows.
+  # Push the changes to the same branch and create a PR against the `main` branch using that branch.
+  docstrings-macos-and-pr:
+    runs-on: macos-latest
+    timeout-minutes: 20
+    needs: [sync, docstrings-windows]
+
+    # Don't run the cron job on forks.
+    # The job will also be skipped if the sync or docstrings-windows jobs failed,
+    # because they're specified in `needs` above and we haven't used an `always()` condition in the `if` here
+    # (https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#example-requiring-successful-dependent-jobs)
+    if: ${{ github.repository == 'astral-sh/ruff' || github.event_name != 'schedule' }}
+
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        name: Checkout Ruff
+        with:
+          persist-credentials: true
+          ref: ${{ env.UPSTREAM_BRANCH}}
+      - uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
+      - name: Setup git
+        run: |
+          git config --global user.name typeshedbot
+          git config --global user.email '<>'
+      - name: Sync macOS docstrings
+        run: ./scripts/codemod_docstrings.sh
+      - name: Commit and push the changes
+        if: ${{ success() }}
+        run: |
+          git commit -am "Sync macOS docstrings" --allow-empty
+
+          # Here we just reformat the codemodded stubs so that they are
+          # consistent with the other typeshed stubs around them.
+          # Typeshed formats code using black in their CI, so we just invoke
+          # black on the stubs the same way that typeshed does.
+          uvx black crates/ty_vendored/vendor/typeshed/stdlib --config crates/ty_vendored/vendor/typeshed/pyproject.toml || true
+          git commit -am "Format codemodded docstrings" --allow-empty
+
+          rm crates/ty_vendored/vendor/typeshed/pyproject.toml
+          git commit -am "Remove pyproject.toml file"
+
+          git push
+      - name: Create a PR
+        if: ${{ success() }}
+        run: |
           gh pr list --repo "$GITHUB_REPOSITORY" --head typeshedbot/sync-typeshed --json id --jq length | grep 1 && exit 0 # exit if there is existing pr
           gh pr create --title "[ty] Sync vendored typeshed stubs" --body "Close and reopen this PR to trigger CI" --label "ty"
 
   create-issue-on-failure:
     name: Create an issue if the typeshed sync failed
     runs-on: ubuntu-latest
-    needs: [sync]
-    if: ${{ github.repository == 'astral-sh/ruff' && always() && github.event_name == 'schedule' && needs.sync.result == 'failure' }}
+    needs: [sync, docstrings-windows, docstrings-macos-and-pr]
+    if: ${{ github.repository == 'astral-sh/ruff' && always() && github.event_name == 'schedule' && (needs.sync.result == 'failure' || needs.docstrings-windows.result == 'failure' || needs.docstrings-macos-and-pr.result == 'failure') }}
     permissions:
       issues: write
     steps:

.github/workflows/ty-ecosystem-analyzer.yaml

@@ -17,6 +17,7 @@ env:
   RUSTUP_MAX_RETRIES: 10
   RUST_BACKTRACE: 1
   REF_NAME: ${{ github.ref_name }}
+  CF_API_TOKEN_EXISTS: ${{ secrets.CF_API_TOKEN != '' }}
 
 jobs:
   ty-ecosystem-analyzer:
@@ -34,7 +35,7 @@ jobs:
       - name: Install the latest version of uv
         uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
 
-      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
         with:
           workspaces: "ruff"
 
@@ -63,32 +64,75 @@ jobs:
 
           cd ..
 
-          uv tool install "git+https://github.com/astral-sh/ecosystem-analyzer@9c34dc514ee9aef6735db1dfebb80f63acbc3440"
+          uv tool install "git+https://github.com/astral-sh/ecosystem-analyzer@f0eec0e549684d8e1d7b8bc3e351202124b63bda"
 
           ecosystem-analyzer \
             --repository ruff \
-            analyze \
-            --projects ruff/projects_old.txt \
-            --commit old_commit \
-            --output diagnostics_old.json
+            diff \
+            --projects-old ruff/projects_old.txt \
+            --projects-new ruff/projects_new.txt \
+            --old old_commit \
+            --new new_commit \
+            --output-old diagnostics-old.json \
+            --output-new diagnostics-new.json
 
-          ecosystem-analyzer \
-            --repository ruff \
-            analyze \
-            --projects ruff/projects_new.txt \
-            --commit new_commit \
-            --output diagnostics_new.json
+          mkdir dist
 
           ecosystem-analyzer \
             generate-diff \
-            diagnostics_old.json \
-            diagnostics_new.json \
+            diagnostics-old.json \
+            diagnostics-new.json \
             --old-name "main (merge base)" \
             --new-name "$REF_NAME" \
-            --output-html diff.html
+            --output-html dist/diff.html
 
-      - name: Upload HTML diff report
+          ecosystem-analyzer \
+            generate-diff-statistics \
+            diagnostics-old.json \
+            diagnostics-new.json \
+            --old-name "main (merge base)" \
+            --new-name "$REF_NAME" \
+            --output diff-statistics.md
+
+          echo '## `ecosystem-analyzer` results' > comment.md
+          echo >> comment.md
+          cat diff-statistics.md >> comment.md
+
+          cat diff-statistics.md >> "$GITHUB_STEP_SUMMARY"
+
+          echo ${{ github.event.number }} > pr-number
+
+      - name: "Deploy to Cloudflare Pages"
+        if: ${{ env.CF_API_TOKEN_EXISTS == 'true' }}
+        id: deploy
+        uses: cloudflare/wrangler-action@da0e0dfe58b7a431659754fdf3f186c529afbe65 # v3.14.1
+        with:
+          apiToken: ${{ secrets.CF_API_TOKEN }}
+          accountId: ${{ secrets.CF_ACCOUNT_ID }}
+          command: pages deploy dist --project-name=ty-ecosystem --branch ${{ github.head_ref }} --commit-hash ${GITHUB_SHA}
+
+      - name: "Append deployment URL"
+        if: ${{ env.CF_API_TOKEN_EXISTS == 'true' }}
+        env:
+          DEPLOYMENT_URL: ${{ steps.deploy.outputs.pages-deployment-alias-url }}
+        run: |
+          echo >> comment.md
+          echo "**[Full report with detailed diff]($DEPLOYMENT_URL/diff)**" >> comment.md
+
+      - name: Upload comment
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: comment.md
+          path: comment.md
+
+      - name: Upload pr-number
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: pr-number
+          path: pr-number
+
+      - name: Upload diagnostics diff
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: diff.html
-          path: diff.html
+          path: dist/diff.html

.github/workflows/ty-ecosystem-analyzer_comment.yaml

@@ -0,0 +1,85 @@
+name: PR comment (ty ecosystem-analyzer)
+
+on: # zizmor: ignore[dangerous-triggers]
+  workflow_run:
+    workflows: [ty ecosystem-analyzer]
+    types: [completed]
+  workflow_dispatch:
+    inputs:
+      workflow_run_id:
+        description: The ty ecosystem-analyzer workflow that triggers the workflow run
+        required: true
+
+jobs:
+  comment:
+    runs-on: ubuntu-24.04
+    permissions:
+      pull-requests: write
+    steps:
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
+        name: Download PR number
+        with:
+          name: pr-number
+          run_id: ${{ github.event.workflow_run.id ||  github.event.inputs.workflow_run_id }}
+          if_no_artifact_found: ignore
+          allow_forks: true
+
+      - name: Parse pull request number
+        id: pr-number
+        run: |
+          if [[ -f pr-number ]]
+          then
+            echo "pr-number=$(<pr-number)" >> "$GITHUB_OUTPUT"
+          fi
+
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
+        name: "Download comment.md"
+        id: download-comment
+        if: steps.pr-number.outputs.pr-number
+        with:
+          name: comment.md
+          workflow: ty-ecosystem-analyzer.yaml
+          pr: ${{ steps.pr-number.outputs.pr-number }}
+          path: pr/comment
+          workflow_conclusion: completed
+          if_no_artifact_found: ignore
+          allow_forks: true
+
+      - name: Generate comment content
+        id: generate-comment
+        if: ${{ steps.download-comment.outputs.found_artifact == 'true' }}
+        run: |
+          # Guard against malicious ty ecosystem-analyzer results that symlink to a secret
+          # file on this runner
+          if [[ -L pr/comment/comment.md ]]
+          then
+              echo "Error: comment.md cannot be a symlink"
+              exit 1
+          fi
+
+          # Note: this identifier is used to find the comment to update on subsequent runs
+          echo '<!-- generated-comment ty ecosystem-analyzer -->' > comment.md
+          echo >> comment.md
+          cat pr/comment/comment.md >> comment.md
+
+          echo 'comment<<EOF' >> "$GITHUB_OUTPUT"
+          cat comment.md >> "$GITHUB_OUTPUT"
+          echo 'EOF' >> "$GITHUB_OUTPUT"
+
+      - name: Find existing comment
+        uses: peter-evans/find-comment@3eae4d37986fb5a8592848f6a574fdf654e61f9e # v3.1.0
+        if: steps.generate-comment.outcome == 'success'
+        id: find-comment
+        with:
+          issue-number: ${{ steps.pr-number.outputs.pr-number }}
+          comment-author: "github-actions[bot]"
+          body-includes: "<!-- generated-comment ty ecosystem-analyzer -->"
+
+      - name: Create or update comment
+        if: steps.find-comment.outcome == 'success'
+        uses: peter-evans/create-or-update-comment@71345be0265236311c031f5c7866368bd1eff043 # v4
+        with:
+          comment-id: ${{ steps.find-comment.outputs.comment-id }}
+          issue-number: ${{ steps.pr-number.outputs.pr-number }}
+          body-path: comment.md
+          edit-mode: replace

.github/workflows/ty-ecosystem-report.yaml

@@ -0,0 +1,76 @@
+name: ty ecosystem-report
+
+permissions: {}
+
+on:
+  workflow_dispatch:
+  schedule:
+    # Run every Wednesday at 5:00 UTC:
+    - cron: 0 5 * * 3
+
+env:
+  CARGO_INCREMENTAL: 0
+  CARGO_NET_RETRY: 10
+  CARGO_TERM_COLOR: always
+  RUSTUP_MAX_RETRIES: 10
+  RUST_BACKTRACE: 1
+  CF_API_TOKEN_EXISTS: ${{ secrets.CF_API_TOKEN != '' }}
+
+jobs:
+  ty-ecosystem-report:
+    name: Create ecosystem report
+    runs-on: depot-ubuntu-22.04-32
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          path: ruff
+          fetch-depth: 0
+          persist-credentials: false
+
+      - name: Install the latest version of uv
+        uses: astral-sh/setup-uv@bd01e18f51369d5a26f1651c3cb451d3417e3bba # v6.3.1
+
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
+        with:
+          workspaces: "ruff"
+
+      - name: Install Rust toolchain
+        run: rustup show
+
+      - name: Create report
+        shell: bash
+        run: |
+          cd ruff
+
+          echo "Enabling configuration overloads (see .github/mypy-primer-ty.toml)"
+          mkdir -p ~/.config/ty
+          cp .github/mypy-primer-ty.toml ~/.config/ty/ty.toml
+
+          cd ..
+
+          uv tool install "git+https://github.com/astral-sh/ecosystem-analyzer@f0eec0e549684d8e1d7b8bc3e351202124b63bda"
+
+          ecosystem-analyzer \
+            --verbose \
+            --repository ruff \
+            analyze \
+            --projects ruff/crates/ty_python_semantic/resources/primer/good.txt \
+            --output ecosystem-diagnostics.json
+
+          mkdir dist
+
+          ecosystem-analyzer \
+            generate-report \
+            --max-diagnostics-per-project=1200 \
+            ecosystem-diagnostics.json \
+            --output dist/index.html
+
+      - name: "Deploy to Cloudflare Pages"
+        if: ${{ env.CF_API_TOKEN_EXISTS == 'true' }}
+        id: deploy
+        uses: cloudflare/wrangler-action@da0e0dfe58b7a431659754fdf3f186c529afbe65 # v3.14.1
+        with:
+          apiToken: ${{ secrets.CF_API_TOKEN }}
+          accountId: ${{ secrets.CF_ACCOUNT_ID }}
+          command: pages deploy dist --project-name=ty-ecosystem --branch main --commit-hash ${GITHUB_SHA}

.github/zizmor.yml

@@ -10,6 +10,8 @@ rules:
     ignore:
       - build-docker.yml
       - publish-playground.yml
+      - ty-ecosystem-analyzer.yaml
+      - ty-ecosystem-report.yaml
   excessive-permissions:
     # it's hard to test what the impact of removing these ignores would be
     # without actually running the release workflow...

.pre-commit-config.yaml

@@ -6,7 +6,7 @@ exclude: |
     crates/ty_vendored/vendor/.*|
     crates/ty_project/resources/.*|
     crates/ty_python_semantic/resources/corpus/.*|
-    crates/ty/docs/(configuration|rules|cli).md|
+    crates/ty/docs/(configuration|rules|cli|environment).md|
     crates/ruff_benchmark/resources/.*|
     crates/ruff_linter/resources/.*|
     crates/ruff_linter/src/rules/.*/snapshots/.*|
@@ -67,7 +67,7 @@ repos:
           - black==25.1.0
 
   - repo: https://github.com/crate-ci/typos
-    rev: v1.33.1
+    rev: v1.34.0
     hooks:
       - id: typos
 
@@ -81,7 +81,7 @@ repos:
         pass_filenames: false # This makes it a lot faster
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.12.1
+    rev: v0.12.3
     hooks:
       - id: ruff-format
       - id: ruff
@@ -99,12 +99,12 @@ repos:
   # zizmor detects security vulnerabilities in GitHub Actions workflows.
   # Additional configuration for the tool is found in `.github/zizmor.yml`
   - repo: https://github.com/woodruffw/zizmor-pre-commit
-    rev: v1.10.0
+    rev: v1.11.0
     hooks:
       - id: zizmor
 
   - repo: https://github.com/python-jsonschema/check-jsonschema
-    rev: 0.33.1
+    rev: 0.33.2
     hooks:
       - id: check-github-workflows
 
@@ -128,5 +128,10 @@ repos:
           # but the integration only works if shellcheck is installed
           - "github.com/wasilibs/go-shellcheck/cmd/shellcheck@v0.10.0"
 
+  - repo: https://github.com/shellcheck-py/shellcheck-py
+    rev: v0.10.0.1
+    hooks:
+      - id: shellcheck
+
 ci:
   skip: [cargo-fmt, dev-generate-all]

CHANGELOG.md

@@ -1,5 +1,89 @@
 # Changelog
 
+## 0.12.3
+
+### Preview features
+
+- \[`flake8-bugbear`\] Support non-context-manager calls in `B017` ([#19063](https://github.com/astral-sh/ruff/pull/19063))
+- \[`flake8-use-pathlib`\] Add autofixes for `PTH100`, `PTH106`, `PTH107`, `PTH108`, `PTH110`, `PTH111`, `PTH112`, `PTH113`, `PTH114`, `PTH115`, `PTH117`, `PTH119`, `PTH120` ([#19213](https://github.com/astral-sh/ruff/pull/19213))
+- \[`flake8-use-pathlib`\] Add autofixes for `PTH203`, `PTH204`, `PTH205` ([#18922](https://github.com/astral-sh/ruff/pull/18922))
+
+### Bug fixes
+
+- \[`flake8-return`\] Fix false-positive for variables used inside nested functions in `RET504` ([#18433](https://github.com/astral-sh/ruff/pull/18433))
+- Treat form feed as valid whitespace before a line continuation ([#19220](https://github.com/astral-sh/ruff/pull/19220))
+- \[`flake8-type-checking`\] Fix syntax error introduced by fix (`TC008`) ([#19150](https://github.com/astral-sh/ruff/pull/19150))
+- \[`pyupgrade`\] Keyword arguments in `super` should suppress the `UP008` fix ([#19131](https://github.com/astral-sh/ruff/pull/19131))
+
+### Documentation
+
+- \[`flake8-pyi`\] Make example error out-of-the-box (`PYI007`, `PYI008`) ([#19103](https://github.com/astral-sh/ruff/pull/19103))
+- \[`flake8-simplify`\] Make example error out-of-the-box (`SIM116`) ([#19111](https://github.com/astral-sh/ruff/pull/19111))
+- \[`flake8-type-checking`\] Make example error out-of-the-box (`TC001`) ([#19151](https://github.com/astral-sh/ruff/pull/19151))
+- \[`flake8-use-pathlib`\] Make example error out-of-the-box (`PTH210`) ([#19189](https://github.com/astral-sh/ruff/pull/19189))
+- \[`pycodestyle`\] Make example error out-of-the-box (`E272`) ([#19191](https://github.com/astral-sh/ruff/pull/19191))
+- \[`pycodestyle`\] Make example not raise unnecessary `SyntaxError` (`E114`) ([#19190](https://github.com/astral-sh/ruff/pull/19190))
+- \[`pydoclint`\] Make example error out-of-the-box (`DOC501`) ([#19218](https://github.com/astral-sh/ruff/pull/19218))
+- \[`pylint`, `pyupgrade`\] Fix syntax errors in examples (`PLW1501`, `UP028`) ([#19127](https://github.com/astral-sh/ruff/pull/19127))
+- \[`pylint`\] Update `missing-maxsplit-arg` docs and error to suggest proper usage (`PLC0207`) ([#18949](https://github.com/astral-sh/ruff/pull/18949))
+- \[`flake8-bandit`\] Make example error out-of-the-box (`S412`) ([#19241](https://github.com/astral-sh/ruff/pull/19241))
+
+## 0.12.2
+
+### Preview features
+
+- \[`flake8-pyi`\] Expand `Optional[A]` to `A | None` (`PYI016`) ([#18572](https://github.com/astral-sh/ruff/pull/18572))
+- \[`pyupgrade`\] Mark `UP008` fix safe if no comments are in range ([#18683](https://github.com/astral-sh/ruff/pull/18683))
+
+### Bug fixes
+
+- \[`flake8-comprehensions`\] Fix `C420` to prepend whitespace when needed ([#18616](https://github.com/astral-sh/ruff/pull/18616))
+- \[`perflint`\] Fix `PERF403` panic on attribute or subscription loop variable ([#19042](https://github.com/astral-sh/ruff/pull/19042))
+- \[`pydocstyle`\] Fix `D413` infinite loop for parenthesized docstring ([#18930](https://github.com/astral-sh/ruff/pull/18930))
+- \[`pylint`\] Fix `PLW0108` autofix introducing a syntax error when the lambda's body contains an assignment expression ([#18678](https://github.com/astral-sh/ruff/pull/18678))
+- \[`refurb`\] Fix false positive on empty tuples (`FURB168`) ([#19058](https://github.com/astral-sh/ruff/pull/19058))
+- \[`ruff`\] Allow more `field` calls from `attrs` (`RUF009`) ([#19021](https://github.com/astral-sh/ruff/pull/19021))
+- \[`ruff`\] Fix syntax error introduced for an empty string followed by a u-prefixed string (`UP025`) ([#18899](https://github.com/astral-sh/ruff/pull/18899))
+
+### Rule changes
+
+- \[`flake8-executable`\] Allow `uvx` in shebang line (`EXE003`) ([#18967](https://github.com/astral-sh/ruff/pull/18967))
+- \[`pandas`\] Avoid flagging `PD002` if `pandas` is not imported ([#18963](https://github.com/astral-sh/ruff/pull/18963))
+- \[`pyupgrade`\] Avoid PEP-604 unions with `typing.NamedTuple` (`UP007`, `UP045`) ([#18682](https://github.com/astral-sh/ruff/pull/18682))
+
+### Documentation
+
+- Document link between `import-outside-top-level (PLC0415)` and `lint.flake8-tidy-imports.banned-module-level-imports` ([#18733](https://github.com/astral-sh/ruff/pull/18733))
+- Fix description of the `format.skip-magic-trailing-comma` example ([#19095](https://github.com/astral-sh/ruff/pull/19095))
+- \[`airflow`\] Make `AIR302` example error out-of-the-box ([#18988](https://github.com/astral-sh/ruff/pull/18988))
+- \[`airflow`\] Make `AIR312` example error out-of-the-box ([#18989](https://github.com/astral-sh/ruff/pull/18989))
+- \[`flake8-annotations`\] Make `ANN401` example error out-of-the-box ([#18974](https://github.com/astral-sh/ruff/pull/18974))
+- \[`flake8-async`\] Make `ASYNC100` example error out-of-the-box ([#18993](https://github.com/astral-sh/ruff/pull/18993))
+- \[`flake8-async`\] Make `ASYNC105` example error out-of-the-box ([#19002](https://github.com/astral-sh/ruff/pull/19002))
+- \[`flake8-async`\] Make `ASYNC110` example error out-of-the-box ([#18975](https://github.com/astral-sh/ruff/pull/18975))
+- \[`flake8-async`\] Make `ASYNC210` example error out-of-the-box ([#18977](https://github.com/astral-sh/ruff/pull/18977))
+- \[`flake8-async`\] Make `ASYNC220`, `ASYNC221`, and `ASYNC222` examples error out-of-the-box ([#18978](https://github.com/astral-sh/ruff/pull/18978))
+- \[`flake8-async`\] Make `ASYNC251` example error out-of-the-box ([#18990](https://github.com/astral-sh/ruff/pull/18990))
+- \[`flake8-bandit`\] Make `S201` example error out-of-the-box ([#19017](https://github.com/astral-sh/ruff/pull/19017))
+- \[`flake8-bandit`\] Make `S604` and `S609` examples error out-of-the-box ([#19049](https://github.com/astral-sh/ruff/pull/19049))
+- \[`flake8-bugbear`\] Make `B028` example error out-of-the-box ([#19054](https://github.com/astral-sh/ruff/pull/19054))
+- \[`flake8-bugbear`\] Make `B911` example error out-of-the-box ([#19051](https://github.com/astral-sh/ruff/pull/19051))
+- \[`flake8-datetimez`\] Make `DTZ011` example error out-of-the-box ([#19055](https://github.com/astral-sh/ruff/pull/19055))
+- \[`flake8-datetimez`\] Make `DTZ901` example error out-of-the-box ([#19056](https://github.com/astral-sh/ruff/pull/19056))
+- \[`flake8-pyi`\] Make `PYI032` example error out-of-the-box ([#19061](https://github.com/astral-sh/ruff/pull/19061))
+- \[`flake8-pyi`\] Make example error out-of-the-box (`PYI014`, `PYI015`) ([#19097](https://github.com/astral-sh/ruff/pull/19097))
+- \[`flake8-pyi`\] Make example error out-of-the-box (`PYI042`) ([#19101](https://github.com/astral-sh/ruff/pull/19101))
+- \[`flake8-pyi`\] Make example error out-of-the-box (`PYI059`) ([#19080](https://github.com/astral-sh/ruff/pull/19080))
+- \[`flake8-pyi`\] Make example error out-of-the-box (`PYI062`) ([#19079](https://github.com/astral-sh/ruff/pull/19079))
+- \[`flake8-pytest-style`\] Make example error out-of-the-box (`PT023`) ([#19104](https://github.com/astral-sh/ruff/pull/19104))
+- \[`flake8-pytest-style`\] Make example error out-of-the-box (`PT030`) ([#19105](https://github.com/astral-sh/ruff/pull/19105))
+- \[`flake8-quotes`\] Make example error out-of-the-box (`Q003`) ([#19106](https://github.com/astral-sh/ruff/pull/19106))
+- \[`flake8-simplify`\] Make example error out-of-the-box (`SIM110`) ([#19113](https://github.com/astral-sh/ruff/pull/19113))
+- \[`flake8-simplify`\] Make example error out-of-the-box (`SIM113`) ([#19109](https://github.com/astral-sh/ruff/pull/19109))
+- \[`flake8-simplify`\] Make example error out-of-the-box (`SIM401`) ([#19110](https://github.com/astral-sh/ruff/pull/19110))
+- \[`pyflakes`\] Fix backslash in docs (`F621`) ([#19098](https://github.com/astral-sh/ruff/pull/19098))
+- \[`pylint`\] Fix `PLC0415` example ([#18970](https://github.com/astral-sh/ruff/pull/18970))
+
 ## 0.12.1
 
 ### Preview features

CONTRIBUTING.md

@@ -266,6 +266,13 @@ Finally, regenerate the documentation and generated code with `cargo dev generat
 
 ## MkDocs
 
+> [!NOTE]
+>
+> The documentation uses Material for MkDocs Insiders, which is closed-source software.
+> This means only members of the Astral organization can preview the documentation exactly as it
+> will appear in production.
+> Outside contributors can still preview the documentation, but there will be some differences. Consult [the Material for MkDocs documentation](https://squidfunk.github.io/mkdocs-material/insiders/benefits/#features) for which features are exclusively available in the insiders version.
+
 To preview any changes to the documentation locally:
 
 1. Install the [Rust toolchain](https://www.rust-lang.org/tools/install).

Cargo.lock

@@ -396,9 +396,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.40"
+version = "4.5.41"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "40b6887a1d8685cebccf115538db5c0efe625ccac9696ad45c409d96566e910f"
+checksum = "be92d32e80243a54711e5d7ce823c35c41c9d929dc4ab58e1276f625841aadf9"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -406,9 +406,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.40"
+version = "4.5.41"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e0c66c08ce9f0c698cbce5c0279d0bb6ac936d8674174fe48f736533b964f59e"
+checksum = "707eab41e9622f9139419d573eca0900137718000c517d47da73045f54331c3d"
 dependencies = [
  "anstream",
  "anstyle",
@@ -449,9 +449,9 @@ dependencies = [
 
 [[package]]
 name = "clap_derive"
-version = "4.5.40"
+version = "4.5.41"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2c7947ae4cc3d851207c1adb5b5e260ff0cca11446b1d6d1423788e442257ce"
+checksum = "ef4f52386a59ca4c860f7393bcf8abd8dfd91ecccc0f774635ff68e92eeef491"
 dependencies = [
  "heck",
  "proc-macro2",
@@ -633,10 +633,22 @@ dependencies = [
  "encode_unicode",
  "libc",
  "once_cell",
- "unicode-width 0.2.1",
  "windows-sys 0.59.0",
 ]
 
+[[package]]
+name = "console"
+version = "0.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e09ced7ebbccb63b4c65413d821f2e00ce54c5ca4514ddc6b3c892fdbcbc69d"
+dependencies = [
+ "encode_unicode",
+ "libc",
+ "once_cell",
+ "unicode-width 0.2.1",
+ "windows-sys 0.60.2",
+]
+
 [[package]]
 name = "console_error_panic_hook"
 version = "0.1.7"
@@ -668,11 +680,6 @@ name = "countme"
 version = "3.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7704b5fdd17b18ae31c4c1da5a2e0305a2bf17b5249300a9ee9ed7b72114c636"
-dependencies = [
- "dashmap 5.5.3",
- "once_cell",
- "rustc-hash 1.1.0",
-]
 
 [[package]]
 name = "cpufeatures"
@@ -840,19 +847,6 @@ dependencies = [
  "syn",
 ]
 
-[[package]]
-name = "dashmap"
-version = "5.5.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "978747c1d849a7d2ee5e8adc0159961c48fb7e5db2f06af6723b80123bb53856"
-dependencies = [
- "cfg-if",
- "hashbrown 0.14.5",
- "lock_api",
- "once_cell",
- "parking_lot_core",
-]
-
 [[package]]
 name = "dashmap"
 version = "6.1.0"
@@ -939,7 +933,7 @@ dependencies = [
  "libc",
  "option-ext",
  "redox_users",
- "windows-sys 0.59.0",
+ "windows-sys 0.60.2",
 ]
 
 [[package]]
@@ -1139,9 +1133,9 @@ dependencies = [
 
 [[package]]
 name = "get-size-derive2"
-version = "0.5.1"
+version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1aac2af9f9a6a50e31b1e541d05b7925add83d3982c2793193fe9d4ee584323c"
+checksum = "028f3cfad7c3e3b1d8d04ef0a1c03576f2d62800803fe1301a4cd262849f2dea"
 dependencies = [
  "attribute-derive",
  "quote",
@@ -1150,9 +1144,9 @@ dependencies = [
 
 [[package]]
 name = "get-size2"
-version = "0.5.1"
+version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "624a0312efd19e1c45922dfcc2d6806d3ffc4bca261f89f31fcc4f63f438d885"
+checksum = "3a09c2043819a3def7bfbb4927e7df96aab0da4cfd8824484b22d0c94e84458e"
 dependencies = [
  "compact_str",
  "get-size-derive2",
@@ -1481,14 +1475,14 @@ dependencies = [
 
 [[package]]
 name = "indicatif"
-version = "0.17.11"
+version = "0.18.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "183b3088984b400f4cfac3620d5e076c84da5364016b4f49473de574b2586235"
+checksum = "70a646d946d06bedbbc4cac4c218acf4bbf2d87757a784857025f4d447e4e1cd"
 dependencies = [
- "console",
- "number_prefix",
+ "console 0.16.0",
  "portable-atomic",
  "unicode-width 0.2.1",
+ "unit-prefix",
  "vt100",
  "web-time",
 ]
@@ -1525,7 +1519,7 @@ version = "1.43.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "154934ea70c58054b556dd430b99a98c2a7ff5309ac9891597e339b5c28f4371"
 dependencies = [
- "console",
+ "console 0.15.11",
  "globset",
  "once_cell",
  "pest",
@@ -2025,12 +2019,11 @@ checksum = "61807f77802ff30975e01f4f071c8ba10c022052f98b3294119f3e615d13e5be"
 
 [[package]]
 name = "notify"
-version = "8.0.0"
+version = "8.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2fee8403b3d66ac7b26aee6e40a897d85dc5ce26f44da36b8b73e987cc52e943"
+checksum = "3163f59cd3fa0e9ef8c32f242966a7b9994fd7378366099593e0e73077cd8c97"
 dependencies = [
  "bitflags 2.9.1",
- "filetime",
  "fsevent-sys",
  "inotify",
  "kqueue",
@@ -2039,7 +2032,7 @@ dependencies = [
  "mio",
  "notify-types",
  "walkdir",
- "windows-sys 0.59.0",
+ "windows-sys 0.60.2",
 ]
 
 [[package]]
@@ -2077,12 +2070,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "number_prefix"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "830b246a0e5f20af87141b25c173cd1b609bd7779a4617d6ec582abaf90870f3"
-
 [[package]]
 name = "once_cell"
 version = "1.21.3"
@@ -2166,7 +2153,7 @@ dependencies = [
  "libc",
  "redox_syscall",
  "smallvec",
- "windows-targets",
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -2257,7 +2244,7 @@ dependencies = [
  "once_cell",
  "pep440_rs",
  "regex",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "serde",
  "smallvec",
  "thiserror 1.0.69",
@@ -2478,7 +2465,7 @@ dependencies = [
  "pep508_rs",
  "serde",
  "thiserror 2.0.12",
- "toml",
+ "toml 0.8.23",
 ]
 
 [[package]]
@@ -2724,7 +2711,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.12.1"
+version = "0.12.3"
 dependencies = [
  "anyhow",
  "argfile",
@@ -2767,7 +2754,7 @@ dependencies = [
  "ruff_source_file",
  "ruff_text_size",
  "ruff_workspace",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "serde",
  "serde_json",
  "shellexpand",
@@ -2776,7 +2763,7 @@ dependencies = [
  "test-case",
  "thiserror 2.0.12",
  "tikv-jemallocator",
- "toml",
+ "toml 0.9.2",
  "tracing",
  "walkdir",
  "wild",
@@ -2792,7 +2779,7 @@ dependencies = [
  "ruff_annotate_snippets",
  "serde",
  "snapbox",
- "toml",
+ "toml 0.9.2",
  "tryfn",
  "unicode-width 0.2.1",
 ]
@@ -2813,7 +2800,7 @@ dependencies = [
  "ruff_python_formatter",
  "ruff_python_parser",
  "ruff_python_trivia",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "serde",
  "serde_json",
  "tikv-jemallocator",
@@ -2842,7 +2829,7 @@ dependencies = [
  "arc-swap",
  "camino",
  "countme",
- "dashmap 6.1.0",
+ "dashmap",
  "dunce",
  "etcetera",
  "filetime",
@@ -2854,20 +2841,23 @@ dependencies = [
  "path-slash",
  "ruff_annotate_snippets",
  "ruff_cache",
+ "ruff_diagnostics",
  "ruff_notebook",
  "ruff_python_ast",
  "ruff_python_parser",
  "ruff_python_trivia",
  "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "salsa",
  "schemars",
  "serde",
+ "serde_json",
  "tempfile",
  "thiserror 2.0.12",
  "tracing",
  "tracing-subscriber",
+ "ty_static",
  "web-time",
  "zip",
 ]
@@ -2905,12 +2895,13 @@ dependencies = [
  "similar",
  "strum",
  "tempfile",
- "toml",
+ "toml 0.9.2",
  "tracing",
  "tracing-indicatif",
  "tracing-subscriber",
  "ty",
  "ty_project",
+ "ty_static",
  "url",
 ]
 
@@ -2918,6 +2909,7 @@ dependencies = [
 name = "ruff_diagnostics"
 version = "0.0.0"
 dependencies = [
+ "get-size2",
  "is-macro",
  "ruff_text_size",
  "serde",
@@ -2931,7 +2923,7 @@ dependencies = [
  "ruff_cache",
  "ruff_macros",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "schemars",
  "serde",
  "static_assertions",
@@ -2970,7 +2962,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_linter"
-version = "0.12.1"
+version = "0.12.3"
 dependencies = [
  "aho-corasick",
  "anyhow",
@@ -3013,7 +3005,7 @@ dependencies = [
  "ruff_python_trivia",
  "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "schemars",
  "serde",
  "serde_json",
@@ -3024,7 +3016,7 @@ dependencies = [
  "tempfile",
  "test-case",
  "thiserror 2.0.12",
- "toml",
+ "toml 0.9.2",
  "typed-arena",
  "unicode-normalization",
  "unicode-width 0.2.1",
@@ -3085,7 +3077,7 @@ dependencies = [
  "ruff_python_trivia",
  "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "salsa",
  "schemars",
  "serde",
@@ -3135,7 +3127,7 @@ dependencies = [
  "ruff_python_trivia",
  "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "salsa",
  "schemars",
  "serde",
@@ -3184,7 +3176,7 @@ dependencies = [
  "ruff_python_trivia",
  "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "serde",
  "serde_json",
  "static_assertions",
@@ -3208,7 +3200,7 @@ dependencies = [
  "ruff_python_parser",
  "ruff_python_stdlib",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "schemars",
  "serde",
  "smallvec",
@@ -3256,6 +3248,7 @@ dependencies = [
  "lsp-server",
  "lsp-types",
  "regex",
+ "ruff_db",
  "ruff_diagnostics",
  "ruff_formatter",
  "ruff_linter",
@@ -3268,12 +3261,12 @@ dependencies = [
  "ruff_source_file",
  "ruff_text_size",
  "ruff_workspace",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "serde",
  "serde_json",
  "shellexpand",
  "thiserror 2.0.12",
- "toml",
+ "toml 0.9.2",
  "tracing",
  "tracing-log",
  "tracing-subscriber",
@@ -3302,7 +3295,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_wasm"
-version = "0.12.1"
+version = "0.12.3"
 dependencies = [
  "console_error_panic_hook",
  "console_log",
@@ -3357,13 +3350,13 @@ dependencies = [
  "ruff_python_semantic",
  "ruff_python_stdlib",
  "ruff_source_file",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "schemars",
  "serde",
  "shellexpand",
  "strum",
  "tempfile",
- "toml",
+ "toml 0.9.2",
 ]
 
 [[package]]
@@ -3376,12 +3369,6 @@ dependencies = [
  "serde_derive",
 ]
 
-[[package]]
-name = "rustc-hash"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
-
 [[package]]
 name = "rustc-hash"
 version = "2.1.1"
@@ -3436,7 +3423,7 @@ dependencies = [
  "parking_lot",
  "portable-atomic",
  "rayon",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "salsa-macro-rules",
  "salsa-macros",
  "smallvec",
@@ -3589,6 +3576,15 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_spanned"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40734c41988f7306bb04f0ecf60ec0f3f1caa34290e4e8ea471dcd3346483b83"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "serde_test"
 version = "1.0.177"
@@ -3600,9 +3596,9 @@ dependencies = [
 
 [[package]]
 name = "serde_with"
-version = "3.12.0"
+version = "3.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d6b6f7f2fcb69f747921f79f3926bd1e203fce4fef62c268dd3abfb6d86029aa"
+checksum = "f2c45cd61fefa9db6f254525d46e392b852e0e61d9a1fd36e5bd183450a556d5"
 dependencies = [
  "serde",
  "serde_derive",
@@ -3611,9 +3607,9 @@ dependencies = [
 
 [[package]]
 name = "serde_with_macros"
-version = "3.12.0"
+version = "3.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8d00caa5193a3c8362ac2b73be6b9e768aa5a4b2f721d8f4b339600c3cb51f8e"
+checksum = "de90945e6565ce0d9a25098082ed4ee4002e047cb59892c318d66821e14bb30f"
 dependencies = [
  "darling",
  "proc-macro2",
@@ -3994,11 +3990,26 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dc1beb996b9d83529a9e75c17a1686767d148d70663143c7854d8b4a09ced362"
 dependencies = [
  "serde",
- "serde_spanned",
- "toml_datetime",
+ "serde_spanned 0.6.9",
+ "toml_datetime 0.6.11",
  "toml_edit",
 ]
 
+[[package]]
+name = "toml"
+version = "0.9.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed0aee96c12fa71097902e0bb061a5e1ebd766a6636bb605ba401c45c1650eac"
+dependencies = [
+ "indexmap",
+ "serde",
+ "serde_spanned 1.0.0",
+ "toml_datetime 0.7.0",
+ "toml_parser",
+ "toml_writer",
+ "winnow",
+]
+
 [[package]]
 name = "toml_datetime"
 version = "0.6.11"
@@ -4008,6 +4019,15 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "toml_datetime"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bade1c3e902f58d73d3f294cd7f20391c1cb2fbcb643b73566bc773971df91e3"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "toml_edit"
 version = "0.22.27"
@@ -4016,17 +4036,25 @@ checksum = "41fe8c660ae4257887cf66394862d21dbca4a6ddd26f04a3560410406a2f819a"
 dependencies = [
  "indexmap",
  "serde",
- "serde_spanned",
- "toml_datetime",
- "toml_write",
+ "serde_spanned 0.6.9",
+ "toml_datetime 0.6.11",
  "winnow",
 ]
 
 [[package]]
-name = "toml_write"
-version = "0.1.2"
+name = "toml_parser"
+version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5d99f8c9a7727884afe522e9bd5edbfc91a3312b36a77b5fb8926e4c31a41801"
+checksum = "97200572db069e74c512a14117b296ba0a80a30123fbbb5aa1f4a348f639ca30"
+dependencies = [
+ "winnow",
+]
+
+[[package]]
+name = "toml_writer"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fcc842091f2def52017664b53082ecbbeb5c7731092bad69d2c63050401dfd64"
 
 [[package]]
 name = "tracing"
@@ -4053,9 +4081,9 @@ dependencies = [
 
 [[package]]
 name = "tracing-core"
-version = "0.1.33"
+version = "0.1.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e672c95779cf947c5311f83787af4fa8fffd12fb27e4993211a84bdfd9610f9c"
+checksum = "b9d12581f227e93f094d3af2ae690a574abb8a2b9b7a96e7cfe9647b2b617678"
 dependencies = [
  "once_cell",
  "valuable",
@@ -4074,9 +4102,9 @@ dependencies = [
 
 [[package]]
 name = "tracing-indicatif"
-version = "0.3.9"
+version = "0.3.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8201ca430e0cd893ef978226fd3516c06d9c494181c8bf4e5b32e30ed4b40aa1"
+checksum = "8c714cc8fc46db04fcfddbd274c6ef59bebb1b435155984e7c6e89c3ce66f200"
 dependencies = [
  "indicatif",
  "tracing",
@@ -4134,7 +4162,6 @@ dependencies = [
  "clap",
  "clap_complete_command",
  "colored 3.0.0",
- "countme",
  "crossbeam",
  "ctrlc",
  "dunce",
@@ -4150,13 +4177,14 @@ dependencies = [
  "ruff_python_trivia",
  "salsa",
  "tempfile",
- "toml",
+ "toml 0.9.2",
  "tracing",
  "tracing-flame",
  "tracing-subscriber",
  "ty_project",
  "ty_python_semantic",
  "ty_server",
+ "ty_static",
  "wild",
 ]
 
@@ -4164,12 +4192,16 @@ dependencies = [
 name = "ty_ide"
 version = "0.0.0"
 dependencies = [
+ "bitflags 2.9.1",
  "insta",
+ "regex",
  "ruff_db",
  "ruff_python_ast",
  "ruff_python_parser",
+ "ruff_python_trivia",
+ "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "salsa",
  "smallvec",
  "tracing",
@@ -4201,12 +4233,12 @@ dependencies = [
  "ruff_python_ast",
  "ruff_python_formatter",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "salsa",
  "schemars",
  "serde",
  "thiserror 2.0.12",
- "toml",
+ "toml 0.9.2",
  "tracing",
  "ty_ide",
  "ty_python_semantic",
@@ -4222,7 +4254,6 @@ dependencies = [
  "camino",
  "colored 3.0.0",
  "compact_str",
- "countme",
  "dir-test",
  "drop_bomb",
  "get-size2",
@@ -4246,7 +4277,7 @@ dependencies = [
  "ruff_python_trivia",
  "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "salsa",
  "schemars",
  "serde",
@@ -4259,6 +4290,7 @@ dependencies = [
  "thiserror 2.0.12",
  "tracing",
  "ty_python_semantic",
+ "ty_static",
  "ty_test",
  "ty_vendored",
 ]
@@ -4275,13 +4307,15 @@ dependencies = [
  "lsp-types",
  "ruff_db",
  "ruff_notebook",
+ "ruff_python_ast",
  "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "salsa",
  "serde",
  "serde_json",
  "shellexpand",
+ "thiserror 2.0.12",
  "tracing",
  "tracing-subscriber",
  "ty_ide",
@@ -4290,6 +4324,13 @@ dependencies = [
  "ty_vendored",
 ]
 
+[[package]]
+name = "ty_static"
+version = "0.0.1"
+dependencies = [
+ "ruff_macros",
+]
+
 [[package]]
 name = "ty_test"
 version = "0.0.0"
@@ -4308,16 +4349,17 @@ dependencies = [
  "ruff_python_trivia",
  "ruff_source_file",
  "ruff_text_size",
- "rustc-hash 2.1.1",
+ "rustc-hash",
  "rustc-stable-hash",
  "salsa",
  "serde",
  "smallvec",
  "tempfile",
  "thiserror 2.0.12",
- "toml",
+ "toml 0.9.2",
  "tracing",
  "ty_python_semantic",
+ "ty_static",
  "ty_vendored",
 ]
 
@@ -4470,6 +4512,12 @@ dependencies = [
  "rand 0.8.5",
 ]
 
+[[package]]
+name = "unit-prefix"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "323402cff2dd658f39ca17c789b502021b3f18707c91cdf22e3838e1b4023817"
+
 [[package]]
 name = "unscanny"
 version = "0.1.0"
@@ -4876,7 +4924,7 @@ version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets",
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -4885,7 +4933,16 @@ version = "0.59.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
 dependencies = [
- "windows-targets",
+ "windows-targets 0.52.6",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.60.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2f500e4d28234f72040990ec9d39e3a6b950f9f22d3dba18416c35882612bcb"
+dependencies = [
+ "windows-targets 0.53.2",
 ]
 
 [[package]]
@@ -4894,14 +4951,30 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm",
- "windows_aarch64_msvc",
- "windows_i686_gnu",
- "windows_i686_gnullvm",
- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
+ "windows_aarch64_gnullvm 0.52.6",
+ "windows_aarch64_msvc 0.52.6",
+ "windows_i686_gnu 0.52.6",
+ "windows_i686_gnullvm 0.52.6",
+ "windows_i686_msvc 0.52.6",
+ "windows_x86_64_gnu 0.52.6",
+ "windows_x86_64_gnullvm 0.52.6",
+ "windows_x86_64_msvc 0.52.6",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.53.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c66f69fcc9ce11da9966ddb31a40968cad001c5bedeb5c2b82ede4253ab48aef"
+dependencies = [
+ "windows_aarch64_gnullvm 0.53.0",
+ "windows_aarch64_msvc 0.53.0",
+ "windows_i686_gnu 0.53.0",
+ "windows_i686_gnullvm 0.53.0",
+ "windows_i686_msvc 0.53.0",
+ "windows_x86_64_gnu 0.53.0",
+ "windows_x86_64_gnullvm 0.53.0",
+ "windows_x86_64_msvc 0.53.0",
 ]
 
 [[package]]
@@ -4910,48 +4983,96 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.53.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "86b8d5f90ddd19cb4a147a5fa63ca848db3df085e25fee3cc10b39b6eebae764"
+
 [[package]]
 name = "windows_aarch64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.53.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7651a1f62a11b8cbd5e0d42526e55f2c99886c77e007179efff86c2b137e66c"
+
 [[package]]
 name = "windows_i686_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
 
+[[package]]
+name = "windows_i686_gnu"
+version = "0.53.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c1dc67659d35f387f5f6c479dc4e28f1d4bb90ddd1a5d3da2e5d97b42d6272c3"
+
 [[package]]
 name = "windows_i686_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.53.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ce6ccbdedbf6d6354471319e781c0dfef054c81fbc7cf83f338a4296c0cae11"
+
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
+[[package]]
+name = "windows_i686_msvc"
+version = "0.53.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "581fee95406bb13382d2f65cd4a908ca7b1e4c2f1917f143ba16efe98a589b5d"
+
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.53.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e55b5ac9ea33f2fc1716d1742db15574fd6fc8dadc51caab1c16a3d3b4190ba"
+
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.53.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0a6e035dd0599267ce1ee132e51c27dd29437f63325753051e71dd9e42406c57"
+
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.53.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "271414315aff87387382ec3d271b52d7ae78726f5d44ac98b4f4030c91880486"
+
 [[package]]
 name = "winnow"
 version = "0.7.10"

Cargo.toml

@@ -44,6 +44,7 @@ ty_ide = { path = "crates/ty_ide" }
 ty_project = { path = "crates/ty_project", default-features = false }
 ty_python_semantic = { path = "crates/ty_python_semantic" }
 ty_server = { path = "crates/ty_server" }
+ty_static = { path = "crates/ty_static" }
 ty_test = { path = "crates/ty_test" }
 ty_vendored = { path = "crates/ty_vendored" }
 
@@ -83,7 +84,7 @@ get-size2 = { version = "0.5.0", features = [
     "derive",
     "smallvec",
     "hashbrown",
-    "compact-str"
+    "compact-str",
 ] }
 glob = { version = "0.3.1" }
 globset = { version = "0.4.14" }
@@ -98,7 +99,7 @@ ignore = { version = "0.4.22" }
 imara-diff = { version = "0.1.5" }
 imperative = { version = "1.0.4" }
 indexmap = { version = "2.6.0" }
-indicatif = { version = "0.17.8" }
+indicatif = { version = "0.18.0" }
 indoc = { version = "2.0.4" }
 insta = { version = "1.35.1" }
 insta-cmd = { version = "0.6.0" }
@@ -164,16 +165,16 @@ tempfile = { version = "3.9.0" }
 test-case = { version = "3.3.1" }
 thiserror = { version = "2.0.0" }
 tikv-jemallocator = { version = "0.6.0" }
-toml = { version = "0.8.11" }
+toml = { version = "0.9.0" }
 tracing = { version = "0.1.40" }
 tracing-flame = { version = "0.2.0" }
-tracing-indicatif = { version = "0.3.6" }
+tracing-indicatif = { version = "0.3.11" }
 tracing-log = { version = "0.2.0" }
 tracing-subscriber = { version = "0.3.18", default-features = false, features = [
     "env-filter",
     "fmt",
     "ansi",
-    "smallvec"
+    "smallvec",
 ] }
 tryfn = { version = "0.2.1" }
 typed-arena = { version = "2.0.2" }
@@ -183,11 +184,7 @@ unicode-width = { version = "0.2.0" }
 unicode_names2 = { version = "1.2.2" }
 unicode-normalization = { version = "0.1.23" }
 url = { version = "2.5.0" }
-uuid = { version = "1.6.1", features = [
-    "v4",
-    "fast-rng",
-    "macro-diagnostics",
-] }
+uuid = { version = "1.6.1", features = ["v4", "fast-rng", "macro-diagnostics"] }
 walkdir = { version = "2.3.2" }
 wasm-bindgen = { version = "0.2.92" }
 wasm-bindgen-test = { version = "0.3.42" }
@@ -222,8 +219,8 @@ must_use_candidate = "allow"
 similar_names = "allow"
 single_match_else = "allow"
 too_many_lines = "allow"
-needless_continue = "allow"       # An explicit continue can be more readable, especially if the alternative is an empty block.
-unnecessary_debug_formatting = "allow"  # too many instances, the display also doesn't quote the path which is often desired in logs where we use them the most often.
+needless_continue = "allow" # An explicit continue can be more readable, especially if the alternative is an empty block.
+unnecessary_debug_formatting = "allow" # too many instances, the display also doesn't quote the path which is often desired in logs where we use them the most often.
 # Without the hashes we run into a `rustfmt` bug in some snapshot tests, see #13250
 needless_raw_string_hashes = "allow"
 # Disallowed restriction lints

README.md

@@ -148,8 +148,8 @@ curl -LsSf https://astral.sh/ruff/install.sh | sh
 powershell -c "irm https://astral.sh/ruff/install.ps1 | iex"
 
 # For a specific version.
-curl -LsSf https://astral.sh/ruff/0.12.1/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.12.1/install.ps1 | iex"
+curl -LsSf https://astral.sh/ruff/0.12.3/install.sh | sh
+powershell -c "irm https://astral.sh/ruff/0.12.3/install.ps1 | iex"
 ```
 
 You can also install Ruff via [Homebrew](https://formulae.brew.sh/formula/ruff), [Conda](https://anaconda.org/conda-forge/ruff),
@@ -182,7 +182,7 @@ Ruff can also be used as a [pre-commit](https://pre-commit.com/) hook via [`ruff
 ```yaml
 - repo: https://github.com/astral-sh/ruff-pre-commit
   # Ruff version.
-  rev: v0.12.1
+  rev: v0.12.3
   hooks:
     # Run the linter.
     - id: ruff-check
@@ -430,6 +430,7 @@ Ruff is used by a number of major open-source projects and companies, including:
 - [Babel](https://github.com/python-babel/babel)
 - Benchling ([Refac](https://github.com/benchling/refac))
 - [Bokeh](https://github.com/bokeh/bokeh)
+- Capital One ([datacompy](https://github.com/capitalone/datacompy))
 - CrowdCent ([NumerBlox](https://github.com/crowdcent/numerblox)) <!-- typos: ignore -->
 - [Cryptography (PyCA)](https://github.com/pyca/cryptography)
 - CERN ([Indico](https://getindico.io/))
@@ -506,6 +507,7 @@ Ruff is used by a number of major open-source projects and companies, including:
 - [Streamlit](https://github.com/streamlit/streamlit)
 - [The Algorithms](https://github.com/TheAlgorithms/Python)
 - [Vega-Altair](https://github.com/altair-viz/altair)
+- [Weblate](https://weblate.org/)
 - WordPress ([Openverse](https://github.com/WordPress/openverse))
 - [ZenML](https://github.com/zenml-io/zenml)
 - [Zulip](https://github.com/zulip/zulip)

crates/ruff/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.12.1"
+version = "0.12.3"
 publish = true
 authors = { workspace = true }
 edition = { workspace = true }

crates/ruff/src/cache.rs

@@ -18,14 +18,15 @@ use rustc_hash::FxHashMap;
 use tempfile::NamedTempFile;
 
 use ruff_cache::{CacheKey, CacheKeyHasher};
+use ruff_db::diagnostic::Diagnostic;
 use ruff_diagnostics::Fix;
-use ruff_linter::message::OldDiagnostic;
+use ruff_linter::message::create_lint_diagnostic;
 use ruff_linter::package::PackageRoot;
 use ruff_linter::{VERSION, warn_user};
 use ruff_macros::CacheKey;
 use ruff_notebook::NotebookIndex;
 use ruff_source_file::SourceFileBuilder;
-use ruff_text_size::{Ranged, TextRange, TextSize};
+use ruff_text_size::{TextRange, TextSize};
 use ruff_workspace::Settings;
 use ruff_workspace::resolver::Resolver;
 
@@ -348,7 +349,7 @@ impl FileCache {
                 lint.messages
                     .iter()
                     .map(|msg| {
-                        OldDiagnostic::lint(
+                        create_lint_diagnostic(
                             &msg.body,
                             msg.suggestion.as_ref(),
                             msg.range,
@@ -428,11 +429,11 @@ pub(crate) struct LintCacheData {
 
 impl LintCacheData {
     pub(crate) fn from_diagnostics(
-        diagnostics: &[OldDiagnostic],
+        diagnostics: &[Diagnostic],
         notebook_index: Option<NotebookIndex>,
     ) -> Self {
         let source = if let Some(msg) = diagnostics.first() {
-            msg.source_file().source_text().to_owned()
+            msg.expect_ruff_source_file().source_text().to_owned()
         } else {
             String::new() // No messages, no need to keep the source!
         };
@@ -446,16 +447,16 @@ impl LintCacheData {
             .map(|(rule, msg)| {
                 // Make sure that all message use the same source file.
                 assert_eq!(
-                    msg.source_file(),
-                    diagnostics.first().unwrap().source_file(),
+                    msg.expect_ruff_source_file(),
+                    diagnostics.first().unwrap().expect_ruff_source_file(),
                     "message uses a different source file"
                 );
                 CacheMessage {
                     rule,
                     body: msg.body().to_string(),
                     suggestion: msg.suggestion().map(ToString::to_string),
-                    range: msg.range(),
-                    parent: msg.parent,
+                    range: msg.expect_range(),
+                    parent: msg.parent(),
                     fix: msg.fix().cloned(),
                     noqa_offset: msg.noqa_offset(),
                 }
@@ -608,12 +609,12 @@ mod tests {
     use anyhow::Result;
     use filetime::{FileTime, set_file_mtime};
     use itertools::Itertools;
-    use ruff_linter::settings::LinterSettings;
     use test_case::test_case;
 
     use ruff_cache::CACHE_DIR_NAME;
-    use ruff_linter::message::OldDiagnostic;
+    use ruff_db::diagnostic::Diagnostic;
     use ruff_linter::package::PackageRoot;
+    use ruff_linter::settings::LinterSettings;
     use ruff_linter::settings::flags;
     use ruff_linter::settings::types::UnsafeFixes;
     use ruff_python_ast::{PySourceType, PythonVersion};
@@ -680,7 +681,7 @@ mod tests {
                     UnsafeFixes::Enabled,
                 )
                 .unwrap();
-                if diagnostics.inner.iter().any(OldDiagnostic::is_syntax_error) {
+                if diagnostics.inner.iter().any(Diagnostic::is_invalid_syntax) {
                     parse_errors.push(path.clone());
                 }
                 paths.push(path);

crates/ruff/src/commands/check.rs

@@ -11,13 +11,13 @@ use log::{debug, error, warn};
 use rayon::prelude::*;
 use rustc_hash::FxHashMap;
 
+use ruff_db::diagnostic::Diagnostic;
 use ruff_db::panic::catch_unwind;
-use ruff_linter::OldDiagnostic;
 use ruff_linter::package::PackageRoot;
 use ruff_linter::registry::Rule;
 use ruff_linter::settings::types::UnsafeFixes;
 use ruff_linter::settings::{LinterSettings, flags};
-use ruff_linter::{IOError, fs, warn_user_once};
+use ruff_linter::{IOError, Violation, fs, warn_user_once};
 use ruff_source_file::SourceFileBuilder;
 use ruff_text_size::TextRange;
 use ruff_workspace::resolver::{
@@ -129,11 +129,7 @@ pub(crate) fn check(
                         SourceFileBuilder::new(path.to_string_lossy().as_ref(), "").finish();
 
                     Diagnostics::new(
-                        vec![OldDiagnostic::new(
-                            IOError { message },
-                            TextRange::default(),
-                            &dummy,
-                        )],
+                        vec![IOError { message }.into_diagnostic(TextRange::default(), &dummy)],
                         FxHashMap::default(),
                     )
                 } else {
@@ -166,7 +162,9 @@ pub(crate) fn check(
             |a, b| (a.0 + b.0, a.1 + b.1),
         );
 
-    all_diagnostics.inner.sort();
+    all_diagnostics
+        .inner
+        .sort_by(Diagnostic::ruff_start_ordering);
 
     // Store the caches.
     caches.persist()?;

crates/ruff/src/commands/check_stdin.rs

@@ -1,6 +1,7 @@
 use std::path::Path;
 
 use anyhow::Result;
+use ruff_db::diagnostic::Diagnostic;
 use ruff_linter::package::PackageRoot;
 use ruff_linter::packaging;
 use ruff_linter::settings::flags;
@@ -52,6 +53,8 @@ pub(crate) fn check_stdin(
         noqa,
         fix_mode,
     )?;
-    diagnostics.inner.sort_unstable();
+    diagnostics
+        .inner
+        .sort_unstable_by(Diagnostic::ruff_start_ordering);
     Ok(diagnostics)
 }

crates/ruff/src/diagnostics.rs

@@ -10,35 +10,35 @@ use std::path::Path;
 use anyhow::{Context, Result};
 use colored::Colorize;
 use log::{debug, warn};
-use rustc_hash::FxHashMap;
-
-use ruff_linter::OldDiagnostic;
+use ruff_db::diagnostic::Diagnostic;
 use ruff_linter::codes::Rule;
 use ruff_linter::linter::{FixTable, FixerResult, LinterResult, ParseSource, lint_fix, lint_only};
+use ruff_linter::message::create_syntax_error_diagnostic;
 use ruff_linter::package::PackageRoot;
 use ruff_linter::pyproject_toml::lint_pyproject_toml;
 use ruff_linter::settings::types::UnsafeFixes;
 use ruff_linter::settings::{LinterSettings, flags};
 use ruff_linter::source_kind::{SourceError, SourceKind};
-use ruff_linter::{IOError, fs};
+use ruff_linter::{IOError, Violation, fs};
 use ruff_notebook::{Notebook, NotebookError, NotebookIndex};
 use ruff_python_ast::{PySourceType, SourceType, TomlSourceType};
 use ruff_source_file::SourceFileBuilder;
 use ruff_text_size::TextRange;
 use ruff_workspace::Settings;
+use rustc_hash::FxHashMap;
 
 use crate::cache::{Cache, FileCacheKey, LintCacheData};
 
 #[derive(Debug, Default, PartialEq)]
 pub(crate) struct Diagnostics {
-    pub(crate) inner: Vec<OldDiagnostic>,
+    pub(crate) inner: Vec<Diagnostic>,
     pub(crate) fixed: FixMap,
     pub(crate) notebook_indexes: FxHashMap<String, NotebookIndex>,
 }
 
 impl Diagnostics {
     pub(crate) fn new(
-        diagnostics: Vec<OldDiagnostic>,
+        diagnostics: Vec<Diagnostic>,
         notebook_indexes: FxHashMap<String, NotebookIndex>,
     ) -> Self {
         Self {
@@ -62,13 +62,12 @@ impl Diagnostics {
                     let name = path.map_or_else(|| "-".into(), Path::to_string_lossy);
                     let source_file = SourceFileBuilder::new(name, "").finish();
                     Self::new(
-                        vec![OldDiagnostic::new(
+                        vec![
                             IOError {
                                 message: err.to_string(),
-                            },
-                            TextRange::default(),
-                            &source_file,
-                        )],
+                            }
+                            .into_diagnostic(TextRange::default(), &source_file),
+                        ],
                         FxHashMap::default(),
                     )
                 } else {
@@ -98,10 +97,10 @@ impl Diagnostics {
                 let name = path.map_or_else(|| "-".into(), Path::to_string_lossy);
                 let dummy = SourceFileBuilder::new(name, "").finish();
                 Self::new(
-                    vec![OldDiagnostic::syntax_error(
+                    vec![create_syntax_error_diagnostic(
+                        dummy,
                         err,
                         TextRange::default(),
-                        dummy,
                     )],
                     FxHashMap::default(),
                 )

crates/ruff/src/lib.rs

@@ -131,6 +131,7 @@ pub fn run(
     }: Args,
 ) -> Result<ExitStatus> {
     {
+        ruff_db::set_program_version(crate::version::version().to_string()).unwrap();
         let default_panic_hook = std::panic::take_hook();
         std::panic::set_hook(Box::new(move |info| {
             #[expect(clippy::print_stderr)]
@@ -439,7 +440,7 @@ pub fn check(args: CheckCommand, global_options: GlobalConfigArgs) -> Result<Exi
         if cli.statistics {
             printer.write_statistics(&diagnostics, &mut summary_writer)?;
         } else {
-            printer.write_once(&diagnostics, &mut summary_writer)?;
+            printer.write_once(&diagnostics, &mut summary_writer, preview)?;
         }
 
         if !cli.exit_zero {

crates/ruff/src/printer.rs

@@ -9,12 +9,14 @@ use itertools::{Itertools, iterate};
 use ruff_linter::linter::FixTable;
 use serde::Serialize;
 
+use ruff_db::diagnostic::{
+    Diagnostic, DiagnosticFormat, DisplayDiagnosticConfig, DisplayDiagnostics, SecondaryCode,
+};
 use ruff_linter::fs::relativize_path;
 use ruff_linter::logging::LogLevel;
 use ruff_linter::message::{
-    AzureEmitter, Emitter, EmitterContext, GithubEmitter, GitlabEmitter, GroupedEmitter,
-    JsonEmitter, JsonLinesEmitter, JunitEmitter, OldDiagnostic, PylintEmitter, RdjsonEmitter,
-    SarifEmitter, SecondaryCode, TextEmitter,
+    Emitter, EmitterContext, GithubEmitter, GitlabEmitter, GroupedEmitter, JunitEmitter,
+    SarifEmitter, TextEmitter,
 };
 use ruff_linter::notify_user;
 use ruff_linter::settings::flags::{self};
@@ -201,6 +203,7 @@ impl Printer {
         &self,
         diagnostics: &Diagnostics,
         writer: &mut dyn Write,
+        preview: bool,
     ) -> Result<()> {
         if matches!(self.log_level, LogLevel::Silent) {
             return Ok(());
@@ -228,13 +231,25 @@ impl Printer {
 
         match self.format {
             OutputFormat::Json => {
-                JsonEmitter.emit(writer, &diagnostics.inner, &context)?;
+                let config = DisplayDiagnosticConfig::default()
+                    .format(DiagnosticFormat::Json)
+                    .preview(preview);
+                let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
+                write!(writer, "{value}")?;
             }
             OutputFormat::Rdjson => {
-                RdjsonEmitter.emit(writer, &diagnostics.inner, &context)?;
+                let config = DisplayDiagnosticConfig::default()
+                    .format(DiagnosticFormat::Rdjson)
+                    .preview(preview);
+                let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
+                write!(writer, "{value}")?;
             }
             OutputFormat::JsonLines => {
-                JsonLinesEmitter.emit(writer, &diagnostics.inner, &context)?;
+                let config = DisplayDiagnosticConfig::default()
+                    .format(DiagnosticFormat::JsonLines)
+                    .preview(preview);
+                let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
+                write!(writer, "{value}")?;
             }
             OutputFormat::Junit => {
                 JunitEmitter.emit(writer, &diagnostics.inner, &context)?;
@@ -279,10 +294,18 @@ impl Printer {
                 GitlabEmitter::default().emit(writer, &diagnostics.inner, &context)?;
             }
             OutputFormat::Pylint => {
-                PylintEmitter.emit(writer, &diagnostics.inner, &context)?;
+                let config = DisplayDiagnosticConfig::default()
+                    .format(DiagnosticFormat::Pylint)
+                    .preview(preview);
+                let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
+                write!(writer, "{value}")?;
             }
             OutputFormat::Azure => {
-                AzureEmitter.emit(writer, &diagnostics.inner, &context)?;
+                let config = DisplayDiagnosticConfig::default()
+                    .format(DiagnosticFormat::Azure)
+                    .preview(preview);
+                let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
+                write!(writer, "{value}")?;
             }
             OutputFormat::Sarif => {
                 SarifEmitter.emit(writer, &diagnostics.inner, &context)?;
@@ -306,8 +329,7 @@ impl Printer {
             .sorted_by_key(|(code, message)| (*code, message.fixable()))
             .fold(
                 vec![],
-                |mut acc: Vec<((Option<&SecondaryCode>, &OldDiagnostic), usize)>,
-                 (code, message)| {
+                |mut acc: Vec<((Option<&SecondaryCode>, &Diagnostic), usize)>, (code, message)| {
                     if let Some(((prev_code, _prev_message), count)) = acc.last_mut() {
                         if *prev_code == code {
                             *count += 1;

crates/ruff/tests/format.rs

@@ -120,7 +120,7 @@ fn nonexistent_config_file() {
 #[test]
 fn config_override_rejected_if_invalid_toml() {
     assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
-        .args(["format", "--config", "foo = bar", "."]), @r#"
+        .args(["format", "--config", "foo = bar", "."]), @r"
     success: false
     exit_code: 2
     ----- stdout -----
@@ -137,12 +137,11 @@ fn config_override_rejected_if_invalid_toml() {
     TOML parse error at line 1, column 7
       |
     1 | foo = bar
-      |       ^
-    invalid string
-    expected `"`, `'`
+      |       ^^^
+    string values must be quoted, expected literal string
 
     For more information, try '--help'.
-    "#);
+    ");
 }
 
 #[test]

crates/ruff/tests/integration_test.rs

@@ -1067,7 +1067,7 @@ fn show_statistics_syntax_errors() {
     success: false
     exit_code: 1
     ----- stdout -----
-    1		syntax-error
+    1		invalid-syntax
     Found 1 error.
 
     ----- stderr -----
@@ -1080,7 +1080,7 @@ fn show_statistics_syntax_errors() {
     success: false
     exit_code: 1
     ----- stdout -----
-    1		syntax-error
+    1		invalid-syntax
     Found 1 error.
 
     ----- stderr -----
@@ -1093,7 +1093,7 @@ fn show_statistics_syntax_errors() {
     success: false
     exit_code: 1
     ----- stdout -----
-    1		syntax-error
+    1		invalid-syntax
     Found 1 error.
 
     ----- stderr -----
@@ -2246,8 +2246,7 @@ fn pyproject_toml_stdin_syntax_error() {
     success: false
     exit_code: 1
     ----- stdout -----
-    pyproject.toml:1:9: RUF200 Failed to parse pyproject.toml: invalid table header
-    expected `.`, `]`
+    pyproject.toml:1:9: RUF200 Failed to parse pyproject.toml: unclosed table, expected `]`
       |
     1 | [project
       |         ^ RUF200

crates/ruff/tests/lint.rs

@@ -534,7 +534,7 @@ fn nonexistent_config_file() {
 fn config_override_rejected_if_invalid_toml() {
     assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
         .args(STDIN_BASE_OPTIONS)
-        .args(["--config", "foo = bar", "."]), @r#"
+        .args(["--config", "foo = bar", "."]), @r"
     success: false
     exit_code: 2
     ----- stdout -----
@@ -551,12 +551,11 @@ fn config_override_rejected_if_invalid_toml() {
     TOML parse error at line 1, column 7
       |
     1 | foo = bar
-      |       ^
-    invalid string
-    expected `"`, `'`
+      |       ^^^
+    string values must be quoted, expected literal string
 
     For more information, try '--help'.
-    "#);
+    ");
 }
 
 #[test]
@@ -733,9 +732,8 @@ select = [E501]
       Cause: TOML parse error at line 3, column 11
       |
     3 | select = [E501]
-      |           ^
-    invalid array
-    expected `]`
+      |           ^^^^
+    string values must be quoted, expected literal string
     ");
     });
 
@@ -876,7 +874,7 @@ fn each_toml_option_requires_a_new_flag_1() {
       |
     1 | extend-select=['F841'], line-length=90
       |                       ^
-    expected newline, `#`
+    unexpected key or value, expected newline, `#`
 
     For more information, try '--help'.
     ");
@@ -907,7 +905,7 @@ fn each_toml_option_requires_a_new_flag_2() {
       |
     1 | extend-select=['F841'] line-length=90
       |                        ^
-    expected newline, `#`
+    unexpected key or value, expected newline, `#`
 
     For more information, try '--help'.
     ");
@@ -995,6 +993,7 @@ fn value_given_to_table_key_is_not_inline_table_2() {
     - `lint.exclude`
     - `lint.preview`
     - `lint.typing-extensions`
+    - `lint.future-annotations`
 
     For more information, try '--help'.
     ");
@@ -5692,3 +5691,79 @@ class Foo:
     "
     );
 }
+
+#[test_case::test_case("concise")]
+#[test_case::test_case("full")]
+#[test_case::test_case("json")]
+#[test_case::test_case("json-lines")]
+#[test_case::test_case("junit")]
+#[test_case::test_case("grouped")]
+#[test_case::test_case("github")]
+#[test_case::test_case("gitlab")]
+#[test_case::test_case("pylint")]
+#[test_case::test_case("rdjson")]
+#[test_case::test_case("azure")]
+#[test_case::test_case("sarif")]
+fn output_format(output_format: &str) -> Result<()> {
+    const CONTENT: &str = "\
+import os  # F401
+x = y      # F821
+match 42:  # invalid-syntax
+    case _: ...
+";
+
+    let tempdir = TempDir::new()?;
+    let input = tempdir.path().join("input.py");
+    fs::write(&input, CONTENT)?;
+
+    let snapshot = format!("output_format_{output_format}");
+
+    insta::with_settings!({
+        filters => vec![
+            (tempdir_filter(&tempdir).as_str(), "[TMP]/"),
+            (r#""[^"]+\\?/?input.py"#, r#""[TMP]/input.py"#),
+            (ruff_linter::VERSION, "[VERSION]"),
+        ]
+    }, {
+        assert_cmd_snapshot!(
+            snapshot,
+            Command::new(get_cargo_bin(BIN_NAME))
+                .args([
+                    "check",
+                    "--no-cache",
+                    "--output-format",
+                    output_format,
+                    "--select",
+                    "F401,F821",
+                    "--target-version",
+                    "py39",
+                    "input.py",
+                ])
+                .current_dir(&tempdir),
+        );
+    });
+
+    Ok(())
+}
+
+#[test]
+fn future_annotations_preview_warning() {
+    assert_cmd_snapshot!(
+        Command::new(get_cargo_bin(BIN_NAME))
+            .args(STDIN_BASE_OPTIONS)
+            .args(["--config", "lint.future-annotations = true"])
+            .args(["--select", "F"])
+            .arg("--no-preview")
+            .arg("-")
+            .pass_stdin("1"),
+        @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    All checks passed!
+
+    ----- stderr -----
+    warning: The `lint.future-annotations` setting will have no effect because `preview` is disabled
+    ",
+    );
+}

crates/ruff/tests/snapshots/lint__output_format_azure.snap

@@ -0,0 +1,23 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - azure
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+##vso[task.logissue type=error;sourcepath=[TMP]/input.py;linenumber=1;columnnumber=8;code=F401;]`os` imported but unused
+##vso[task.logissue type=error;sourcepath=[TMP]/input.py;linenumber=2;columnnumber=5;code=F821;]Undefined name `y`
+##vso[task.logissue type=error;sourcepath=[TMP]/input.py;linenumber=3;columnnumber=1;]SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)
+
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_concise.snap

@@ -0,0 +1,25 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - concise
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+input.py:1:8: F401 [*] `os` imported but unused
+input.py:2:5: F821 Undefined name `y`
+input.py:3:1: SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)
+Found 3 errors.
+[*] 1 fixable with the `--fix` option.
+
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_full.snap

@@ -0,0 +1,49 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - full
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+input.py:1:8: F401 [*] `os` imported but unused
+  |
+1 | import os  # F401
+  |        ^^ F401
+2 | x = y      # F821
+3 | match 42:  # invalid-syntax
+  |
+  = help: Remove unused import: `os`
+
+input.py:2:5: F821 Undefined name `y`
+  |
+1 | import os  # F401
+2 | x = y      # F821
+  |     ^ F821
+3 | match 42:  # invalid-syntax
+4 |     case _: ...
+  |
+
+input.py:3:1: SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)
+  |
+1 | import os  # F401
+2 | x = y      # F821
+3 | match 42:  # invalid-syntax
+  | ^^^^^
+4 |     case _: ...
+  |
+
+Found 3 errors.
+[*] 1 fixable with the `--fix` option.
+
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_github.snap

@@ -0,0 +1,23 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - github
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+::error title=Ruff (F401),file=[TMP]/input.py,line=1,col=8,endLine=1,endColumn=10::input.py:1:8: F401 `os` imported but unused
+::error title=Ruff (F821),file=[TMP]/input.py,line=2,col=5,endLine=2,endColumn=6::input.py:2:5: F821 Undefined name `y`
+::error title=Ruff,file=[TMP]/input.py,line=3,col=1,endLine=3,endColumn=6::input.py:3:1: SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)
+
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_gitlab.snap

@@ -0,0 +1,60 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - gitlab
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+[
+  {
+    "check_name": "F401",
+    "description": "`os` imported but unused",
+    "fingerprint": "4dbad37161e65c72",
+    "location": {
+      "lines": {
+        "begin": 1,
+        "end": 1
+      },
+      "path": "input.py"
+    },
+    "severity": "major"
+  },
+  {
+    "check_name": "F821",
+    "description": "Undefined name `y`",
+    "fingerprint": "7af59862a085230",
+    "location": {
+      "lines": {
+        "begin": 2,
+        "end": 2
+      },
+      "path": "input.py"
+    },
+    "severity": "major"
+  },
+  {
+    "check_name": "syntax-error",
+    "description": "Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)",
+    "fingerprint": "e558cec859bb66e8",
+    "location": {
+      "lines": {
+        "begin": 3,
+        "end": 3
+      },
+      "path": "input.py"
+    },
+    "severity": "major"
+  }
+]
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_grouped.snap

@@ -0,0 +1,27 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - grouped
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+input.py:
+  1:8 F401 [*] `os` imported but unused
+  2:5 F821 Undefined name `y`
+  3:1 SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)
+
+Found 3 errors.
+[*] 1 fixable with the `--fix` option.
+
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_json-lines.snap

@@ -0,0 +1,23 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - json-lines
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+{"cell":null,"code":"F401","end_location":{"column":10,"row":1},"filename":"[TMP]/input.py","fix":{"applicability":"safe","edits":[{"content":"","end_location":{"column":1,"row":2},"location":{"column":1,"row":1}}],"message":"Remove unused import: `os`"},"location":{"column":8,"row":1},"message":"`os` imported but unused","noqa_row":1,"url":"https://docs.astral.sh/ruff/rules/unused-import"}
+{"cell":null,"code":"F821","end_location":{"column":6,"row":2},"filename":"[TMP]/input.py","fix":null,"location":{"column":5,"row":2},"message":"Undefined name `y`","noqa_row":2,"url":"https://docs.astral.sh/ruff/rules/undefined-name"}
+{"cell":null,"code":null,"end_location":{"column":6,"row":3},"filename":"[TMP]/input.py","fix":null,"location":{"column":1,"row":3},"message":"SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)","noqa_row":null,"url":null}
+
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_json.snap

@@ -0,0 +1,88 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - json
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+[
+  {
+    "cell": null,
+    "code": "F401",
+    "end_location": {
+      "column": 10,
+      "row": 1
+    },
+    "filename": "[TMP]/input.py",
+    "fix": {
+      "applicability": "safe",
+      "edits": [
+        {
+          "content": "",
+          "end_location": {
+            "column": 1,
+            "row": 2
+          },
+          "location": {
+            "column": 1,
+            "row": 1
+          }
+        }
+      ],
+      "message": "Remove unused import: `os`"
+    },
+    "location": {
+      "column": 8,
+      "row": 1
+    },
+    "message": "`os` imported but unused",
+    "noqa_row": 1,
+    "url": "https://docs.astral.sh/ruff/rules/unused-import"
+  },
+  {
+    "cell": null,
+    "code": "F821",
+    "end_location": {
+      "column": 6,
+      "row": 2
+    },
+    "filename": "[TMP]/input.py",
+    "fix": null,
+    "location": {
+      "column": 5,
+      "row": 2
+    },
+    "message": "Undefined name `y`",
+    "noqa_row": 2,
+    "url": "https://docs.astral.sh/ruff/rules/undefined-name"
+  },
+  {
+    "cell": null,
+    "code": null,
+    "end_location": {
+      "column": 6,
+      "row": 3
+    },
+    "filename": "[TMP]/input.py",
+    "fix": null,
+    "location": {
+      "column": 1,
+      "row": 3
+    },
+    "message": "SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)",
+    "noqa_row": null,
+    "url": null
+  }
+]
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_junit.snap

@@ -0,0 +1,34 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - junit
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+<?xml version="1.0" encoding="UTF-8"?>
+<testsuites name="ruff" tests="3" failures="3" errors="0">
+    <testsuite name="[TMP]/input.py" tests="3" disabled="0" errors="0" failures="3" package="org.ruff">
+        <testcase name="org.ruff.F401" classname="[TMP]/input" line="1" column="8">
+            <failure message="`os` imported but unused">line 1, col 8, `os` imported but unused</failure>
+        </testcase>
+        <testcase name="org.ruff.F821" classname="[TMP]/input" line="2" column="5">
+            <failure message="Undefined name `y`">line 2, col 5, Undefined name `y`</failure>
+        </testcase>
+        <testcase name="org.ruff" classname="[TMP]/input" line="3" column="1">
+            <failure message="SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)">line 3, col 1, SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)</failure>
+        </testcase>
+    </testsuite>
+</testsuites>
+
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_pylint.snap

@@ -0,0 +1,23 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - pylint
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+input.py:1: [F401] `os` imported but unused
+input.py:2: [F821] Undefined name `y`
+input.py:3: [invalid-syntax] SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)
+
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_rdjson.snap

@@ -0,0 +1,102 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - rdjson
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+{
+  "diagnostics": [
+    {
+      "code": {
+        "url": "https://docs.astral.sh/ruff/rules/unused-import",
+        "value": "F401"
+      },
+      "location": {
+        "path": "[TMP]/input.py",
+        "range": {
+          "end": {
+            "column": 10,
+            "line": 1
+          },
+          "start": {
+            "column": 8,
+            "line": 1
+          }
+        }
+      },
+      "message": "`os` imported but unused",
+      "suggestions": [
+        {
+          "range": {
+            "end": {
+              "column": 1,
+              "line": 2
+            },
+            "start": {
+              "column": 1,
+              "line": 1
+            }
+          },
+          "text": ""
+        }
+      ]
+    },
+    {
+      "code": {
+        "url": "https://docs.astral.sh/ruff/rules/undefined-name",
+        "value": "F821"
+      },
+      "location": {
+        "path": "[TMP]/input.py",
+        "range": {
+          "end": {
+            "column": 6,
+            "line": 2
+          },
+          "start": {
+            "column": 5,
+            "line": 2
+          }
+        }
+      },
+      "message": "Undefined name `y`"
+    },
+    {
+      "code": {
+        "value": "invalid-syntax"
+      },
+      "location": {
+        "path": "[TMP]/input.py",
+        "range": {
+          "end": {
+            "column": 6,
+            "line": 3
+          },
+          "start": {
+            "column": 1,
+            "line": 3
+          }
+        }
+      },
+      "message": "SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)"
+    }
+  ],
+  "severity": "WARNING",
+  "source": {
+    "name": "ruff",
+    "url": "https://docs.astral.sh/ruff"
+  }
+}
+----- stderr -----

crates/ruff/tests/snapshots/lint__output_format_sarif.snap

@@ -0,0 +1,142 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - sarif
+    - "--select"
+    - "F401,F821"
+    - "--target-version"
+    - py39
+    - input.py
+---
+success: false
+exit_code: 1
+----- stdout -----
+{
+  "$schema": "https://json.schemastore.org/sarif-2.1.0.json",
+  "runs": [
+    {
+      "results": [
+        {
+          "level": "error",
+          "locations": [
+            {
+              "physicalLocation": {
+                "artifactLocation": {
+                  "uri": "[TMP]/input.py"
+                },
+                "region": {
+                  "endColumn": 10,
+                  "endLine": 1,
+                  "startColumn": 8,
+                  "startLine": 1
+                }
+              }
+            }
+          ],
+          "message": {
+            "text": "`os` imported but unused"
+          },
+          "ruleId": "F401"
+        },
+        {
+          "level": "error",
+          "locations": [
+            {
+              "physicalLocation": {
+                "artifactLocation": {
+                  "uri": "[TMP]/input.py"
+                },
+                "region": {
+                  "endColumn": 6,
+                  "endLine": 2,
+                  "startColumn": 5,
+                  "startLine": 2
+                }
+              }
+            }
+          ],
+          "message": {
+            "text": "Undefined name `y`"
+          },
+          "ruleId": "F821"
+        },
+        {
+          "level": "error",
+          "locations": [
+            {
+              "physicalLocation": {
+                "artifactLocation": {
+                  "uri": "[TMP]/input.py"
+                },
+                "region": {
+                  "endColumn": 6,
+                  "endLine": 3,
+                  "startColumn": 1,
+                  "startLine": 3
+                }
+              }
+            }
+          ],
+          "message": {
+            "text": "SyntaxError: Cannot use `match` statement on Python 3.9 (syntax was added in Python 3.10)"
+          },
+          "ruleId": null
+        }
+      ],
+      "tool": {
+        "driver": {
+          "informationUri": "https://github.com/astral-sh/ruff",
+          "name": "ruff",
+          "rules": [
+            {
+              "fullDescription": {
+                "text": "## What it does\nChecks for unused imports.\n\n## Why is this bad?\nUnused imports add a performance overhead at runtime, and risk creating\nimport cycles. They also increase the cognitive load of reading the code.\n\nIf an import statement is used to check for the availability or existence\nof a module, consider using `importlib.util.find_spec` instead.\n\nIf an import statement is used to re-export a symbol as part of a module's\npublic interface, consider using a \"redundant\" import alias, which\ninstructs Ruff (and other tools) to respect the re-export, and avoid\nmarking it as unused, as in:\n\n```python\nfrom module import member as member\n```\n\nAlternatively, you can use `__all__` to declare a symbol as part of the module's\ninterface, as in:\n\n```python\n# __init__.py\nimport some_module\n\n__all__ = [\"some_module\"]\n```\n\n## Fix safety\n\nFixes to remove unused imports are safe, except in `__init__.py` files.\n\nApplying fixes to `__init__.py` files is currently in preview. The fix offered depends on the\ntype of the unused import. Ruff will suggest a safe fix to export first-party imports with\neither a redundant alias or, if already present in the file, an `__all__` entry. If multiple\n`__all__` declarations are present, Ruff will not offer a fix. Ruff will suggest an unsafe fix\nto remove third-party and standard library imports -- the fix is unsafe because the module's\ninterface changes.\n\n## Example\n\n```python\nimport numpy as np  # unused import\n\n\ndef area(radius):\n    return 3.14 * radius**2\n```\n\nUse instead:\n\n```python\ndef area(radius):\n    return 3.14 * radius**2\n```\n\nTo check the availability of a module, use `importlib.util.find_spec`:\n\n```python\nfrom importlib.util import find_spec\n\nif find_spec(\"numpy\") is not None:\n    print(\"numpy is installed\")\nelse:\n    print(\"numpy is not installed\")\n```\n\n## Preview\nWhen [preview](https://docs.astral.sh/ruff/preview/) is enabled,\nthe criterion for determining whether an import is first-party\nis stricter, which could affect the suggested fix. See [this FAQ section](https://docs.astral.sh/ruff/faq/#how-does-ruff-determine-which-of-my-imports-are-first-party-third-party-etc) for more details.\n\n## Options\n- `lint.ignore-init-module-imports`\n- `lint.pyflakes.allowed-unused-imports`\n\n## References\n- [Python documentation: `import`](https://docs.python.org/3/reference/simple_stmts.html#the-import-statement)\n- [Python documentation: `importlib.util.find_spec`](https://docs.python.org/3/library/importlib.html#importlib.util.find_spec)\n- [Typing documentation: interface conventions](https://typing.python.org/en/latest/source/libraries.html#library-interface-public-and-private-symbols)\n"
+              },
+              "help": {
+                "text": "`{name}` imported but unused; consider using `importlib.util.find_spec` to test for availability"
+              },
+              "helpUri": "https://docs.astral.sh/ruff/rules/unused-import",
+              "id": "F401",
+              "properties": {
+                "id": "F401",
+                "kind": "Pyflakes",
+                "name": "unused-import",
+                "problem.severity": "error"
+              },
+              "shortDescription": {
+                "text": "`{name}` imported but unused; consider using `importlib.util.find_spec` to test for availability"
+              }
+            },
+            {
+              "fullDescription": {
+                "text": "## What it does\nChecks for uses of undefined names.\n\n## Why is this bad?\nAn undefined name is likely to raise `NameError` at runtime.\n\n## Example\n```python\ndef double():\n    return n * 2  # raises `NameError` if `n` is undefined when `double` is called\n```\n\nUse instead:\n```python\ndef double(n):\n    return n * 2\n```\n\n## Options\n- [`target-version`]: Can be used to configure which symbols Ruff will understand\n  as being available in the `builtins` namespace.\n\n## References\n- [Python documentation: Naming and binding](https://docs.python.org/3/reference/executionmodel.html#naming-and-binding)\n"
+              },
+              "help": {
+                "text": "Undefined name `{name}`. {tip}"
+              },
+              "helpUri": "https://docs.astral.sh/ruff/rules/undefined-name",
+              "id": "F821",
+              "properties": {
+                "id": "F821",
+                "kind": "Pyflakes",
+                "name": "undefined-name",
+                "problem.severity": "error"
+              },
+              "shortDescription": {
+                "text": "Undefined name `{name}`. {tip}"
+              }
+            }
+          ],
+          "version": "[VERSION]"
+        }
+      }
+    }
+  ],
+  "version": "2.1.0"
+}
+----- stderr -----

crates/ruff/tests/version.rs

@@ -60,7 +60,7 @@ fn config_option_ignored_but_validated() {
         assert_cmd_snapshot!(
             Command::new(get_cargo_bin(BIN_NAME))
                 .arg("version")
-                .args(["--config", "foo = bar"]), @r#"
+                .args(["--config", "foo = bar"]), @r"
         success: false
         exit_code: 2
         ----- stdout -----
@@ -77,12 +77,11 @@ fn config_option_ignored_but_validated() {
         TOML parse error at line 1, column 7
           |
         1 | foo = bar
-          |       ^
-        invalid string
-        expected `"`, `'`
+          |       ^^^
+        string values must be quoted, expected literal string
 
         For more information, try '--help'.
-        "#
+        "
         );
     });
 }

crates/ruff_benchmark/benches/ty.rs

@@ -2,6 +2,7 @@
 use ruff_benchmark::criterion;
 use ruff_benchmark::real_world_projects::{InstalledProject, RealWorldProject};
 
+use std::fmt::Write;
 use std::ops::Range;
 
 use criterion::{BatchSize, Criterion, criterion_group, criterion_main};
@@ -441,6 +442,37 @@ fn benchmark_complex_constrained_attributes_2(criterion: &mut Criterion) {
     });
 }
 
+fn benchmark_many_enum_members(criterion: &mut Criterion) {
+    const NUM_ENUM_MEMBERS: usize = 512;
+
+    setup_rayon();
+
+    let mut code = String::new();
+    writeln!(&mut code, "from enum import Enum").ok();
+
+    writeln!(&mut code, "class E(Enum):").ok();
+    for i in 0..NUM_ENUM_MEMBERS {
+        writeln!(&mut code, "    m{i} = {i}").ok();
+    }
+    writeln!(&mut code).ok();
+
+    for i in 0..NUM_ENUM_MEMBERS {
+        writeln!(&mut code, "print(E.m{i})").ok();
+    }
+
+    criterion.bench_function("ty_micro[many_enum_members]", |b| {
+        b.iter_batched_ref(
+            || setup_micro_case(&code),
+            |case| {
+                let Case { db, .. } = case;
+                let result = db.check();
+                assert_eq!(result.len(), 0);
+            },
+            BatchSize::SmallInput,
+        );
+    });
+}
+
 struct ProjectBenchmark<'a> {
     project: InstalledProject<'a>,
     fs: MemoryFileSystem,
@@ -498,11 +530,8 @@ fn bench_project(benchmark: &ProjectBenchmark, criterion: &mut Criterion) {
         let diagnostics = result.len();
 
         assert!(
-            diagnostics > 1 && diagnostics <= max_diagnostics,
-            "Expected between {} and {} diagnostics but got {}",
-            1,
-            max_diagnostics,
-            diagnostics
+            diagnostics <= max_diagnostics,
+            "Expected <={max_diagnostics} diagnostics but got {diagnostics}"
         );
     }
 
@@ -570,6 +599,23 @@ fn anyio(criterion: &mut Criterion) {
     bench_project(&benchmark, criterion);
 }
 
+fn datetype(criterion: &mut Criterion) {
+    let benchmark = ProjectBenchmark::new(
+        RealWorldProject {
+            name: "DateType",
+            repository: "https://github.com/glyph/DateType",
+            commit: "57c9c93cf2468069f72945fc04bf27b64100dad8",
+            paths: vec![SystemPath::new("src")],
+            dependencies: vec![],
+            max_dep_date: "2025-07-04",
+            python_version: PythonVersion::PY313,
+        },
+        0,
+    );
+
+    bench_project(&benchmark, criterion);
+}
+
 criterion_group!(check_file, benchmark_cold, benchmark_incremental);
 criterion_group!(
     micro,
@@ -577,6 +623,7 @@ criterion_group!(
     benchmark_many_tuple_assignments,
     benchmark_complex_constrained_attributes_1,
     benchmark_complex_constrained_attributes_2,
+    benchmark_many_enum_members,
 );
-criterion_group!(project, anyio, attrs, hydra);
+criterion_group!(project, anyio, attrs, hydra, datetype);
 criterion_main!(check_file, micro, project);

crates/ruff_benchmark/benches/ty_walltime.rs

@@ -242,7 +242,7 @@ fn large(bencher: Bencher, benchmark: &Benchmark) {
     run_single_threaded(bencher, benchmark);
 }
 
-#[bench(args=[&*PYDANTIC], sample_size=3, sample_count=3)]
+#[bench(args=[&*PYDANTIC], sample_size=3, sample_count=8)]
 fn multithreaded(bencher: Bencher, benchmark: &Benchmark) {
     let thread_pool = ThreadPoolBuilder::new().build().unwrap();
 

crates/ruff_db/Cargo.toml

@@ -13,12 +13,14 @@ license = { workspace = true }
 [dependencies]
 ruff_annotate_snippets = { workspace = true }
 ruff_cache = { workspace = true, optional = true }
+ruff_diagnostics = { workspace = true }
 ruff_notebook = { workspace = true }
 ruff_python_ast = { workspace = true, features = ["get-size"] }
 ruff_python_parser = { workspace = true }
 ruff_python_trivia = { workspace = true }
 ruff_source_file = { workspace = true, features = ["get-size"] }
 ruff_text_size = { workspace = true }
+ty_static = { workspace = true }
 
 anstyle = { workspace = true }
 arc-swap = { workspace = true }
@@ -36,6 +38,7 @@ rustc-hash = { workspace = true }
 salsa = { workspace = true }
 schemars = { workspace = true, optional = true }
 serde = { workspace = true, optional = true }
+serde_json = { workspace = true, optional = true }
 thiserror = { workspace = true }
 tracing = { workspace = true }
 tracing-subscriber = { workspace = true, optional = true }
@@ -54,6 +57,6 @@ tempfile = { workspace = true }
 [features]
 cache = ["ruff_cache"]
 os = ["ignore", "dep:etcetera"]
-serde = ["dep:serde", "camino/serde1"]
+serde = ["camino/serde1", "dep:serde", "dep:serde_json", "ruff_diagnostics/serde"]
 # Exposes testing utilities.
 testing = ["tracing-subscriber"]

crates/ruff_db/src/diagnostic/mod.rs

@@ -1,12 +1,12 @@
-use std::{fmt::Formatter, sync::Arc};
+use std::{fmt::Formatter, path::Path, sync::Arc};
 
-use render::{FileResolver, Input};
-use ruff_source_file::{SourceCode, SourceFile};
+use ruff_diagnostics::Fix;
+use ruff_source_file::{LineColumn, SourceCode, SourceFile};
 
 use ruff_annotate_snippets::Level as AnnotateLevel;
-use ruff_text_size::{Ranged, TextRange};
+use ruff_text_size::{Ranged, TextRange, TextSize};
 
-pub use self::render::DisplayDiagnostic;
+pub use self::render::{DisplayDiagnostic, DisplayDiagnostics, FileResolver, Input};
 use crate::{Db, files::File};
 
 mod render;
@@ -62,10 +62,37 @@ impl Diagnostic {
             message: message.into_diagnostic_message(),
             annotations: vec![],
             subs: vec![],
+            fix: None,
+            parent: None,
+            noqa_offset: None,
+            secondary_code: None,
         });
         Diagnostic { inner }
     }
 
+    /// Creates a `Diagnostic` for a syntax error.
+    ///
+    /// Unlike the more general [`Diagnostic::new`], this requires a [`Span`] and a [`TextRange`]
+    /// attached to it.
+    ///
+    /// This should _probably_ be a method on the syntax errors, but
+    /// at time of writing, `ruff_db` depends on `ruff_python_parser` instead of
+    /// the other way around. And since we want to do this conversion in a couple
+    /// places, it makes sense to centralize it _somewhere_. So it's here for now.
+    ///
+    /// Note that `message` is stored in the primary annotation, _not_ in the primary diagnostic
+    /// message.
+    pub fn invalid_syntax(
+        span: impl Into<Span>,
+        message: impl IntoDiagnosticMessage,
+        range: impl Ranged,
+    ) -> Diagnostic {
+        let mut diag = Diagnostic::new(DiagnosticId::InvalidSyntax, Severity::Error, "");
+        let span = span.into().with_range(range.range());
+        diag.annotate(Annotation::primary(span).message(message));
+        diag
+    }
+
     /// Add an annotation to this diagnostic.
     ///
     /// Annotations for a diagnostic are optional, but if any are added,
@@ -226,6 +253,11 @@ impl Diagnostic {
         self.primary_annotation().map(|ann| ann.span.clone())
     }
 
+    /// Returns a reference to the primary span of this diagnostic.
+    pub fn primary_span_ref(&self) -> Option<&Span> {
+        self.primary_annotation().map(|ann| &ann.span)
+    }
+
     /// Returns the tags from the primary annotation of this diagnostic if it exists.
     pub fn primary_tags(&self) -> Option<&[DiagnosticTag]> {
         self.primary_annotation().map(|ann| ann.tags.as_slice())
@@ -268,6 +300,168 @@ impl Diagnostic {
     pub fn sub_diagnostics(&self) -> &[SubDiagnostic] {
         &self.inner.subs
     }
+
+    /// Returns the fix for this diagnostic if it exists.
+    pub fn fix(&self) -> Option<&Fix> {
+        self.inner.fix.as_ref()
+    }
+
+    /// Set the fix for this diagnostic.
+    pub fn set_fix(&mut self, fix: Fix) {
+        debug_assert!(
+            self.primary_span().is_some(),
+            "Expected a source file for a diagnostic with a fix"
+        );
+        Arc::make_mut(&mut self.inner).fix = Some(fix);
+    }
+
+    /// Remove the fix for this diagnostic.
+    pub fn remove_fix(&mut self) {
+        Arc::make_mut(&mut self.inner).fix = None;
+    }
+
+    /// Returns `true` if the diagnostic contains a [`Fix`].
+    pub fn fixable(&self) -> bool {
+        self.fix().is_some()
+    }
+
+    /// Returns the offset of the parent statement for this diagnostic if it exists.
+    ///
+    /// This is primarily used for checking noqa/secondary code suppressions.
+    pub fn parent(&self) -> Option<TextSize> {
+        self.inner.parent
+    }
+
+    /// Set the offset of the diagnostic's parent statement.
+    pub fn set_parent(&mut self, parent: TextSize) {
+        Arc::make_mut(&mut self.inner).parent = Some(parent);
+    }
+
+    /// Returns the remapped offset for a suppression comment if it exists.
+    ///
+    /// Like [`Diagnostic::parent`], this is used for noqa code suppression comments in Ruff.
+    pub fn noqa_offset(&self) -> Option<TextSize> {
+        self.inner.noqa_offset
+    }
+
+    /// Set the remapped offset for a suppression comment.
+    pub fn set_noqa_offset(&mut self, noqa_offset: TextSize) {
+        Arc::make_mut(&mut self.inner).noqa_offset = Some(noqa_offset);
+    }
+
+    /// Returns the secondary code for the diagnostic if it exists.
+    ///
+    /// The "primary" code for the diagnostic is its lint name. Diagnostics in ty don't have
+    /// secondary codes (yet), but in Ruff the noqa code is used.
+    pub fn secondary_code(&self) -> Option<&SecondaryCode> {
+        self.inner.secondary_code.as_ref()
+    }
+
+    /// Set the secondary code for this diagnostic.
+    pub fn set_secondary_code(&mut self, code: SecondaryCode) {
+        Arc::make_mut(&mut self.inner).secondary_code = Some(code);
+    }
+
+    /// Returns the name used to represent the diagnostic.
+    pub fn name(&self) -> &'static str {
+        self.id().as_str()
+    }
+
+    /// Returns `true` if `self` is a syntax error message.
+    pub fn is_invalid_syntax(&self) -> bool {
+        self.id().is_invalid_syntax()
+    }
+
+    /// Returns the message body to display to the user.
+    pub fn body(&self) -> &str {
+        self.primary_message()
+    }
+
+    /// Returns the fix suggestion for the violation.
+    pub fn suggestion(&self) -> Option<&str> {
+        self.primary_annotation()?.get_message()
+    }
+
+    /// Returns the URL for the rule documentation, if it exists.
+    pub fn to_ruff_url(&self) -> Option<String> {
+        if self.is_invalid_syntax() {
+            None
+        } else {
+            Some(format!(
+                "{}/rules/{}",
+                env!("CARGO_PKG_HOMEPAGE"),
+                self.name()
+            ))
+        }
+    }
+
+    /// Returns the filename for the message.
+    ///
+    /// Panics if the diagnostic has no primary span, or if its file is not a `SourceFile`.
+    pub fn expect_ruff_filename(&self) -> String {
+        self.expect_primary_span()
+            .expect_ruff_file()
+            .name()
+            .to_string()
+    }
+
+    /// Computes the start source location for the message.
+    ///
+    /// Panics if the diagnostic has no primary span, if its file is not a `SourceFile`, or if the
+    /// span has no range.
+    pub fn expect_ruff_start_location(&self) -> LineColumn {
+        self.expect_primary_span()
+            .expect_ruff_file()
+            .to_source_code()
+            .line_column(self.expect_range().start())
+    }
+
+    /// Computes the end source location for the message.
+    ///
+    /// Panics if the diagnostic has no primary span, if its file is not a `SourceFile`, or if the
+    /// span has no range.
+    pub fn expect_ruff_end_location(&self) -> LineColumn {
+        self.expect_primary_span()
+            .expect_ruff_file()
+            .to_source_code()
+            .line_column(self.expect_range().end())
+    }
+
+    /// Returns the [`SourceFile`] which the message belongs to.
+    pub fn ruff_source_file(&self) -> Option<&SourceFile> {
+        self.primary_span_ref()?.as_ruff_file()
+    }
+
+    /// Returns the [`SourceFile`] which the message belongs to.
+    ///
+    /// Panics if the diagnostic has no primary span, or if its file is not a `SourceFile`.
+    pub fn expect_ruff_source_file(&self) -> &SourceFile {
+        self.ruff_source_file()
+            .expect("Expected a ruff source file")
+    }
+
+    /// Returns the [`TextRange`] for the diagnostic.
+    pub fn range(&self) -> Option<TextRange> {
+        self.primary_span()?.range()
+    }
+
+    /// Returns the [`TextRange`] for the diagnostic.
+    ///
+    /// Panics if the diagnostic has no primary span or if the span has no range.
+    pub fn expect_range(&self) -> TextRange {
+        self.range().expect("Expected a range for the primary span")
+    }
+
+    /// Returns the ordering of diagnostics based on the start of their ranges, if they have any.
+    ///
+    /// Panics if either diagnostic has no primary span, if the span has no range, or if its file is
+    /// not a `SourceFile`.
+    pub fn ruff_start_ordering(&self, other: &Self) -> std::cmp::Ordering {
+        (self.expect_ruff_source_file(), self.expect_range().start()).cmp(&(
+            other.expect_ruff_source_file(),
+            other.expect_range().start(),
+        ))
+    }
 }
 
 #[derive(Debug, Clone, Eq, PartialEq, get_size2::GetSize)]
@@ -277,6 +471,10 @@ struct DiagnosticInner {
     message: DiagnosticMessage,
     annotations: Vec<Annotation>,
     subs: Vec<SubDiagnostic>,
+    fix: Option<Fix>,
+    parent: Option<TextSize>,
+    noqa_offset: Option<TextSize>,
+    secondary_code: Option<SecondaryCode>,
 }
 
 struct RenderingSortKey<'a> {
@@ -814,6 +1012,18 @@ impl UnifiedFile {
         }
     }
 
+    /// Return the file's path relative to the current working directory.
+    pub fn relative_path<'a>(&'a self, resolver: &'a dyn FileResolver) -> &'a Path {
+        let cwd = resolver.current_directory();
+        let path = Path::new(self.path(resolver));
+
+        if let Ok(path) = path.strip_prefix(cwd) {
+            return path;
+        }
+
+        path
+    }
+
     fn diagnostic_source(&self, resolver: &dyn FileResolver) -> DiagnosticSource {
         match self {
             UnifiedFile::Ty(file) => DiagnosticSource::Ty(resolver.input(*file)),
@@ -897,9 +1107,15 @@ impl Span {
     ///
     /// Panics if the file is a [`UnifiedFile::Ty`] instead of a [`UnifiedFile::Ruff`].
     pub fn expect_ruff_file(&self) -> &SourceFile {
+        self.as_ruff_file()
+            .expect("Expected a ruff `SourceFile`, found a ty `File`")
+    }
+
+    /// Returns the [`SourceFile`] attached to this [`Span`].
+    pub fn as_ruff_file(&self) -> Option<&SourceFile> {
         match &self.file {
-            UnifiedFile::Ty(_) => panic!("Expected a ruff `SourceFile`, found a ty `File`"),
-            UnifiedFile::Ruff(file) => file,
+            UnifiedFile::Ty(_) => None,
+            UnifiedFile::Ruff(file) => Some(file),
         }
     }
 }
@@ -974,6 +1190,12 @@ pub struct DisplayDiagnosticConfig {
     /// here for now as the most "sensible" place for it to live until
     /// we had more concrete use cases. ---AG
     context: usize,
+    /// Whether to use preview formatting for Ruff diagnostics.
+    #[allow(
+        dead_code,
+        reason = "This is currently only used for JSON but will be needed soon for other formats"
+    )]
+    preview: bool,
 }
 
 impl DisplayDiagnosticConfig {
@@ -994,6 +1216,14 @@ impl DisplayDiagnosticConfig {
             ..self
         }
     }
+
+    /// Whether to enable preview behavior or not.
+    pub fn preview(self, yes: bool) -> DisplayDiagnosticConfig {
+        DisplayDiagnosticConfig {
+            preview: yes,
+            ..self
+        }
+    }
 }
 
 impl Default for DisplayDiagnosticConfig {
@@ -1002,6 +1232,7 @@ impl Default for DisplayDiagnosticConfig {
             format: DiagnosticFormat::default(),
             color: false,
             context: 2,
+            preview: false,
         }
     }
 }
@@ -1029,6 +1260,28 @@ pub enum DiagnosticFormat {
     ///
     /// This may use color when printing to a `tty`.
     Concise,
+    /// Print diagnostics in the [Azure Pipelines] format.
+    ///
+    /// [Azure Pipelines]: https://learn.microsoft.com/en-us/azure/devops/pipelines/scripts/logging-commands?view=azure-devops&tabs=bash#logissue-log-an-error-or-warning
+    Azure,
+    /// Print diagnostics in JSON format.
+    ///
+    /// Unlike `json-lines`, this prints all of the diagnostics as a JSON array.
+    #[cfg(feature = "serde")]
+    Json,
+    /// Print diagnostics in JSON format, one per line.
+    ///
+    /// This will print each diagnostic as a separate JSON object on its own line. See the `json`
+    /// format for an array of all diagnostics. See <https://jsonlines.org/> for more details.
+    #[cfg(feature = "serde")]
+    JsonLines,
+    /// Print diagnostics in the JSON format expected by [reviewdog].
+    ///
+    /// [reviewdog]: https://github.com/reviewdog/reviewdog
+    #[cfg(feature = "serde")]
+    Rdjson,
+    /// Print diagnostics in the format emitted by Pylint.
+    Pylint,
 }
 
 /// A representation of the kinds of messages inside a diagnostic.
@@ -1147,41 +1400,52 @@ impl<T: std::fmt::Display> IntoDiagnosticMessage for T {
     }
 }
 
-/// Creates a `Diagnostic` from a parse error.
+/// A secondary identifier for a lint diagnostic.
 ///
-/// This should _probably_ be a method on `ruff_python_parser::ParseError`, but
-/// at time of writing, `ruff_db` depends on `ruff_python_parser` instead of
-/// the other way around. And since we want to do this conversion in a couple
-/// places, it makes sense to centralize it _somewhere_. So it's here for now.
-pub fn create_parse_diagnostic(file: File, err: &ruff_python_parser::ParseError) -> Diagnostic {
-    let mut diag = Diagnostic::new(DiagnosticId::InvalidSyntax, Severity::Error, "");
-    let span = Span::from(file).with_range(err.location);
-    diag.annotate(Annotation::primary(span).message(&err.error));
-    diag
+/// For Ruff rules this means the noqa code.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Default, Hash, get_size2::GetSize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize), serde(transparent))]
+pub struct SecondaryCode(String);
+
+impl SecondaryCode {
+    pub fn new(code: String) -> Self {
+        Self(code)
+    }
+
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
 }
 
-/// Creates a `Diagnostic` from an unsupported syntax error.
-///
-/// See [`create_parse_diagnostic`] for more details.
-pub fn create_unsupported_syntax_diagnostic(
-    file: File,
-    err: &ruff_python_parser::UnsupportedSyntaxError,
-) -> Diagnostic {
-    let mut diag = Diagnostic::new(DiagnosticId::InvalidSyntax, Severity::Error, "");
-    let span = Span::from(file).with_range(err.range);
-    diag.annotate(Annotation::primary(span).message(err.to_string()));
-    diag
+impl std::fmt::Display for SecondaryCode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&self.0)
+    }
 }
 
-/// Creates a `Diagnostic` from a semantic syntax error.
-///
-/// See [`create_parse_diagnostic`] for more details.
-pub fn create_semantic_syntax_diagnostic(
-    file: File,
-    err: &ruff_python_parser::semantic_errors::SemanticSyntaxError,
-) -> Diagnostic {
-    let mut diag = Diagnostic::new(DiagnosticId::InvalidSyntax, Severity::Error, "");
-    let span = Span::from(file).with_range(err.range);
-    diag.annotate(Annotation::primary(span).message(err.to_string()));
-    diag
+impl std::ops::Deref for SecondaryCode {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl PartialEq<&str> for SecondaryCode {
+    fn eq(&self, other: &&str) -> bool {
+        self.0 == *other
+    }
+}
+
+impl PartialEq<SecondaryCode> for &str {
+    fn eq(&self, other: &SecondaryCode) -> bool {
+        other.eq(self)
+    }
+}
+
+// for `hashbrown::EntryRef`
+impl From<&SecondaryCode> for SecondaryCode {
+    fn from(value: &SecondaryCode) -> Self {
+        value.clone()
+    }
 }

crates/ruff_db/src/diagnostic/render.rs

@@ -1,9 +1,11 @@
 use std::collections::BTreeMap;
+use std::path::Path;
 
 use ruff_annotate_snippets::{
     Annotation as AnnotateAnnotation, Level as AnnotateLevel, Message as AnnotateMessage,
     Renderer as AnnotateRenderer, Snippet as AnnotateSnippet,
 };
+use ruff_notebook::{Notebook, NotebookIndex};
 use ruff_source_file::{LineIndex, OneIndexed, SourceCode};
 use ruff_text_size::{TextRange, TextSize};
 
@@ -17,9 +19,21 @@ use crate::{
 
 use super::{
     Annotation, Diagnostic, DiagnosticFormat, DiagnosticSource, DisplayDiagnosticConfig, Severity,
-    SubDiagnostic,
+    SubDiagnostic, UnifiedFile,
 };
 
+use azure::AzureRenderer;
+use pylint::PylintRenderer;
+
+mod azure;
+#[cfg(feature = "serde")]
+mod json;
+#[cfg(feature = "serde")]
+mod json_lines;
+mod pylint;
+#[cfg(feature = "serde")]
+mod rdjson;
+
 /// A type that implements `std::fmt::Display` for diagnostic rendering.
 ///
 /// It is created via [`Diagnostic::display`].
@@ -34,7 +48,6 @@ use super::{
 pub struct DisplayDiagnostic<'a> {
     config: &'a DisplayDiagnosticConfig,
     resolver: &'a dyn FileResolver,
-    annotate_renderer: AnnotateRenderer,
     diag: &'a Diagnostic,
 }
 
@@ -44,16 +57,9 @@ impl<'a> DisplayDiagnostic<'a> {
         config: &'a DisplayDiagnosticConfig,
         diag: &'a Diagnostic,
     ) -> DisplayDiagnostic<'a> {
-        let annotate_renderer = if config.color {
-            AnnotateRenderer::styled()
-        } else {
-            AnnotateRenderer::plain()
-        };
-
         DisplayDiagnostic {
             config,
             resolver,
-            annotate_renderer,
             diag,
         }
     }
@@ -61,68 +67,138 @@ impl<'a> DisplayDiagnostic<'a> {
 
 impl std::fmt::Display for DisplayDiagnostic<'_> {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        let stylesheet = if self.config.color {
-            DiagnosticStylesheet::styled()
-        } else {
-            DiagnosticStylesheet::plain()
-        };
+        DisplayDiagnostics::new(self.resolver, self.config, std::slice::from_ref(self.diag)).fmt(f)
+    }
+}
 
-        if matches!(self.config.format, DiagnosticFormat::Concise) {
-            let (severity, severity_style) = match self.diag.severity() {
-                Severity::Info => ("info", stylesheet.info),
-                Severity::Warning => ("warning", stylesheet.warning),
-                Severity::Error => ("error", stylesheet.error),
-                Severity::Fatal => ("fatal", stylesheet.error),
-            };
+/// A type that implements `std::fmt::Display` for rendering a collection of diagnostics.
+///
+/// It is intended for collections of diagnostics that need to be serialized together, as is the
+/// case for JSON, for example.
+///
+/// See [`DisplayDiagnostic`] for rendering individual `Diagnostic`s and details about the lifetime
+/// constraints.
+pub struct DisplayDiagnostics<'a> {
+    config: &'a DisplayDiagnosticConfig,
+    resolver: &'a dyn FileResolver,
+    diagnostics: &'a [Diagnostic],
+}
 
-            write!(
-                f,
-                "{severity}[{id}]",
-                severity = fmt_styled(severity, severity_style),
-                id = fmt_styled(self.diag.id(), stylesheet.emphasis)
-            )?;
+impl<'a> DisplayDiagnostics<'a> {
+    pub fn new(
+        resolver: &'a dyn FileResolver,
+        config: &'a DisplayDiagnosticConfig,
+        diagnostics: &'a [Diagnostic],
+    ) -> DisplayDiagnostics<'a> {
+        DisplayDiagnostics {
+            config,
+            resolver,
+            diagnostics,
+        }
+    }
+}
 
-            if let Some(span) = self.diag.primary_span() {
-                write!(
-                    f,
-                    " {path}",
-                    path = fmt_styled(span.file().path(self.resolver), stylesheet.emphasis)
-                )?;
-                if let Some(range) = span.range() {
-                    let diagnostic_source = span.file().diagnostic_source(self.resolver);
-                    let start = diagnostic_source
-                        .as_source_code()
-                        .line_column(range.start());
+impl std::fmt::Display for DisplayDiagnostics<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self.config.format {
+            DiagnosticFormat::Concise => {
+                let stylesheet = if self.config.color {
+                    DiagnosticStylesheet::styled()
+                } else {
+                    DiagnosticStylesheet::plain()
+                };
 
+                for diag in self.diagnostics {
+                    let (severity, severity_style) = match diag.severity() {
+                        Severity::Info => ("info", stylesheet.info),
+                        Severity::Warning => ("warning", stylesheet.warning),
+                        Severity::Error => ("error", stylesheet.error),
+                        Severity::Fatal => ("fatal", stylesheet.error),
+                    };
                     write!(
                         f,
-                        ":{line}:{col}",
-                        line = fmt_styled(start.line, stylesheet.emphasis),
-                        col = fmt_styled(start.column, stylesheet.emphasis),
+                        "{severity}[{id}]",
+                        severity = fmt_styled(severity, severity_style),
+                        id = fmt_styled(diag.id(), stylesheet.emphasis)
                     )?;
+                    if let Some(span) = diag.primary_span() {
+                        write!(
+                            f,
+                            " {path}",
+                            path = fmt_styled(span.file().path(self.resolver), stylesheet.emphasis)
+                        )?;
+                        if let Some(range) = span.range() {
+                            let diagnostic_source = span.file().diagnostic_source(self.resolver);
+                            let start = diagnostic_source
+                                .as_source_code()
+                                .line_column(range.start());
+
+                            write!(
+                                f,
+                                ":{line}:{col}",
+                                line = fmt_styled(start.line, stylesheet.emphasis),
+                                col = fmt_styled(start.column, stylesheet.emphasis),
+                            )?;
+                        }
+                        write!(f, ":")?;
+                    }
+                    writeln!(f, " {message}", message = diag.concise_message())?;
                 }
-                write!(f, ":")?;
             }
-            return writeln!(f, " {message}", message = self.diag.concise_message());
+            DiagnosticFormat::Full => {
+                let stylesheet = if self.config.color {
+                    DiagnosticStylesheet::styled()
+                } else {
+                    DiagnosticStylesheet::plain()
+                };
+
+                let mut renderer = if self.config.color {
+                    AnnotateRenderer::styled()
+                } else {
+                    AnnotateRenderer::plain()
+                };
+
+                renderer = renderer
+                    .error(stylesheet.error)
+                    .warning(stylesheet.warning)
+                    .info(stylesheet.info)
+                    .note(stylesheet.note)
+                    .help(stylesheet.help)
+                    .line_no(stylesheet.line_no)
+                    .emphasis(stylesheet.emphasis)
+                    .none(stylesheet.none);
+
+                for diag in self.diagnostics {
+                    let resolved = Resolved::new(self.resolver, diag);
+                    let renderable = resolved.to_renderable(self.config.context);
+                    for diag in renderable.diagnostics.iter() {
+                        writeln!(f, "{}", renderer.render(diag.to_annotate()))?;
+                    }
+                    writeln!(f)?;
+                }
+            }
+            DiagnosticFormat::Azure => {
+                AzureRenderer::new(self.resolver).render(f, self.diagnostics)?;
+            }
+            #[cfg(feature = "serde")]
+            DiagnosticFormat::Json => {
+                json::JsonRenderer::new(self.resolver, self.config).render(f, self.diagnostics)?;
+            }
+            #[cfg(feature = "serde")]
+            DiagnosticFormat::JsonLines => {
+                json_lines::JsonLinesRenderer::new(self.resolver, self.config)
+                    .render(f, self.diagnostics)?;
+            }
+            #[cfg(feature = "serde")]
+            DiagnosticFormat::Rdjson => {
+                rdjson::RdjsonRenderer::new(self.resolver).render(f, self.diagnostics)?;
+            }
+            DiagnosticFormat::Pylint => {
+                PylintRenderer::new(self.resolver).render(f, self.diagnostics)?;
+            }
         }
 
-        let mut renderer = self.annotate_renderer.clone();
-        renderer = renderer
-            .error(stylesheet.error)
-            .warning(stylesheet.warning)
-            .info(stylesheet.info)
-            .note(stylesheet.note)
-            .help(stylesheet.help)
-            .line_no(stylesheet.line_no)
-            .emphasis(stylesheet.emphasis)
-            .none(stylesheet.none);
-
-        let resolved = Resolved::new(self.resolver, self.diag);
-        let renderable = resolved.to_renderable(self.config.context);
-        for diag in renderable.diagnostics.iter() {
-            writeln!(f, "{}", renderer.render(diag.to_annotate()))?;
-        }
-        writeln!(f)
+        Ok(())
     }
 }
 
@@ -635,6 +711,15 @@ pub trait FileResolver {
 
     /// Returns the input contents associated with the file given.
     fn input(&self, file: File) -> Input;
+
+    /// Returns the [`NotebookIndex`] associated with the file given, if it's a Jupyter notebook.
+    fn notebook_index(&self, file: &UnifiedFile) -> Option<NotebookIndex>;
+
+    /// Returns whether the file given is a Jupyter notebook.
+    fn is_notebook(&self, file: &UnifiedFile) -> bool;
+
+    /// Returns the current working directory.
+    fn current_directory(&self) -> &Path;
 }
 
 impl<T> FileResolver for T
@@ -651,6 +736,29 @@ where
             line_index: line_index(self, file),
         }
     }
+
+    fn notebook_index(&self, file: &UnifiedFile) -> Option<NotebookIndex> {
+        match file {
+            UnifiedFile::Ty(file) => self
+                .input(*file)
+                .text
+                .as_notebook()
+                .map(Notebook::index)
+                .cloned(),
+            UnifiedFile::Ruff(_) => unimplemented!("Expected an interned ty file"),
+        }
+    }
+
+    fn is_notebook(&self, file: &UnifiedFile) -> bool {
+        match file {
+            UnifiedFile::Ty(file) => self.input(*file).text.as_notebook().is_some(),
+            UnifiedFile::Ruff(_) => unimplemented!("Expected an interned ty file"),
+        }
+    }
+
+    fn current_directory(&self) -> &Path {
+        self.system().current_directory().as_std_path()
+    }
 }
 
 impl FileResolver for &dyn Db {
@@ -664,6 +772,29 @@ impl FileResolver for &dyn Db {
             line_index: line_index(*self, file),
         }
     }
+
+    fn notebook_index(&self, file: &UnifiedFile) -> Option<NotebookIndex> {
+        match file {
+            UnifiedFile::Ty(file) => self
+                .input(*file)
+                .text
+                .as_notebook()
+                .map(Notebook::index)
+                .cloned(),
+            UnifiedFile::Ruff(_) => unimplemented!("Expected an interned ty file"),
+        }
+    }
+
+    fn is_notebook(&self, file: &UnifiedFile) -> bool {
+        match file {
+            UnifiedFile::Ty(file) => self.input(*file).text.as_notebook().is_some(),
+            UnifiedFile::Ruff(_) => unimplemented!("Expected an interned ty file"),
+        }
+    }
+
+    fn current_directory(&self) -> &Path {
+        self.system().current_directory().as_std_path()
+    }
 }
 
 /// An abstraction over a unit of user input.
@@ -724,7 +855,9 @@ fn relativize_path<'p>(cwd: &SystemPath, path: &'p str) -> &'p str {
 #[cfg(test)]
 mod tests {
 
-    use crate::diagnostic::{Annotation, DiagnosticId, Severity, Span};
+    use ruff_diagnostics::{Edit, Fix};
+
+    use crate::diagnostic::{Annotation, DiagnosticId, SecondaryCode, Severity, Span};
     use crate::files::system_path_to_file;
     use crate::system::{DbWithWritableSystem, SystemPath};
     use crate::tests::TestDb;
@@ -2121,7 +2254,7 @@ watermelon
 
     /// A small harness for setting up an environment specifically for testing
     /// diagnostic rendering.
-    struct TestEnvironment {
+    pub(super) struct TestEnvironment {
         db: TestDb,
         config: DisplayDiagnosticConfig,
     }
@@ -2130,7 +2263,7 @@ watermelon
         /// Create a new test harness.
         ///
         /// This uses the default diagnostic rendering configuration.
-        fn new() -> TestEnvironment {
+        pub(super) fn new() -> TestEnvironment {
             TestEnvironment {
                 db: TestDb::new(),
                 config: DisplayDiagnosticConfig::default(),
@@ -2149,8 +2282,26 @@ watermelon
             self.config = config;
         }
 
+        /// Set the output format to use in diagnostic rendering.
+        pub(super) fn format(&mut self, format: DiagnosticFormat) {
+            let mut config = std::mem::take(&mut self.config);
+            config = config.format(format);
+            self.config = config;
+        }
+
+        /// Enable preview functionality for diagnostic rendering.
+        #[allow(
+            dead_code,
+            reason = "This is currently only used for JSON but will be needed soon for other formats"
+        )]
+        pub(super) fn preview(&mut self, yes: bool) {
+            let mut config = std::mem::take(&mut self.config);
+            config = config.preview(yes);
+            self.config = config;
+        }
+
         /// Add a file with the given path and contents to this environment.
-        fn add(&mut self, path: &str, contents: &str) {
+        pub(super) fn add(&mut self, path: &str, contents: &str) {
             let path = SystemPath::new(path);
             self.db.write_file(path, contents).unwrap();
         }
@@ -2200,7 +2351,7 @@ watermelon
         /// A convenience function for returning a builder for a diagnostic
         /// with "error" severity and canned values for its identifier
         /// and message.
-        fn err(&mut self) -> DiagnosticBuilder<'_> {
+        pub(super) fn err(&mut self) -> DiagnosticBuilder<'_> {
             self.builder(
                 "test-diagnostic",
                 Severity::Error,
@@ -2226,6 +2377,12 @@ watermelon
             DiagnosticBuilder { env: self, diag }
         }
 
+        /// A convenience function for returning a builder for an invalid syntax diagnostic.
+        fn invalid_syntax(&mut self, message: &str) -> DiagnosticBuilder<'_> {
+            let diag = Diagnostic::new(DiagnosticId::InvalidSyntax, Severity::Error, message);
+            DiagnosticBuilder { env: self, diag }
+        }
+
         /// Returns a builder for tersely constructing sub-diagnostics.
         fn sub_builder(&mut self, severity: Severity, message: &str) -> SubDiagnosticBuilder<'_> {
             let subdiag = SubDiagnostic::new(severity, message);
@@ -2235,9 +2392,18 @@ watermelon
         /// Render the given diagnostic into a `String`.
         ///
         /// (This will set the "printed" flag on `Diagnostic`.)
-        fn render(&self, diag: &Diagnostic) -> String {
+        pub(super) fn render(&self, diag: &Diagnostic) -> String {
             diag.display(&self.db, &self.config).to_string()
         }
+
+        /// Render the given diagnostics into a `String`.
+        ///
+        /// See `render` for rendering a single diagnostic.
+        ///
+        /// (This will set the "printed" flag on `Diagnostic`.)
+        pub(super) fn render_diagnostics(&self, diagnostics: &[Diagnostic]) -> String {
+            DisplayDiagnostics::new(&self.db, &self.config, diagnostics).to_string()
+        }
     }
 
     /// A helper builder for tersely populating a `Diagnostic`.
@@ -2246,14 +2412,14 @@ watermelon
     /// supported by this builder, and this only needs to be done
     /// infrequently, consider doing it more verbosely on `diag`
     /// itself.
-    struct DiagnosticBuilder<'e> {
+    pub(super) struct DiagnosticBuilder<'e> {
         env: &'e mut TestEnvironment,
         diag: Diagnostic,
     }
 
     impl<'e> DiagnosticBuilder<'e> {
         /// Return the built diagnostic.
-        fn build(self) -> Diagnostic {
+        pub(super) fn build(self) -> Diagnostic {
             self.diag
         }
 
@@ -2302,6 +2468,25 @@ watermelon
             self.diag.annotate(ann);
             self
         }
+
+        /// Set the secondary code on the diagnostic.
+        fn secondary_code(mut self, secondary_code: &str) -> DiagnosticBuilder<'e> {
+            self.diag
+                .set_secondary_code(SecondaryCode::new(secondary_code.to_string()));
+            self
+        }
+
+        /// Set the fix on the diagnostic.
+        pub(super) fn fix(mut self, fix: Fix) -> DiagnosticBuilder<'e> {
+            self.diag.set_fix(fix);
+            self
+        }
+
+        /// Set the noqa offset on the diagnostic.
+        fn noqa_offset(mut self, noqa_offset: TextSize) -> DiagnosticBuilder<'e> {
+            self.diag.set_noqa_offset(noqa_offset);
+            self
+        }
     }
 
     /// A helper builder for tersely populating a `SubDiagnostic`.
@@ -2381,4 +2566,199 @@ watermelon
         let offset = TextSize::from(offset.parse::<u32>().unwrap());
         (line_number, Some(offset))
     }
+
+    /// Create Ruff-style diagnostics for testing the various output formats.
+    pub(crate) fn create_diagnostics(
+        format: DiagnosticFormat,
+    ) -> (TestEnvironment, Vec<Diagnostic>) {
+        let mut env = TestEnvironment::new();
+        env.add(
+            "fib.py",
+            r#"import os
+
+
+def fibonacci(n):
+    """Compute the nth number in the Fibonacci sequence."""
+    x = 1
+    if n == 0:
+        return 0
+    elif n == 1:
+        return 1
+    else:
+        return fibonacci(n - 1) + fibonacci(n - 2)
+"#,
+        );
+        env.add("undef.py", r"if a == 1: pass");
+        env.format(format);
+
+        let diagnostics = vec![
+            env.builder("unused-import", Severity::Error, "`os` imported but unused")
+                .primary("fib.py", "1:7", "1:9", "Remove unused import: `os`")
+                .secondary_code("F401")
+                .fix(Fix::unsafe_edit(Edit::range_deletion(TextRange::new(
+                    TextSize::from(0),
+                    TextSize::from(10),
+                ))))
+                .noqa_offset(TextSize::from(7))
+                .build(),
+            env.builder(
+                "unused-variable",
+                Severity::Error,
+                "Local variable `x` is assigned to but never used",
+            )
+            .primary(
+                "fib.py",
+                "6:4",
+                "6:5",
+                "Remove assignment to unused variable `x`",
+            )
+            .secondary_code("F841")
+            .fix(Fix::unsafe_edit(Edit::deletion(
+                TextSize::from(94),
+                TextSize::from(99),
+            )))
+            .noqa_offset(TextSize::from(94))
+            .build(),
+            env.builder("undefined-name", Severity::Error, "Undefined name `a`")
+                .primary("undef.py", "1:3", "1:4", "")
+                .secondary_code("F821")
+                .noqa_offset(TextSize::from(3))
+                .build(),
+        ];
+
+        (env, diagnostics)
+    }
+
+    /// Create Ruff-style syntax error diagnostics for testing the various output formats.
+    pub(crate) fn create_syntax_error_diagnostics(
+        format: DiagnosticFormat,
+    ) -> (TestEnvironment, Vec<Diagnostic>) {
+        let mut env = TestEnvironment::new();
+        env.add(
+            "syntax_errors.py",
+            r"from os import
+
+if call(foo
+    def bar():
+        pass
+",
+        );
+        env.format(format);
+
+        let diagnostics = vec![
+            env.invalid_syntax("SyntaxError: Expected one or more symbol names after import")
+                .primary("syntax_errors.py", "1:14", "1:15", "")
+                .build(),
+            env.invalid_syntax("SyntaxError: Expected ')', found newline")
+                .primary("syntax_errors.py", "3:11", "3:12", "")
+                .build(),
+        ];
+
+        (env, diagnostics)
+    }
+
+    /// Create Ruff-style diagnostics for testing the various output formats for a notebook.
+    #[allow(
+        dead_code,
+        reason = "This is currently only used for JSON but will be needed soon for other formats"
+    )]
+    pub(crate) fn create_notebook_diagnostics(
+        format: DiagnosticFormat,
+    ) -> (TestEnvironment, Vec<Diagnostic>) {
+        let mut env = TestEnvironment::new();
+        env.add(
+            "notebook.ipynb",
+            r##"
+        {
+ "cells": [
+  {
+   "cell_type": "code",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# cell 1\n",
+    "import os"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# cell 2\n",
+    "import math\n",
+    "\n",
+    "print('hello world')"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# cell 3\n",
+    "def foo():\n",
+    "    print()\n",
+    "    x = 1\n"
+   ]
+  }
+ ],
+ "metadata": {},
+ "nbformat": 4,
+ "nbformat_minor": 5
+}
+"##,
+        );
+        env.format(format);
+
+        let diagnostics = vec![
+            env.builder("unused-import", Severity::Error, "`os` imported but unused")
+                .primary("notebook.ipynb", "2:7", "2:9", "Remove unused import: `os`")
+                .secondary_code("F401")
+                .fix(Fix::safe_edit(Edit::range_deletion(TextRange::new(
+                    TextSize::from(9),
+                    TextSize::from(19),
+                ))))
+                .noqa_offset(TextSize::from(16))
+                .build(),
+            env.builder(
+                "unused-import",
+                Severity::Error,
+                "`math` imported but unused",
+            )
+            .primary(
+                "notebook.ipynb",
+                "4:7",
+                "4:11",
+                "Remove unused import: `math`",
+            )
+            .secondary_code("F401")
+            .fix(Fix::safe_edit(Edit::range_deletion(TextRange::new(
+                TextSize::from(28),
+                TextSize::from(40),
+            ))))
+            .noqa_offset(TextSize::from(35))
+            .build(),
+            env.builder(
+                "unused-variable",
+                Severity::Error,
+                "Local variable `x` is assigned to but never used",
+            )
+            .primary(
+                "notebook.ipynb",
+                "10:4",
+                "10:5",
+                "Remove assignment to unused variable `x`",
+            )
+            .secondary_code("F841")
+            .fix(Fix::unsafe_edit(Edit::range_deletion(TextRange::new(
+                TextSize::from(94),
+                TextSize::from(104),
+            ))))
+            .noqa_offset(TextSize::from(98))
+            .build(),
+        ];
+
+        (env, diagnostics)
+    }
 }

crates/ruff_db/src/diagnostic/render/azure.rs

@@ -0,0 +1,83 @@
+use ruff_source_file::LineColumn;
+
+use crate::diagnostic::{Diagnostic, Severity};
+
+use super::FileResolver;
+
+pub(super) struct AzureRenderer<'a> {
+    resolver: &'a dyn FileResolver,
+}
+
+impl<'a> AzureRenderer<'a> {
+    pub(super) fn new(resolver: &'a dyn FileResolver) -> Self {
+        Self { resolver }
+    }
+}
+
+impl AzureRenderer<'_> {
+    pub(super) fn render(
+        &self,
+        f: &mut std::fmt::Formatter,
+        diagnostics: &[Diagnostic],
+    ) -> std::fmt::Result {
+        for diag in diagnostics {
+            let severity = match diag.severity() {
+                Severity::Info | Severity::Warning => "warning",
+                Severity::Error | Severity::Fatal => "error",
+            };
+            write!(f, "##vso[task.logissue type={severity};")?;
+            if let Some(span) = diag.primary_span() {
+                let filename = span.file().path(self.resolver);
+                write!(f, "sourcepath={filename};")?;
+                if let Some(range) = span.range() {
+                    let location = if self.resolver.notebook_index(span.file()).is_some() {
+                        // We can't give a reasonable location for the structured formats,
+                        // so we show one that's clearly a fallback
+                        LineColumn::default()
+                    } else {
+                        span.file()
+                            .diagnostic_source(self.resolver)
+                            .as_source_code()
+                            .line_column(range.start())
+                    };
+                    write!(
+                        f,
+                        "linenumber={line};columnnumber={col};",
+                        line = location.line,
+                        col = location.column,
+                    )?;
+                }
+            }
+            writeln!(
+                f,
+                "{code}]{body}",
+                code = diag
+                    .secondary_code()
+                    .map_or_else(String::new, |code| format!("code={code};")),
+                body = diag.body(),
+            )?;
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostic::{
+        DiagnosticFormat,
+        render::tests::{create_diagnostics, create_syntax_error_diagnostics},
+    };
+
+    #[test]
+    fn output() {
+        let (env, diagnostics) = create_diagnostics(DiagnosticFormat::Azure);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn syntax_errors() {
+        let (env, diagnostics) = create_syntax_error_diagnostics(DiagnosticFormat::Azure);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+}

crates/ruff_db/src/diagnostic/render/json.rs

@@ -0,0 +1,352 @@
+use serde::{Serialize, Serializer, ser::SerializeSeq};
+use serde_json::{Value, json};
+
+use ruff_diagnostics::{Applicability, Edit};
+use ruff_notebook::NotebookIndex;
+use ruff_source_file::{LineColumn, OneIndexed};
+use ruff_text_size::Ranged;
+
+use crate::diagnostic::{Diagnostic, DiagnosticSource, DisplayDiagnosticConfig, SecondaryCode};
+
+use super::FileResolver;
+
+pub(super) struct JsonRenderer<'a> {
+    resolver: &'a dyn FileResolver,
+    config: &'a DisplayDiagnosticConfig,
+}
+
+impl<'a> JsonRenderer<'a> {
+    pub(super) fn new(resolver: &'a dyn FileResolver, config: &'a DisplayDiagnosticConfig) -> Self {
+        Self { resolver, config }
+    }
+}
+
+impl JsonRenderer<'_> {
+    pub(super) fn render(
+        &self,
+        f: &mut std::fmt::Formatter,
+        diagnostics: &[Diagnostic],
+    ) -> std::fmt::Result {
+        write!(
+            f,
+            "{:#}",
+            diagnostics_to_json_value(diagnostics, self.resolver, self.config)
+        )
+    }
+}
+
+fn diagnostics_to_json_value<'a>(
+    diagnostics: impl IntoIterator<Item = &'a Diagnostic>,
+    resolver: &dyn FileResolver,
+    config: &DisplayDiagnosticConfig,
+) -> Value {
+    let values: Vec<_> = diagnostics
+        .into_iter()
+        .map(|diag| diagnostic_to_json(diag, resolver, config))
+        .collect();
+    json!(values)
+}
+
+pub(super) fn diagnostic_to_json<'a>(
+    diagnostic: &'a Diagnostic,
+    resolver: &'a dyn FileResolver,
+    config: &'a DisplayDiagnosticConfig,
+) -> JsonDiagnostic<'a> {
+    let span = diagnostic.primary_span_ref();
+    let filename = span.map(|span| span.file().path(resolver));
+    let range = span.and_then(|span| span.range());
+    let diagnostic_source = span.map(|span| span.file().diagnostic_source(resolver));
+    let source_code = diagnostic_source
+        .as_ref()
+        .map(|diagnostic_source| diagnostic_source.as_source_code());
+    let notebook_index = span.and_then(|span| resolver.notebook_index(span.file()));
+
+    let mut start_location = None;
+    let mut end_location = None;
+    let mut noqa_location = None;
+    let mut notebook_cell_index = None;
+    if let Some(source_code) = source_code {
+        noqa_location = diagnostic
+            .noqa_offset()
+            .map(|offset| source_code.line_column(offset));
+        if let Some(range) = range {
+            let mut start = source_code.line_column(range.start());
+            let mut end = source_code.line_column(range.end());
+            if let Some(notebook_index) = &notebook_index {
+                notebook_cell_index =
+                    Some(notebook_index.cell(start.line).unwrap_or(OneIndexed::MIN));
+                start = notebook_index.translate_line_column(&start);
+                end = notebook_index.translate_line_column(&end);
+                noqa_location =
+                    noqa_location.map(|location| notebook_index.translate_line_column(&location));
+            }
+            start_location = Some(start);
+            end_location = Some(end);
+        }
+    }
+
+    let fix = diagnostic.fix().map(|fix| JsonFix {
+        applicability: fix.applicability(),
+        message: diagnostic.suggestion(),
+        edits: ExpandedEdits {
+            edits: fix.edits(),
+            notebook_index,
+            config,
+            diagnostic_source,
+        },
+    });
+
+    // In preview, the locations and filename can be optional.
+    if config.preview {
+        JsonDiagnostic {
+            code: diagnostic.secondary_code(),
+            url: diagnostic.to_ruff_url(),
+            message: diagnostic.body(),
+            fix,
+            cell: notebook_cell_index,
+            location: start_location.map(JsonLocation::from),
+            end_location: end_location.map(JsonLocation::from),
+            filename,
+            noqa_row: noqa_location.map(|location| location.line),
+        }
+    } else {
+        JsonDiagnostic {
+            code: diagnostic.secondary_code(),
+            url: diagnostic.to_ruff_url(),
+            message: diagnostic.body(),
+            fix,
+            cell: notebook_cell_index,
+            location: Some(start_location.unwrap_or_default().into()),
+            end_location: Some(end_location.unwrap_or_default().into()),
+            filename: Some(filename.unwrap_or_default()),
+            noqa_row: noqa_location.map(|location| location.line),
+        }
+    }
+}
+
+struct ExpandedEdits<'a> {
+    edits: &'a [Edit],
+    notebook_index: Option<NotebookIndex>,
+    config: &'a DisplayDiagnosticConfig,
+    diagnostic_source: Option<DiagnosticSource>,
+}
+
+impl Serialize for ExpandedEdits<'_> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut s = serializer.serialize_seq(Some(self.edits.len()))?;
+
+        for edit in self.edits {
+            let (location, end_location) = if let Some(diagnostic_source) = &self.diagnostic_source
+            {
+                let source_code = diagnostic_source.as_source_code();
+                let mut location = source_code.line_column(edit.start());
+                let mut end_location = source_code.line_column(edit.end());
+
+                if let Some(notebook_index) = &self.notebook_index {
+                    // There exists a newline between each cell's source code in the
+                    // concatenated source code in Ruff. This newline doesn't actually
+                    // exists in the JSON source field.
+                    //
+                    // Now, certain edits may try to remove this newline, which means
+                    // the edit will spill over to the first character of the next cell.
+                    // If it does, we need to translate the end location to the last
+                    // character of the previous cell.
+                    match (
+                        notebook_index.cell(location.line),
+                        notebook_index.cell(end_location.line),
+                    ) {
+                        (Some(start_cell), Some(end_cell)) if start_cell != end_cell => {
+                            debug_assert_eq!(end_location.column.get(), 1);
+
+                            let prev_row = end_location.line.saturating_sub(1);
+                            end_location = LineColumn {
+                                line: notebook_index.cell_row(prev_row).unwrap_or(OneIndexed::MIN),
+                                column: source_code
+                                    .line_column(source_code.line_end_exclusive(prev_row))
+                                    .column,
+                            };
+                        }
+                        (Some(_), None) => {
+                            debug_assert_eq!(end_location.column.get(), 1);
+
+                            let prev_row = end_location.line.saturating_sub(1);
+                            end_location = LineColumn {
+                                line: notebook_index.cell_row(prev_row).unwrap_or(OneIndexed::MIN),
+                                column: source_code
+                                    .line_column(source_code.line_end_exclusive(prev_row))
+                                    .column,
+                            };
+                        }
+                        _ => {
+                            end_location = notebook_index.translate_line_column(&end_location);
+                        }
+                    }
+                    location = notebook_index.translate_line_column(&location);
+                }
+
+                (Some(location), Some(end_location))
+            } else {
+                (None, None)
+            };
+
+            // In preview, the locations can be optional.
+            let value = if self.config.preview {
+                JsonEdit {
+                    content: edit.content().unwrap_or_default(),
+                    location: location.map(JsonLocation::from),
+                    end_location: end_location.map(JsonLocation::from),
+                }
+            } else {
+                JsonEdit {
+                    content: edit.content().unwrap_or_default(),
+                    location: Some(location.unwrap_or_default().into()),
+                    end_location: Some(end_location.unwrap_or_default().into()),
+                }
+            };
+
+            s.serialize_element(&value)?;
+        }
+
+        s.end()
+    }
+}
+
+/// A serializable version of `Diagnostic`.
+///
+/// The `Old` variant only exists to preserve backwards compatibility. Both this and `JsonEdit`
+/// should become structs with the `New` definitions in a future Ruff release.
+#[derive(Serialize)]
+pub(crate) struct JsonDiagnostic<'a> {
+    cell: Option<OneIndexed>,
+    code: Option<&'a SecondaryCode>,
+    end_location: Option<JsonLocation>,
+    filename: Option<&'a str>,
+    fix: Option<JsonFix<'a>>,
+    location: Option<JsonLocation>,
+    message: &'a str,
+    noqa_row: Option<OneIndexed>,
+    url: Option<String>,
+}
+
+#[derive(Serialize)]
+struct JsonFix<'a> {
+    applicability: Applicability,
+    edits: ExpandedEdits<'a>,
+    message: Option<&'a str>,
+}
+
+#[derive(Serialize)]
+struct JsonLocation {
+    column: OneIndexed,
+    row: OneIndexed,
+}
+
+impl From<LineColumn> for JsonLocation {
+    fn from(location: LineColumn) -> Self {
+        JsonLocation {
+            row: location.line,
+            column: location.column,
+        }
+    }
+}
+
+#[derive(Serialize)]
+struct JsonEdit<'a> {
+    content: &'a str,
+    end_location: Option<JsonLocation>,
+    location: Option<JsonLocation>,
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostic::{
+        DiagnosticFormat,
+        render::tests::{
+            TestEnvironment, create_diagnostics, create_notebook_diagnostics,
+            create_syntax_error_diagnostics,
+        },
+    };
+
+    #[test]
+    fn output() {
+        let (env, diagnostics) = create_diagnostics(DiagnosticFormat::Json);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn syntax_errors() {
+        let (env, diagnostics) = create_syntax_error_diagnostics(DiagnosticFormat::Json);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn notebook_output() {
+        let (env, diagnostics) = create_notebook_diagnostics(DiagnosticFormat::Json);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn missing_file_stable() {
+        let mut env = TestEnvironment::new();
+        env.format(DiagnosticFormat::Json);
+        env.preview(false);
+
+        let diag = env.err().build();
+
+        insta::assert_snapshot!(
+            env.render(&diag),
+            @r#"
+        [
+          {
+            "cell": null,
+            "code": null,
+            "end_location": {
+              "column": 1,
+              "row": 1
+            },
+            "filename": "",
+            "fix": null,
+            "location": {
+              "column": 1,
+              "row": 1
+            },
+            "message": "main diagnostic message",
+            "noqa_row": null,
+            "url": "https://docs.astral.sh/ruff/rules/test-diagnostic"
+          }
+        ]
+        "#,
+        );
+    }
+
+    #[test]
+    fn missing_file_preview() {
+        let mut env = TestEnvironment::new();
+        env.format(DiagnosticFormat::Json);
+        env.preview(true);
+
+        let diag = env.err().build();
+
+        insta::assert_snapshot!(
+            env.render(&diag),
+            @r#"
+        [
+          {
+            "cell": null,
+            "code": null,
+            "end_location": null,
+            "filename": null,
+            "fix": null,
+            "location": null,
+            "message": "main diagnostic message",
+            "noqa_row": null,
+            "url": "https://docs.astral.sh/ruff/rules/test-diagnostic"
+          }
+        ]
+        "#,
+        );
+    }
+}

crates/ruff_db/src/diagnostic/render/json_lines.rs

@@ -0,0 +1,59 @@
+use crate::diagnostic::{Diagnostic, DisplayDiagnosticConfig, render::json::diagnostic_to_json};
+
+use super::FileResolver;
+
+pub(super) struct JsonLinesRenderer<'a> {
+    resolver: &'a dyn FileResolver,
+    config: &'a DisplayDiagnosticConfig,
+}
+
+impl<'a> JsonLinesRenderer<'a> {
+    pub(super) fn new(resolver: &'a dyn FileResolver, config: &'a DisplayDiagnosticConfig) -> Self {
+        Self { resolver, config }
+    }
+}
+
+impl JsonLinesRenderer<'_> {
+    pub(super) fn render(
+        &self,
+        f: &mut std::fmt::Formatter,
+        diagnostics: &[Diagnostic],
+    ) -> std::fmt::Result {
+        for diag in diagnostics {
+            writeln!(
+                f,
+                "{}",
+                serde_json::json!(diagnostic_to_json(diag, self.resolver, self.config))
+            )?;
+        }
+
+        Ok(())
+    }
+}
+#[cfg(test)]
+mod tests {
+    use crate::diagnostic::{
+        DiagnosticFormat,
+        render::tests::{
+            create_diagnostics, create_notebook_diagnostics, create_syntax_error_diagnostics,
+        },
+    };
+
+    #[test]
+    fn output() {
+        let (env, diagnostics) = create_diagnostics(DiagnosticFormat::JsonLines);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn syntax_errors() {
+        let (env, diagnostics) = create_syntax_error_diagnostics(DiagnosticFormat::JsonLines);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn notebook_output() {
+        let (env, diagnostics) = create_notebook_diagnostics(DiagnosticFormat::JsonLines);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+}

crates/ruff_db/src/diagnostic/render/pylint.rs

@@ -0,0 +1,97 @@
+use crate::diagnostic::{Diagnostic, SecondaryCode, render::FileResolver};
+
+/// Generate violations in Pylint format.
+///
+/// The format is given by this string:
+///
+/// ```python
+/// "%(path)s:%(row)d: [%(code)s] %(text)s"
+/// ```
+///
+/// See: [Flake8 documentation](https://flake8.pycqa.org/en/latest/internal/formatters.html#pylint-formatter)
+pub(super) struct PylintRenderer<'a> {
+    resolver: &'a dyn FileResolver,
+}
+
+impl<'a> PylintRenderer<'a> {
+    pub(super) fn new(resolver: &'a dyn FileResolver) -> Self {
+        Self { resolver }
+    }
+}
+
+impl PylintRenderer<'_> {
+    pub(super) fn render(
+        &self,
+        f: &mut std::fmt::Formatter,
+        diagnostics: &[Diagnostic],
+    ) -> std::fmt::Result {
+        for diagnostic in diagnostics {
+            let (filename, row) = diagnostic
+                .primary_span_ref()
+                .map(|span| {
+                    let file = span.file();
+
+                    let row = span
+                        .range()
+                        .filter(|_| !self.resolver.is_notebook(file))
+                        .map(|range| {
+                            file.diagnostic_source(self.resolver)
+                                .as_source_code()
+                                .line_column(range.start())
+                                .line
+                        });
+
+                    (file.relative_path(self.resolver).to_string_lossy(), row)
+                })
+                .unwrap_or_default();
+
+            let code = diagnostic
+                .secondary_code()
+                .map_or_else(|| diagnostic.name(), SecondaryCode::as_str);
+
+            let row = row.unwrap_or_default();
+
+            writeln!(
+                f,
+                "{path}:{row}: [{code}] {body}",
+                path = filename,
+                body = diagnostic.body()
+            )?;
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostic::{
+        DiagnosticFormat,
+        render::tests::{TestEnvironment, create_diagnostics, create_syntax_error_diagnostics},
+    };
+
+    #[test]
+    fn output() {
+        let (env, diagnostics) = create_diagnostics(DiagnosticFormat::Pylint);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn syntax_errors() {
+        let (env, diagnostics) = create_syntax_error_diagnostics(DiagnosticFormat::Pylint);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn missing_file() {
+        let mut env = TestEnvironment::new();
+        env.format(DiagnosticFormat::Pylint);
+
+        let diag = env.err().build();
+
+        insta::assert_snapshot!(
+            env.render(&diag),
+            @":1: [test-diagnostic] main diagnostic message",
+        );
+    }
+}

crates/ruff_db/src/diagnostic/render/rdjson.rs

@@ -0,0 +1,235 @@
+use serde::ser::SerializeSeq;
+use serde::{Serialize, Serializer};
+
+use ruff_diagnostics::{Edit, Fix};
+use ruff_source_file::{LineColumn, SourceCode};
+use ruff_text_size::Ranged;
+
+use crate::diagnostic::Diagnostic;
+
+use super::FileResolver;
+
+pub struct RdjsonRenderer<'a> {
+    resolver: &'a dyn FileResolver,
+}
+
+impl<'a> RdjsonRenderer<'a> {
+    pub(super) fn new(resolver: &'a dyn FileResolver) -> Self {
+        Self { resolver }
+    }
+
+    pub(super) fn render(
+        &self,
+        f: &mut std::fmt::Formatter,
+        diagnostics: &[Diagnostic],
+    ) -> std::fmt::Result {
+        write!(
+            f,
+            "{:#}",
+            serde_json::json!(RdjsonDiagnostics::new(diagnostics, self.resolver))
+        )
+    }
+}
+
+struct ExpandedDiagnostics<'a> {
+    resolver: &'a dyn FileResolver,
+    diagnostics: &'a [Diagnostic],
+}
+
+impl Serialize for ExpandedDiagnostics<'_> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut s = serializer.serialize_seq(Some(self.diagnostics.len()))?;
+
+        for diagnostic in self.diagnostics {
+            let value = diagnostic_to_rdjson(diagnostic, self.resolver);
+            s.serialize_element(&value)?;
+        }
+
+        s.end()
+    }
+}
+
+fn diagnostic_to_rdjson<'a>(
+    diagnostic: &'a Diagnostic,
+    resolver: &'a dyn FileResolver,
+) -> RdjsonDiagnostic<'a> {
+    let span = diagnostic.primary_span_ref();
+    let source_file = span.map(|span| {
+        let file = span.file();
+        (file.path(resolver), file.diagnostic_source(resolver))
+    });
+
+    let location = source_file.as_ref().map(|(path, source)| {
+        let range = diagnostic.range().map(|range| {
+            let source_code = source.as_source_code();
+            let start = source_code.line_column(range.start());
+            let end = source_code.line_column(range.end());
+            RdjsonRange::new(start, end)
+        });
+
+        RdjsonLocation { path, range }
+    });
+
+    let edits = diagnostic.fix().map(Fix::edits).unwrap_or_default();
+
+    RdjsonDiagnostic {
+        message: diagnostic.body(),
+        location,
+        code: RdjsonCode {
+            value: diagnostic
+                .secondary_code()
+                .map_or_else(|| diagnostic.name(), |code| code.as_str()),
+            url: diagnostic.to_ruff_url(),
+        },
+        suggestions: rdjson_suggestions(
+            edits,
+            source_file
+                .as_ref()
+                .map(|(_, source)| source.as_source_code()),
+        ),
+    }
+}
+
+fn rdjson_suggestions<'a>(
+    edits: &'a [Edit],
+    source_code: Option<SourceCode>,
+) -> Vec<RdjsonSuggestion<'a>> {
+    if edits.is_empty() {
+        return Vec::new();
+    }
+
+    let Some(source_code) = source_code else {
+        debug_assert!(false, "Expected a source file for a diagnostic with a fix");
+        return Vec::new();
+    };
+
+    edits
+        .iter()
+        .map(|edit| {
+            let start = source_code.line_column(edit.start());
+            let end = source_code.line_column(edit.end());
+            let range = RdjsonRange::new(start, end);
+
+            RdjsonSuggestion {
+                range,
+                text: edit.content().unwrap_or_default(),
+            }
+        })
+        .collect()
+}
+
+#[derive(Serialize)]
+struct RdjsonDiagnostics<'a> {
+    diagnostics: ExpandedDiagnostics<'a>,
+    severity: &'static str,
+    source: RdjsonSource,
+}
+
+impl<'a> RdjsonDiagnostics<'a> {
+    fn new(diagnostics: &'a [Diagnostic], resolver: &'a dyn FileResolver) -> Self {
+        Self {
+            source: RdjsonSource {
+                name: "ruff",
+                url: env!("CARGO_PKG_HOMEPAGE"),
+            },
+            severity: "WARNING",
+            diagnostics: ExpandedDiagnostics {
+                diagnostics,
+                resolver,
+            },
+        }
+    }
+}
+
+#[derive(Serialize)]
+struct RdjsonSource {
+    name: &'static str,
+    url: &'static str,
+}
+
+#[derive(Serialize)]
+struct RdjsonDiagnostic<'a> {
+    code: RdjsonCode<'a>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    location: Option<RdjsonLocation<'a>>,
+    message: &'a str,
+    #[serde(skip_serializing_if = "Vec::is_empty")]
+    suggestions: Vec<RdjsonSuggestion<'a>>,
+}
+
+#[derive(Serialize)]
+struct RdjsonLocation<'a> {
+    path: &'a str,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    range: Option<RdjsonRange>,
+}
+
+#[derive(Default, Serialize)]
+struct RdjsonRange {
+    end: LineColumn,
+    start: LineColumn,
+}
+
+impl RdjsonRange {
+    fn new(start: LineColumn, end: LineColumn) -> Self {
+        Self { start, end }
+    }
+}
+
+#[derive(Serialize)]
+struct RdjsonCode<'a> {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    url: Option<String>,
+    value: &'a str,
+}
+
+#[derive(Serialize)]
+struct RdjsonSuggestion<'a> {
+    range: RdjsonRange,
+    text: &'a str,
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostic::{
+        DiagnosticFormat,
+        render::tests::{TestEnvironment, create_diagnostics, create_syntax_error_diagnostics},
+    };
+
+    #[test]
+    fn output() {
+        let (env, diagnostics) = create_diagnostics(DiagnosticFormat::Rdjson);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn syntax_errors() {
+        let (env, diagnostics) = create_syntax_error_diagnostics(DiagnosticFormat::Rdjson);
+        insta::assert_snapshot!(env.render_diagnostics(&diagnostics));
+    }
+
+    #[test]
+    fn missing_file_stable() {
+        let mut env = TestEnvironment::new();
+        env.format(DiagnosticFormat::Rdjson);
+        env.preview(false);
+
+        let diag = env.err().build();
+
+        insta::assert_snapshot!(env.render(&diag));
+    }
+
+    #[test]
+    fn missing_file_preview() {
+        let mut env = TestEnvironment::new();
+        env.format(DiagnosticFormat::Rdjson);
+        env.preview(true);
+
+        let diag = env.err().build();
+
+        insta::assert_snapshot!(env.render(&diag));
+    }
+}

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__azure__tests__output.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/azure.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/azure.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 ##vso[task.logissue type=error;sourcepath=fib.py;linenumber=1;columnnumber=8;code=F401;]`os` imported but unused
 ##vso[task.logissue type=error;sourcepath=fib.py;linenumber=6;columnnumber=5;code=F841;]Local variable `x` is assigned to but never used

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__azure__tests__syntax_errors.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/azure.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/azure.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 ##vso[task.logissue type=error;sourcepath=syntax_errors.py;linenumber=1;columnnumber=15;]SyntaxError: Expected one or more symbol names after import
 ##vso[task.logissue type=error;sourcepath=syntax_errors.py;linenumber=3;columnnumber=12;]SyntaxError: Expected ')', found newline

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__json__tests__notebook_output.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/json.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/json.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 [
   {
@@ -84,8 +83,8 @@ snapshot_kind: text
         {
           "content": "",
           "end_location": {
-            "column": 10,
-            "row": 4
+            "column": 1,
+            "row": 5
           },
           "location": {
             "column": 1,

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__json__tests__output.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/json.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/json.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 [
   {

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__json__tests__syntax_errors.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/json.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/json.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 [
   {

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__json_lines__tests__notebook_output.snap

@@ -1,8 +1,7 @@
 ---
-source: crates/ruff_linter/src/message/json_lines.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/json_lines.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 {"cell":1,"code":"F401","end_location":{"column":10,"row":2},"filename":"notebook.ipynb","fix":{"applicability":"safe","edits":[{"content":"","end_location":{"column":10,"row":2},"location":{"column":1,"row":2}}],"message":"Remove unused import: `os`"},"location":{"column":8,"row":2},"message":"`os` imported but unused","noqa_row":2,"url":"https://docs.astral.sh/ruff/rules/unused-import"}
 {"cell":2,"code":"F401","end_location":{"column":12,"row":2},"filename":"notebook.ipynb","fix":{"applicability":"safe","edits":[{"content":"","end_location":{"column":1,"row":3},"location":{"column":1,"row":2}}],"message":"Remove unused import: `math`"},"location":{"column":8,"row":2},"message":"`math` imported but unused","noqa_row":2,"url":"https://docs.astral.sh/ruff/rules/unused-import"}
-{"cell":3,"code":"F841","end_location":{"column":6,"row":4},"filename":"notebook.ipynb","fix":{"applicability":"unsafe","edits":[{"content":"","end_location":{"column":10,"row":4},"location":{"column":1,"row":4}}],"message":"Remove assignment to unused variable `x`"},"location":{"column":5,"row":4},"message":"Local variable `x` is assigned to but never used","noqa_row":4,"url":"https://docs.astral.sh/ruff/rules/unused-variable"}
+{"cell":3,"code":"F841","end_location":{"column":6,"row":4},"filename":"notebook.ipynb","fix":{"applicability":"unsafe","edits":[{"content":"","end_location":{"column":1,"row":5},"location":{"column":1,"row":4}}],"message":"Remove assignment to unused variable `x`"},"location":{"column":5,"row":4},"message":"Local variable `x` is assigned to but never used","noqa_row":4,"url":"https://docs.astral.sh/ruff/rules/unused-variable"}

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__json_lines__tests__output.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/json_lines.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/json_lines.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 {"cell":null,"code":"F401","end_location":{"column":10,"row":1},"filename":"fib.py","fix":{"applicability":"unsafe","edits":[{"content":"","end_location":{"column":1,"row":2},"location":{"column":1,"row":1}}],"message":"Remove unused import: `os`"},"location":{"column":8,"row":1},"message":"`os` imported but unused","noqa_row":1,"url":"https://docs.astral.sh/ruff/rules/unused-import"}
 {"cell":null,"code":"F841","end_location":{"column":6,"row":6},"filename":"fib.py","fix":{"applicability":"unsafe","edits":[{"content":"","end_location":{"column":10,"row":6},"location":{"column":5,"row":6}}],"message":"Remove assignment to unused variable `x`"},"location":{"column":5,"row":6},"message":"Local variable `x` is assigned to but never used","noqa_row":6,"url":"https://docs.astral.sh/ruff/rules/unused-variable"}

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__json_lines__tests__syntax_errors.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/json_lines.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/json_lines.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 {"cell":null,"code":null,"end_location":{"column":1,"row":2},"filename":"syntax_errors.py","fix":null,"location":{"column":15,"row":1},"message":"SyntaxError: Expected one or more symbol names after import","noqa_row":null,"url":null}
 {"cell":null,"code":null,"end_location":{"column":1,"row":4},"filename":"syntax_errors.py","fix":null,"location":{"column":12,"row":3},"message":"SyntaxError: Expected ')', found newline","noqa_row":null,"url":null}

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__pylint__tests__output.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/pylint.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/pylint.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 fib.py:1: [F401] `os` imported but unused
 fib.py:6: [F841] Local variable `x` is assigned to but never used

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__pylint__tests__syntax_errors.snap

@@ -0,0 +1,6 @@
+---
+source: crates/ruff_db/src/diagnostic/render/pylint.rs
+expression: env.render_diagnostics(&diagnostics)
+---
+syntax_errors.py:1: [invalid-syntax] SyntaxError: Expected one or more symbol names after import
+syntax_errors.py:3: [invalid-syntax] SyntaxError: Expected ')', found newline

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__rdjson__tests__missing_file_preview.snap

@@ -0,0 +1,20 @@
+---
+source: crates/ruff_db/src/diagnostic/render/rdjson.rs
+expression: env.render(&diag)
+---
+{
+  "diagnostics": [
+    {
+      "code": {
+        "url": "https://docs.astral.sh/ruff/rules/test-diagnostic",
+        "value": "test-diagnostic"
+      },
+      "message": "main diagnostic message"
+    }
+  ],
+  "severity": "WARNING",
+  "source": {
+    "name": "ruff",
+    "url": "https://docs.astral.sh/ruff"
+  }
+}

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__rdjson__tests__missing_file_stable.snap

@@ -0,0 +1,20 @@
+---
+source: crates/ruff_db/src/diagnostic/render/rdjson.rs
+expression: env.render(&diag)
+---
+{
+  "diagnostics": [
+    {
+      "code": {
+        "url": "https://docs.astral.sh/ruff/rules/test-diagnostic",
+        "value": "test-diagnostic"
+      },
+      "message": "main diagnostic message"
+    }
+  ],
+  "severity": "WARNING",
+  "source": {
+    "name": "ruff",
+    "url": "https://docs.astral.sh/ruff"
+  }
+}

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__rdjson__tests__output.snap

@@ -1,7 +1,6 @@
 ---
-source: crates/ruff_linter/src/message/rdjson.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/rdjson.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 {
   "diagnostics": [
@@ -96,7 +95,7 @@ snapshot_kind: text
       "message": "Undefined name `a`"
     }
   ],
-  "severity": "warning",
+  "severity": "WARNING",
   "source": {
     "name": "ruff",
     "url": "https://docs.astral.sh/ruff"

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__rdjson__tests__syntax_errors.snap

@@ -1,14 +1,12 @@
 ---
-source: crates/ruff_linter/src/message/rdjson.rs
-expression: content
-snapshot_kind: text
+source: crates/ruff_db/src/diagnostic/render/rdjson.rs
+expression: env.render_diagnostics(&diagnostics)
 ---
 {
   "diagnostics": [
     {
       "code": {
-        "url": null,
-        "value": null
+        "value": "invalid-syntax"
       },
       "location": {
         "path": "syntax_errors.py",
@@ -27,8 +25,7 @@ snapshot_kind: text
     },
     {
       "code": {
-        "url": null,
-        "value": null
+        "value": "invalid-syntax"
       },
       "location": {
         "path": "syntax_errors.py",
@@ -46,7 +43,7 @@ snapshot_kind: text
       "message": "SyntaxError: Expected ')', found newline"
     }
   ],
-  "severity": "warning",
+  "severity": "WARNING",
   "source": {
     "name": "ruff",
     "url": "https://docs.astral.sh/ruff"

crates/ruff_db/src/lib.rs

@@ -5,6 +5,7 @@ use ruff_python_ast::PythonVersion;
 use rustc_hash::FxHasher;
 use std::hash::BuildHasherDefault;
 use std::num::NonZeroUsize;
+use ty_static::EnvVars;
 
 pub mod diagnostic;
 pub mod display;
@@ -27,6 +28,21 @@ pub use web_time::{Instant, SystemTime, SystemTimeError};
 pub type FxDashMap<K, V> = dashmap::DashMap<K, V, BuildHasherDefault<FxHasher>>;
 pub type FxDashSet<K> = dashmap::DashSet<K, BuildHasherDefault<FxHasher>>;
 
+static VERSION: std::sync::OnceLock<String> = std::sync::OnceLock::new();
+
+/// Returns the version of the executing program if set.
+pub fn program_version() -> Option<&'static str> {
+    VERSION.get().map(|version| version.as_str())
+}
+
+/// Sets the version of the executing program.
+///
+/// ## Errors
+/// If the version has already been initialized (can only be set once).
+pub fn set_program_version(version: String) -> Result<(), String> {
+    VERSION.set(version)
+}
+
 /// Most basic database that gives access to files, the host system, source code, and parsed AST.
 #[salsa::db]
 pub trait Db: salsa::Database {
@@ -50,8 +66,8 @@ pub trait Db: salsa::Database {
 /// ty can still spawn more threads for other tasks, e.g. to wait for a Ctrl+C signal or
 /// watching the files for changes.
 pub fn max_parallelism() -> NonZeroUsize {
-    std::env::var("TY_MAX_PARALLELISM")
-        .or_else(|_| std::env::var("RAYON_NUM_THREADS"))
+    std::env::var(EnvVars::TY_MAX_PARALLELISM)
+        .or_else(|_| std::env::var(EnvVars::RAYON_NUM_THREADS))
         .ok()
         .and_then(|s| s.parse().ok())
         .unwrap_or_else(|| {

crates/ruff_db/src/vendored.rs

@@ -21,6 +21,19 @@ type LockedZipArchive<'a> = MutexGuard<'a, VendoredZipArchive>;
 ///
 /// "Files" in the `VendoredFileSystem` are read-only and immutable.
 /// Directories are supported, but symlinks and hardlinks cannot exist.
+///
+/// # Path separators
+///
+/// At time of writing (2025-07-11), this implementation always uses `/` as a
+/// path separator, even in Windows environments where `\` is traditionally
+/// used as a file path separator. Namely, this is only currently used with zip
+/// files built by `crates/ty_vendored/build.rs`.
+///
+/// Callers using this may provide paths that use a `\` as a separator. It will
+/// be transparently normalized to `/`.
+///
+/// This is particularly important because the presence of a trailing separator
+/// in a zip file is conventionally used to indicate a directory entry.
 #[derive(Clone)]
 pub struct VendoredFileSystem {
     inner: Arc<Mutex<VendoredZipArchive>>,
@@ -115,6 +128,68 @@ impl VendoredFileSystem {
         read_to_string(self, path.as_ref())
     }
 
+    /// Read the direct children of the directory
+    /// identified by `path`.
+    ///
+    /// If `path` is not a directory, then this will
+    /// return an empty `Vec`.
+    pub fn read_directory(&self, dir: impl AsRef<VendoredPath>) -> Vec<DirectoryEntry> {
+        // N.B. We specifically do not return an iterator here to avoid
+        // holding a lock for the lifetime of the iterator returned.
+        // That is, it seems like a footgun to keep the zip archive
+        // locked during iteration, since the unit of work for each
+        // item in the iterator could be arbitrarily long. Allocating
+        // up front and stuffing all entries into it is probably the
+        // simplest solution and what we do here. If this becomes
+        // a problem, there are other strategies we could pursue.
+        // (Amortizing allocs, using a different synchronization
+        // behavior or even exposing additional APIs.) ---AG
+
+        fn read_directory(fs: &VendoredFileSystem, dir: &VendoredPath) -> Vec<DirectoryEntry> {
+            let mut normalized = NormalizedVendoredPath::from(dir);
+            if !normalized.as_str().ends_with('/') {
+                normalized = normalized.with_trailing_slash();
+            }
+            let archive = fs.lock_archive();
+            let mut entries = vec![];
+            for name in archive.0.file_names() {
+                // Any entry that doesn't have the `path` (with a
+                // trailing slash) as a prefix cannot possibly be in
+                // the directory referenced by `path`.
+                let Some(without_dir_prefix) = name.strip_prefix(normalized.as_str()) else {
+                    continue;
+                };
+                // Filter out an entry equivalent to the path given
+                // since we only want children of the directory.
+                if without_dir_prefix.is_empty() {
+                    continue;
+                }
+                // We only want *direct* children. Files that are
+                // direct children cannot have any slashes (or else
+                // they are not direct children). Directories that
+                // are direct children can only have one slash and
+                // it must be at the end.
+                //
+                // (We do this manually ourselves to avoid doing a
+                // full file lookup and metadata retrieval via the
+                // `zip` crate.)
+                let file_type = FileType::from_zip_file_name(without_dir_prefix);
+                let slash_count = without_dir_prefix.matches('/').count();
+                match file_type {
+                    FileType::File if slash_count > 0 => continue,
+                    FileType::Directory if slash_count > 1 => continue,
+                    _ => {}
+                }
+                entries.push(DirectoryEntry {
+                    path: VendoredPathBuf::from(name),
+                    file_type,
+                });
+            }
+            entries
+        }
+        read_directory(self, dir.as_ref())
+    }
+
     /// Acquire a lock on the underlying zip archive.
     /// The call will block until it is able to acquire the lock.
     ///
@@ -206,6 +281,14 @@ pub enum FileType {
 }
 
 impl FileType {
+    fn from_zip_file_name(name: &str) -> FileType {
+        if name.ends_with('/') {
+            FileType::Directory
+        } else {
+            FileType::File
+        }
+    }
+
     pub const fn is_file(self) -> bool {
         matches!(self, Self::File)
     }
@@ -244,6 +327,30 @@ impl Metadata {
     }
 }
 
+#[derive(Debug, PartialEq, Eq)]
+pub struct DirectoryEntry {
+    path: VendoredPathBuf,
+    file_type: FileType,
+}
+
+impl DirectoryEntry {
+    pub fn new(path: VendoredPathBuf, file_type: FileType) -> Self {
+        Self { path, file_type }
+    }
+
+    pub fn into_path(self) -> VendoredPathBuf {
+        self.path
+    }
+
+    pub fn path(&self) -> &VendoredPath {
+        &self.path
+    }
+
+    pub fn file_type(&self) -> FileType {
+        self.file_type
+    }
+}
+
 /// Newtype wrapper around a ZipArchive.
 #[derive(Debug)]
 struct VendoredZipArchive(ZipArchive<io::Cursor<Cow<'static, [u8]>>>);
@@ -498,6 +605,60 @@ pub(crate) mod tests {
         test_directory("./stdlib/asyncio/../asyncio/")
     }
 
+    fn readdir_snapshot(fs: &VendoredFileSystem, path: &str) -> String {
+        let mut paths = fs
+            .read_directory(VendoredPath::new(path))
+            .into_iter()
+            .map(|entry| entry.path().to_string())
+            .collect::<Vec<String>>();
+        paths.sort();
+        paths.join("\n")
+    }
+
+    #[test]
+    fn read_directory_stdlib() {
+        let mock_typeshed = mock_typeshed();
+
+        assert_snapshot!(readdir_snapshot(&mock_typeshed, "stdlib"), @r"
+        vendored://stdlib/asyncio/
+        vendored://stdlib/functools.pyi
+        ");
+        assert_snapshot!(readdir_snapshot(&mock_typeshed, "stdlib/"), @r"
+        vendored://stdlib/asyncio/
+        vendored://stdlib/functools.pyi
+        ");
+        assert_snapshot!(readdir_snapshot(&mock_typeshed, "./stdlib"), @r"
+        vendored://stdlib/asyncio/
+        vendored://stdlib/functools.pyi
+        ");
+        assert_snapshot!(readdir_snapshot(&mock_typeshed, "./stdlib/"), @r"
+        vendored://stdlib/asyncio/
+        vendored://stdlib/functools.pyi
+        ");
+    }
+
+    #[test]
+    fn read_directory_asyncio() {
+        let mock_typeshed = mock_typeshed();
+
+        assert_snapshot!(
+            readdir_snapshot(&mock_typeshed, "stdlib/asyncio"),
+            @"vendored://stdlib/asyncio/tasks.pyi",
+        );
+        assert_snapshot!(
+            readdir_snapshot(&mock_typeshed, "./stdlib/asyncio"),
+            @"vendored://stdlib/asyncio/tasks.pyi",
+        );
+        assert_snapshot!(
+            readdir_snapshot(&mock_typeshed, "stdlib/asyncio/"),
+            @"vendored://stdlib/asyncio/tasks.pyi",
+        );
+        assert_snapshot!(
+            readdir_snapshot(&mock_typeshed, "./stdlib/asyncio/"),
+            @"vendored://stdlib/asyncio/tasks.pyi",
+        );
+    }
+
     fn test_nonexistent_path(path: &str) {
         let mock_typeshed = mock_typeshed();
         let path = VendoredPath::new(path);

crates/ruff_db/src/vendored/path.rs

@@ -17,6 +17,10 @@ impl VendoredPath {
         unsafe { &*(path as *const Utf8Path as *const VendoredPath) }
     }
 
+    pub fn file_name(&self) -> Option<&str> {
+        self.0.file_name()
+    }
+
     pub fn to_path_buf(&self) -> VendoredPathBuf {
         VendoredPathBuf(self.0.to_path_buf())
     }

crates/ruff_dev/Cargo.toml

@@ -13,6 +13,7 @@ license = { workspace = true }
 [dependencies]
 ty = { workspace = true }
 ty_project = { workspace = true, features = ["schemars"] }
+ty_static = { workspace = true }
 ruff = { workspace = true }
 ruff_formatter = { workspace = true }
 ruff_linter = { workspace = true, features = ["schemars"] }

crates/ruff_dev/src/generate_all.rs

@@ -4,7 +4,7 @@ use anyhow::Result;
 
 use crate::{
     generate_cli_help, generate_docs, generate_json_schema, generate_ty_cli_reference,
-    generate_ty_options, generate_ty_rules, generate_ty_schema,
+    generate_ty_env_vars_reference, generate_ty_options, generate_ty_rules, generate_ty_schema,
 };
 
 pub(crate) const REGENERATE_ALL_COMMAND: &str = "cargo dev generate-all";
@@ -44,5 +44,8 @@ pub(crate) fn main(args: &Args) -> Result<()> {
     generate_ty_options::main(&generate_ty_options::Args { mode: args.mode })?;
     generate_ty_rules::main(&generate_ty_rules::Args { mode: args.mode })?;
     generate_ty_cli_reference::main(&generate_ty_cli_reference::Args { mode: args.mode })?;
+    generate_ty_env_vars_reference::main(&generate_ty_env_vars_reference::Args {
+        mode: args.mode,
+    })?;
     Ok(())
 }

crates/ruff_dev/src/generate_ty_env_vars_reference.rs

@@ -0,0 +1,119 @@
+//! Generate the environment variables reference from `ty_static::EnvVars`.
+
+use std::collections::BTreeSet;
+use std::fs;
+use std::path::PathBuf;
+
+use anyhow::bail;
+use pretty_assertions::StrComparison;
+
+use ty_static::EnvVars;
+
+use crate::generate_all::Mode;
+
+#[derive(clap::Args)]
+pub(crate) struct Args {
+    #[arg(long, default_value_t, value_enum)]
+    pub(crate) mode: Mode,
+}
+
+pub(crate) fn main(args: &Args) -> anyhow::Result<()> {
+    let reference_string = generate();
+    let filename = "environment.md";
+    let reference_path = PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+        .parent()
+        .unwrap()
+        .parent()
+        .unwrap()
+        .join("crates")
+        .join("ty")
+        .join("docs")
+        .join(filename);
+
+    match args.mode {
+        Mode::DryRun => {
+            println!("{reference_string}");
+        }
+        Mode::Check => match fs::read_to_string(&reference_path) {
+            Ok(current) => {
+                if current == reference_string {
+                    println!("Up-to-date: {filename}");
+                } else {
+                    let comparison = StrComparison::new(&current, &reference_string);
+                    bail!(
+                        "{filename} changed, please run `cargo dev generate-ty-env-vars-reference`:\n{comparison}"
+                    );
+                }
+            }
+            Err(err) if err.kind() == std::io::ErrorKind::NotFound => {
+                bail!(
+                    "{filename} not found, please run `cargo dev generate-ty-env-vars-reference`"
+                );
+            }
+            Err(err) => {
+                bail!(
+                    "{filename} changed, please run `cargo dev generate-ty-env-vars-reference`:\n{err}"
+                );
+            }
+        },
+        Mode::Write => {
+            // Ensure the docs directory exists
+            if let Some(parent) = reference_path.parent() {
+                fs::create_dir_all(parent)?;
+            }
+
+            match fs::read_to_string(&reference_path) {
+                Ok(current) => {
+                    if current == reference_string {
+                        println!("Up-to-date: {filename}");
+                    } else {
+                        println!("Updating: {filename}");
+                        fs::write(&reference_path, reference_string.as_bytes())?;
+                    }
+                }
+                Err(err) if err.kind() == std::io::ErrorKind::NotFound => {
+                    println!("Updating: {filename}");
+                    fs::write(&reference_path, reference_string.as_bytes())?;
+                }
+                Err(err) => {
+                    bail!(
+                        "{filename} changed, please run `cargo dev generate-ty-env-vars-reference`:\n{err}"
+                    );
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+fn generate() -> String {
+    let mut output = String::new();
+
+    output.push_str("# Environment variables\n\n");
+
+    // Partition and sort environment variables into TY_ and external variables.
+    let (ty_vars, external_vars): (BTreeSet<_>, BTreeSet<_>) = EnvVars::metadata()
+        .iter()
+        .partition(|(var, _)| var.starts_with("TY_"));
+
+    output.push_str("ty defines and respects the following environment variables:\n\n");
+
+    for (var, doc) in ty_vars {
+        output.push_str(&render(var, doc));
+    }
+
+    output.push_str("## Externally-defined variables\n\n");
+    output.push_str("ty also reads the following externally defined environment variables:\n\n");
+
+    for (var, doc) in external_vars {
+        output.push_str(&render(var, doc));
+    }
+
+    output
+}
+
+/// Render an environment variable and its documentation.
+fn render(var: &str, doc: &str) -> String {
+    format!("### `{var}`\n\n{doc}\n\n")
+}

crates/ruff_dev/src/main.rs

@@ -18,6 +18,7 @@ mod generate_json_schema;
 mod generate_options;
 mod generate_rules_table;
 mod generate_ty_cli_reference;
+mod generate_ty_env_vars_reference;
 mod generate_ty_options;
 mod generate_ty_rules;
 mod generate_ty_schema;
@@ -53,6 +54,8 @@ enum Command {
     /// Generate a Markdown-compatible listing of configuration options.
     GenerateOptions,
     GenerateTyOptions(generate_ty_options::Args),
+    /// Generate environment variables reference for ty.
+    GenerateTyEnvVarsReference(generate_ty_env_vars_reference::Args),
     /// Generate CLI help.
     GenerateCliHelp(generate_cli_help::Args),
     /// Generate Markdown docs.
@@ -98,6 +101,7 @@ fn main() -> Result<ExitCode> {
         Command::GenerateTyRules(args) => generate_ty_rules::main(&args)?,
         Command::GenerateOptions => println!("{}", generate_options::generate()),
         Command::GenerateTyOptions(args) => generate_ty_options::main(&args)?,
+        Command::GenerateTyEnvVarsReference(args) => generate_ty_env_vars_reference::main(&args)?,
         Command::GenerateCliHelp(args) => generate_cli_help::main(&args)?,
         Command::GenerateDocs(args) => generate_docs::main(&args)?,
         Command::PrintAST(args) => print_ast::main(&args)?,

crates/ruff_diagnostics/Cargo.toml

@@ -16,5 +16,6 @@ doctest = false
 [dependencies]
 ruff_text_size = { workspace = true }
 
+get-size2 = { workspace = true }
 is-macro = { workspace = true }
 serde = { workspace = true, optional = true, features = [] }

crates/ruff_diagnostics/src/edit.rs

@@ -7,7 +7,7 @@ use ruff_text_size::{Ranged, TextRange, TextSize};
 
 /// A text edit to be applied to a source file. Inserts, deletes, or replaces
 /// content at a given location.
-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, get_size2::GetSize)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct Edit {
     /// The start location of the edit.

crates/ruff_diagnostics/src/fix.rs

@@ -6,7 +6,9 @@ use ruff_text_size::{Ranged, TextSize};
 use crate::edit::Edit;
 
 /// Indicates if a fix can be applied.
-#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, is_macro::Is)]
+#[derive(
+    Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, is_macro::Is, get_size2::GetSize,
+)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "serde", serde(rename_all = "lowercase"))]
 pub enum Applicability {
@@ -30,7 +32,7 @@ pub enum Applicability {
 }
 
 /// Indicates the level of isolation required to apply a fix.
-#[derive(Default, Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Default, Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, get_size2::GetSize)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum IsolationLevel {
     /// The fix should be applied as long as no other fixes in the same group have been applied.
@@ -41,7 +43,7 @@ pub enum IsolationLevel {
 }
 
 /// A collection of [`Edit`] elements to be applied to a source file.
-#[derive(Debug, PartialEq, Eq, Clone)]
+#[derive(Debug, PartialEq, Eq, Clone, get_size2::GetSize)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct Fix {
     /// The [`Edit`] elements to be applied, sorted by [`Edit::start`] in ascending order.

crates/ruff_linter/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff_linter"
-version = "0.12.1"
+version = "0.12.3"
 publish = false
 authors = { workspace = true }
 edition = { workspace = true }
@@ -15,7 +15,7 @@ license = { workspace = true }
 [dependencies]
 ruff_annotate_snippets = { workspace = true }
 ruff_cache = { workspace = true }
-ruff_db = { workspace = true }
+ruff_db = { workspace = true, features = ["serde"] }
 ruff_diagnostics = { workspace = true, features = ["serde"] }
 ruff_notebook = { workspace = true }
 ruff_macros = { workspace = true }

crates/ruff_linter/resources/test/fixtures/flake8_bandit/S112.py

@@ -1,29 +1,30 @@
-try:
-    pass
-except Exception:
-    continue
+for _ in []:
+    try:
+        pass
+    except Exception:
+        continue
 
-try:
-    pass
-except:
-    continue
+    try:
+        pass
+    except:
+        continue
 
-try:
-    pass
-except (Exception,):
-    continue
+    try:
+        pass
+    except (Exception,):
+        continue
 
-try:
-    pass
-except (Exception, ValueError):
-    continue
+    try:
+        pass
+    except (Exception, ValueError):
+        continue
 
-try:
-    pass
-except ValueError:
-    continue
+    try:
+        pass
+    except ValueError:
+        continue
 
-try:
-    pass
-except (ValueError,):
-    continue
+    try:
+        pass
+    except (ValueError,):
+        continue

crates/ruff_linter/resources/test/fixtures/flake8_bugbear/B017_0.py

@@ -1,10 +1,10 @@
 """
 Should emit:
-B017 - on lines 23 and 41
+B017 - on lines 24, 28, 46, 49, 52, 58, 62, 68, and 71
 """
 import asyncio
 import unittest
-import pytest
+import pytest, contextlib
 
 CONSTANT = True
 
@@ -56,3 +56,17 @@ def test_pytest_raises():
 
     with contextlib.nullcontext(), pytest.raises(Exception):
         raise ValueError("Multiple context managers")
+
+
+def test_pytest_raises_keyword():
+    with pytest.raises(expected_exception=Exception):
+        raise ValueError("Should be flagged")
+
+def test_assert_raises_keyword():
+    class TestKwargs(unittest.TestCase):
+        def test_method(self):
+            with self.assertRaises(exception=Exception):
+                raise ValueError("Should be flagged")
+
+            with self.assertRaises(exception=BaseException):
+                raise ValueError("Should be flagged")

crates/ruff_linter/resources/test/fixtures/flake8_bugbear/B017_1.py

@@ -0,0 +1,28 @@
+"""
+Should emit:
+B017 - on lines 20, 21, 25, and 26
+"""
+import unittest
+import pytest
+
+
+def something_else() -> None:
+    for i in (1, 2, 3):
+        print(i)
+
+
+class Foo:
+    pass
+
+
+class Foobar(unittest.TestCase):
+    def call_form_raises(self) -> None:
+        self.assertRaises(Exception, something_else)
+        self.assertRaises(BaseException, something_else)
+
+
+def test_pytest_call_form() -> None:
+    pytest.raises(Exception, something_else)
+    pytest.raises(BaseException, something_else)
+
+    pytest.raises(Exception, something_else, match="hello")

crates/ruff_linter/resources/test/fixtures/flake8_bugbear/B031.py

@@ -185,38 +185,45 @@ for _section, section_items in groupby(items, key=lambda p: p[1]):
     collect_shop_items(shopper, section_items)
 
 # Shouldn't trigger the warning when there is a return statement.
-for _section, section_items in groupby(items, key=lambda p: p[1]):
-    if _section == "greens":
+def foo():
+    for _section, section_items in groupby(items, key=lambda p: p[1]):
+        if _section == "greens":
+            collect_shop_items(shopper, section_items)
+            return
+        elif _section == "frozen items":
+            return section_items
         collect_shop_items(shopper, section_items)
-        return
-    elif _section == "frozen items":
-        return section_items
-    collect_shop_items(shopper, section_items)
 
 # Should trigger the warning for duplicate access, even if is a return statement after.
-for _section, section_items in groupby(items, key=lambda p: p[1]):
-    if _section == "greens":
-        collect_shop_items(shopper, section_items)
-        collect_shop_items(shopper, section_items)
-        return
+def foo():
+    from itertools import groupby
+    for _section, section_items in groupby(items, key=lambda p: p[1]):
+        if _section == "greens":
+            collect_shop_items(shopper, section_items)
+            collect_shop_items(shopper, section_items)
+            return
 
 # Should trigger the warning for duplicate access, even if is a return in another branch.
-for _section, section_items in groupby(items, key=lambda p: p[1]):
-    if _section == "greens":
-        collect_shop_items(shopper, section_items)
-        return
-    elif _section == "frozen items":
-        collect_shop_items(shopper, section_items)
-        collect_shop_items(shopper, section_items)
+def foo():
+    from itertools import groupby
+    for _section, section_items in groupby(items, key=lambda p: p[1]):
+        if _section == "greens":
+            collect_shop_items(shopper, section_items)
+            return
+        elif _section == "frozen items":
+            collect_shop_items(shopper, section_items)
+            collect_shop_items(shopper, section_items)
 
 # Should trigger, since only one branch has a return statement.
-for _section, section_items in groupby(items, key=lambda p: p[1]):
-    if _section == "greens":
-        collect_shop_items(shopper, section_items)
-        return
-    elif _section == "frozen items":
-        collect_shop_items(shopper, section_items)
-    collect_shop_items(shopper, section_items)  # B031
+def foo():
+    from itertools import groupby
+    for _section, section_items in groupby(items, key=lambda p: p[1]):
+        if _section == "greens":
+            collect_shop_items(shopper, section_items)
+            return
+        elif _section == "frozen items":
+            collect_shop_items(shopper, section_items)
+        collect_shop_items(shopper, section_items)  # B031
 
 # Let's redefine the `groupby` function to make sure we pick up the correct one.
 # NOTE: This should always be at the end of the file.

crates/ruff_linter/resources/test/fixtures/flake8_django/DJ008.py

@@ -181,3 +181,51 @@ class SubclassTestModel2(TestModel4):
 # Subclass without __str__
 class SubclassTestModel3(TestModel1):
     pass
+
+
+# Test cases for type-annotated abstract models - these should NOT trigger DJ008
+from typing import ClassVar
+from django_stubs_ext.db.models import TypedModelMeta
+
+
+class TypeAnnotatedAbstractModel1(models.Model):
+    """Model with type-annotated abstract = True - should not trigger DJ008"""
+    new_field = models.CharField(max_length=10)
+
+    class Meta(TypedModelMeta):
+        abstract: ClassVar[bool] = True
+
+
+class TypeAnnotatedAbstractModel2(models.Model):
+    """Model with type-annotated abstract = True using regular Meta - should not trigger DJ008"""  
+    new_field = models.CharField(max_length=10)
+
+    class Meta:
+        abstract: ClassVar[bool] = True
+
+
+class TypeAnnotatedAbstractModel3(models.Model):
+    """Model with type-annotated abstract = True but without ClassVar - should not trigger DJ008"""
+    new_field = models.CharField(max_length=10)
+
+    class Meta:
+        abstract: bool = True
+
+
+class TypeAnnotatedNonAbstractModel(models.Model):
+    """Model with type-annotated abstract = False - should trigger DJ008"""
+    new_field = models.CharField(max_length=10)
+
+    class Meta:
+        abstract: ClassVar[bool] = False
+
+
+class TypeAnnotatedAbstractModelWithStr(models.Model):
+    """Model with type-annotated abstract = True and __str__ method - should not trigger DJ008"""
+    new_field = models.CharField(max_length=10)
+
+    class Meta(TypedModelMeta):
+        abstract: ClassVar[bool] = True
+
+    def __str__(self):
+        return self.new_field

crates/ruff_linter/resources/test/fixtures/flake8_gettext/INT001.py

@@ -1 +1,4 @@
 _(f"{'value'}")
+
+# Don't trigger for t-strings
+_(t"{'value'}")

crates/ruff_linter/resources/test/fixtures/flake8_logging_format/G004.py

@@ -13,3 +13,7 @@ from logging import info
 
 info(f"{name}")
 info(f"{__name__}")
+
+# Don't trigger for t-strings
+info(t"{name}")
+info(t"{__name__}")

crates/ruff_linter/resources/test/fixtures/flake8_pie/PIE804.py

@@ -26,8 +26,9 @@ abc(**{'a': b}, **{'a': c})  # PIE804
 abc(a=1, **{'a': c}, **{'b': c})  # PIE804
 
 # Some values need to be parenthesized.
-abc(foo=1, **{'bar': (bar := 1)})  # PIE804
-abc(foo=1, **{'bar': (yield 1)})  # PIE804
+def foo():
+    abc(foo=1, **{'bar': (bar := 1)})  # PIE804
+    abc(foo=1, **{'bar': (yield 1)})  # PIE804
 
 # https://github.com/astral-sh/ruff/issues/18036
 # The autofix for this is unsafe due to the comments inside the dictionary.

crates/ruff_linter/resources/test/fixtures/flake8_pytest_style/PT011.py

@@ -47,3 +47,7 @@ def test_error_match_is_empty():
 
     with pytest.raises(ValueError, match=f""):
         raise ValueError("Can't divide 1 by 0")
+
+def test_ok_t_string_match():
+    with pytest.raises(ValueError, match=t""):
+        raise ValueError("Can't divide 1 by 0")

crates/ruff_linter/resources/test/fixtures/flake8_pytest_style/PT016.py

@@ -23,3 +23,9 @@ def f():
     pytest.fail(msg=f"")
     pytest.fail(reason="")
     pytest.fail(reason=f"")
+
+# Skip for t-strings
+def g():
+    pytest.fail(t"")
+    pytest.fail(msg=t"")
+    pytest.fail(reason=t"")

crates/ruff_linter/resources/test/fixtures/flake8_pytest_style/PT030.py

@@ -32,3 +32,7 @@ def test_error_match_is_empty():
 
     with pytest.warns(UserWarning, match=f""):
         pass
+
+def test_ok_match_t_string():
+    with pytest.warns(UserWarning, match=t""):
+        pass

crates/ruff_linter/resources/test/fixtures/flake8_return/RET504.py

@@ -422,6 +422,35 @@ def func(a: dict[str, int]) -> list[dict[str, int]]:
         services = a["services"]
         return services
 
+
+# See: https://github.com/astral-sh/ruff/issues/14052
+def outer() -> list[object]:
+    @register
+    async def inner() -> None:
+        print(layout)
+
+    layout = [...]
+    return layout
+
+def outer() -> list[object]:
+    with open("") as f:
+        async def inner() -> None:
+            print(layout)
+
+    layout = [...]
+    return layout
+
+
+def outer() -> list[object]:
+    def inner():
+        with open("") as f:
+            async def inner_inner() -> None:
+                print(layout)
+
+    layout = [...]
+    return layout
+
+
 # See: https://github.com/astral-sh/ruff/issues/18411
 def f():
     (#=

crates/ruff_linter/resources/test/fixtures/flake8_simplify/SIM115.py

@@ -27,8 +27,9 @@ with contextlib.ExitStack() as stack:
     close_files = stack.pop_all().close
 
 # OK
-with contextlib.AsyncExitStack() as exit_stack:
-    f = await exit_stack.enter_async_context(open("filename"))
+async def foo():
+    with contextlib.AsyncExitStack() as exit_stack:
+        f = await exit_stack.enter_async_context(open("filename"))
 
 # OK (false negative)
 with contextlib.ExitStack():
@@ -275,9 +276,10 @@ class ExampleClassTests(TestCase):
         cls.enterClassContext(open("filename"))
 
 # OK
-class ExampleAsyncTests(IsolatedAsyncioTestCase):
-    async def test_something(self):
-        await self.enterAsyncContext(open("filename"))
+async def foo():
+    class ExampleAsyncTests(IsolatedAsyncioTestCase):
+        async def test_something(self):
+            await self.enterAsyncContext(open("filename"))
 
 # OK
 class ExampleTests(TestCase):

crates/ruff_linter/resources/test/fixtures/flake8_simplify/SIM116.py

@@ -1,98 +1,99 @@
-# Errors
-a = "hello"
+def foo():
+    # Errors
+    a = "hello"
 
-# SIM116
-if a == "foo":
-    return "bar"
-elif a == "bar":
-    return "baz"
-elif a == "boo":
-    return "ooh"
-else:
-    return 42
-
-# SIM116
-if a == 1:
-    return (1, 2, 3)
-elif a == 2:
-    return (4, 5, 6)
-elif a == 3:
-    return (7, 8, 9)
-else:
-    return (10, 11, 12)
-
-# SIM116
-if a == 1:
-    return (1, 2, 3)
-elif a == 2:
-    return (4, 5, 6)
-elif a == 3:
-    return (7, 8, 9)
-
-# SIM116
-if a == "hello 'sir'":
-    return (1, 2, 3)
-elif a == 'goodbye "mam"':
-    return (4, 5, 6)
-elif a == """Fairwell 'mister'""":
-    return (7, 8, 9)
-else:
-    return (10, 11, 12)
-
-# SIM116
-if a == b"one":
-    return 1
-elif a == b"two":
-    return 2
-elif a == b"three":
-    return 3
-
-# SIM116
-if a == "hello 'sir'":
-    return ("hello'", 'hi"', 3)
-elif a == 'goodbye "mam"':
-    return (4, 5, 6)
-elif a == """Fairwell 'mister'""":
-    return (7, 8, 9)
-else:
-    return (10, 11, 12)
-
-# OK
-if a == "foo":
-    return "bar"
-elif a == "bar":
-    return baz()
-elif a == "boo":
-    return "ooh"
-else:
-    return 42
-
-# OK
-if a == b"one":
-    return 1
-elif b == b"two":
-    return 2
-elif a == b"three":
-    return 3
-
-# SIM116
-if func_name == "create":
-    return "A"
-elif func_name == "modify":
-    return "M"
-elif func_name == "remove":
-    return "D"
-elif func_name == "move":
-    return "MV"
-
-# OK
-def no_return_in_else(platform):
-    if platform == "linux":
-        return "auditwheel repair -w {dest_dir} {wheel}"
-    elif platform == "macos":
-        return "delocate-wheel --require-archs {delocate_archs} -w {dest_dir} -v {wheel}"
-    elif platform == "windows":
-        return ""
+    # SIM116
+    if a == "foo":
+        return "bar"
+    elif a == "bar":
+        return "baz"
+    elif a == "boo":
+        return "ooh"
     else:
-        msg = f"Unknown platform: {platform!r}"
-        raise ValueError(msg)
+        return 42
+
+    # SIM116
+    if a == 1:
+        return (1, 2, 3)
+    elif a == 2:
+        return (4, 5, 6)
+    elif a == 3:
+        return (7, 8, 9)
+    else:
+        return (10, 11, 12)
+
+    # SIM116
+    if a == 1:
+        return (1, 2, 3)
+    elif a == 2:
+        return (4, 5, 6)
+    elif a == 3:
+        return (7, 8, 9)
+
+    # SIM116
+    if a == "hello 'sir'":
+        return (1, 2, 3)
+    elif a == 'goodbye "mam"':
+        return (4, 5, 6)
+    elif a == """Fairwell 'mister'""":
+        return (7, 8, 9)
+    else:
+        return (10, 11, 12)
+
+    # SIM116
+    if a == b"one":
+        return 1
+    elif a == b"two":
+        return 2
+    elif a == b"three":
+        return 3
+
+    # SIM116
+    if a == "hello 'sir'":
+        return ("hello'", 'hi"', 3)
+    elif a == 'goodbye "mam"':
+        return (4, 5, 6)
+    elif a == """Fairwell 'mister'""":
+        return (7, 8, 9)
+    else:
+        return (10, 11, 12)
+
+    # OK
+    if a == "foo":
+        return "bar"
+    elif a == "bar":
+        return baz()
+    elif a == "boo":
+        return "ooh"
+    else:
+        return 42
+
+    # OK
+    if a == b"one":
+        return 1
+    elif b == b"two":
+        return 2
+    elif a == b"three":
+        return 3
+
+    # SIM116
+    if func_name == "create":
+        return "A"
+    elif func_name == "modify":
+        return "M"
+    elif func_name == "remove":
+        return "D"
+    elif func_name == "move":
+        return "MV"
+
+    # OK
+    def no_return_in_else(platform):
+        if platform == "linux":
+            return "auditwheel repair -w {dest_dir} {wheel}"
+        elif platform == "macos":
+            return "delocate-wheel --require-archs {delocate_archs} -w {dest_dir} -v {wheel}"
+        elif platform == "windows":
+            return ""
+        else:
+            msg = f"Unknown platform: {platform!r}"
+            raise ValueError(msg)

crates/ruff_linter/resources/test/fixtures/flake8_type_checking/TC001-3_future.py

@@ -0,0 +1,10 @@
+from collections import Counter
+
+from elsewhere import third_party
+
+from . import first_party
+
+
+def f(x: first_party.foo): ...
+def g(x: third_party.bar): ...
+def h(x: Counter): ...

crates/ruff_linter/resources/test/fixtures/flake8_type_checking/TC001_future.py

@@ -0,0 +1,68 @@
+def f():
+    from . import first_party
+
+    def f(x: first_party.foo): ...
+
+
+# Type parameter bounds
+def g():
+    from . import foo
+
+    class C[T: foo.Ty]: ...
+
+
+def h():
+    from . import foo
+
+    def f[T: foo.Ty](x: T): ...
+
+
+def i():
+    from . import foo
+
+    type Alias[T: foo.Ty] = list[T]
+
+
+# Type parameter defaults
+def j():
+    from . import foo
+
+    class C[T = foo.Ty]: ...
+
+
+def k():
+    from . import foo
+
+    def f[T = foo.Ty](x: T): ...
+
+
+def l():
+    from . import foo
+
+    type Alias[T = foo.Ty] = list[T]
+
+
+# non-generic type alias
+def m():
+    from . import foo
+
+    type Alias = foo.Ty
+
+
+# unions
+from typing import Union
+
+
+def n():
+    from . import foo
+
+    def f(x: Union[foo.Ty, int]): ...
+    def g(x: foo.Ty | int): ...
+
+
+# runtime and typing usage
+def o():
+    from . import foo
+
+    def f(x: foo.Ty):
+        return foo.Ty()

crates/ruff_linter/resources/test/fixtures/flake8_type_checking/TC001_future_present.py

@@ -0,0 +1,6 @@
+from __future__ import annotations
+
+from . import first_party
+
+
+def f(x: first_party.foo): ...

crates/ruff_linter/resources/test/fixtures/flake8_type_checking/TC008.py

@@ -50,3 +50,23 @@ class Baz:
     class Nested:
         a: TypeAlias = 'Baz'  # OK
         type A = 'Baz'  # TC008
+
+# O should have parenthesis added
+o: TypeAlias = """int
+| None"""
+type O = """int
+| None"""
+
+# P, Q, and R should not have parenthesis added
+p: TypeAlias = ("""int
+| None""")
+type P = ("""int
+| None""")
+
+q: TypeAlias = """(int
+| None)"""
+type Q = """(int
+| None)"""
+
+r: TypeAlias = """int | None"""
+type R = """int | None"""

crates/ruff_linter/resources/test/fixtures/flake8_type_checking/whitespace.py

@@ -0,0 +1,6 @@
+# Regression test for: https://github.com/astral-sh/ruff/issues/19175
+# there is a (potentially invisible) unicode formfeed character (000C) between `TYPE_CHECKING` and the backslash
+from typing import TYPE_CHECKING\
+
+if TYPE_CHECKING: import builtins
+builtins.print("!")

crates/ruff_linter/resources/test/fixtures/flake8_unused_arguments/ARG.py

@@ -245,3 +245,14 @@ def f(bar: str):
 class C:
     def __init__(self, x) -> None:
         print(locals())
+
+###
+# Should trigger for t-string here
+# even though the corresponding f-string
+# does not trigger (since it is common in stubs)
+###
+class C:
+    def f(self, x, y):
+        """Docstring."""
+        msg = t"{x}..."
+        raise NotImplementedError(msg)

crates/ruff_linter/resources/test/fixtures/flake8_use_pathlib/PTH203.py

@@ -1,4 +1,4 @@
-import os.path
+import os.path, pathlib
 from pathlib import Path
 from os.path import getatime
 
@@ -10,3 +10,26 @@ os.path.getatime(Path("filename"))
 getatime("filename")
 getatime(b"filename")
 getatime(Path("filename"))
+
+
+file = __file__
+
+os.path.getatime(file)
+os.path.getatime(filename="filename")
+os.path.getatime(filename=Path("filename"))
+
+os.path.getatime(  # comment 1
+    # comment 2
+    "filename"  # comment 3
+    # comment 4
+    ,  # comment 5
+    # comment 6
+)  # comment 7
+
+os.path.getatime("file" + "name")
+
+getatime(Path("filename").resolve())
+
+os.path.getatime(pathlib.Path("filename"))
+
+getatime(Path("dir") / "file.txt")

crates/ruff_linter/resources/test/fixtures/flake8_use_pathlib/PTH210.py

@@ -54,6 +54,13 @@ windows_path.with_suffix(r"s")
 windows_path.with_suffix(u'' "json")
 windows_path.with_suffix(suffix="js")
 
+Path().with_suffix(".")
+Path().with_suffix("py")
+PosixPath().with_suffix("py")
+PurePath().with_suffix("py")
+PurePosixPath().with_suffix("py")
+PureWindowsPath().with_suffix("py")
+WindowsPath().with_suffix("py")
 
 ### No errors
 path.with_suffix()

crates/ruff_linter/resources/test/fixtures/flake8_use_pathlib/PTH210_2.py

@@ -0,0 +1,26 @@
+from pathlib import (
+    Path,
+    PosixPath,
+    PurePath,
+    PurePosixPath,
+    PureWindowsPath,
+    WindowsPath,
+)
+import pathlib
+
+
+path = Path()
+posix_path: pathlib.PosixPath = PosixPath()
+pure_path: PurePath = PurePath()
+pure_posix_path = pathlib.PurePosixPath()
+pure_windows_path: PureWindowsPath = pathlib.PureWindowsPath()
+windows_path: pathlib.WindowsPath = pathlib.WindowsPath()
+
+
+### No Errors
+path.with_suffix(".")
+posix_path.with_suffix(".")
+pure_path.with_suffix(".")
+pure_posix_path.with_suffix(".")
+pure_windows_path.with_suffix(".")
+windows_path.with_suffix(".")

crates/ruff_linter/resources/test/fixtures/isort/required_imports/multiple_strings.py

@@ -0,0 +1,5 @@
+"""This is a docstring."""
+"This is not a docstring."
+"This is also not a docstring."
+
+x = 1 

crates/ruff_linter/resources/test/fixtures/isort/required_imports/whitespace.py

@@ -0,0 +1,5 @@
+# This is a regression test for https://github.com/astral-sh/ruff/issues/19310
+# there is a (potentially invisible) unicode formfeed character (000C) between "docstring" and the semicolon
+"docstring"; print(
+    f"{__doc__=}",
+)

crates/ruff_linter/resources/test/fixtures/pep8_naming/N802.py

@@ -48,6 +48,39 @@ from typing import override, overload
 def BAD_FUNC():
     pass
 
+
 @overload
 def BAD_FUNC():
     pass
+
+
+import ast
+from ast import NodeTransformer
+
+
+class Visitor(ast.NodeVisitor):
+    def visit_Constant(self, node):
+        pass
+
+    def bad_Name(self):
+        pass
+
+class ExtendsVisitor(Visitor):
+    def visit_Constant(self, node):
+        pass
+
+class Transformer(NodeTransformer):
+    def visit_Constant(self, node):
+        pass
+
+
+from http.server import BaseHTTPRequestHandler
+
+
+class MyRequestHandler(BaseHTTPRequestHandler):
+    def do_GET(self):
+        pass
+
+    def dont_GET(self):
+        pass
+