🔖 Release version 0.140.10 (#16093)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

.github/workflows/test.yml

@@ -201,6 +201,78 @@ jobs:
           mode: memory
           run: uv run --no-sync pytest tests/memory_benchmarks --codspeed
 
+  regression-test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - name: Check out the pull request
+        if: github.event_name == 'pull_request'
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          ref: ${{ github.sha }}
+          path: pr
+          persist-credentials: false
+          fetch-depth: 0
+      - name: Find changed tests
+        if: github.event_name == 'pull_request'
+        id: changed-tests
+        working-directory: pr
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+        run: |
+          git diff --name-only --diff-filter=AM -z "$BASE_SHA" "$HEAD_SHA" -- tests \
+            | while IFS= read -r -d '' file; do
+                case "$(basename "$file")" in
+                  test_*.py) printf '%s\0' "$file" ;;
+                esac
+              done > "$RUNNER_TEMP/changed-tests"
+          if [ -s "$RUNNER_TEMP/changed-tests" ]; then
+            echo "found=true" >> "$GITHUB_OUTPUT"
+            git diff --binary "$BASE_SHA" "$HEAD_SHA" -- tests \
+              > "$RUNNER_TEMP/tests.patch"
+          else
+            echo "found=false" >> "$GITHUB_OUTPUT"
+            echo "No added or modified test files; regression proof is not applicable."
+          fi
+      - name: Check out the base revision
+        if: steps.changed-tests.outputs.found == 'true'
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          ref: ${{ github.event.pull_request.base.sha }}
+          path: base
+          persist-credentials: false
+      - name: Set up Python
+        if: steps.changed-tests.outputs.found == 'true'
+        uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6.3.0
+        with:
+          python-version-file: "base/.python-version"
+      - name: Setup uv
+        if: steps.changed-tests.outputs.found == 'true'
+        uses: astral-sh/setup-uv@d31148d669074a8d0a63714ba94f3201e7020bc3 # v8.3.0
+        with:
+          # Before upgrading uv version, make sure astral-sh/setup-uv knows its checksum.
+          # See: https://github.com/astral-sh/setup-uv/issues/851#issuecomment-4282017837
+          version: "0.11.18"
+          enable-cache: true
+      - name: Run the changed tests against the base code
+        if: steps.changed-tests.outputs.found == 'true'
+        working-directory: base
+        run: |
+          git apply "$RUNNER_TEMP/tests.patch"
+          uv sync --locked --no-dev --group tests --extra all
+          set +e
+          xargs -0 uv run --no-sync pytest -- < "$RUNNER_TEMP/changed-tests"
+          status=$?
+          set -e
+          if [ "$status" -eq 0 ]; then
+            echo "::warning::The changed tests already pass on the base revision. Check whether the fix is still needed."
+            echo "### Regression proof: base already passes :warning:" >> "$GITHUB_STEP_SUMMARY"
+            echo "The changed tests pass without the pull request's code changes." >> "$GITHUB_STEP_SUMMARY"
+          else
+            echo "The changed tests fail on the base revision as expected (pytest exit code $status)."
+            echo "### Regression proof: base fails as expected :white_check_mark:" >> "$GITHUB_STEP_SUMMARY"
+          fi
   coverage-combine:
     needs:
       - test
@@ -253,6 +325,7 @@ jobs:
       - test
       - coverage-combine
       - benchmark
+      - regression-test
     runs-on: ubuntu-latest
     timeout-minutes: 5
     steps:

docs/en/docs/release-notes.md

@@ -7,6 +7,18 @@ hide:
 
 ## Latest Changes
 
+## 0.140.10 (2026-07-28)
+
+### Fixes
+
+* 🐛 Fix handling sequences with nested Annotated types. PR [#14874](https://github.com/fastapi/fastapi/pull/14874) by [@YuriiMotov](https://github.com/YuriiMotov).
+
+### Internal
+
+* 🐛 Accept any base test failure as regression. PR [#16092](https://github.com/fastapi/fastapi/pull/16092) by [@tiangolo](https://github.com/tiangolo).
+* 🐛 Preserve pytest exit code in regression check. PR [#16091](https://github.com/fastapi/fastapi/pull/16091) by [@tiangolo](https://github.com/tiangolo).
+* ✅ Test PR regressions against base code. PR [#16090](https://github.com/fastapi/fastapi/pull/16090) by [@tiangolo](https://github.com/tiangolo).
+
 ## 0.140.9 (2026-07-28)
 
 ### Fixes

fastapi/__init__.py

@@ -1,6 +1,6 @@
 """FastAPI framework, high performance, easy to learn, fast to code, ready for production"""
 
-__version__ = "0.140.9"
+__version__ = "0.140.10"
 
 from starlette import status as status
 

fastapi/_compat/shared.py

@@ -63,6 +63,10 @@ def _annotation_is_sequence(annotation: type[Any] | None) -> bool:
 
 def field_annotation_is_sequence(annotation: type[Any] | None) -> bool:
     origin = get_origin(annotation)
+
+    if origin is Annotated:
+        return field_annotation_is_sequence(get_args(annotation)[0])
+
     if origin is Union or origin is UnionType:
         for arg in get_args(annotation):
             if field_annotation_is_sequence(arg):
@@ -108,6 +112,10 @@ def field_annotation_is_scalar(annotation: Any) -> bool:
 
 def field_annotation_is_scalar_sequence(annotation: type[Any] | None) -> bool:
     origin = get_origin(annotation)
+
+    if origin is Annotated:
+        return field_annotation_is_scalar_sequence(get_args(annotation)[0])
+
     if origin is Union or origin is UnionType:
         at_least_one_scalar_sequence = False
         for arg in get_args(annotation):

tests/test_nested_annotated_in_sequence.py

@@ -0,0 +1,143 @@
+from typing import Annotated
+
+from dirty_equals import IsList
+from fastapi import FastAPI, Query
+from fastapi.testclient import TestClient
+from inline_snapshot import snapshot
+from pydantic import Field
+
+MaxSizedSet = Annotated[set[str], Field(max_length=3)]
+
+app = FastAPI()
+
+
+@app.get("/")
+def read_root(foo: Annotated[MaxSizedSet | None, Query()] = None):
+    return {"foo": foo}
+
+
+client = TestClient(app)
+
+
+def test_endpoint_none():
+    response = client.get("/")
+    assert response.status_code == 200
+    assert response.json() == {"foo": None}
+
+
+def test_endpoint_valid():
+    response = client.get("/", params={"foo": ["a", "b"]})
+    assert response.status_code == 200
+    assert response.json() == {"foo": IsList("a", "b", check_order=False)}
+
+
+def test_endpoint_too_long():
+    response = client.get("/", params={"foo": ["a", "b", "c", "d"]})
+    assert response.status_code == 422
+    assert response.json() == snapshot(
+        {
+            "detail": [
+                {
+                    "type": "too_long",
+                    "loc": ["query", "foo"],
+                    "msg": "Set should have at most 3 items after validation, not more",
+                    "input": IsList("a", "b", "c", "d", check_order=False),
+                    "ctx": {
+                        "actual_length": None,
+                        "field_type": "Set",
+                        "max_length": 3,
+                    },
+                }
+            ]
+        }
+    )
+
+
+def test_openapi():
+    assert app.openapi() == snapshot(
+        {
+            "components": {
+                "schemas": {
+                    "HTTPValidationError": {
+                        "properties": {
+                            "detail": {
+                                "items": {
+                                    "$ref": "#/components/schemas/ValidationError"
+                                },
+                                "title": "Detail",
+                                "type": "array",
+                            },
+                        },
+                        "title": "HTTPValidationError",
+                        "type": "object",
+                    },
+                    "ValidationError": {
+                        "properties": {
+                            "ctx": {"title": "Context", "type": "object"},
+                            "input": {"title": "Input"},
+                            "loc": {
+                                "items": {
+                                    "anyOf": [{"type": "string"}, {"type": "integer"}],
+                                },
+                                "title": "Location",
+                                "type": "array",
+                            },
+                            "msg": {"title": "Message", "type": "string"},
+                            "type": {"title": "Error Type", "type": "string"},
+                        },
+                        "required": ["loc", "msg", "type"],
+                        "title": "ValidationError",
+                        "type": "object",
+                    },
+                },
+            },
+            "info": {
+                "title": "FastAPI",
+                "version": "0.1.0",
+            },
+            "openapi": "3.1.0",
+            "paths": {
+                "/": {
+                    "get": {
+                        "operationId": "read_root__get",
+                        "parameters": [
+                            {
+                                "in": "query",
+                                "name": "foo",
+                                "required": False,
+                                "schema": {
+                                    "anyOf": [
+                                        {
+                                            "items": {"type": "string"},
+                                            "maxItems": 3,
+                                            "type": "array",
+                                            "uniqueItems": True,
+                                        },
+                                        {"type": "null"},
+                                    ],
+                                    "title": "Foo",
+                                },
+                            },
+                        ],
+                        "responses": {
+                            "200": {
+                                "content": {"application/json": {"schema": {}}},
+                                "description": "Successful Response",
+                            },
+                            "422": {
+                                "content": {
+                                    "application/json": {
+                                        "schema": {
+                                            "$ref": "#/components/schemas/HTTPValidationError",
+                                        },
+                                    },
+                                },
+                                "description": "Validation Error",
+                            },
+                        },
+                        "summary": "Read Root",
+                    },
+                },
+            },
+        }
+    )