feat(api): add POST/GET /v1/files with auth, error envelope, and request-id middleware

Why:
- Wires the ADR-0008 error envelope, per-request correlation id, and the
  /v1/files routes into the app.

Changes:
- Extend AppResources/lifespan with the ingestion CapacityLimiter and
  ObjectStorage adapter.

Impact:
- /v1 now exposes routes for the first time.

src/api/dependencies/auth.py

@@ -0,0 +1,38 @@
+"""Auth dependencies (ADR-0008): resolve `AuthContext` from a bearer token,
+then gate routes on scope.
+"""
+
+from collections.abc import Awaitable, Callable
+from typing import Annotated
+
+from fastapi import Depends
+from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
+
+from src.application.auth.context import AuthContext
+from src.application.auth.errors import InvalidApiKeyError, MissingScopeError
+from src.application.auth.service import resolve_auth_context
+from src.bootstrap.dependencies import get_sessionmaker
+
+_bearer_scheme = HTTPBearer(auto_error=False)
+
+
+async def get_auth_context(
+    credentials: Annotated[HTTPAuthorizationCredentials | None, Depends(_bearer_scheme)],
+    sessionmaker: Annotated[async_sessionmaker[AsyncSession], Depends(get_sessionmaker)],
+) -> AuthContext:
+    if credentials is None:
+        raise InvalidApiKeyError("missing Authorization header")
+    return await resolve_auth_context(sessionmaker, credentials.credentials)
+
+
+AuthContextDep = Annotated[AuthContext, Depends(get_auth_context)]
+
+
+def require_scope(scope: str) -> Callable[[AuthContext], Awaitable[AuthContext]]:
+    async def _dependency(auth: AuthContextDep) -> AuthContext:
+        if not auth.has_scope(scope):
+            raise MissingScopeError(f"missing required scope '{scope}'")
+        return auth
+
+    return _dependency

src/api/errors.py

@@ -0,0 +1,97 @@
+"""Maps application exceptions to the ADR-0008 error envelope.
+
+This is the single place that knows the exception-type -> status-code
+mapping; application/infrastructure code never imports FastAPI or raises
+`HTTPException` (ADR-0015).
+"""
+
+import structlog
+from fastapi import FastAPI, Request, status
+from fastapi.exceptions import RequestValidationError
+from fastapi.responses import JSONResponse
+from starlette.exceptions import HTTPException as StarletteHTTPException
+
+from src.application.auth.errors import (
+    InvalidApiKeyError,
+    MissingScopeError,
+    TenantInactiveError,
+)
+from src.application.files.errors import FileTooLargeError, InvalidUploadError
+from src.application.ingestion.errors import DocumentParseError, UnsupportedSourceTypeError
+
+logger = structlog.get_logger(__name__)
+
+# (exception type, status code, stable error code)
+_MAPPING: tuple[tuple[type[Exception], int, str], ...] = (
+    (InvalidApiKeyError, status.HTTP_401_UNAUTHORIZED, "invalid_api_key"),
+    (TenantInactiveError, status.HTTP_401_UNAUTHORIZED, "tenant_not_found"),
+    (MissingScopeError, status.HTTP_403_FORBIDDEN, "missing_scope"),
+    (InvalidUploadError, status.HTTP_400_BAD_REQUEST, "validation_error"),
+    (DocumentParseError, status.HTTP_400_BAD_REQUEST, "validation_error"),
+    (UnsupportedSourceTypeError, status.HTTP_415_UNSUPPORTED_MEDIA_TYPE, "unsupported_media_type"),
+    (FileTooLargeError, status.HTTP_413_CONTENT_TOO_LARGE, "payload_too_large"),
+)
+
+
+def _request_id(request: Request) -> str | None:
+    return getattr(request.state, "request_id", None)
+
+
+def _envelope(
+    code: str, message: str, request_id: str | None, details: dict[str, object] | None = None
+) -> dict[str, object]:
+    return {
+        "error": {
+            "code": code,
+            "message": message,
+            "details": details or {},
+            "request_id": request_id,
+        }
+    }
+
+
+def register_exception_handlers(app: FastAPI) -> None:
+    for exc_type, status_code, error_code in _MAPPING:
+
+        def _handler(
+            request: Request,
+            exc: Exception,
+            status_code: int = status_code,
+            error_code: str = error_code,
+        ) -> JSONResponse:
+            return JSONResponse(
+                status_code=status_code,
+                content=_envelope(error_code, str(exc), _request_id(request)),
+            )
+
+        app.add_exception_handler(exc_type, _handler)
+
+    @app.exception_handler(RequestValidationError)
+    def _validation_handler(request: Request, exc: RequestValidationError) -> JSONResponse:
+        return JSONResponse(
+            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+            content=_envelope(
+                "validation_error",
+                "request validation failed",
+                _request_id(request),
+                details={"errors": exc.errors()},
+            ),
+        )
+
+    @app.exception_handler(StarletteHTTPException)
+    def _http_exception_handler(request: Request, exc: StarletteHTTPException) -> JSONResponse:
+        code = "not_found" if exc.status_code == status.HTTP_404_NOT_FOUND else "http_error"
+        return JSONResponse(
+            status_code=exc.status_code,
+            content=_envelope(code, str(exc.detail), _request_id(request)),
+        )
+
+    @app.exception_handler(Exception)
+    def _unhandled_exception_handler(request: Request, exc: Exception) -> JSONResponse:
+        logger.exception("api.unhandled_exception", path=request.url.path)
+        return JSONResponse(
+            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+            content=_envelope(
+                "internal_error", "an unexpected error occurred", _request_id(request)
+            ),
+        )

src/api/middleware.py

@@ -0,0 +1,38 @@
+"""Per-request correlation id (ADR-0008, ADR-0011).
+
+Every request gets a `request_id`: reused from an incoming `X-Request-Id` if
+the caller supplied one, otherwise generated. It is bound into structlog's
+contextvars so every log line emitted while handling the request carries it,
+stored on `request.state` for exception handlers, and echoed back in the
+response header.
+"""
+
+import uuid
+from collections.abc import Awaitable, Callable
+from typing import override
+
+import structlog
+from starlette.middleware.base import BaseHTTPMiddleware
+from starlette.requests import Request
+from starlette.responses import Response
+
+_HEADER = "X-Request-Id"
+
+
+class RequestIdMiddleware(BaseHTTPMiddleware):
+    @override
+    async def dispatch(
+        self, request: Request, call_next: Callable[[Request], Awaitable[Response]]
+    ) -> Response:
+        request_id = request.headers.get(_HEADER) or str(uuid.uuid4())
+        request.state.request_id = request_id
+
+        structlog.contextvars.clear_contextvars()
+        structlog.contextvars.bind_contextvars(request_id=request_id)
+        try:
+            response = await call_next(request)
+        finally:
+            structlog.contextvars.clear_contextvars()
+
+        response.headers[_HEADER] = request_id
+        return response

src/api/router.py

@@ -1,3 +1,6 @@
 from fastapi import APIRouter
 
+from src.api.routers.files import router as files_router
+
 router = APIRouter()
+router.include_router(files_router)

src/api/routers/files.py

@@ -0,0 +1,74 @@
+"""`POST /v1/files`, `GET /v1/files/{file_id}` (ADR-0008).
+
+Routes adapt HTTP to `application/files` calls; they do not parse, hash,
+touch MinIO/Qdrant, or otherwise carry ingestion business logic (ADR-0015).
+"""
+
+import uuid
+from typing import Annotated
+
+from anyio import CapacityLimiter
+from fastapi import APIRouter, Depends, Form, HTTPException, Response, UploadFile, status
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
+
+from src.api.dependencies.auth import require_scope
+from src.api.schemas.files import FileStatusResponse, FileUploadResponse
+from src.application.auth.context import AuthContext
+from src.application.files.status import get_file_status
+from src.application.files.upload import upload_source_file
+from src.application.ports.object_storage import ObjectStorage
+from src.bootstrap.dependencies import (
+    get_ingestion_limiter,
+    get_object_storage,
+    get_sessionmaker,
+    get_settings,
+)
+from src.config import Settings
+
+router = APIRouter(prefix="/files", tags=["files"])
+
+_RequireFilesWrite = Annotated[AuthContext, Depends(require_scope("files:write"))]
+_SessionmakerDep = Annotated[async_sessionmaker[AsyncSession], Depends(get_sessionmaker)]
+_ObjectStorageDep = Annotated[ObjectStorage, Depends(get_object_storage)]
+_SettingsDep = Annotated[Settings, Depends(get_settings)]
+_IngestionLimiterDep = Annotated[CapacityLimiter, Depends(get_ingestion_limiter)]
+
+
+@router.post("", status_code=status.HTTP_201_CREATED)
+async def upload_file(
+    response: Response,
+    file: UploadFile,
+    domain: Annotated[str, Form()],
+    auth: _RequireFilesWrite,
+    sessionmaker: _SessionmakerDep,
+    storage: _ObjectStorageDep,
+    settings: _SettingsDep,
+    limiter: _IngestionLimiterDep,
+) -> FileUploadResponse:
+    data = await file.read()
+    result = await upload_source_file(
+        sessionmaker=sessionmaker,
+        storage=storage,
+        auth=auth,
+        domain=domain,
+        filename=file.filename or "",
+        data=data,
+        max_upload_size_bytes=settings.ingestion.max_upload_size_bytes,
+        chunking_strategy=settings.chunking.strategy,
+        validation_limiter=limiter,
+    )
+    if not result.is_new_attempt:
+        response.status_code = status.HTTP_200_OK
+    return FileUploadResponse.from_result(result)
+
+
+@router.get("/{file_id}")
+async def get_file(
+    file_id: uuid.UUID,
+    auth: _RequireFilesWrite,
+    sessionmaker: _SessionmakerDep,
+) -> FileStatusResponse:
+    result = await get_file_status(sessionmaker, tenant_id=auth.tenant_id, source_file_id=file_id)
+    if result is None:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="file not found")
+    return FileStatusResponse.from_result(result)

src/api/schemas/errors.py

@@ -0,0 +1,16 @@
+"""The ADR-0008 error envelope."""
+
+from typing import Any
+
+from pydantic import BaseModel
+
+
+class ErrorDetail(BaseModel):
+    code: str
+    message: str
+    details: dict[str, Any] = {}
+    request_id: str | None = None
+
+
+class ErrorResponse(BaseModel):
+    error: ErrorDetail

src/api/schemas/files.py

@@ -0,0 +1,50 @@
+"""Public request/response models for `/v1/files` (ADR-0008).
+
+Separate from the SQLAlchemy ORM models and the `application/files` domain
+dataclasses (ADR-0015): this is the shape callers see.
+"""
+
+import uuid
+
+from pydantic import BaseModel
+
+from src.application.files.models import UploadResult
+from src.application.files.status import FileStatusResult
+
+
+class FileUploadResponse(BaseModel):
+    file_id: uuid.UUID
+    ingestion_job_id: uuid.UUID
+    status: str
+    chunks_indexed: int
+
+    @classmethod
+    def from_result(cls, result: UploadResult) -> "FileUploadResponse":
+        return cls(
+            file_id=result.file_id,
+            ingestion_job_id=result.ingestion_job_id,
+            status=result.status,
+            chunks_indexed=result.chunks_indexed,
+        )
+
+
+class FileStatusResponse(BaseModel):
+    file_id: uuid.UUID
+    source_filename: str
+    domain: str
+    status: str
+    ingestion_job_id: uuid.UUID | None
+    ingestion_status: str | None
+    chunks_indexed: int
+
+    @classmethod
+    def from_result(cls, result: FileStatusResult) -> "FileStatusResponse":
+        return cls(
+            file_id=result.file_id,
+            source_filename=result.source_filename,
+            domain=result.domain,
+            status=result.status,
+            ingestion_job_id=result.ingestion_job_id,
+            ingestion_status=result.ingestion_status,
+            chunks_indexed=result.chunks_indexed,
+        )