Add API anti-abuse hardening: disable docs in prod, origin validator, exception handler

- Disable OpenAPI docs/redoc/openapi.json when APP_ENV=production
- Strip uvicorn Server header with --no-server-header in Dockerfile and docker-compose.yml
- Add OriginValidatorMiddleware to reject state-changing requests from disallowed origins
- Add global exception handler to prevent stack trace leakage on unhandled errors
- Add tests for all new security features (OpenAPI, origin validation, exception handler, server header)

tests/unit/test_openapi_disabled.py

@@ -0,0 +1,42 @@
+"""Unit tests for OpenAPI docs disabled in production."""
+from unittest import mock
+
+from starlette.testclient import TestClient
+
+
+class TestOpenAPIDisabledInProduction:
+    """Verify docs/redoc/openapi are disabled when APP_ENV=production."""
+
+    def test_docs_disabled_in_production(self) -> None:
+        prod_env = {
+            "APP_ENV": "production",
+            "OIDC_CLIENT_ID": "test-client-id",
+            "JWT_SECRET": "test-secret-not-default",
+        }
+        with mock.patch.dict("os.environ", prod_env):
+            # Re-import to pick up the new env
+            import importlib
+            import api.config
+            importlib.reload(api.config)
+            import api.app
+            importlib.reload(api.app)
+            app = api.app.app
+
+        client = TestClient(app, raise_server_exceptions=False)
+        assert client.get("/docs").status_code == 404
+        assert client.get("/redoc").status_code == 404
+        assert client.get("/openapi.json").status_code == 404
+
+    def test_docs_enabled_in_dev(self) -> None:
+        with mock.patch.dict("os.environ", {"APP_ENV": "dev"}):
+            import importlib
+            import api.config
+            importlib.reload(api.config)
+            import api.app
+            importlib.reload(api.app)
+            app = api.app.app
+
+        client = TestClient(app, raise_server_exceptions=False)
+        # /docs should return 200 (Swagger UI) in non-production
+        assert client.get("/docs").status_code == 200
+        assert client.get("/openapi.json").status_code == 200

tests/unit/test_origin_validator.py

@@ -0,0 +1,81 @@
+"""Unit tests for api/origin_validator.py."""
+from starlette.testclient import TestClient
+from starlette.applications import Starlette
+from starlette.requests import Request
+from starlette.responses import JSONResponse
+from starlette.routing import Route
+
+from api.origin_validator import OriginValidatorMiddleware
+
+
+ALLOWED_ORIGINS = ["https://example.com", "https://app.example.com/"]
+
+
+async def _ok_endpoint(request: Request) -> JSONResponse:
+    return JSONResponse({"ok": True})
+
+
+def _build_app() -> Starlette:
+    app = Starlette(routes=[
+        Route("/test", _ok_endpoint, methods=["GET", "POST", "PUT", "DELETE", "PATCH"]),
+    ])
+    app.add_middleware(OriginValidatorMiddleware, allowed_origins=ALLOWED_ORIGINS)
+    return app
+
+
+class TestOriginValidator:
+    """Tests for OriginValidatorMiddleware."""
+
+    def test_get_request_bypasses_check(self) -> None:
+        """GET requests should not be checked for origin."""
+        client = TestClient(_build_app())
+        resp = client.get("/test", headers={"Origin": "https://evil.com"})
+        assert resp.status_code == 200
+
+    def test_post_with_allowed_origin(self) -> None:
+        client = TestClient(_build_app())
+        resp = client.post("/test", headers={"Origin": "https://example.com"})
+        assert resp.status_code == 200
+
+    def test_post_with_allowed_origin_trailing_slash(self) -> None:
+        """Trailing slash on origin should be normalized."""
+        client = TestClient(_build_app())
+        resp = client.post("/test", headers={"Origin": "https://app.example.com/"})
+        assert resp.status_code == 200
+
+    def test_post_with_disallowed_origin(self) -> None:
+        client = TestClient(_build_app())
+        resp = client.post("/test", headers={"Origin": "https://evil.com"})
+        assert resp.status_code == 403
+        assert resp.json() == {"detail": "Origin not allowed"}
+
+    def test_put_with_disallowed_origin(self) -> None:
+        client = TestClient(_build_app())
+        resp = client.put("/test", headers={"Origin": "https://evil.com"})
+        assert resp.status_code == 403
+
+    def test_delete_with_disallowed_origin(self) -> None:
+        client = TestClient(_build_app())
+        resp = client.delete("/test", headers={"Origin": "https://evil.com"})
+        assert resp.status_code == 403
+
+    def test_patch_with_disallowed_origin(self) -> None:
+        client = TestClient(_build_app())
+        resp = client.patch("/test", headers={"Origin": "https://evil.com"})
+        assert resp.status_code == 403
+
+    def test_post_without_origin_passes(self) -> None:
+        """Requests without an Origin header should pass through."""
+        client = TestClient(_build_app())
+        resp = client.post("/test")
+        assert resp.status_code == 200
+
+    def test_no_allowed_origins_configured(self) -> None:
+        """If no allowed origins are given, all origins are rejected."""
+        app = Starlette(routes=[
+            Route("/test", _ok_endpoint, methods=["POST"]),
+        ])
+        app.add_middleware(OriginValidatorMiddleware, allowed_origins=[])
+        client = TestClient(app)
+        resp = client.post("/test", headers={"Origin": "https://example.com"})
+        assert resp.status_code == 403

tests/unit/test_security_headers.py

@@ -54,3 +54,9 @@ class TestSecurityHeaders:
         client = TestClient(_build_app())
         resp = client.get("/test")
         assert "Strict-Transport-Security" not in resp.headers
+
+    def test_server_header_not_present(self) -> None:
+        """The Server header should not leak server software info."""
+        client = TestClient(_build_app())
+        resp = client.get("/test")
+        assert "Server" not in resp.headers or "uvicorn" not in resp.headers.get("Server", "").lower()

tests/unit/test_unhandled_exception.py

@@ -0,0 +1,65 @@
+"""Unit tests for the unhandled exception handler in api/app.py."""
+from unittest import mock
+
+import pytest
+from fastapi import FastAPI, HTTPException
+from fastapi.responses import JSONResponse
+from starlette.requests import Request
+from starlette.testclient import TestClient
+
+
+def _build_app() -> FastAPI:
+    """Build a minimal FastAPI app with the unhandled exception handler."""
+    app = FastAPI()
+
+    @app.exception_handler(Exception)
+    async def unhandled_exception_handler(request: Request, exc: Exception) -> JSONResponse:
+        return JSONResponse(
+            status_code=500,
+            content={"detail": "Internal server error"},
+        )
+
+    @app.get("/ok")
+    async def ok() -> dict[str, str]:
+        return {"status": "ok"}
+
+    @app.get("/crash")
+    async def crash() -> None:
+        raise RuntimeError("something unexpected")
+
+    @app.get("/http-error")
+    async def http_error() -> None:
+        raise HTTPException(status_code=403, detail="forbidden")
+
+    return app
+
+
+class TestUnhandledExceptionHandler:
+    """Tests for the global exception handler."""
+
+    def test_normal_request_unaffected(self) -> None:
+        client = TestClient(_build_app())
+        resp = client.get("/ok")
+        assert resp.status_code == 200
+        assert resp.json() == {"status": "ok"}
+
+    def test_unhandled_exception_returns_generic_500(self) -> None:
+        client = TestClient(_build_app(), raise_server_exceptions=False)
+        resp = client.get("/crash")
+        assert resp.status_code == 500
+        assert resp.json() == {"detail": "Internal server error"}
+
+    def test_http_exception_not_caught(self) -> None:
+        """HTTPException should still be handled by FastAPI's built-in handler."""
+        client = TestClient(_build_app())
+        resp = client.get("/http-error")
+        assert resp.status_code == 403
+        assert resp.json() == {"detail": "forbidden"}
+
+    def test_error_body_does_not_leak_details(self) -> None:
+        """The response must not contain the actual exception message."""
+        client = TestClient(_build_app(), raise_server_exceptions=False)
+        resp = client.get("/crash")
+        body = resp.text
+        assert "something unexpected" not in body
+        assert "RuntimeError" not in body