Handle CLI request errors and backend whisper timeout

backend/src/server.py

@@ -17,6 +17,7 @@ CONTENT_TYPES = {
 }
 
 app = FastAPI(title="whisper-remote-backend")
+WHISPER_PROCESS_TIMEOUT_SECONDS = 300
 
 
 def validate_output_format(output_format: str) -> str:
@@ -112,12 +113,21 @@ async def transcribe(
                 check=False,
                 capture_output=True,
                 text=True,
+                timeout=WHISPER_PROCESS_TIMEOUT_SECONDS,
             )
         except FileNotFoundError as exc:
             raise HTTPException(
                 status_code=500,
                 detail="The 'whisper' CLI was not found on PATH on the backend host.",
             ) from exc
+        except subprocess.TimeoutExpired as exc:
+            raise HTTPException(
+                status_code=504,
+                detail=(
+                    "Whisper CLI timed out after "
+                    f"{WHISPER_PROCESS_TIMEOUT_SECONDS}s and was terminated."
+                ),
+            ) from exc
 
         if completed.returncode != 0:
             detail = completed.stderr.strip() or completed.stdout.strip() or "Whisper CLI failed."

backend/tests/test_server.py

@@ -64,3 +64,22 @@ def test_transcriptions_maps_subprocess_failure(monkeypatch) -> None:
 
     assert response.status_code == 502
     assert response.json()["detail"] == "bad whisper day"
+
+
+def test_transcriptions_maps_subprocess_timeout(monkeypatch) -> None:
+    def fake_run(command: list[str], check: bool, capture_output: bool, text: bool, timeout: int):
+        raise server.subprocess.TimeoutExpired(cmd=command, timeout=timeout)
+
+    monkeypatch.setattr(server.subprocess, "run", fake_run)
+
+    response = client.post(
+        "/transcriptions",
+        data={"model": "base", "output_format": "txt"},
+        files={"file": ("clip.wav", b"audio", "audio/wav")},
+    )
+
+    assert response.status_code == 504
+    assert (
+        response.json()["detail"]
+        == f"Whisper CLI timed out after {server.WHISPER_PROCESS_TIMEOUT_SECONDS}s and was terminated."
+    )