fix(05-12): close 3 UAT gaps — OAuth 400 preflight, 502 cloud fallback, upload hint

- oauth_initiate: pre-flight check returns 400 with env-var hint when
  GOOGLE_CLIENT_ID/SECRET or ONEDRIVE_CLIENT_ID/SECRET are not configured,
  preventing opaque MSAL/OAuth library 500 errors on misconfigured servers
- stream_document_content: broad except-clause catches non-CloudConnectionError
  exceptions and returns 502 with user-friendly message (was raw 500)
- docker-compose.yml: add volumes: - ./backend:/app to celery-worker so code
  changes are picked up by docker compose restart without a rebuild
- CloudStorageView: upload hint paragraph directs users to navigate into a
  cloud folder; no DropZone added (no folder context at overview level)
- 3 new backend tests pass; 2 existing tests patched with credential monkeypatch;
  full suite: 293 passed, 0 new failures, 1 pre-existing (test_extract_docx)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.planning/phases/05-cloud-storage-backends/05-12-PLAN.md

@@ -0,0 +1,304 @@
+---
+phase: 05-cloud-storage-backends
+plan: 12
+type: execute
+wave: 1
+depends_on: []
+files_modified:
+  - backend/api/cloud.py
+  - backend/api/documents.py
+  - docker-compose.yml
+  - frontend/src/views/CloudStorageView.vue
+  - backend/tests/test_cloud_api.py
+autonomous: true
+requirements: [CLOUD-01, CLOUD-02, CLOUD-07]
+gap_closure: true
+
+must_haves:
+  truths:
+    - "OneDrive OAuth initiate returns HTTP 400 with a descriptive message when ONEDRIVE_CLIENT_ID or ONEDRIVE_CLIENT_SECRET is not configured — not a 500 from MSAL"
+    - "Google Drive OAuth initiate returns HTTP 400 with a descriptive message when GOOGLE_CLIENT_ID or GOOGLE_CLIENT_SECRET is not configured"
+    - "stream_document_content returns 502 (not 500) when a cloud backend raises an unexpected exception"
+    - "celery-worker in docker-compose.yml has a volume mount so code changes are picked up by docker compose restart (no rebuild required)"
+    - "CloudStorageView shows an upload hint directing users to navigate into a cloud folder to upload files"
+  artifacts:
+    - path: "backend/api/cloud.py"
+      provides: "Pre-flight config check in oauth_initiate for both onedrive and google_drive providers"
+    - path: "backend/api/documents.py"
+      provides: "Broad except-clause in stream_document_content catches non-CloudConnectionError exceptions and returns 502"
+    - path: "docker-compose.yml"
+      provides: "celery-worker service has volumes: - ./backend:/app matching the backend service"
+    - path: "frontend/src/views/CloudStorageView.vue"
+      provides: "Upload hint paragraph shown when connections exist, directing users to navigate into a folder"
+  key_links:
+    - from: "frontend Settings → Cloud Storage → Connect OneDrive"
+      to: "GET /api/cloud/oauth/initiate/onedrive"
+      via: "Returns 400 with readable error when env vars missing"
+    - from: "frontend document preview"
+      to: "GET /api/documents/{id}/content"
+      via: "Returns 502 instead of 500 on cloud backend failure"
+---
+
+<objective>
+Close 3 UAT gaps from Phase 5 testing:
+
+1. **OneDrive OAuth 500** (major): When ONEDRIVE_CLIENT_ID/SECRET env vars are not set, MSAL raises an exception that surfaces as a 500 error. Users cannot distinguish misconfiguration from a code bug. Add a pre-flight check that returns 400 with a human-readable message before touching MSAL. Same check for Google Drive.
+
+2. **Cloud document stream opaque 500** (blocker): `stream_document_content` catches `CloudConnectionError` → 503, but any other exception from the cloud backend becomes a raw 500. Add a broad `except Exception` → 502 with a user-friendly message. Also add `volumes: ./backend:/app` to celery-worker in docker-compose.yml so code changes are reflected by `docker compose restart` without a full rebuild.
+
+3. **Upload hint in CloudStorageView** (blocker): The sidebar "Cloud Storage" link now navigates to `/cloud` (CloudStorageView) which shows provider connections but has no DropZone. Users expect to be able to upload there. Adding a DropZone would require knowing which cloud folder to target (not available at this level). Instead, add a clear inline hint: "To upload files, navigate into a cloud folder first."
+</objective>
+
+<execution_context>
+@$HOME/.claude/get-shit-done/workflows/execute-plan.md
+@$HOME/.claude/get-shit-done/templates/summary.md
+</execution_context>
+
+<context>
+@.planning/PROJECT.md
+@.planning/ROADMAP.md
+@.planning/STATE.md
+@.planning/phases/05-cloud-storage-backends/05-UAT.md
+</context>
+
+<interfaces>
+<!-- Key contracts the executor needs. -->
+
+From backend/api/cloud.py — oauth_initiate (lines ~314–384):
+- Route: GET /api/cloud/oauth/initiate/{provider}
+- Provider validation at line ~336: `if provider not in VALID_OAUTH_PROVIDERS: raise HTTPException(400, ...)`
+- google_drive block starts at line ~348 with `if provider == "google_drive":`
+- onedrive block starts at line ~370 with `elif provider == "onedrive":`
+- settings fields: `settings.google_client_id`, `settings.google_client_secret` (config.py line ~62); `settings.onedrive_client_id`, `settings.onedrive_client_secret`, `settings.onedrive_tenant_id` (config.py line ~64)
+- All three onedrive fields default to empty string — no startup validation
+
+From backend/api/documents.py — stream_document_content (lines ~708–780):
+- CloudConnectionError catch at line ~754 returns 503
+- No broad except-clause after it — any other cloud exception becomes unhandled 500
+- `from storage import get_storage_backend, get_storage_backend_for_document` at line 40
+
+From docker-compose.yml — celery-worker service (lines ~81–100):
+- Has no `volumes:` block — backend code changes require `docker compose up --build celery-worker`
+- `backend` service at line ~53 has `volumes: - ./backend:/app` — same pattern needed for celery-worker
+
+From frontend/src/views/CloudStorageView.vue:
+- Content section starts at line ~12: `<div class="flex-1 overflow-y-auto px-6 py-5">`
+- Empty state div at line ~23: `<div v-else-if="connections.length === 0" ...>`
+- Connections list at line ~30: `<div v-else class="flex flex-col divide-y ...">` (rows listing providers)
+- No DropZone imported or rendered anywhere in the component
+- Upload hint must appear AFTER the connections list (inside the `v-else` branch) — not in the empty state
+
+From backend/tests/test_cloud_api.py:
+- Read the file to understand existing test fixtures before adding new tests
+- Add tests for the 400 response when env vars are missing (mock settings)
+</interfaces>
+
+<tasks>
+
+<task type="auto" tdd="true">
+  <name>Task 1: Backend — pre-flight config validation in oauth_initiate</name>
+  <files>backend/api/cloud.py, backend/tests/test_cloud_api.py</files>
+  <read_first>
+    - backend/api/cloud.py (lines 310–390: oauth_initiate function)
+    - backend/config.py (lines 60–70: onedrive_client_id, google_client_id fields)
+    - backend/tests/test_cloud_api.py (full file: existing fixtures and test patterns)
+  </read_first>
+  <behavior>
+    - GET /api/cloud/oauth/initiate/google_drive with google_client_id="" → 400 {"detail": "Google Drive OAuth is not configured on this server. Set GOOGLE_CLIENT_ID and GOOGLE_CLIENT_SECRET in your environment."}
+    - GET /api/cloud/oauth/initiate/onedrive with onedrive_client_id="" → 400 {"detail": "OneDrive OAuth is not configured on this server. Set ONEDRIVE_CLIENT_ID, ONEDRIVE_CLIENT_SECRET, and ONEDRIVE_TENANT_ID in your environment."}
+    - GET /api/cloud/oauth/initiate/onedrive with all onedrive env vars set → still attempts MSAL (existing behavior, not broken)
+    - GET /api/cloud/oauth/initiate/unknown_provider → still 400 "Unsupported OAuth provider" (existing behavior unchanged)
+  </behavior>
+  <action>
+    In backend/api/cloud.py, inside the `oauth_initiate` function, AFTER the existing `VALID_OAUTH_PROVIDERS` check and BEFORE the `if provider == "google_drive":` block, insert two pre-flight checks:
+
+    1. For google_drive: immediately before `if provider == "google_drive":`, add:
+       ```
+       if provider == "google_drive" and (not settings.google_client_id or not settings.google_client_secret):
+           raise HTTPException(
+               status_code=status.HTTP_400_BAD_REQUEST,
+               detail="Google Drive OAuth is not configured on this server. Set GOOGLE_CLIENT_ID and GOOGLE_CLIENT_SECRET in your environment.",
+           )
+       ```
+
+    2. For onedrive: immediately before `elif provider == "onedrive":`, add:
+       ```
+       if provider == "onedrive" and (not settings.onedrive_client_id or not settings.onedrive_client_secret):
+           raise HTTPException(
+               status_code=status.HTTP_400_BAD_REQUEST,
+               detail="OneDrive OAuth is not configured on this server. Set ONEDRIVE_CLIENT_ID, ONEDRIVE_CLIENT_SECRET, and ONEDRIVE_TENANT_ID in your environment.",
+           )
+       ```
+
+    These checks must fire before the `if provider == "google_drive":` / `elif provider == "onedrive":` blocks — do NOT restructure the if/elif chain.
+
+    In backend/tests/test_cloud_api.py, add two tests using `monkeypatch` (pytest) to override settings fields:
+    1. `test_oauth_initiate_google_drive_not_configured` — monkeypatch `settings.google_client_id = ""` and `settings.google_client_secret = ""`, call GET /api/cloud/oauth/initiate/google_drive as an authenticated regular user, assert 400, assert "GOOGLE_CLIENT_ID" in detail.
+    2. `test_oauth_initiate_onedrive_not_configured` — monkeypatch `settings.onedrive_client_id = ""`, call GET /api/cloud/oauth/initiate/onedrive, assert 400, assert "ONEDRIVE_CLIENT_ID" in detail.
+
+    Use the existing authenticated client fixture from the test file — read the file to find its name before writing tests.
+  </action>
+  <acceptance_criteria>
+    - backend/api/cloud.py oauth_initiate contains `if provider == "google_drive" and (not settings.google_client_id or not settings.google_client_secret)` before the `if provider == "google_drive":` block
+    - backend/api/cloud.py oauth_initiate contains `if provider == "onedrive" and (not settings.onedrive_client_id or not settings.onedrive_client_secret)` before the `elif provider == "onedrive":` block
+    - `pytest backend/tests/test_cloud_api.py::test_oauth_initiate_google_drive_not_configured backend/tests/test_cloud_api.py::test_oauth_initiate_onedrive_not_configured -v` exits 0
+    - Both tests assert HTTP 400 and the relevant env var name in the detail string
+  </acceptance_criteria>
+  <verify>
+    <automated>cd /Users/nik/Documents/Progamming/document_scanner/backend && python -m pytest tests/test_cloud_api.py::test_oauth_initiate_google_drive_not_configured tests/test_cloud_api.py::test_oauth_initiate_onedrive_not_configured -v</automated>
+  </verify>
+  <done>Two new tests pass. oauth_initiate returns 400 with descriptive message when provider credentials are empty. Existing tests unchanged.</done>
+</task>
+
+<task type="auto">
+  <name>Task 2: Backend — 502 fallback in stream_document_content + celery-worker volume mount</name>
+  <files>backend/api/documents.py, docker-compose.yml, backend/tests/test_documents_api.py</files>
+  <read_first>
+    - backend/api/documents.py (lines 708–780: stream_document_content function)
+    - docker-compose.yml (lines 53–100: backend and celery-worker service definitions)
+    - backend/tests/test_documents_api.py (read to find fixtures for mocking get_storage_backend_for_document)
+  </read_first>
+  <behavior>
+    - GET /api/documents/{id}/content when cloud backend raises CloudConnectionError → 503 "Cloud connection requires re-authentication" (EXISTING, unchanged)
+    - GET /api/documents/{id}/content when cloud backend raises any other Exception (e.g., aiohttp.ClientError, timeout, generic RuntimeError) → 502 "Cloud backend unreachable. Please try again or reconnect in Settings."
+    - GET /api/documents/{id}/content for a MinIO document → 200 with file bytes (unchanged, MinIO errors are not affected by the new clause)
+  </behavior>
+  <action>
+    ### 1. backend/api/documents.py — add broad except-clause
+
+    In the `stream_document_content` function, find the `except CloudConnectionError as exc:` block (lines ~754–758). IMMEDIATELY AFTER its closing line (`from exc`), add a second except clause:
+
+    ```python
+    except Exception as exc:
+        raise HTTPException(
+            status_code=502,
+            detail="Cloud backend unreachable. Please try again or reconnect in Settings.",
+        ) from exc
+    ```
+
+    The final try/except structure must be:
+    ```
+    try:
+        storage_backend = await get_storage_backend_for_document(...)
+        file_bytes = await storage_backend.get_object(doc.object_key)
+    except CloudConnectionError as exc:
+        raise HTTPException(503, ...) from exc
+    except Exception as exc:
+        raise HTTPException(502, ...) from exc
+    ```
+
+    Do NOT catch Exception before CloudConnectionError — order matters (specific before broad).
+
+    ### 2. docker-compose.yml — add volume mount to celery-worker
+
+    In the `celery-worker` service block, add a `volumes:` key with the same bind mount as the `backend` service:
+    ```yaml
+    volumes:
+      - ./backend:/app
+    ```
+
+    Place it after `environment:` and before `extra_hosts:` (or after `extra_hosts:` if that reads more cleanly). Match the indentation of surrounding keys (2 spaces).
+
+    Also add `PYTHONDONTWRITEBYTECODE=1` to the celery-worker environment if it is not already there (prevents .pyc files from cluttering the bind-mounted source).
+
+    ### 3. backend/tests/test_documents_api.py — add test for 502 path
+
+    Add `test_stream_document_content_cloud_backend_error`: 
+    - Create a document with `storage_backend = "google_drive"` (or any non-minio value)
+    - Mock `get_storage_backend_for_document` to raise `RuntimeError("connection timeout")`
+    - Call GET /api/documents/{doc.id}/content as the document owner
+    - Assert 502 and "Cloud backend unreachable" in the response detail
+    
+    Read existing document stream tests to find the right fixture pattern before writing.
+  </action>
+  <acceptance_criteria>
+    - backend/api/documents.py stream_document_content has `except Exception as exc:` AFTER `except CloudConnectionError as exc:` block, raising HTTPException(502)
+    - docker-compose.yml celery-worker service has `volumes: - ./backend:/app`
+    - `pytest backend/tests/test_documents_api.py::test_stream_document_content_cloud_backend_error -v` exits 0
+    - `pytest backend/tests/ -v -k "stream_document_content"` — all stream tests pass (no regression)
+  </acceptance_criteria>
+  <verify>
+    <automated>cd /Users/nik/Documents/Progamming/document_scanner/backend && python -m pytest tests/test_documents_api.py -v -k "stream" 2>&1 | tail -20</automated>
+  </verify>
+  <done>502 except-clause added. Volume mount added to docker-compose.yml. New test passes. Existing stream tests pass.</done>
+</task>
+
+<task type="auto">
+  <name>Task 3: Frontend — upload hint in CloudStorageView</name>
+  <files>frontend/src/views/CloudStorageView.vue</files>
+  <read_first>
+    - frontend/src/views/CloudStorageView.vue (full file — understand existing template structure)
+    - frontend/src/views/CloudFolderView.vue (for reference — how upload works inside a folder)
+  </read_first>
+  <behavior>
+    - When at /cloud with at least one active connection, a hint paragraph is visible below the connections list: "To upload files, navigate into a cloud folder first."
+    - The hint does not appear on the empty state (no connections) — that state already directs to Settings.
+    - Clicking a connection row still navigates to /cloud/{provider}/root (existing behavior unchanged).
+    - No DropZone component is added to this view (no cloud folder context is available at this level).
+  </behavior>
+  <action>
+    In frontend/src/views/CloudStorageView.vue, inside the `v-else` block (the div that renders the connections list, starting at `<div v-else class="flex flex-col divide-y ...`), add a hint paragraph immediately AFTER the closing `</div>` of the connections list (after the `</div>` that closes `v-for`), still inside the `v-else` wrapper:
+
+    ```html
+    <p class="mt-4 text-xs text-gray-400 text-center">
+      To upload files, navigate into a cloud folder first.
+    </p>
+    ```
+
+    The hint must be a sibling of the connections list `<div>`, not nested inside it. Keep both inside the single `v-else` block so the hint is only visible when connections exist.
+  </action>
+  <acceptance_criteria>
+    - CloudStorageView.vue contains `To upload files, navigate into a cloud folder first.` in a `<p>` element inside the `v-else` block
+    - The `<p>` is NOT inside the `v-else-if="connections.length === 0"` empty state block
+    - `cd frontend && npm run build` exits 0 with no errors
+    - No DropZone or UploadProgress imported or rendered in CloudStorageView.vue
+  </acceptance_criteria>
+  <verify>
+    <automated>cd /Users/nik/Documents/Progamming/document_scanner/frontend && npm run build 2>&1 | tail -5</automated>
+  </verify>
+  <done>Upload hint added below connections list. Build passes. No DropZone added. Existing connection click behavior unchanged.</done>
+</task>
+
+</tasks>
+
+<threat_model>
+## Trust Boundaries
+
+| Boundary | Description |
+|----------|-------------|
+| oauth_initiate preflight | User-supplied provider string already validated; new checks only inspect server-side settings values — no user input involved |
+| 502 error message | Static string, no user data reflected in the error detail |
+| volume mount | Read-only to container — same bind mount pattern as backend service |
+
+## STRIDE Threat Register
+
+| Threat ID | Category | Component | Disposition | Mitigation Plan |
+|-----------|----------|-----------|-------------|-----------------|
+| T-05-12-01 | Information Disclosure | 400 error message for missing creds | mitigate | Message names env vars (server config), not any user data or secret values — safe to expose |
+| T-05-12-02 | Information Disclosure | 502 error message | mitigate | Static string "Cloud backend unreachable" — no stack trace, no exception detail leaked to client |
+| T-05-12-03 | Tampering | celery-worker volume mount | accept | Bind mount is same as backend service; only developer-controlled source files are mounted; production deployments use image builds, not bind mounts |
+| T-05-12-SC | Tampering | npm/pip installs | mitigate | No new packages installed in this plan |
+</threat_model>
+
+<verification>
+After all tasks complete:
+- `cd backend && python -m pytest tests/test_cloud_api.py::test_oauth_initiate_google_drive_not_configured tests/test_cloud_api.py::test_oauth_initiate_onedrive_not_configured -v` — 2 tests pass
+- `cd backend && python -m pytest tests/test_documents_api.py::test_stream_document_content_cloud_backend_error -v` — 1 test passes
+- `cd backend && python -m pytest -v` — zero new failures
+- `cd frontend && npm run build` — zero errors
+- Manual: docker-compose.yml celery-worker service has `volumes: - ./backend:/app`
+- Manual: open CloudStorageView at /cloud — upload hint visible below connections list
+- Manual: curl -H "Authorization: Bearer <token>" http://localhost:8000/api/cloud/oauth/initiate/onedrive (with empty OneDrive creds) → 400 with "ONEDRIVE_CLIENT_ID" in detail
+</verification>
+
+<success_criteria>
+- oauth_initiate returns 400 with descriptive env-var hint for unconfigured google_drive and onedrive
+- stream_document_content returns 502 (not 500) for non-CloudConnectionError cloud exceptions
+- celery-worker has volume mount so `docker compose restart celery-worker` picks up code changes
+- CloudStorageView shows upload hint directing users to navigate into a folder
+- 3 new backend tests pass; full pytest suite has zero new failures; frontend build clean
+</success_criteria>
+
+<output>
+Create `.planning/phases/05-cloud-storage-backends/05-12-SUMMARY.md` when done
+</output>

.planning/phases/05-cloud-storage-backends/05-12-SUMMARY.md

@@ -0,0 +1,51 @@
+---
+phase: 05-cloud-storage-backends
+plan: 12
+status: complete
+completed: 2026-05-30
+---
+
+# Plan 05-12 Summary — UAT Gap Closure
+
+## What Was Built
+
+Closed 3 UAT gaps from Phase 5 testing:
+
+**Task 1 — Pre-flight config validation in oauth_initiate (backend/api/cloud.py)**
+- Added config checks before entering OAuth library code for both providers
+- `GET /api/cloud/oauth/initiate/google_drive` with empty `GOOGLE_CLIENT_ID`/`SECRET` → 400 with env-var hint
+- `GET /api/cloud/oauth/initiate/onedrive` with empty `ONEDRIVE_CLIENT_ID`/`SECRET` → 400 with env-var hint
+- Existing MSAL / google-auth flows unchanged when credentials are present
+- Added 2 new tests in `backend/tests/test_cloud.py`; fixed 2 existing tests that needed credential monkeypatching
+
+**Task 2 — 502 fallback in stream_document_content + celery-worker volume mount**
+- Added broad `except Exception → 502` clause after the existing `except CloudConnectionError → 503` in `stream_document_content`
+- Cloud backend runtime errors now return a user-friendly "Cloud backend unreachable" message instead of an opaque 500
+- Added `volumes: - ./backend:/app` to celery-worker in `docker-compose.yml` — code changes now reflected via `docker compose restart celery-worker` without a full rebuild
+- Added 1 new test `test_stream_document_content_cloud_backend_error` in `backend/tests/test_documents.py`
+
+**Task 3 — Upload hint in CloudStorageView (frontend/src/views/CloudStorageView.vue)**
+- Added `<p>` hint below the connections list: "To upload files, navigate into a cloud folder first."
+- Hint only visible when `connections.length > 0` (not on empty state)
+- No DropZone added (no cloud folder context available at this level)
+
+## Key Files Modified
+
+- `backend/api/cloud.py` — pre-flight config checks in oauth_initiate
+- `backend/api/documents.py` — broad 502 except-clause in stream_document_content
+- `docker-compose.yml` — volume mount for celery-worker
+- `frontend/src/views/CloudStorageView.vue` — upload hint paragraph
+- `backend/tests/test_cloud.py` — 2 new pre-flight tests; 2 existing tests patched
+- `backend/tests/test_documents.py` — 1 new 502 path test
+
+## Test Results
+
+- `pytest tests/test_cloud.py::test_oauth_initiate_google_drive_not_configured` ✅ PASS
+- `pytest tests/test_cloud.py::test_oauth_initiate_onedrive_not_configured` ✅ PASS
+- `pytest tests/test_documents.py::test_stream_document_content_cloud_backend_error` ✅ PASS
+- `pytest -v` — 293 passed, 1 pre-existing failure (test_extract_docx / missing module), 5 skipped, 24 xfailed
+- `npm run build` — ✅ clean exit
+
+## Self-Check: PASSED
+
+All acceptance criteria met. Zero new test failures introduced.

backend/api/cloud.py

@@ -345,6 +345,17 @@ async def oauth_initiate(
 
     redirect_uri = f"{settings.backend_url}/api/cloud/oauth/callback/{provider}"
 
+    if provider == "google_drive" and (not settings.google_client_id or not settings.google_client_secret):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Google Drive OAuth is not configured on this server. Set GOOGLE_CLIENT_ID and GOOGLE_CLIENT_SECRET in your environment.",
+        )
+    if provider == "onedrive" and (not settings.onedrive_client_id or not settings.onedrive_client_secret):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="OneDrive OAuth is not configured on this server. Set ONEDRIVE_CLIENT_ID, ONEDRIVE_CLIENT_SECRET, and ONEDRIVE_TENANT_ID in your environment.",
+        )
+
     if provider == "google_drive":
         from google_auth_oauthlib.flow import Flow  # lazy import
 

backend/api/documents.py

@@ -756,6 +756,11 @@ async def stream_document_content(
             status_code=503,
             detail="Cloud connection requires re-authentication. Please reconnect in Settings.",
         ) from exc
+    except Exception as exc:
+        raise HTTPException(
+            status_code=502,
+            detail="Cloud backend unreachable. Please try again or reconnect in Settings.",
+        ) from exc
     file_size = len(file_bytes)
 
     headers = {

backend/tests/test_cloud.py

@@ -184,9 +184,14 @@ async def test_connect_google_drive(async_client, db_session, monkeypatch):
     so the frontend can inject the Bearer Authorization header before navigating.
     """
     from main import app
+    from config import settings
 
     auth = await _create_user_and_token(db_session, role="user")
 
+    # Ensure pre-flight config check passes (plan 05-12)
+    monkeypatch.setattr(settings, "google_client_id", "test_google_client_id")
+    monkeypatch.setattr(settings, "google_client_secret", "test_google_client_secret")
+
     # Mock Redis to avoid needing a real Redis connection
     fake_redis = FakeRedis()
     app.state.redis = fake_redis
@@ -728,7 +733,7 @@ async def test_reanalyze_cloud_document_routes_to_cloud_backend():
 # ── Plan 10 tests: OAuth initiate returns JSON URL ────────────────────────────
 
 
-async def test_oauth_initiate_returns_json_url(async_client, db_session):
+async def test_oauth_initiate_returns_json_url(async_client, db_session, monkeypatch):
     """GET /api/cloud/oauth/initiate/google_drive returns 200 JSON {url} (not 302).
 
     Verifies the fix for CLOUD-01 / T-05-10-01: authenticated users receive
@@ -736,9 +741,14 @@ async def test_oauth_initiate_returns_json_url(async_client, db_session):
     header before navigating (plan 05-10).
     """
     from main import app
+    from config import settings
 
     auth = await _create_user_and_token(db_session, role="user")
 
+    # Ensure pre-flight config check passes (plan 05-12)
+    monkeypatch.setattr(settings, "google_client_id", "test_google_client_id")
+    monkeypatch.setattr(settings, "google_client_secret", "test_google_client_secret")
+
     # Set up fake Redis so state token storage works
     fake_redis = FakeRedis()
     app.state.redis = fake_redis
@@ -771,6 +781,60 @@ async def test_oauth_initiate_returns_json_url(async_client, db_session):
     app.state.redis = None
 
 
+async def test_oauth_initiate_google_drive_not_configured(async_client, db_session, monkeypatch):
+    """GET /api/cloud/oauth/initiate/google_drive returns 400 with env-var hint when creds missing.
+
+    Pre-flight check (plan 05-12): empty GOOGLE_CLIENT_ID/SECRET → 400 before touching OAuth libs.
+    """
+    from main import app
+    from config import settings
+
+    auth = await _create_user_and_token(db_session, role="user")
+    fake_redis = FakeRedis()
+    app.state.redis = fake_redis
+
+    monkeypatch.setattr(settings, "google_client_id", "")
+    monkeypatch.setattr(settings, "google_client_secret", "")
+
+    resp = await async_client.get(
+        "/api/cloud/oauth/initiate/google_drive",
+        headers=auth["headers"],
+        follow_redirects=False,
+    )
+
+    app.state.redis = None
+
+    assert resp.status_code == 400, f"Expected 400, got {resp.status_code}: {resp.text}"
+    assert "GOOGLE_CLIENT_ID" in resp.json()["detail"], f"Unexpected detail: {resp.json()['detail']}"
+
+
+async def test_oauth_initiate_onedrive_not_configured(async_client, db_session, monkeypatch):
+    """GET /api/cloud/oauth/initiate/onedrive returns 400 with env-var hint when creds missing.
+
+    Pre-flight check (plan 05-12): empty ONEDRIVE_CLIENT_ID → 400 before touching MSAL.
+    """
+    from main import app
+    from config import settings
+
+    auth = await _create_user_and_token(db_session, role="user")
+    fake_redis = FakeRedis()
+    app.state.redis = fake_redis
+
+    monkeypatch.setattr(settings, "onedrive_client_id", "")
+    monkeypatch.setattr(settings, "onedrive_client_secret", "")
+
+    resp = await async_client.get(
+        "/api/cloud/oauth/initiate/onedrive",
+        headers=auth["headers"],
+        follow_redirects=False,
+    )
+
+    app.state.redis = None
+
+    assert resp.status_code == 400, f"Expected 400, got {resp.status_code}: {resp.text}"
+    assert "ONEDRIVE_CLIENT_ID" in resp.json()["detail"], f"Unexpected detail: {resp.json()['detail']}"
+
+
 async def test_oauth_initiate_requires_auth(async_client, db_session):
     """GET /api/cloud/oauth/initiate/google_drive without token returns 401 or 403.
 

backend/tests/test_documents.py

@@ -593,3 +593,40 @@ async def test_parse_range_416(async_client, auth_user, db_session, monkeypatch)
         headers={**auth_user["headers"], "Range": "bytes=100-200"},
     )
     assert resp.status_code == 416
+
+
+async def test_stream_document_content_cloud_backend_error(async_client, auth_user, db_session, monkeypatch):
+    """GET /api/documents/{id}/content returns 502 when cloud backend raises a non-CloudConnectionError exception.
+
+    Plan 05-12 gap closure: broad except-clause catches RuntimeError, timeout, etc. and
+    returns a user-friendly 502 instead of an opaque 500.
+    """
+    import uuid as _uuid
+    from unittest.mock import AsyncMock
+    from db.models import Document
+
+    doc_id = _uuid.uuid4()
+    doc = Document(
+        id=doc_id,
+        user_id=auth_user["user"].id,
+        filename="cloud_doc.pdf",
+        content_type="application/pdf",
+        size_bytes=1024,
+        storage_backend="google_drive",
+        status="uploaded",
+        object_key=f"{auth_user['user'].id}/{doc_id}/{_uuid.uuid4()}.pdf",
+    )
+    db_session.add(doc)
+    await db_session.commit()
+
+    async def raise_runtime_error(*args, **kwargs):
+        raise RuntimeError("connection timeout")
+
+    monkeypatch.setattr("api.documents.get_storage_backend_for_document", raise_runtime_error)
+
+    resp = await async_client.get(
+        f"/api/documents/{doc_id}/content",
+        headers=auth_user["headers"],
+    )
+    assert resp.status_code == 502, f"Expected 502, got {resp.status_code}: {resp.text}"
+    assert "Cloud backend unreachable" in resp.json()["detail"]

docker-compose.yml

@@ -88,6 +88,8 @@ services:
       - MINIO_BUCKET=${MINIO_BUCKET}
       - REDIS_URL=${REDIS_URL}
       - PYTHONDONTWRITEBYTECODE=1
+    volumes:
+      - ./backend:/app
     extra_hosts:
       - "host.docker.internal:host-gateway"
     command: celery -A celery_app worker --loglevel=info -Q documents

frontend/src/views/CloudStorageView.vue

@@ -50,6 +50,10 @@
         </div>
       </div>
 
+      <p v-if="connections.length > 0" class="mt-4 text-xs text-gray-400 text-center">
+        To upload files, navigate into a cloud folder first.
+      </p>
+
     </div>
   </div>
 </template>