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# BUG: Discover Button Not Working **Reported:** 2025-04-10 **Status:** Resolved (2025-04-10) ## Description The "Discover" button in the frontend is not triggering the expected API call to the backend (`/api/discover`) or initiating the `crawl4ai` process. The backend logs show no activity related to this action. This issue started occurring after a recent merge commit. ## Initial Investigation Plan (To be created by Debug mode) - [ ] TBD ## Expert Opinion Review (Received 2025-04-10) **Overall:** Plan is solid (9/10), methodical, covers full flow. Emphasizes non-invasive diagnostics. **Suggestions for Improvement:** - **UI State:** Verify button isn't hidden/disabled by React state/props. - **Console Errors:** Check browser console for existing errors *before* adding logs. - **API Call Details:** Explicitly check request headers (auth, content-type) and payload shape. - **API Route Specifics:** Verify HTTP method match, check for middleware/edge configs affecting the route. - **Backend Call:** Verify inter-service communication method (HTTP, etc.) and check related env vars/configs. - **Merge Impact:** Explicitly search for leftover conflict markers (`<<<<`, `====`, `>>>>`). - **Documentation:** Log findings progressively in this document during diagnosis. - **Minor:** Check CORS, API route auth, consider `curl`/Postman testing. **Confidence in Revised Plan:** 9.5/10 ## Refined Diagnostic Plan (Incorporating Expert Feedback - 2025-04-10) This plan focuses on non-invasive diagnostics (observation, verification, documentation) before any code changes. **1. Initial UI & Console Inspection** - [ ] **1.1. Verify UI State:** Confirm button visible/enabled in DOM, check React state/props for conditional rendering/disabling. - [ ] **1.2. Check Browser Console:** Look for existing JS errors/warnings *before* adding new logs. Document findings. **2. Network Request Verification** - [ ] **2.1. Observe API Calls:** Use browser dev tools (Network tab) to check if clicking button triggers API request. - [ ] **2.2. Inspect Request Details:** If request exists, verify method, URL, headers (auth, content-type, CORS), and payload shape/data. - [ ] **2.3. Test API Endpoint Independently:** Use `curl`/Postman to invoke API directly. Document results. **3. Backend API Route & Middleware Checks** - [ ] **3.1. Verify API Route Implementation:** Confirm route exists and matches HTTP method. - [ ] **3.2. Inspect Middleware/Configs/Auth:** Check middleware (auth, rate limit, CORS), edge configs, and auth requirements affecting the route. - [ ] **3.3. Search for Merge Conflict Markers:** Search codebase for leftover markers (`<<<<`, `====`, `>>>>`). **4. Backend Service & Environment Validation** - [ ] **4.1. Trace Backend Call Chain:** Determine how API route calls backend (HTTP, RPC, etc.). - [ ] **4.2. Check Env Vars & Configs:** Verify env vars/configs used in backend calls. **5. Progressive Documentation** - [ ] **Throughout:** Log all findings progressively in this document. **6. Summary & Next Steps** - [ ] Summarize findings and propose next steps *after* completing diagnostics. ## Debugging and Resolution Summary (2025-04-10) **Initial Problem:** Clicking the "Discover" button resulted in a browser console error `net::ERR_NAME_NOT_RESOLVED` when trying to POST to `http://backend:24125/api/discover`. The backend service was not being called. **Debugging Steps & Findings:** 1. **Initial Hypothesis & Plan:** Suspected an issue with frontend-backend communication, possibly related to Docker configuration or a regression from a recent merge. Created a diagnostic plan focusing on verifying the request flow from UI to backend. Received expert feedback suggesting checks for UI state, console errors, request details, middleware, backend configs, and merge markers. 2. **Console Error Analysis:** User provided console output confirming the `net::ERR_NAME_NOT_RESOLVED` error, indicating the browser was trying to resolve the internal Docker hostname `backend`. 3. **Review Previous Fixes:** Examined `docs/features/fix_backend_url_resolution_plan.md`, `docs/features/fix_frontend_build_env_var_plan.md`, and `docs/features/fix_discover_url.md`. Confirmed previous issues involved backend URL resolution and environment variables during Docker builds. 4. **Docker Configuration Check:** * Verified `docker-compose.yml` correctly passed `NEXT_PUBLIC_BACKEND_URL` via `build.args`. * Found incorrect `ENV NEXT_PUBLIC_BACKEND_URL http://backend:24125` lines in `docker/dockerfiles/Dockerfile.frontend` that were overriding the build argument. 5. **Fix 1 (Dockerfile ENV Override):** Removed the incorrect `ENV` lines from `Dockerfile.frontend`. **Result:** Error persisted. 6. **Environment Variable Check:** Verified `.env` file correctly set `NEXT_PUBLIC_BACKEND_URL=http://localhost:24125`. Verified shell environment variable was also correct (`echo $NEXT_PUBLIC_BACKEND_URL` showed `http://localhost:24125`). 7. **Next.js Cache Hypothesis:** Suspected persistent `.next` cache might ignore Dockerfile changes. 8. **Fix 2 (Dockerfile Cache Clear):** Added `RUN rm -rf .next` before `RUN npm run build` in `Dockerfile.frontend`. **Result:** Error persisted. 9. **Client-Side Code Analysis:** * Searched for hardcoded `http://backend:24125` (found only in a server-side API route, not the cause of the browser error). * Searched for `/api/discover` usage. Found direct client-side calls in `lib/crawl-service.ts` using a `BACKEND_URL` variable. * Examined `lib/crawl-service.ts`: `BACKEND_URL` was derived from `process.env.NEXT_PUBLIC_BACKEND_URL`. Console log `Using backend URL: http://backend:24125` confirmed the build process was still baking in the wrong URL despite correct `.env` and shell variables. This pointed back to a misunderstanding based on previous fixes (`fix_discover_url.md`) which *intended* to use the internal name, conflicting with the client-side call strategy. 10. **Architecture Correction:** Determined the correct approach was to proxy all browser calls through Next.js API routes. 11. **Fix 3 (Client-Side Relative URLs):** * Updated `lib/crawl-service.ts` to remove `BACKEND_URL` and use relative paths (e.g., `/api/discover`, `/api/crawl`). * Updated `app/page.tsx` polling logic similarly (`/api/crawl-status/...`). * Renamed backend URL usage in `app/api/discover/route.ts` to `INTERNAL_BACKEND_URL` for clarity. **Result:** `net::ERR_NAME_NOT_RESOLVED` fixed, but a new error appeared: `No job_id in response`. 12. **API Route Response Check:** * Examined backend `/api/discover` in `backend/app/main.py`: Confirmed it *does* return `job_id`. * Examined Next.js API route `app/api/discover/route.ts`: Found it was receiving the backend response but constructing a *new* response for the browser, omitting the `job_id`. 13. **Fix 4 (API Route Response Forwarding):** Modified `app/api/discover/route.ts` to forward the full JSON response from the backend directly to the browser. **Result:** "No job_id" error fixed, but status polling failed with `404 Not Found` for `/api/crawl-status/[job_id]`. 14. **Missing API Route Check:** Listed files in `app/api/crawl-status` and found it empty. 15. **Fix 5 (Create Status API Route):** Created `app/api/crawl-status/[job_id]/route.ts` to handle status polling requests and proxy them to the backend service. **Result:** 404 error fixed, but backend logs showed `NameError: name 'poll_url' is not defined` in `backend/app/crawler.py`. 16. **Backend Crawler Bug Check:** Examined `backend/app/crawler.py`. 17. **Fix 6 (Backend NameError):** Corrected the `NameError` in the `discover_pages` function (around line 225) to use the correct variable for polling the Crawl4AI task status URL. **Result:** All errors resolved, discovery and status polling working correctly. ## Final Resolution The initial `net::ERR_NAME_NOT_RESOLVED` error stemmed from a conflict between the frontend attempting direct client-side calls to the backend and an environment setup (influenced by previous fixes) that provided the internal Docker hostname during the build. The correct architecture was implemented by routing all client-side calls through Next.js API routes. Subsequent issues involved the discover API route not forwarding the `job_id`, a missing status polling API route, and finally a `NameError` in the backend crawler code. **Files Modified:** - `docker/dockerfiles/Dockerfile.frontend` (Removed ENV override, added cache clear) - `lib/crawl-service.ts` (Switched to relative API paths, removed BACKEND_URL) - `app/page.tsx` (Switched polling to relative API path) - `app/api/discover/route.ts` (Corrected response forwarding, renamed internal URL variable) - `app/api/crawl-status/[job_id]/route.ts` (Created file and implemented proxy logic) - `backend/app/crawler.py` (Fixed `NameError` in `discover_pages`) **Required Action (Completed by User):** Rebuild relevant Docker images (`frontend`, `backend`) and restart services. Clear browser cache.