shettydev · Jun 29, 2026 · Jun 28, 2026 · Jun 28, 2026 · Jun 28, 2026 · Jun 28, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -9,6 +9,10 @@ jobs:
   test:
     name: Test (Python ${{ matrix.python-version }})
     runs-on: ubuntu-latest
+    defaults:
+      run:
+        # The Python backend lives in backend/ since the monorepo split.
+        working-directory: backend
     strategy:
       fail-fast: false
       matrix:
@@ -41,6 +45,7 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
           cache: pip
+          cache-dependency-path: backend/requirements*.txt
 
       - name: Set up Node.js
         # Node powers the JavaScript code runner; without it the JS runner tests

diff --git a/README.md b/README.md
@@ -26,34 +26,58 @@ Most interview platforms are puzzle grinders. O(1) Prep puts you in a real inter
 
 ## Quick Start
 
+The repository is a monorepo: the Python API lives in **`backend/`**, the web client in **`frontend/`**, and shared infrastructure (`docker-compose.yml`) at the root.
+
 ```bash
 git clone <repo-url>
 cd o1prep
+docker compose up -d                  # start PostgreSQL (from the repo root)
+
+cd backend                            # the Python API lives here
 python3 -m venv venv && source venv/bin/activate
 pip install -r requirements.txt
 ```
 
-Copy `.env.example` to `.env` and set your values (database URL, a secret key, and your OpenAI key):
+Copy `backend/.env.example` to `backend/.env` and set your values (database URL, a secret key, and your OpenAI key):
 
 ```
 DATABASE_URL=postgresql+psycopg://o1prep:o1prep@localhost:5433/o1prep
 SECRET_KEY=change-me
 OPENAI_API_KEY=sk-your-key-here
 ```
 
-Start PostgreSQL, create the schema, load the problems, and run:
+Create the schema, load the problems, and run — all from `backend/`:
 
 ```bash
-docker compose up -d                  # start PostgreSQL
 export FLASK_APP=app
 flask db upgrade                      # create tables
 python scripts/seed_problems.py       # load the problem library
 python app.py
 ```
 
-Open **http://localhost:5000**, create an account, and start practicing.
+This serves the API (and the legacy server-rendered UI) on **http://localhost:5000**.
+
+### Frontend (Next.js)
+
+The web client is a separate Next.js app in `frontend/` that talks to the Flask
+API. In a second terminal:
+
+```bash
+cd frontend
+npm install
+npm run dev                           # http://localhost:3000
+```
+
+Open **http://localhost:3000**. The dev server proxies `/api/*` to Flask on
+`127.0.0.1:5000` (see `frontend/next.config.ts`), so the session cookie stays
+same-origin and auth works with no CORS setup. Point it elsewhere with
+`API_ORIGIN=http://host:port npm run dev`.
+
+> On macOS, the AirPlay Receiver squats on port 5000 over IPv6 — the proxy
+> targets `127.0.0.1` (IPv4) specifically to avoid it. If you change the Flask
+> port, update `API_ORIGIN`.
 
-> **Prerequisites:** Python 3.11+, Docker (for PostgreSQL), a paid OpenAI API key, and a modern browser (Chrome/Firefox/Safari). Node.js is optional — install it (or set `NODE_BIN`) to run and test solutions in JavaScript.
+> **Prerequisites:** Python 3.11+, Node.js 20+, Docker (for PostgreSQL), a paid OpenAI API key, and a modern browser (Chrome/Firefox/Safari).
 
 ---
 

diff --git a/.env.example → backend/.env.example b/.env.example → backend/.env.example
diff --git a/app.py → backend/app.py b/app.py → backend/app.py
diff --git a/config.py → backend/config.py b/config.py → backend/config.py
diff --git a/migrations/README → backend/migrations/README b/migrations/README → backend/migrations/README
diff --git a/migrations/alembic.ini → backend/migrations/alembic.ini b/migrations/alembic.ini → backend/migrations/alembic.ini
diff --git a/migrations/env.py → backend/migrations/env.py b/migrations/env.py → backend/migrations/env.py
diff --git a/migrations/script.py.mako → backend/migrations/script.py.mako b/migrations/script.py.mako → backend/migrations/script.py.mako
diff --git a/...4ba59_initial_schema_problems_problem_.py → ...4ba59_initial_schema_problems_problem_.py b/...4ba59_initial_schema_problems_problem_.py → ...4ba59_initial_schema_problems_problem_.py
diff --git a/problems/01-lru-cache.yaml → backend/problems/01-lru-cache.yaml b/problems/01-lru-cache.yaml → backend/problems/01-lru-cache.yaml
diff --git a/problems/02-time-based-key-value-store.yaml → ...oblems/02-time-based-key-value-store.yaml b/problems/02-time-based-key-value-store.yaml → ...oblems/02-time-based-key-value-store.yaml
diff --git a/problems/03-versioned-dictionary.yaml → ...end/problems/03-versioned-dictionary.yaml b/problems/03-versioned-dictionary.yaml → ...end/problems/03-versioned-dictionary.yaml
diff --git a/problems/04-sliding-window-rate-limiter.yaml → ...blems/04-sliding-window-rate-limiter.yaml b/problems/04-sliding-window-rate-limiter.yaml → ...blems/04-sliding-window-rate-limiter.yaml
diff --git a/problems/05-undo-redo-text-buffer.yaml → ...nd/problems/05-undo-redo-text-buffer.yaml b/problems/05-undo-redo-text-buffer.yaml → ...nd/problems/05-undo-redo-text-buffer.yaml
diff --git a/problems/06-expiring-key-value-cache.yaml → ...problems/06-expiring-key-value-cache.yaml b/problems/06-expiring-key-value-cache.yaml → ...problems/06-expiring-key-value-cache.yaml
diff --git a/.../07-ordered-event-stream-reassembler.yaml → .../07-ordered-event-stream-reassembler.yaml b/.../07-ordered-event-stream-reassembler.yaml → .../07-ordered-event-stream-reassembler.yaml
diff --git a/problems/08-expression-evaluator.yaml → ...end/problems/08-expression-evaluator.yaml b/problems/08-expression-evaluator.yaml → ...end/problems/08-expression-evaluator.yaml
diff --git a/problems/09-config-file-parser.yaml → backend/problems/09-config-file-parser.yaml b/problems/09-config-file-parser.yaml → backend/problems/09-config-file-parser.yaml
diff --git a/problems/10-dependency-graph-resolver.yaml → ...roblems/10-dependency-graph-resolver.yaml b/problems/10-dependency-graph-resolver.yaml → ...roblems/10-dependency-graph-resolver.yaml
diff --git a/problems/100-itertools.yaml → backend/problems/100-itertools.yaml b/problems/100-itertools.yaml → backend/problems/100-itertools.yaml
diff --git a/problems/101-reverse-linked-list.yaml → ...end/problems/101-reverse-linked-list.yaml b/problems/101-reverse-linked-list.yaml → ...end/problems/101-reverse-linked-list.yaml
diff --git a/problems/102-linked-list-cycle.yaml → backend/problems/102-linked-list-cycle.yaml b/problems/102-linked-list-cycle.yaml → backend/problems/102-linked-list-cycle.yaml
diff --git a/problems/103-merge-two-sorted-lists.yaml → .../problems/103-merge-two-sorted-lists.yaml b/problems/103-merge-two-sorted-lists.yaml → .../problems/103-merge-two-sorted-lists.yaml
diff --git a/problems/104-binary-tree-level-order.yaml → ...problems/104-binary-tree-level-order.yaml b/problems/104-binary-tree-level-order.yaml → ...problems/104-binary-tree-level-order.yaml
diff --git a/problems/105-validate-bst.yaml → backend/problems/105-validate-bst.yaml b/problems/105-validate-bst.yaml → backend/problems/105-validate-bst.yaml
diff --git a/problems/106-lowest-common-ancestor.yaml → .../problems/106-lowest-common-ancestor.yaml b/problems/106-lowest-common-ancestor.yaml → .../problems/106-lowest-common-ancestor.yaml
diff --git a/problems/107-binary-tree-max-path-sum.yaml → ...roblems/107-binary-tree-max-path-sum.yaml b/problems/107-binary-tree-max-path-sum.yaml → ...roblems/107-binary-tree-max-path-sum.yaml
diff --git a/problems/108-coin-change.yaml → backend/problems/108-coin-change.yaml b/problems/108-coin-change.yaml → backend/problems/108-coin-change.yaml
diff --git a/...s/109-longest-increasing-subsequence.yaml → ...s/109-longest-increasing-subsequence.yaml b/...s/109-longest-increasing-subsequence.yaml → ...s/109-longest-increasing-subsequence.yaml
diff --git a/problems/11-json-path-query-engine.yaml → ...d/problems/11-json-path-query-engine.yaml b/problems/11-json-path-query-engine.yaml → ...d/problems/11-json-path-query-engine.yaml
diff --git a/problems/110-knapsack.yaml → backend/problems/110-knapsack.yaml b/problems/110-knapsack.yaml → backend/problems/110-knapsack.yaml
diff --git a/problems/111-edit-distance.yaml → backend/problems/111-edit-distance.yaml b/problems/111-edit-distance.yaml → backend/problems/111-edit-distance.yaml
diff --git a/problems/112-number-of-islands.yaml → backend/problems/112-number-of-islands.yaml b/problems/112-number-of-islands.yaml → backend/problems/112-number-of-islands.yaml
diff --git a/problems/113-spiral-matrix.yaml → backend/problems/113-spiral-matrix.yaml b/problems/113-spiral-matrix.yaml → backend/problems/113-spiral-matrix.yaml
diff --git a/problems/114-container-with-most-water.yaml → ...oblems/114-container-with-most-water.yaml b/problems/114-container-with-most-water.yaml → ...oblems/114-container-with-most-water.yaml
diff --git a/problems/115-three-sum.yaml → backend/problems/115-three-sum.yaml b/problems/115-three-sum.yaml → backend/problems/115-three-sum.yaml
diff --git a/...lems/116-longest-substring-no-repeat.yaml → ...lems/116-longest-substring-no-repeat.yaml b/...lems/116-longest-substring-no-repeat.yaml → ...lems/116-longest-substring-no-repeat.yaml
diff --git a/problems/117-subarray-sum-equals-k.yaml → ...d/problems/117-subarray-sum-equals-k.yaml b/problems/117-subarray-sum-equals-k.yaml → ...d/problems/117-subarray-sum-equals-k.yaml
diff --git a/problems/118-generate-subsets.yaml → backend/problems/118-generate-subsets.yaml b/problems/118-generate-subsets.yaml → backend/problems/118-generate-subsets.yaml
diff --git a/problems/119-word-break.yaml → backend/problems/119-word-break.yaml b/problems/119-word-break.yaml → backend/problems/119-word-break.yaml
diff --git a/problems/12-cron-expression-scheduler.yaml → ...roblems/12-cron-expression-scheduler.yaml b/problems/12-cron-expression-scheduler.yaml → ...roblems/12-cron-expression-scheduler.yaml
diff --git a/problems/120-combinations.yaml → backend/problems/120-combinations.yaml b/problems/120-combinations.yaml → backend/problems/120-combinations.yaml
diff --git a/problems/121-tic-tac-toe.yaml → backend/problems/121-tic-tac-toe.yaml b/problems/121-tic-tac-toe.yaml → backend/problems/121-tic-tac-toe.yaml
diff --git a/problems/122-connect-four.yaml → backend/problems/122-connect-four.yaml b/problems/122-connect-four.yaml → backend/problems/122-connect-four.yaml
diff --git a/problems/123-battleship.yaml → backend/problems/123-battleship.yaml b/problems/123-battleship.yaml → backend/problems/123-battleship.yaml
diff --git a/problems/124-snake-game.yaml → backend/problems/124-snake-game.yaml b/problems/124-snake-game.yaml → backend/problems/124-snake-game.yaml
diff --git a/problems/125-chess-move-validator.yaml → ...nd/problems/125-chess-move-validator.yaml b/problems/125-chess-move-validator.yaml → ...nd/problems/125-chess-move-validator.yaml
diff --git a/problems/126-deck-of-cards.yaml → backend/problems/126-deck-of-cards.yaml b/problems/126-deck-of-cards.yaml → backend/problems/126-deck-of-cards.yaml
diff --git a/problems/127-flatten-iterator.yaml → backend/problems/127-flatten-iterator.yaml b/problems/127-flatten-iterator.yaml → backend/problems/127-flatten-iterator.yaml
diff --git a/problems/128-transaction-manager.yaml → ...end/problems/128-transaction-manager.yaml b/problems/128-transaction-manager.yaml → ...end/problems/128-transaction-manager.yaml
diff --git a/problems/129-alternating-generators.yaml → .../problems/129-alternating-generators.yaml b/problems/129-alternating-generators.yaml → .../problems/129-alternating-generators.yaml
diff --git a/problems/13-template-engine.yaml → backend/problems/13-template-engine.yaml b/problems/13-template-engine.yaml → backend/problems/13-template-engine.yaml
diff --git a/problems/130-debug-binary-search.yaml → ...end/problems/130-debug-binary-search.yaml b/problems/130-debug-binary-search.yaml → ...end/problems/130-debug-binary-search.yaml
diff --git a/problems/131-optimize-duplicates.yaml → ...end/problems/131-optimize-duplicates.yaml b/problems/131-optimize-duplicates.yaml → ...end/problems/131-optimize-duplicates.yaml
diff --git a/problems/132-debug-sliding-window.yaml → ...nd/problems/132-debug-sliding-window.yaml b/problems/132-debug-sliding-window.yaml → ...nd/problems/132-debug-sliding-window.yaml
diff --git a/problems/133-sum-of-digits.yaml → backend/problems/133-sum-of-digits.yaml b/problems/133-sum-of-digits.yaml → backend/problems/133-sum-of-digits.yaml
diff --git a/problems/134-is-power-of-two.yaml → backend/problems/134-is-power-of-two.yaml b/problems/134-is-power-of-two.yaml → backend/problems/134-is-power-of-two.yaml
diff --git a/problems/135-fibonacci.yaml → backend/problems/135-fibonacci.yaml b/problems/135-fibonacci.yaml → backend/problems/135-fibonacci.yaml
diff --git a/problems/136-count-evens.yaml → backend/problems/136-count-evens.yaml b/problems/136-count-evens.yaml → backend/problems/136-count-evens.yaml
diff --git a/problems/137-second-largest.yaml → backend/problems/137-second-largest.yaml b/problems/137-second-largest.yaml → backend/problems/137-second-largest.yaml
diff --git a/problems/138-flatten-one-level.yaml → backend/problems/138-flatten-one-level.yaml b/problems/138-flatten-one-level.yaml → backend/problems/138-flatten-one-level.yaml
diff --git a/problems/139-title-case.yaml → backend/problems/139-title-case.yaml b/problems/139-title-case.yaml → backend/problems/139-title-case.yaml
diff --git a/problems/14-log-pattern-matcher.yaml → backend/problems/14-log-pattern-matcher.yaml b/problems/14-log-pattern-matcher.yaml → backend/problems/14-log-pattern-matcher.yaml
diff --git a/problems/140-remove-duplicates-ordered.yaml → ...oblems/140-remove-duplicates-ordered.yaml b/problems/140-remove-duplicates-ordered.yaml → ...oblems/140-remove-duplicates-ordered.yaml
diff --git a/problems/141-chunk-list.yaml → backend/problems/141-chunk-list.yaml b/problems/141-chunk-list.yaml → backend/problems/141-chunk-list.yaml
diff --git a/problems/142-sum-of-evens.yaml → backend/problems/142-sum-of-evens.yaml b/problems/142-sum-of-evens.yaml → backend/problems/142-sum-of-evens.yaml
diff --git a/problems/143-longest-word.yaml → backend/problems/143-longest-word.yaml b/problems/143-longest-word.yaml → backend/problems/143-longest-word.yaml
diff --git a/problems/144-is-sorted.yaml → backend/problems/144-is-sorted.yaml b/problems/144-is-sorted.yaml → backend/problems/144-is-sorted.yaml
diff --git a/problems/145-caesar-cipher.yaml → backend/problems/145-caesar-cipher.yaml b/problems/145-caesar-cipher.yaml → backend/problems/145-caesar-cipher.yaml
diff --git a/problems/146-count-pairs.yaml → backend/problems/146-count-pairs.yaml b/problems/146-count-pairs.yaml → backend/problems/146-count-pairs.yaml
diff --git a/problems/147-palindrome-number.yaml → backend/problems/147-palindrome-number.yaml b/problems/147-palindrome-number.yaml → backend/problems/147-palindrome-number.yaml
diff --git a/problems/148-list-intersection.yaml → backend/problems/148-list-intersection.yaml b/problems/148-list-intersection.yaml → backend/problems/148-list-intersection.yaml
diff --git a/problems/149-is-leap-year.yaml → backend/problems/149-is-leap-year.yaml b/problems/149-is-leap-year.yaml → backend/problems/149-is-leap-year.yaml
diff --git a/problems/15-course-schedule-builder.yaml → .../problems/15-course-schedule-builder.yaml b/problems/15-course-schedule-builder.yaml → .../problems/15-course-schedule-builder.yaml
diff --git a/problems/150-all-unique-chars.yaml → backend/problems/150-all-unique-chars.yaml b/problems/150-all-unique-chars.yaml → backend/problems/150-all-unique-chars.yaml
diff --git a/problems/151-repeat-chars.yaml → backend/problems/151-repeat-chars.yaml b/problems/151-repeat-chars.yaml → backend/problems/151-repeat-chars.yaml
diff --git a/problems/152-reverse-words.yaml → backend/problems/152-reverse-words.yaml b/problems/152-reverse-words.yaml → backend/problems/152-reverse-words.yaml
diff --git a/problems/153-two-sum-indices.yaml → backend/problems/153-two-sum-indices.yaml b/problems/153-two-sum-indices.yaml → backend/problems/153-two-sum-indices.yaml
diff --git a/problems/154-product-of-array.yaml → backend/problems/154-product-of-array.yaml b/problems/154-product-of-array.yaml → backend/problems/154-product-of-array.yaml
diff --git a/problems/155-stack-with-max.yaml → backend/problems/155-stack-with-max.yaml b/problems/155-stack-with-max.yaml → backend/problems/155-stack-with-max.yaml
diff --git a/problems/156-rotate-left.yaml → backend/problems/156-rotate-left.yaml b/problems/156-rotate-left.yaml → backend/problems/156-rotate-left.yaml
diff --git a/problems/157-count-occurrences.yaml → backend/problems/157-count-occurrences.yaml b/problems/157-count-occurrences.yaml → backend/problems/157-count-occurrences.yaml
diff --git a/problems/158-gcd.yaml → backend/problems/158-gcd.yaml b/problems/158-gcd.yaml → backend/problems/158-gcd.yaml
diff --git a/...ems/16-task-scheduler-with-cooldowns.yaml → ...ems/16-task-scheduler-with-cooldowns.yaml b/...ems/16-task-scheduler-with-cooldowns.yaml → ...ems/16-task-scheduler-with-cooldowns.yaml
diff --git a/problems/17-meeting-room-allocator.yaml → ...d/problems/17-meeting-room-allocator.yaml b/problems/17-meeting-room-allocator.yaml → ...d/problems/17-meeting-room-allocator.yaml
diff --git a/problems/18-interval-merge-and-query.yaml → ...problems/18-interval-merge-and-query.yaml b/problems/18-interval-merge-and-query.yaml → ...problems/18-interval-merge-and-query.yaml
diff --git a/problems/19-job-queue-with-retries.yaml → ...d/problems/19-job-queue-with-retries.yaml b/problems/19-job-queue-with-retries.yaml → ...d/problems/19-job-queue-with-retries.yaml
diff --git a/problems/20-batch-request-coalescer.yaml → .../problems/20-batch-request-coalescer.yaml b/problems/20-batch-request-coalescer.yaml → .../problems/20-batch-request-coalescer.yaml
diff --git a/problems/21-file-system-path-resolver.yaml → ...roblems/21-file-system-path-resolver.yaml b/problems/21-file-system-path-resolver.yaml → ...roblems/21-file-system-path-resolver.yaml
diff --git a/...s/22-permission-inheritance-resolver.yaml → ...s/22-permission-inheritance-resolver.yaml b/...s/22-permission-inheritance-resolver.yaml → ...s/22-permission-inheritance-resolver.yaml
diff --git a/problems/23-autocomplete-system.yaml → backend/problems/23-autocomplete-system.yaml b/problems/23-autocomplete-system.yaml → backend/problems/23-autocomplete-system.yaml
diff --git a/...ms/24-shortest-path-with-constraints.yaml → ...ms/24-shortest-path-with-constraints.yaml b/...ms/24-shortest-path-with-constraints.yaml → ...ms/24-shortest-path-with-constraints.yaml
diff --git a/problems/25-in-memory-search-index.yaml → ...d/problems/25-in-memory-search-index.yaml b/problems/25-in-memory-search-index.yaml → ...d/problems/25-in-memory-search-index.yaml
diff --git a/problems/26-wildcard-file-matcher.yaml → ...nd/problems/26-wildcard-file-matcher.yaml b/problems/26-wildcard-file-matcher.yaml → ...nd/problems/26-wildcard-file-matcher.yaml
diff --git a/problems/27-real-time-leaderboard.yaml → ...nd/problems/27-real-time-leaderboard.yaml b/problems/27-real-time-leaderboard.yaml → ...nd/problems/27-real-time-leaderboard.yaml
diff --git a/problems/28-moving-average-stream.yaml → ...nd/problems/28-moving-average-stream.yaml b/problems/28-moving-average-stream.yaml → ...nd/problems/28-moving-average-stream.yaml
diff --git a/...ms/29-top-k-frequent-items-in-stream.yaml → ...ms/29-top-k-frequent-items-in-stream.yaml b/...ms/29-top-k-frequent-items-in-stream.yaml → ...ms/29-top-k-frequent-items-in-stream.yaml
diff --git a/problems/30-stream-deduplicator.yaml → backend/problems/30-stream-deduplicator.yaml b/problems/30-stream-deduplicator.yaml → backend/problems/30-stream-deduplicator.yaml
diff --git a/problems/31-windowed-event-counter.yaml → ...d/problems/31-windowed-event-counter.yaml b/problems/31-windowed-event-counter.yaml → ...d/problems/31-windowed-event-counter.yaml
diff --git a/problems/32-log-aggregator-pipeline.yaml → .../problems/32-log-aggregator-pipeline.yaml b/problems/32-log-aggregator-pipeline.yaml → .../problems/32-log-aggregator-pipeline.yaml
diff --git a/problems/33-running-median-tracker.yaml → ...d/problems/33-running-median-tracker.yaml b/problems/33-running-median-tracker.yaml → ...d/problems/33-running-median-tracker.yaml
diff --git a/problems/34-connection-pool.yaml → backend/problems/34-connection-pool.yaml b/problems/34-connection-pool.yaml → backend/problems/34-connection-pool.yaml
diff --git a/...ms/35-retry-with-exponential-backoff.yaml → ...ms/35-retry-with-exponential-backoff.yaml b/...ms/35-retry-with-exponential-backoff.yaml → ...ms/35-retry-with-exponential-backoff.yaml
diff --git a/problems/36-circuit-breaker.yaml → backend/problems/36-circuit-breaker.yaml b/problems/36-circuit-breaker.yaml → backend/problems/36-circuit-breaker.yaml
diff --git a/problems/37-streaming-line-reader.yaml → ...nd/problems/37-streaming-line-reader.yaml b/problems/37-streaming-line-reader.yaml → ...nd/problems/37-streaming-line-reader.yaml
diff --git a/problems/38-batched-writer-with-flush.yaml → ...roblems/38-batched-writer-with-flush.yaml b/problems/38-batched-writer-with-flush.yaml → ...roblems/38-batched-writer-with-flush.yaml
diff --git a/problems/39-middleware-pipeline.yaml → backend/problems/39-middleware-pipeline.yaml b/problems/39-middleware-pipeline.yaml → backend/problems/39-middleware-pipeline.yaml
diff --git a/problems/40-event-emitter.yaml → backend/problems/40-event-emitter.yaml b/problems/40-event-emitter.yaml → backend/problems/40-event-emitter.yaml
diff --git a/problems/41-thread-safe-bounded-queue.yaml → ...roblems/41-thread-safe-bounded-queue.yaml b/problems/41-thread-safe-bounded-queue.yaml → ...roblems/41-thread-safe-bounded-queue.yaml
diff --git a/problems/42-read-write-lock.yaml → backend/problems/42-read-write-lock.yaml b/problems/42-read-write-lock.yaml → backend/problems/42-read-write-lock.yaml
diff --git a/problems/43-worker-pool.yaml → backend/problems/43-worker-pool.yaml b/problems/43-worker-pool.yaml → backend/problems/43-worker-pool.yaml
diff --git a/problems/44-async-rate-limited-fetcher.yaml → ...oblems/44-async-rate-limited-fetcher.yaml b/problems/44-async-rate-limited-fetcher.yaml → ...oblems/44-async-rate-limited-fetcher.yaml
diff --git a/problems/45-consistent-hash-ring.yaml → ...end/problems/45-consistent-hash-ring.yaml b/problems/45-consistent-hash-ring.yaml → ...end/problems/45-consistent-hash-ring.yaml
diff --git a/problems/46-cursor-based-paginator.yaml → ...d/problems/46-cursor-based-paginator.yaml b/problems/46-cursor-based-paginator.yaml → ...d/problems/46-cursor-based-paginator.yaml
diff --git a/problems/47-query-builder.yaml → backend/problems/47-query-builder.yaml b/problems/47-query-builder.yaml → backend/problems/47-query-builder.yaml
diff --git a/problems/48-plugin-registry.yaml → backend/problems/48-plugin-registry.yaml b/problems/48-plugin-registry.yaml → backend/problems/48-plugin-registry.yaml
diff --git a/problems/49-diff-and-patch.yaml → backend/problems/49-diff-and-patch.yaml b/problems/49-diff-and-patch.yaml → backend/problems/49-diff-and-patch.yaml
diff --git a/problems/50-schema-validator.yaml → backend/problems/50-schema-validator.yaml b/problems/50-schema-validator.yaml → backend/problems/50-schema-validator.yaml
diff --git a/problems/51-valid-parentheses.yaml → backend/problems/51-valid-parentheses.yaml b/problems/51-valid-parentheses.yaml → backend/problems/51-valid-parentheses.yaml
diff --git a/problems/52-two-sum.yaml → backend/problems/52-two-sum.yaml b/problems/52-two-sum.yaml → backend/problems/52-two-sum.yaml
diff --git a/problems/53-palindrome-checker.yaml → backend/problems/53-palindrome-checker.yaml b/problems/53-palindrome-checker.yaml → backend/problems/53-palindrome-checker.yaml
diff --git a/problems/54-prefix-sum-query.yaml → backend/problems/54-prefix-sum-query.yaml b/problems/54-prefix-sum-query.yaml → backend/problems/54-prefix-sum-query.yaml
diff --git a/problems/55-merge-sorted-arrays.yaml → backend/problems/55-merge-sorted-arrays.yaml b/problems/55-merge-sorted-arrays.yaml → backend/problems/55-merge-sorted-arrays.yaml
diff --git a/problems/56-contains-duplicate.yaml → backend/problems/56-contains-duplicate.yaml b/problems/56-contains-duplicate.yaml → backend/problems/56-contains-duplicate.yaml
diff --git a/problems/57-recent-counter.yaml → backend/problems/57-recent-counter.yaml b/problems/57-recent-counter.yaml → backend/problems/57-recent-counter.yaml
diff --git a/problems/58-anagram-grouper.yaml → backend/problems/58-anagram-grouper.yaml b/problems/58-anagram-grouper.yaml → backend/problems/58-anagram-grouper.yaml
diff --git a/problems/59-query-string-parser.yaml → backend/problems/59-query-string-parser.yaml b/problems/59-query-string-parser.yaml → backend/problems/59-query-string-parser.yaml
diff --git a/problems/60-min-stack.yaml → backend/problems/60-min-stack.yaml b/problems/60-min-stack.yaml → backend/problems/60-min-stack.yaml
diff --git a/problems/61-reverse-string.yaml → backend/problems/61-reverse-string.yaml b/problems/61-reverse-string.yaml → backend/problems/61-reverse-string.yaml
diff --git a/problems/62-fizzbuzz.yaml → backend/problems/62-fizzbuzz.yaml b/problems/62-fizzbuzz.yaml → backend/problems/62-fizzbuzz.yaml
diff --git a/problems/63-running-sum.yaml → backend/problems/63-running-sum.yaml b/problems/63-running-sum.yaml → backend/problems/63-running-sum.yaml
diff --git a/problems/64-max-consecutive-ones.yaml → ...end/problems/64-max-consecutive-ones.yaml b/problems/64-max-consecutive-ones.yaml → ...end/problems/64-max-consecutive-ones.yaml
diff --git a/problems/65-binary-search.yaml → backend/problems/65-binary-search.yaml b/problems/65-binary-search.yaml → backend/problems/65-binary-search.yaml
diff --git a/problems/66-length-of-last-word.yaml → backend/problems/66-length-of-last-word.yaml b/problems/66-length-of-last-word.yaml → backend/problems/66-length-of-last-word.yaml
diff --git a/problems/67-count-vowels.yaml → backend/problems/67-count-vowels.yaml b/problems/67-count-vowels.yaml → backend/problems/67-count-vowels.yaml
diff --git a/problems/68-remove-vowels.yaml → backend/problems/68-remove-vowels.yaml b/problems/68-remove-vowels.yaml → backend/problems/68-remove-vowels.yaml
diff --git a/problems/69-first-unique-character.yaml → ...d/problems/69-first-unique-character.yaml b/problems/69-first-unique-character.yaml → ...d/problems/69-first-unique-character.yaml
diff --git a/problems/70-missing-number.yaml → backend/problems/70-missing-number.yaml b/problems/70-missing-number.yaml → backend/problems/70-missing-number.yaml
diff --git a/problems/71-majority-element.yaml → backend/problems/71-majority-element.yaml b/problems/71-majority-element.yaml → backend/problems/71-majority-element.yaml
diff --git a/problems/72-valid-anagram.yaml → backend/problems/72-valid-anagram.yaml b/problems/72-valid-anagram.yaml → backend/problems/72-valid-anagram.yaml
diff --git a/problems/73-can-construct.yaml → backend/problems/73-can-construct.yaml b/problems/73-can-construct.yaml → backend/problems/73-can-construct.yaml
diff --git a/problems/74-simple-counter.yaml → backend/problems/74-simple-counter.yaml b/problems/74-simple-counter.yaml → backend/problems/74-simple-counter.yaml
diff --git a/problems/75-word-counter.yaml → backend/problems/75-word-counter.yaml b/problems/75-word-counter.yaml → backend/problems/75-word-counter.yaml
diff --git a/problems/76-rotate-right.yaml → backend/problems/76-rotate-right.yaml b/problems/76-rotate-right.yaml → backend/problems/76-rotate-right.yaml
diff --git a/problems/77-longest-common-prefix.yaml → ...nd/problems/77-longest-common-prefix.yaml b/problems/77-longest-common-prefix.yaml → ...nd/problems/77-longest-common-prefix.yaml
diff --git a/problems/78-simple-queue.yaml → backend/problems/78-simple-queue.yaml b/problems/78-simple-queue.yaml → backend/problems/78-simple-queue.yaml
diff --git a/problems/79-clamp-values.yaml → backend/problems/79-clamp-values.yaml b/problems/79-clamp-values.yaml → backend/problems/79-clamp-values.yaml
diff --git a/problems/80-toggle-set.yaml → backend/problems/80-toggle-set.yaml b/problems/80-toggle-set.yaml → backend/problems/80-toggle-set.yaml
diff --git a/problems/81-for-loops.yaml → backend/problems/81-for-loops.yaml b/problems/81-for-loops.yaml → backend/problems/81-for-loops.yaml
diff --git a/problems/82-while-loops.yaml → backend/problems/82-while-loops.yaml b/problems/82-while-loops.yaml → backend/problems/82-while-loops.yaml
diff --git a/problems/83-list-slicing.yaml → backend/problems/83-list-slicing.yaml b/problems/83-list-slicing.yaml → backend/problems/83-list-slicing.yaml
diff --git a/problems/84-list-comprehensions.yaml → backend/problems/84-list-comprehensions.yaml b/problems/84-list-comprehensions.yaml → backend/problems/84-list-comprehensions.yaml
diff --git a/problems/85-dict-comprehensions.yaml → backend/problems/85-dict-comprehensions.yaml b/problems/85-dict-comprehensions.yaml → backend/problems/85-dict-comprehensions.yaml
diff --git a/problems/86-string-methods.yaml → backend/problems/86-string-methods.yaml b/problems/86-string-methods.yaml → backend/problems/86-string-methods.yaml
diff --git a/problems/87-sorting-key.yaml → backend/problems/87-sorting-key.yaml b/problems/87-sorting-key.yaml → backend/problems/87-sorting-key.yaml
diff --git a/problems/88-counter.yaml → backend/problems/88-counter.yaml b/problems/88-counter.yaml → backend/problems/88-counter.yaml
diff --git a/problems/89-defaultdict.yaml → backend/problems/89-defaultdict.yaml b/problems/89-defaultdict.yaml → backend/problems/89-defaultdict.yaml
diff --git a/problems/90-deque.yaml → backend/problems/90-deque.yaml b/problems/90-deque.yaml → backend/problems/90-deque.yaml
diff --git a/problems/91-unpacking.yaml → backend/problems/91-unpacking.yaml b/problems/91-unpacking.yaml → backend/problems/91-unpacking.yaml
diff --git a/problems/92-set-operations.yaml → backend/problems/92-set-operations.yaml b/problems/92-set-operations.yaml → backend/problems/92-set-operations.yaml
diff --git a/problems/93-any-all-builtins.yaml → backend/problems/93-any-all-builtins.yaml b/problems/93-any-all-builtins.yaml → backend/problems/93-any-all-builtins.yaml
diff --git a/problems/94-zip-enumerate.yaml → backend/problems/94-zip-enumerate.yaml b/problems/94-zip-enumerate.yaml → backend/problems/94-zip-enumerate.yaml
diff --git a/problems/95-heapq.yaml → backend/problems/95-heapq.yaml b/problems/95-heapq.yaml → backend/problems/95-heapq.yaml
diff --git a/problems/96-bisect.yaml → backend/problems/96-bisect.yaml b/problems/96-bisect.yaml → backend/problems/96-bisect.yaml
diff --git a/problems/97-generators.yaml → backend/problems/97-generators.yaml b/problems/97-generators.yaml → backend/problems/97-generators.yaml
diff --git a/problems/98-string-formatting.yaml → backend/problems/98-string-formatting.yaml b/problems/98-string-formatting.yaml → backend/problems/98-string-formatting.yaml
diff --git a/problems/99-dict-methods.yaml → backend/problems/99-dict-methods.yaml b/problems/99-dict-methods.yaml → backend/problems/99-dict-methods.yaml
diff --git a/prompts/focus_prompts.json → backend/prompts/focus_prompts.json b/prompts/focus_prompts.json → backend/prompts/focus_prompts.json
diff --git a/prompts/interviewer.txt → backend/prompts/interviewer.txt b/prompts/interviewer.txt → backend/prompts/interviewer.txt
diff --git a/prompts/session_config.txt → backend/prompts/session_config.txt b/prompts/session_config.txt → backend/prompts/session_config.txt
diff --git a/prompts/test_generation.txt → backend/prompts/test_generation.txt b/prompts/test_generation.txt → backend/prompts/test_generation.txt
diff --git a/prompts/tutor.txt → backend/prompts/tutor.txt b/prompts/tutor.txt → backend/prompts/tutor.txt
diff --git a/prompts/voice_interviewer.txt → backend/prompts/voice_interviewer.txt b/prompts/voice_interviewer.txt → backend/prompts/voice_interviewer.txt
diff --git a/pyproject.toml → backend/pyproject.toml b/pyproject.toml → backend/pyproject.toml
diff --git a/requirements-dev.txt → backend/requirements-dev.txt b/requirements-dev.txt → backend/requirements-dev.txt
diff --git a/requirements.txt → backend/requirements.txt b/requirements.txt → backend/requirements.txt
diff --git a/routes/__init__.py → backend/routes/__init__.py b/routes/__init__.py → backend/routes/__init__.py
diff --git a/routes/auth.py → backend/routes/auth.py b/routes/auth.py → backend/routes/auth.py
diff --git a/routes/code.py → backend/routes/code.py b/routes/code.py → backend/routes/code.py
diff --git a/routes/problems.py → backend/routes/problems.py b/routes/problems.py → backend/routes/problems.py
diff --git a/routes/realtime.py → backend/routes/realtime.py b/routes/realtime.py → backend/routes/realtime.py
diff --git a/routes/research.py → backend/routes/research.py b/routes/research.py → backend/routes/research.py
diff --git a/routes/sessions.py → backend/routes/sessions.py b/routes/sessions.py → backend/routes/sessions.py
diff --git a/scripts/_jsgen_lib.py → backend/scripts/_jsgen_lib.py b/scripts/_jsgen_lib.py → backend/scripts/_jsgen_lib.py
diff --git a/scripts/apply_js_variant.py → backend/scripts/apply_js_variant.py b/scripts/apply_js_variant.py → backend/scripts/apply_js_variant.py
diff --git a/scripts/generate_js_variants.py → backend/scripts/generate_js_variants.py b/scripts/generate_js_variants.py → backend/scripts/generate_js_variants.py
diff --git a/scripts/seed_problems.py → backend/scripts/seed_problems.py b/scripts/seed_problems.py → backend/scripts/seed_problems.py
diff --git a/services/__init__.py → backend/services/__init__.py b/services/__init__.py → backend/services/__init__.py
diff --git a/services/ai.py → backend/services/ai.py b/services/ai.py → backend/services/ai.py
diff --git a/services/code_runner.py → backend/services/code_runner.py b/services/code_runner.py → backend/services/code_runner.py
diff --git a/services/db.py → backend/services/db.py b/services/db.py → backend/services/db.py
diff --git a/services/extensions.py → backend/services/extensions.py b/services/extensions.py → backend/services/extensions.py
diff --git a/services/languages.py → backend/services/languages.py b/services/languages.py → backend/services/languages.py
diff --git a/services/models.py → backend/services/models.py b/services/models.py → backend/services/models.py
diff --git a/services/problems.py → backend/services/problems.py b/services/problems.py → backend/services/problems.py
diff --git a/services/providers/__init__.py → backend/services/providers/__init__.py b/services/providers/__init__.py → backend/services/providers/__init__.py
diff --git a/services/providers/claude_provider.py → ...end/services/providers/claude_provider.py b/services/providers/claude_provider.py → ...end/services/providers/claude_provider.py
diff --git a/services/providers/openai_provider.py → ...end/services/providers/openai_provider.py b/services/providers/openai_provider.py → ...end/services/providers/openai_provider.py
diff --git a/services/runners/__init__.py → backend/services/runners/__init__.py b/services/runners/__init__.py → backend/services/runners/__init__.py
diff --git a/services/runners/base.py → backend/services/runners/base.py b/services/runners/base.py → backend/services/runners/base.py
diff --git a/services/runners/javascript_runner.py → ...end/services/runners/javascript_runner.py b/services/runners/javascript_runner.py → ...end/services/runners/javascript_runner.py
diff --git a/services/runners/python_runner.py → backend/services/runners/python_runner.py b/services/runners/python_runner.py → backend/services/runners/python_runner.py
diff --git a/services/runners/typescript_runner.py → ...end/services/runners/typescript_runner.py b/services/runners/typescript_runner.py → ...end/services/runners/typescript_runner.py
diff --git a/services/sessions.py → backend/services/sessions.py b/services/sessions.py → backend/services/sessions.py
diff --git a/static/favicon.ico → backend/static/favicon.ico b/static/favicon.ico → backend/static/favicon.ico
diff --git a/static/favicon.svg → backend/static/favicon.svg b/static/favicon.svg → backend/static/favicon.svg
diff --git a/static/js/auth.js → backend/static/js/auth.js b/static/js/auth.js → backend/static/js/auth.js
diff --git a/static/js/editor.js → backend/static/js/editor.js b/static/js/editor.js → backend/static/js/editor.js
diff --git a/static/js/init.js → backend/static/js/init.js b/static/js/init.js → backend/static/js/init.js
diff --git a/static/js/interview.js → backend/static/js/interview.js b/static/js/interview.js → backend/static/js/interview.js
diff --git a/static/js/problems.js → backend/static/js/problems.js b/static/js/problems.js → backend/static/js/problems.js
diff --git a/static/js/sessions.js → backend/static/js/sessions.js b/static/js/sessions.js → backend/static/js/sessions.js
diff --git a/static/js/settings.js → backend/static/js/settings.js b/static/js/settings.js → backend/static/js/settings.js
diff --git a/static/js/state.js → backend/static/js/state.js b/static/js/state.js → backend/static/js/state.js
diff --git a/static/js/study.js → backend/static/js/study.js b/static/js/study.js → backend/static/js/study.js
diff --git a/static/js/utils.js → backend/static/js/utils.js b/static/js/utils.js → backend/static/js/utils.js
diff --git a/static/js/voice.js → backend/static/js/voice.js b/static/js/voice.js → backend/static/js/voice.js
diff --git a/static/style.css → backend/static/style.css b/static/style.css → backend/static/style.css
diff --git a/templates/index.html → backend/templates/index.html b/templates/index.html → backend/templates/index.html
diff --git a/tests/conftest.py → backend/tests/conftest.py b/tests/conftest.py → backend/tests/conftest.py
diff --git a/tests/test_auth.py → backend/tests/test_auth.py b/tests/test_auth.py → backend/tests/test_auth.py
diff --git a/tests/test_code_runner.py → backend/tests/test_code_runner.py b/tests/test_code_runner.py → backend/tests/test_code_runner.py
diff --git a/tests/test_db.py → backend/tests/test_db.py b/tests/test_db.py → backend/tests/test_db.py
diff --git a/tests/test_problem_schema.py → backend/tests/test_problem_schema.py b/tests/test_problem_schema.py → backend/tests/test_problem_schema.py
diff --git a/tests/test_problems.py → backend/tests/test_problems.py b/tests/test_problems.py → backend/tests/test_problems.py
diff --git a/tests/test_problems_multilang.py → backend/tests/test_problems_multilang.py b/tests/test_problems_multilang.py → backend/tests/test_problems_multilang.py
diff --git a/tests/test_routes_language.py → backend/tests/test_routes_language.py b/tests/test_routes_language.py → backend/tests/test_routes_language.py
diff --git a/tests/test_runners_js.py → backend/tests/test_runners_js.py b/tests/test_runners_js.py → backend/tests/test_runners_js.py
diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
@@ -247,36 +247,38 @@ User ends interview
 
 ```
 o1prep/
-├── app.py                   # Flask app factory, index route, blueprint registration
-├── config.py                # All settings, model names, prompt loading
-├── services/                # Business logic
-│   ├── ai.py                # OpenAI client, streaming, test generation
-│   ├── sessions.py          # Session file I/O
-│   ├── problems.py          # DB-backed problem access + YAML seeding
-│   ├── db.py                # Problem agnostic/per-language split helpers
-│   ├── models.py            # SQLAlchemy models (Problem, User, Session, ...)
-│   ├── extensions.py        # db / login_manager / migrate singletons
-│   └── code_runner.py       # Subprocess code execution
-├── routes/                  # HTTP layer (Flask Blueprints)
-│   ├── auth.py              # Register / login / logout
-│   ├── sessions.py          # Session CRUD, chat, code, transcript endpoints
-│   ├── problems.py          # Problem list and detail endpoints
-│   ├── code.py              # Ad-hoc code execution endpoint
-│   ├── realtime.py          # WebRTC SDP proxy for voice mode
-│   └── research.py          # Study/tutor chat endpoint
-├── migrations/              # Alembic (Flask-Migrate) migrations
-├── docker-compose.yml       # Local PostgreSQL service
-├── scripts/
-│   └── seed_problems.py     # Seed the database from the problem YAMLs
-├── templates/
-│   └── index.html           # Single-page app shell + CDN library imports
-├── static/                  # Flask-served app assets
-│   ├── style.css
-│   ├── favicon.*
-│   └── js/                  # Frontend modules (9 files, ~2400 lines total)
-├── prompts/                 # LLM system prompts (6 files)
-├── problems/                # 150+ YAML problem definitions (canonical source)
-├── tests/                   # pytest suite (code runner, problems, DB, schema)
-├── docs/                    # Documentation and screenshots
-└── .env                     # DATABASE_URL, SECRET_KEY, OpenAI API key (git-ignored)
+├── backend/                 # Python API (Flask) — run everything from here
+│   ├── app.py               # Flask app factory, index route, blueprint registration
+│   ├── config.py            # All settings, model names, prompt loading
+│   ├── services/            # Business logic
+│   │   ├── ai.py            # OpenAI client, streaming, test generation
+│   │   ├── sessions.py      # Session file I/O
+│   │   ├── problems.py      # DB-backed problem access + YAML seeding
+│   │   ├── db.py            # Problem agnostic/per-language split helpers
+│   │   ├── models.py        # SQLAlchemy models (Problem, User, Session, ...)
+│   │   ├── extensions.py    # db / login_manager / migrate singletons
+│   │   └── code_runner.py   # Subprocess code execution
+│   ├── routes/              # HTTP layer (Flask Blueprints)
+│   │   ├── auth.py          # Register / login / logout
+│   │   ├── sessions.py      # Session CRUD, chat, code, transcript endpoints
+│   │   ├── problems.py      # Problem list and detail endpoints
+│   │   ├── code.py          # Ad-hoc code execution endpoint
+│   │   ├── realtime.py      # WebRTC SDP proxy for voice mode
+│   │   └── research.py      # Study/tutor chat endpoint
+│   ├── migrations/          # Alembic (Flask-Migrate) migrations
+│   ├── scripts/
+│   │   └── seed_problems.py # Seed the database from the problem YAMLs
+│   ├── templates/           # Legacy server-rendered shell (removed once the
+│   │   └── index.html       #   Next.js frontend reaches parity)
+│   ├── static/              # Legacy Flask-served app assets (same lifecycle)
+│   │   ├── style.css
+│   │   ├── favicon.*
+│   │   └── js/              # Legacy vanilla-JS modules (~2400 lines total)
+│   ├── prompts/             # LLM system prompts (6 files)
+│   ├── problems/            # 150+ YAML problem definitions (canonical source)
+│   ├── tests/               # pytest suite (code runner, problems, DB, schema)
+│   └── .env                 # DATABASE_URL, SECRET_KEY, OpenAI API key (git-ignored)
+├── frontend/                # Next.js + TypeScript web client (consumes the API)
+├── docker-compose.yml       # Local PostgreSQL service (shared infra)
+└── docs/                    # Documentation and screenshots
 ```
diff --git a/frontend/.gitignore b/frontend/.gitignore
@@ -0,0 +1,41 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/versions
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# env files (can opt-in for committing if needed)
+.env*
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts
diff --git a/frontend/AGENTS.md b/frontend/AGENTS.md
@@ -0,0 +1,5 @@
+<!-- BEGIN:nextjs-agent-rules -->
+# This is NOT the Next.js you know
+
+This version has breaking changes — APIs, conventions, and file structure may all differ from your training data. Read the relevant guide in `node_modules/next/dist/docs/` before writing any code. Heed deprecation notices.
+<!-- END:nextjs-agent-rules -->
diff --git a/frontend/CLAUDE.md b/frontend/CLAUDE.md
@@ -0,0 +1 @@
+@AGENTS.md
diff --git a/frontend/README.md b/frontend/README.md
@@ -0,0 +1,36 @@
+This is a [Next.js](https://nextjs.org) project bootstrapped with [`create-next-app`](https://nextjs.org/docs/app/api-reference/cli/create-next-app).
+
+## Getting Started
+
+First, run the development server:
+
+```bash
+npm run dev
+# or
+yarn dev
+# or
+pnpm dev
+# or
+bun dev
+```
+
+Open [http://localhost:3000](http://localhost:3000) with your browser to see the result.
+
+You can start editing the page by modifying `app/page.tsx`. The page auto-updates as you edit the file.
+
+This project uses [`next/font`](https://nextjs.org/docs/app/building-your-application/optimizing/fonts) to automatically optimize and load [Geist](https://vercel.com/font), a new font family for Vercel.
+
+## Learn More
+
+To learn more about Next.js, take a look at the following resources:
+
+- [Next.js Documentation](https://nextjs.org/docs) - learn about Next.js features and API.
+- [Learn Next.js](https://nextjs.org/learn) - an interactive Next.js tutorial.
+
+You can check out [the Next.js GitHub repository](https://github.com/vercel/next.js) - your feedback and contributions are welcome!
+
+## Deploy on Vercel
+
+The easiest way to deploy your Next.js app is to use the [Vercel Platform](https://vercel.com/new?utm_medium=default-template&filter=next.js&utm_source=create-next-app&utm_campaign=create-next-app-readme) from the creators of Next.js.
+
+Check out our [Next.js deployment documentation](https://nextjs.org/docs/app/building-your-application/deploying) for more details.
diff --git a/frontend/eslint.config.mjs b/frontend/eslint.config.mjs
@@ -0,0 +1,18 @@
+import { defineConfig, globalIgnores } from "eslint/config";
+import nextVitals from "eslint-config-next/core-web-vitals";
+import nextTs from "eslint-config-next/typescript";
+
+const eslintConfig = defineConfig([
+  ...nextVitals,
+  ...nextTs,
+  // Override default ignores of eslint-config-next.
+  globalIgnores([
+    // Default ignores of eslint-config-next:
+    ".next/**",
+    "out/**",
+    "build/**",
+    "next-env.d.ts",
+  ]),
+]);
+
+export default eslintConfig;
diff --git a/frontend/next.config.ts b/frontend/next.config.ts
@@ -0,0 +1,21 @@
+import type { NextConfig } from "next";
+
+// The Flask API runs separately (default :5000). We proxy every /api/* request
+// to it so the browser only ever talks to the Next origin — this keeps the
+// Flask-Login session cookie same-origin, so auth works with no CORS setup.
+// Use 127.0.0.1 (not localhost): on macOS, localhost resolves to ::1 first,
+// where the AirPlay Receiver squats on port 5000 — 127.0.0.1 forces IPv4/Flask.
+const API_ORIGIN = process.env.API_ORIGIN ?? "http://127.0.0.1:5000";
+
+const nextConfig: NextConfig = {
+  async rewrites() {
+    return [
+      {
+        source: "/api/:path*",
+        destination: `${API_ORIGIN}/api/:path*`,
+      },
+    ];
+  },
+};
+
+export default nextConfig;