Maze generator & solver · kimi-k3

Let me build the index.html file with a maze generator and solver. Plan:

- 25 cols x 15 rows grid.
- Recursive backtracking with randomized iterative approach (to avoid recursion issues with animation). Actually for animation, do a step-by-step carve: maintain stack, carve a few steps per frame via requestAnimationFrame or setTimeout.
- Draw walls on canvas. Cell size ~ e.g., 24px → 25*24=600 wide, 15*24=360 tall plus padding.
- Generation animation: show carved cells / current cell highlighted.
- After generation finishes, run BFS animation: frontier cells colored, visited cells shaded, then path highlighted via parent tracking.
- Buttons: New Maze, Replay Solver. New Maze cancels animations (token/generation id check), regenerates. Replay Solver resets solver overlay, re-runs BFS.
- Legend: start (green), finish (red), explored (light blue), frontier (yellow?), solution path (orange).
- Use token-based cancellation: increment runId on new maze / replay, each animation step checks token.

Let me write it.

Now run in browser and inspect. One issue: "Replay Solver" during generation — replaySolver calls solveMaze which uses current grid (partially carved). That's acceptable? Requirement says Replay Solver uses the existing maze without changing its walls. If clicked mid-generation, it would solve a partial maze. Better to guard: only allow replay after generation completed. Let me add a mazeReady flag. Also solver during generation — BFS might not find path, status says "No path found (unexpected)." Better to disable replay until generation completes.

Let me update: track `mazeReady` boolean; set false at generate start, true at onDone. In replaySolver, if !mazeReady, ignore (or show status).

The indentation differs — my oldText had 8 spaces before "if (stack.length === 0)" but actual has 10. Let me retry with exact text.

Generation is animating — carving progress visible (yellow head, blue trail). Now click New Maze mid-generation to verify clean replacement, then wait for solving to complete.

New Maze cleanly restarted generation — canvas was reset and fresh carving is in progress. Now let me wait for generation + solving to finish. Generation: 375 cells, 4 steps/frame, ~94 frames ~1.6s, plus 350ms pause, plus solver ~125 frames ~2s. Let me wait a few seconds then screenshot.

Solved — path from S to F highlighted in orange, explored cells blue, one stray yellow frontier cell (frontier cells that were dequeued but their neighbors added then the finish was found mid-frame... actually a leftover frontier cell remains colored yellow because once found, we stop clearing the frontier set — minor cosmetic). Actually the yellow cell is a frontier cell never dequeued. That's fine visually, but slightly confusing post-solve. Minor: could clear frontier coloring when drawing the final path. Let me fix: in drawSolverState, when path is provided, skip frontier coloring.

Also, verify the maze is a perfect maze (all reachable, exactly one path) — recursive backtracking guarantees that by construction. Could run a quick node-based check by extracting the algorithm... not necessary; algorithm is provably a perfect maze generator (spanning tree). But a quick sanity test could be nice. Time budget — I can do a quick headless test using node? No node modules needed; replicate algorithm quickly. Let me just do a quick node script replicating the same logic to validate perfectness over many trials.

Now reload, and test Replay Solver: after solving completes, click Replay Solver and check animation replays on same maze. Let me reload and wait for solve, then click Replay and take a motion/screenshot mid-replay.

Replay Solver works — BFS restarted on the same maze walls (explored cells adjacent to open passages only, visible spreading from Start through open corridors). Wait for it to finish and confirm solved path.

Replay Solver completed: same maze walls, orange path from S to F, no leftover yellow frontier cells, path crosses only open passages (visual inspection confirms the orange trail follows corridors). Console clean (only sandbox warning from harness iframe).

Everything verified. Final file is in place. Done — report.