Pagoda City: MiMo-V2.6-Flash-RL, thinking on vs thinking off

The setup, the caveats, the limits.

Prompt, verbatim:

Create a single self-contained HTML file using Three.js (load it from a CDN via an import map) that renders an interactive voxel world: a tall multi-tiered pagoda standing on a mountainside, with a voxel city spread around and below it — houses with sloped roofs, narrow streets, stairways climbing the slope, a river or waterfall coming down the mountain, bridges, trees, and lanterns. Everything is built from cubes (voxels); no imported models or textures.

Requirements:
- Terrain: procedurally generated voxel mountains with the pagoda on a prominent ridge and the city terraced down the slope toward a valley. Use at least 3 distinct height bands (snow / rock / grass) with color variation so it doesn't look flat.
- The pagoda must have at least 5 tiers with upturned eaves, a spire, and lit windows.
- Rendering must be efficient: use InstancedMesh (or merged geometry) so tens of thousands of voxels render at 60 fps on a laptop GPU. Add shadows from a directional sun and a soft sky/ambient light.
- On load, the camera performs a slow cinematic orbit around the pagoda and city for the first 10 seconds, then hands off to the user.
- Interactivity (all must work):
  1. Orbit / zoom / pan camera with mouse (OrbitControls), starting from a cinematic view of the pagoda.
  2. A day/night slider or button that moves the sun, shifts the sky color, and turns on the pagoda and city lanterns at night (emissive voxels, and a few point lights near the pagoda). Lanterns should switch on in a visible sequence, not all at once.
  3. Clicking on any voxel of the city or pagoda highlights it and shows a small tooltip with what it is (e.g. "Pagoda tier 3", "House roof", "Bridge") — use raycasting against the instanced meshes.
  4. A "regenerate" button that rebuilds the terrain and city from a new random seed without reloading the page.
- Add subtle ambient animation: drifting clouds (voxel clouds), flickering lantern light at night, and a slow water animation on the river.
- Include a small on-screen legend/help panel describing the controls, and an FPS counter.
- The page must load with no console errors, must not rely on any files other than Three.js from the CDN, and must not use any deprecated Three.js APIs (r160+).

Return only the complete HTML file in a single code block.

Sampling on both arms: temperature 0.7, top_k 20, top_p 0.95, seed 42, max_tokens set to the full 300K serving window (not a budget). The only difference between the arms is enable_thinking in the chat template.

Serving. MiMo-V2.6-Flash-RL (the September 21 release), as published by Xiaomi, on vLLM TP2 across two DGX Sparks using tonyd2wild's image with the DFlash drafter (k=7) and fp8 KV cache. The checkpoint on disk was verified SHA-256 identical to the HF repo's current files; the one post-upload code fix (a trailing comma in the DFlash config) is applied. Xiaomi released the MOPD revision (a tool-call repetition fix) the same day this was recorded; it was not used here and this brief involves no tool calls.

Repairs. The thinking-on file has two defects, both mechanical: a garbled duplicate line inside the pagoda builder that references a name that does not exist, and a hover handler that uses a variable from another function's scope. Each is a one-line edit, listed in REPAIRS.md with the untouched original beside the repaired copy. The recording shows the repaired build. Receipt numbers are unaffected. The thinking-off file needed nothing.

Recording. Headless Chromium on Metal at 1280×720 with a fixed 24 fps clock, 12 seconds per arm, scripted zoom and a slow orbit so the pagoda fills the frame. The thinking-off page re-seeds its world from Math.random() on every load, so for a repeatable shot the capture harness pinned that function — on the capture side only; the published file is untouched. Its panel is a 2× centre crop.

What this shows. The pagoda in the top panel is a much better answer to the brief. It also cost 17× the tokens, 32× the wall time, and needed two fixes before it ran. The thinking-off answer is small, correct, fast, and dull. The same prompt on the same model produced a 131K-token thinking-on pagoda five days earlier in the four-way study; this is an independent second generation, not a reuse.