loop-gauntlet

Loop Gauntlet

Version: 1.6.1 | Created: 2026-09-09 | Last updated: 2026-10-10 | Status: public-safe (no studio paths; the run evidence lives in the workspace session log) Version history: reference/version_history.md.

A gauntlet loop is a builder that keeps going until an authored quality bar says stop. The pattern comes from the "builder plus fresh-eyes critic" idea and from this workspace's fine-tune lane C, whose first lesson is the whole skill in one line: the checks are authored by the human before the loop starts; the builder never invents its own. A builder that writes its own rubric grades itself against whatever it happened to do.

First run (2026-09-09, GPT-6 Astra in Codex driving a live Blender 5.1 through MCP, six matched views of a three-zone museum environment): seven reviewed iterations, 42 loop renders plus six finals, visible progress every iteration, and an honest stop under the stall rule with the target NOT met. The lessons from that run are folded in below and in reference/first_run_lessons.md.

The contract - five things the human authors before the loop

1. Reference set. Clean plates only: remove people (Magnific edit, see magnific-local-upload), copy to one folder, and SETTLE DISAGREEMENTS between references before the loop. Two refs that disagree on an object count or a hero prop shape cannot both be matched by one scene; the first run lost a view to exactly that. Curate a lead-supplied set by allowlist. A plan drawing or a generated "orthographic" elevation is a MEASURING reference, never a view: a dimension table with one human-stated anchor, bands classified as geometry or projection (reference/contract_authoring.md 1-3).
2. Matched views. One camera per reference, named CAM_<view>. A tile inside a contact sheet is a view too: give the crop box in the spec so the comparison uses the tile, not the sheet. Lighting feasibility pre-check: for each view, list the key lit surfaces the reference shows and confirm the planned key light can reach them (normal dot light direction), or record in the spec that the view will be scored with that limitation. Two views of the same curved corridor from opposite ends cannot both show a sunlit wall from one sun; catching this before the loop starts (not after several lighting-only iterations) turned out to require moving a camera, not tweaking the light. Trace each lit EVENT (patch, streak, beam, glow) through the real openings: a painted concept can need one light per event. Also check (reference/contract_authoring.md 4-6, 8): a reference whose aspect differs from render_size caps that view (readback flag ref_aspect_mismatch); the human states the up axis and units (scene block); solve a repeated-element hero view before building.
3. Rubric. Fixed criteria scored 1 to 5 per view, a pass score, and a priority order for fixes (composition > scale > inventory > lighting > materials > detail). Materials are never polished while geometry is wrong. Every element needs an instrument that can fail (Rubric instruments).
4. Evidence rule. An iteration counts only when every render file has been read back (path, bytes, mtime, pixels) and the comparison image has been LOOKED AT. compare_views.py also flags a suspect-blank render; a blank frame is a valid PNG of plausible size (operating rule 8).
5. Stop rules. Target met (all views, all criteria >= pass for N consecutive iterations), max iterations, or STALLED. Stalled means neither the global minimum nor the total score improved for K iterations - the dual rule exists because a minimum-only rule froze the first run while four of six views were still improving. min_iterations is the floor below which a stall cannot fire: with composition fixed first, a builder plateaus on structure early, and one round-2 run stalled at iteration 5 before the materials tier had a single iteration of its own. Size max_iterations against the runner's remaining budget: estimate cost per iteration by subject class (roughly 30k tokens for a prop, 75k for an environment), record both numbers, require finals by the halfway iteration, keep a RESUME.md (reference/contract_authoring.md 10).