Record final visual decision and retain v3 production model

DEPLOYMENT.md

@@ -1,7 +1,7 @@
 # Deployment and final-run promotion
 
 The live Space is https://huggingface.co/spaces/User-2468/mini-unet-colorizer.
-Default model revision remains `1a9eb8af2754ad2329a24cfe50d388cb559441d0` (v3.0). The final longer job is https://huggingface.co/jobs/User-2468/6abaef6552d0dbd7f1da7286.
+Default model revision remains `1a9eb8af2754ad2329a24cfe50d388cb559441d0` (v3.0). The final longer job completed at https://huggingface.co/jobs/User-2468/6abaef6552d0dbd7f1da7286. Its selected checkpoint was rejected for production; see reports/FINAL_CHECKPOINT_REVIEW.md.
 
 ## ZeroGPU
 Use `app.py`, `inference.py`, `semantic_model.py`, `decision_model.py`, and `requirements-space.txt` (renamed `requirements.txt` in the Space). Space README SDK is Gradio6.28.0; requirements use the same version. Select ZeroGPU hardware. Import `spaces` before `torch`; load/place the model on CUDA at startup. Only chroma inference runs inside `@spaces.GPU(duration=15)`. CPU handles image preparation, guided rendering, and cached strength changes. Do not enable `torch.compile` in ZeroGPU.

README.md

@@ -19,9 +19,9 @@ A compact automatic photo colouriser with **3,994,676 learned parameters in tota
 
 [Try the ZeroGPU Space](https://huggingface.co/spaces/User-2468/mini-unet-colorizer).
 
-Root weights and ONNX remain the reviewed **v3.0** release. A final continuation of the3,995,832-parameter four-palette challenger is running under [`experiments/final-20260929`](experiments/final-20260929); it is **not yet approved as a production replacement**. See the [visual review and training decision](reports/FINAL_TRAINING_REVIEW.md) and [exact configuration](training/final_config.json). The pilot showed modest patch reductions, not elimination of blotches.
+Root weights and ONNX are the reviewed **v3.0 production release**. The completed 3,995,832-parameter four-palette continuation was **not promoted** after [final checkpoint review](reports/FINAL_CHECKPOINT_REVIEW.md): it lowered patch measures modestly but reduced colour coverage and left historical photos muted. Its selected checkpoint and all training artifacts remain at [experiments/final-20260929](experiments/final-20260929). See the [experiment decision](reports/FINAL_TRAINING_REVIEW.md) and [configuration](training/final_config.json).
 
-The updated Space offers Standard, Detailed and Maximum input detail, full-resolution PNG output, and cached strength adjustments. Higher input detail can help some photos but can also change their colours. The default stays at256 pixels. The Space can load future multi-palette checkpoints after review without downloading arbitrary Python code.
+The updated Space offers Standard, Detailed and Maximum input detail, full-resolution PNG output, and cached strength adjustments. Higher input detail can help some photos but can also change their colours. The default stays at256 pixels. The Space can load compatible multi-palette checkpoints for experiments without downloading arbitrary Python code; its default is v3.
 
 Historical research documents have moved to `reports/history/`. See [the report index](reports/README.md). The `stable` branch and existing release weights are preserved.
 

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reports/FINAL_CHECKPOINT_REVIEW.md

@@ -0,0 +1,25 @@
+# Final checkpoint review — 29 September 2026
+
+## Decision
+Keep **v3.0** as the production model. The completed four-palette multi_mix continuation is retained on main at experiments/final-20260929/multi_mix/candidate, but is not promoted to root weights or the Space default. The stable branch is unchanged.
+
+The final run completed 16,000 additional updates, then stopped by the prespecified development patience rule. The development-selected candidate was step 4,000 (after the prior 2,000-step pilot), not the last training step. It has 3,995,832 parameters in total including the MobileNetV3 encoder.
+
+## Held-out comparison against v3
+| Measure | Gray v3 → candidate | Film gray v3 → candidate |
+|---|---:|---:|
+| Guided patch excess (lower) | 0.794 → 0.767 | 0.745 → 0.698 |
+| Raw patch excess (lower) | 0.996 → 0.947 | 0.937 → 0.862 |
+| Neutral spill (lower) | 0.234 → 0.197 | 0.245 → 0.216 |
+| Colour coverage (higher) | 51.50% → 48.38% | 50.68% → 47.98% |
+| Mean chroma | 13.24 → 12.54 | 12.95 → 12.33 |
+| Lab ab error (lower) | 12.64 → 12.52 | 12.79 → 12.71 |
+
+Exploratory paired 95% intervals for guided patch change are [-0.0619, +0.0049] on gray and [-0.0800, -0.0145] on film. The corresponding coverage drops have intervals [-0.0468, -0.0158] and [-0.0437, -0.0108]. This is not a human preference study.
+
+I reviewed all fourteen archival comparisons, held-out modern production grids and special probes. Most archival outputs are nearly identical and remain warm/sepia or muted. The candidate smooths some local artifacts and preserves useful sky/foliage in a few images, but more clothes, interiors and backgrounds remain essentially gray. The Moon probe is still implausibly pink. Neither model eliminates residual blotches. The modest patch improvement does not compensate for the consistent loss of colour on the user's main grayscale-photo use case.
+
+The pilot had a more favourable colour-retention trade-off; this continuation moved toward desaturation. Selection within the final course did not establish that it surpasses the released v3. Checkpoints, metrics, source, diagnostics and comparison grids are saved under experiments/final-20260929, with summary.json and multi_mix_test_paired.json providing exact figures.
+
+## Production state
+Root model.safetensors, config.json and colorizer.onnx remain v3.0, with 3,994,676 total learned parameters. The ZeroGPU Space remains pinned to immutable v3 revision 1a9eb8af2754ad2329a24cfe50d388cb559441d0 and live inference was verified on a historical photograph. No further training job is scheduled. This is the best release among the tested candidates, not evidence that no future sub-4M model could improve.