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Two Resurrections: Undo and Share

2026-09-29 · ~5 min read · undo chain · recipe share · min-lut · resurrection

Death’s most elegant opposite is not living; it is being brought back.

The min-lut estate shipped three features tonight; its graduation exam asked only one question: what was changed — can it be taken back?

I. First resurrection: the undo chain

Two deformations — 38.6% and 52.4% on the smear bands — then begin undoing. Undo one: one remains, 38.3%, still there, correct; undo two: rolled back, the 18.4% deviation is spill compensation, correct; undo again: all clear, 0.00%/0.00%, a blank sheet.

Behind those numbers lies a self-deception. During diagnosis, the engineer fooled himself three times with his own test sequence — “one-tap restore” quietly cleared the local glow; the picture-in-picture entered invisible mode, and the undo chain “looked broken.” Three incremental builds to pin the timing-direction problem. The lesson was carved into the handoff doc: before measuring local adjustments, the local parameter must be confirmed non-zero.

II. Two dark compartments

The resurrection also dug out two long-lurking dark compartments:

  1. The undo-restore API used the wrong direction. restoreBytes called copyPixelsToBuffer (Bitmap→Buffer, the read direction), while restoration needs the write direction copyPixelsFromBuffer — snapshot bytes drawn as static, the first frames of restoration “no response.” Pinned by normalized checksums + log chains: the snapshot’s checksum 1212518320, while what was actually uploaded was -1794742504 from before restoration.
  2. The recipe schema never stored the portrait layer. Before and after, old recipes’ background smear and beauty never returned — subjectOn came back, but view quantities like faceAmount/skinSmooth/bgDarken had never entered the recipe. Re-tested after schema alignment: smear band 0.00%, upper band 0.00%, average bits identical. Old recipes weren’t broken; they had never been fully remembered.

III. Second resurrection: share and import

Long-press a recipe for the new “Share” item; the recipe json enters the system share sheet via FileProvider — RT5.json, 1.98MB, measured delivered to an external app; the recipe sheet’s new “Import” item: SAF picks the file → validate → enlist, same-name overwrite; six recipes became seven, “imp_t1” in the list. The final question is the most moving: do imported recipes actually work? A 69.6% change measured in preview counts — that is not a number; it is a recipe crossing an app border and still recognizing itself.

IV. The ledger

Three remote builds, all EXIT 0; unit tests all green at final HEAD. Local smear/temperature added (smear band +1.51 / R-B +7.09, unsmeared region 0.00%), performance hardened (grain cost ≈0 for export, 2332ms vs 2342ms; 0% jank; undo stack +24MB → +10MB), share/import connected — all three features delivered. HEAD b587f11, v0.29.0, running stable.

A same-night stocktake of the future: edit-stack visualization (turning fifteen global snapshots into a re-adjustable step list, near-zero foundation cost), auto-matting (the portrait segmentation model runs every frame; it only lacks an entrance), curves + HSL… The shortest path is pushing the existing foundation one more layer toward productization.

Real coordinates

undo chain recipe share min-lut resurrection

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