Advance Blender 5.2 web parity through M12-03D

docs/status/M12-02A.md

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+# M12-02A Status
+
+status: done
+task: inventory Blender preview dimensions, color semantics, and no-preview state
+updated: 2026-08-17 America/New_York
+enablingTask: true
+parityStateChange: false
+
+## Scope
+
+The machine inventory binds Blender 5.2 PreviewImage DNA, slot enum, BKE/RNA implementation,
+Blend reader, asset preview generator, render-size constants, current Web v1/v2 preview protocols,
+and two runtime fixtures. It records both ICON and PREVIEW slots, persisted dimensions/flags/pixel
+arrays, runtime-only state, and absent-pointer behavior.
+
+Preview pixels are packed 32-bit RGBA with four byte components and Blender's deferred load path
+premultiplies alpha. PreviewImage has no persisted or RNA color-space field, and float access only
+divides byte components by 255 without a color transform. The inventory therefore records color
+space as unknown instead of assuming sRGB.
+
+## Evidence
+
+- `npm --prefix web run test:asset-preview-inventory` launched locked Blender 5.2 twice and
+  reported `slots=2 rna=9 absent=3 loaded=8x8 next=M12-02B`.
+- The checked-in asset fixture reopened with Object, Material, and World `preview == null`.
+- A real 8x8 PNG loaded through Blender's preview API produced an 8x8 PREVIEW slot, 32x32 ICON
+  slot, 64/256 image packed/float counts, and 1024 icon packed pixels.
+- Typecheck, lint, status consistency, and `git diff --check` passed.
+
+## Artifact Hashes
+
+- inventory: `a4427426d94afdf1a2ccf5379d76d1797f8604a742a3f0d15bdca629272864bd`
+- checker: `c9cc83d21bac5f34c6d68cb1225dffcd92a5ec76c158ddce909b620cbbcb245c`
+- package command: `04f832a3c5773c8cc5294ecdcf175478eed9710496e48c63698d79043384e328`
+
+## Next Task
+
+`M12-02B`: define preview source/content SHA-256, MIME, dimensions, and generator identity.
+
+## Rollback
+
+Remove the M12-02A inventory, checker, package command, and this status entry. Restore M12-02A
+to pending and `nextTask` to M12-02A. No parity ledger rollback is required.