Advance M8-M11 parity workflows

docs/status/M10-09.md

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+# M10-09 Status
+
+status: done
+task: Preserve the previous usable material pipeline on compile failure
+updated: 2026-08-16 America/New_York
+
+## Scope
+
+`PBRMaterialPipeline` makes material replacement transactional. A successfully
+compiled candidate becomes current only after compilation; the previous material
+is disposed exactly once after replacement. A blocked candidate is disposed and
+the current material remains usable, with the failed report stored as
+`shaderCompileFailure` for diagnostics. This does not claim arbitrary Shader Node
+support or a WebGPU pipeline.
+
+The Engine Worker independently rejects blocked `setShaderGraph` requests before
+the Blender Main transaction, so a failed graph cannot publish a new SceneIR
+snapshot in addition to the viewport-side rollback.
+
+## Evidence
+
+- `WEB_TEST_PORT=5525 npm --prefix web run test:shader-pipeline`: Chromium 1/1.
+  The test confirms the failed candidate reports `SHADER_NODE_UNSUPPORTED`, keeps
+  object identity and the previous compiled report, and that a later successful
+  compile replaces the material.
+- `npm --prefix web run typecheck` and `npm --prefix web run lint` passed after the
+  pipeline helper was added.
+- `tests/golden/M10-09/shader-pipeline.json` fixes the rollback invariants.
+
+## Implementation Hashes
+
+- PBR adapter: `8a9cb52c8e7b1481096017cc659d93541c21724c1203d22755e37e1e3c365250`.
+- Chromium spec: `e6771f672e885250db199cbf97a0a3866084ab9bb3f2ad25d17f5c53edaa99af`.
+- Golden: `5dbb916e512935a76dacde37242b123707897f54ab10d7b99e246f57afbc94ac`.
+
+## Rollback
+
+Remove `PBRMaterialPipeline`, its Chromium test/golden and this status file. Keep
+the M10-08 compile key and Engine Worker pre-transaction gate, and restore the M10
+count to 8/15.