Continue Blender Web parity task handoff

docs/status/M16-GAP-00190.md

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+# M16-GAP-00190 Status
+
+status: done
+task: anim.keying_set_active_set operator LOCAL_EXACT slice
+updated: 2026-08-22 America/New_York
+
+scope:
+
+- The minimal fixture contains one selected/active object with a custom `active_target` property, a three-key Action, and two named Keying Sets. A foreground `VIEW_3D` context invokes `ANIM_OT_keying_set_active_set(type=WebGapAnimKeyingSetActiveB)` (`poll=true`, `FINISHED`), changing the active Keying Set from A to B without changing the Action.
+
+evidence:
+
+- Desktop evidence records active Keying Set `WebGapAnimKeyingSetActiveA` changing to `WebGapAnimKeyingSetActiveB`; the Action remains `[1, 3, 5]`, the property remains 3.0, and save/reopen is exact.
+- WASM/Main reads the same fixture with the visible Action unchanged and save/reopen exact. The current scene snapshot does not expose Keying Set metadata, so the report explicitly records `keyingSetMetadata: NOT_EXPOSED_BY_SCENE_SNAPSHOT`; malformed Blend input is rejected without Main mutation.
+- Fixture generation, foreground `VIEW_3D` checker, npm comparator, direct idempotent comparator, and artifact hashing passed. No production reader or protocol change was made.
+
+nextTask: `M16-GAP-00191`