Checkpoint web parity through Chromium input tasks

docs/status/M12-03L.md

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+# M12-03L Status
+
+status: done
+task: block override stale source/revision before Main commit
+updated: 2026-08-17 America/New_York
+enablingTask: false
+parityStateChange: false
+
+## Scope
+
+Schema-1 override freshness binds the local override to its source library ID, source generation,
+source revision, dependency-closure SHA-256, invalidation token, and local/reference/hierarchy IDs.
+Only a fully matching `COMMIT_OVERRIDE` request reaches `READY`; no Main mutation is performed by
+this gate.
+
+Stale generation/revision, dependency closure, invalidation token, linked ownership, identity drift,
+alternate operation, malformed token, and undeclared fields return stable blocking codes before Main.
+
+## Evidence
+
+- `npm --prefix web run test:library-override-freshness` passed 4/4 unit tests.
+- The exact source generation/revision/closure/token binding returns `READY`.
+- Stale source fields return `REVISION_CONFLICT`; local identity drift returns
+  `ASSET_SOURCE_HASH_MISMATCH`; linked ownership returns `LINKED_DATA_MUTATION_BLOCKED`.
+
+## Artifact Hashes
+
+- protocol: `2eff7ea7605b1579d7551336d87d4f30adb996b585596ff9eee67aea04ca7d22`
+- unit: `d48344f31e1ba12e557ca30ece56643583efa633da556f5de3896a8e9175ef8f`
+- manifest: `237f3f168e037b67b805ba8d9c9455250c889a5e90c45cbb17d2d20d9fbdcc50`
+- package commands: `cfb232baa494ff59f6c8d65514a08c86332ee9354350b2a0392b6f932a7ee42c`
+
+## Next Task
+
+`M12-03M`: dependency cycle, ID collision, cross-library cycle, and duplicate reload negatives.
+
+## Rollback
+
+Remove the override freshness protocol, unit suite, manifest, package command, and this status entry.
+Restore M12-03K to pending and move the machine queue back to `M12-03L`. No parity ledger rollback
+is required.