Checkpoint web parity through Chromium input tasks

docs/status/M12-04G.md

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+# M12-04G Status
+
+status: done
+task: reject archive compression bombs, overlapping ranges, duplicate paths, and prefix conflicts
+updated: 2026-08-18 America/New_York
+enablingTask: false
+parityStateChange: false
+
+## Scope
+
+Archive range validation now checks each compressed range against the declared source length and the
+global archive bound, sorts ranges by offset, and rejects overlap before any payload read. It also
+rejects duplicate canonical paths, file/directory prefix conflicts, zero-byte compression bombs, and
+expansion ratios above 100:1. Valid ranges return deterministic totals and explicit non-overlap/path
+invariants.
+
+## Evidence
+
+- `npm --prefix web run test:library-archive-conflicts` passed 4/4 unit tests.
+- Non-overlapping ranges produce stable compressed/uncompressed totals.
+- Compression-ratio, overlap, duplicate, prefix, source-bound, and undeclared-field negatives all
+  return `IO_ARCHIVE_UNSAFE` before payload scheduling.
+
+## Artifact Hashes
+
+- parent manifest: `cda905b1e27b62d9ea3a05170f975015480ce6739c15bdf1f5a1f0b79f93ce06`
+- protocol: `3bec372e4f67ec309f28534cebcbaf8b492144adfa82ff6c8603f88c3ba16254`
+- unit: `3f2d44dce33b1c17b3a48f58b04fdd821abc88d98ce3d3b5bb724859e0f0ab3c`
+- package commands: `cfb232baa494ff59f6c8d65514a08c86332ee9354350b2a0392b6f932a7ee42c`
+
+## Next Task
+
+`M12-04H`: cancellation removes staging and never modifies the committed project.
+
+## Rollback
+
+Remove the archive conflict protocol, unit suite, manifest, package command, and this status entry.
+Restore M12-04F to pending and move the machine queue back to `M12-04G`. No parity ledger rollback is
+required.