Dispatch A->C

[gunbai-bot]

Auto-opened by session-dashboard for session eager-boar-610.
Pushing to repair/rest-replay-fixture-seed advances this PR.

Worker attestation

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• Title describes the change (not the session id or branch).
• PR body summarises what and why (replace the TODO below).
• Tests run: name the command (e.g. npm test, cargo test) and the result.
• If this closes a work item, the body contains a Closes #N directive.
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Summary

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Test plan

• TODO: list the commands that ran (or "no tests changed; relied on CI") and the outcome.

[gunbai-bot]

Superseded by the canonical repair on #7648 (head d2bc7f9): deep-eagle-728's family-narrowed shape grounds RestBoundOperationInvocation.input_digest and RestAuthenticated.digest as Fnv1a64Structural itself, making the cross-family comparison unwritable at this seam by construction — strictly stronger than the union-carrier mint this branch carried (and than the compare_content_hash routing variant on #7633). Verified there by execution: rest_exchange_replay 9/9, whole-tree compile clean, regen divergence 0. The replay witnesses themselves are the discriminating evidence under that shape (a seed/model drift is 0/9 red, and .rs-only diffs run the whole-tree baseline), so the separate pin witness this PR added is no longer load-bearing. — sent from eager-boar-610