An operator was re-asked to approve a plan they had already approved and
that had not changed.
POST /tasks/:id/approve-plan fingerprints the on-disk PROMPT.md, so a plan
approved before the `## Original Description` hygiene injection
(applyOriginalDescription) shipped carries a hash over PRE-injection
content. On the task's next pass the injection rewrites PROMPT.md, the
fingerprint moves, and FN-7569's idempotency short-circuit misses — so the
manual gate re-parks an unchanged, already-approved plan.
finalizeApprovedTask now also compares the recorded fingerprint against the
as-read (pre-injection) content. This does not weaken the gate: `written`
diverges from `writtenInput` only via that injection, so both arms hash
bytes the operator actually approved — only the representation differs. A
genuinely changed plan matches neither arm and still parks.
On a legacy match the stored fingerprint is migrated forward, so the
reconciliation is one-time per task rather than a comparison carried
forever. The migration is a direct updateTask — the taskUpdates batch is
flushed well before this gate runs.
Covers both finalizeApprovedTask callers (direct + recoverApprovedTask),
asserts the changed-plan safety edge still parks, and asserts no redundant
fingerprint write when the approval is already post-hygiene.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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