The recovery fallback that replays edits onto current text when the structured-patch 3-way merge refuses guarded only on line-count equality. If a prior in-session edit rewrote the very line a later stale-hash edit re-targets, replay overwrote the new content with the stale-anchored payload and emitted a 'Verify the diff matches your intent' warning that does not block the write.
Concrete window: v0 line 5 = 'L5', v1 = 'L5-CHANGED' (same line count). Edit E2 authored against H0 anchored at line 5 lands on v1 because the line-count gate passes, silently replacing L5-CHANGED with the model's L5-MODEL.
Add a verifyAnchorContent gate: walk every edit's anchors and require previousText[line] === currentText[line]. Any mismatch returns null so the caller raises MismatchError and the model re-reads. The success path now emits the standard RECOVERY_SESSION_CHAIN_WARNING (the hedged REPLAY_WARNING text was only sensible when content was partially aligned; that case is now unreachable, and the constant is removed).
Tests: packages/hashline/test/recovery-session-chain.test.ts pins both the corruption refusal and the safe-replay positive case (anchor on an unchanged line, 3-way merge fails on neighbouring rewritten context, replay succeeds with the standard chain warning). packages/coding-agent/test/core/hashline.test.ts adds an end-to-end through executeHashlineSingle so the production patcher path is covered too.
oldschoola
56a7212035