The prompt fix stops planners writing the verdict in prose, but it relies on
every model reading one sentence correctly. This closes the hole underneath it.
When the finalize read finds no spec at all, the planner's streamed reply is
searched for a line that is exactly `DUPLICATE: FN-NNNN`. If found, the engine
writes the canonical marker file and continues — so marker parsing, keep/delete
resolution, and the sourceMetadata.nearDuplicateOf that renders the operator's
decision all run on the unchanged file contract rather than a second code path
that could drift from it.
Deliberately narrow. The marker must occupy a whole line, only the first counts,
and recovery is gated on the plan being genuinely absent — a planner that wrote
a real spec is never overridden by something it said in passing. The text tail
is bounded because the verdict lands in the closing summary, and it tees off
onText rather than reading AgentLogger, whose buffer is flushed on a timer.
Verified both directions: the tests fail without the recovery block, and the
"wrote a real spec while mentioning a marker" case keeps its spec.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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