## Summary
Repeated review and executor sessions could replay a follow-up creation
step and produce another live task whenever the wording changed. In the
incident behind this fix, 21 creation calls for three intended
follow-ups left 18 duplicate tasks.
Agent-created tasks now retain their parent and agent provenance across
step sessions, heartbeats, and the published CLI surface. Same-parent
paraphrases converge on the existing task through a serialized pre-check
and a database-backed intent claim, while distinct sibling actions
remain separate. Candidate lookup is parent-indexed, uniqueness failures
abort creation, and canonical reuse no longer emits misleading creation
audit events or workflow claims.
Related: FN-8277
## Validation
- Core duplicate guard and intake: 24 tests passed
- Engine task creation and heartbeat: 154 tests passed
- CLI extension: 66 tests passed, 95 skipped
- Core, engine, and CLI typechecks passed
- Core, engine, and CLI builds passed before rebase; the rebase was
conflict-free
- Scoped lint, strict changeset validation, and diff checks passed
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **Bug Fixes**
* Prevented retried agent steps from creating duplicate follow-up tasks.
* Improved parent-scoped deduplication for paraphrased follow-ups while
preserving distinct sibling actions.
* Preserved parent-task and agent context for created follow-ups.
* Concurrent follow-up requests are now serialized/deduplicated so
duplicates link to the existing task instead of showing as newly
created.
* Updated agent follow-up/heartbeat activity so reused follow-ups no
longer appear in run results as fresh creations.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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