fix(coding-agent): preserve compaction preflight ownership

[minpeter]

Summary

Fixes the current-main compaction lifecycle ownership regression: a synchronous listener can supersede the controller during compaction_start, and stale preflight terminals must not emit afterward.

Verification

• focused lifecycle: 3 passed
• compaction domain: 51 files / 400 tests passed
• root build and root check passed
• real CLI QA: isolation 9/9, RPC 4/4, mock loop 38/38, smoke 7/7

Evidence directory: local-ignore/qa-evidence/20260724-compaction-contract-current-st_019f9584/

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Summary by cubic

Fixes a compaction ownership regression in coding-agent so preflight auto-compaction can’t emit a stale compaction_end, and preserves overflow recovery state when a start listener aborts or supersedes preflight.

• Bug Fixes
  • Recheck ownership after compaction_start; skip terminal if superseded; reset overflow-retry state only when the same controller still owns the run.
  • Added tests for balanced start/end with no work, no stale terminal after abort, no overflow-retry consumption on abort, and exhaustion preserved when superseded.

^{Written for commit 3ae7498. Summary will update on new commits.}

[minpeter]

Delivery evidence matrix

Delivery	Live status	Verification / evidence
#328 compaction progress	Draft; prior CI record predates lifecycle ownership repair	Live xterm.js 80-column capture, local-ignore/qa-evidence/20260724-compaction-progress-live-cdp-final/
#334 eval history bound	Draft; historical broad CI failure classified against pre-repair main	256 MB real CLI: 125 reads -> 100 rows / 26 omitted; 20,000 reads -> 100 rows / 19,901 omitted; evidence local-ignore/qa-evidence/20260724-eval-status-history-current-main/
#336 Inspector VM recovery	Draft; historical broad CI failure classified against pre-repair main	enabled recovery and disabled fatal real CLI scenarios passed; evidence local-ignore/qa-evidence/20260725-inspector-vm-import-crash-current-main/
#341 compaction ownership	Draft; current delivery	head 3ae7498; 5/5 checks green; lifecycle focused, compaction domain, root build/check, RPC/mock-loop/smoke QA, and five-lane review passed; evidence local-ignore/qa-evidence/20260725-compaction-preflight-listener-abort/

#340 is closed as superseded. QA processes and isolated sandboxes were cleaned; real auth remained unchanged.