fix: preserve workspace finalization during watchdog recovery (#16247)

Keep task completion separate from runtime and workspace settlement. Permit verified board file-only repair of successful legacy retained-source runs without authorizing replay.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

doc/execution-semantics.md

@@ -1025,6 +1025,14 @@ In the normal non-terminal case, critical silence remains a UI signal and does n
 
 Source-resolved watchdog folding concerns stale active-run bookkeeping after a valid terminal disposition. It does not infer productivity from run counts, comment frequency, or elapsed task time.
 
+Terminal task activity does not prove that the execution runtime has finished.
+The scan leaves native runs with their native lifecycle owner. An active managed
+environment lease, running or failed workspace finalization, or recorded
+copy-back failure also prevents folding. These obligations are checked before
+local process cleanup and again when the run is committed. The owning runtime
+or its bounded recovery saves the files and settles the run; the watchdog does
+not replace that work with a successful result or release its execution locks.
+
 Detached process cleanup is operational hygiene, not source issue liveness. Cleanup should be best-effort and auditable. If cleanup fails but the source issue is already terminal with same-run durable evidence, Paperclip should preserve the cleanup failure on the run/watchdog audit trail and route only the cleanup concern to bounded recovery when a real owner/action remains.
 
 ## 13. Auto-Recover vs Explicit Recovery vs Human Escalation