Tracking #1382: abandoned-subtask saveClineMessages race (#1021)

[easonLiangWorldedtech]

Tracking issue for upstream PR #1382 (branch fix/abandoned-subtask-save-race-1021).

Part of the file-write safety series — plan: easonLiangWorldedtech/Zoo-Code#33, epic: #1375. Related upstream issue: #1021.

Scope

• Guard so saveClineMessages from an abandoned subtask cannot clobber the parent task's persisted messages (the race behind fix(task): guard saveClineMessages against abandoned tasks to prevent race in abandonSubtask #1021): the abandoned-task save path no longer overwrites the owning task's history.
• Regression tests in Task.spec (including the double-assertion justification comment flagged by the bot).

Acceptance

• Abandoned-subtask save cannot overwrite parent history
• CI green (ubuntu unit-test gate)
• Bot comments resolved

Status

• PR: OPEN, MERGEABLE — CI green (platform-unit-test ubuntu SUCCESS, codecov/patch SUCCESS, CodeRabbit SUCCESS)