Fix duplicate rehydrate during reasoning; centralize rehydrate and preserve cancel metadata

[hannesrudolph]

Closes #8153

Before:

FocuSee.Project.2025-09-19.18-07-19.mp4

AFTER

FocuSee.Project.2025-09-19.18-12-22.mp4

Problem

• Users occasionally saw a duplicate/overlaid task after pressing “Cancel” or after a mid-stream network failure—most visibly during “reasoning” streaming.
• Root cause: two independent rehydration paths racing:
  • Task-level catch during the streaming loop rehydrated from history
    Task.recursivelyMakeClineRequests()
  • Provider cancel path also rehydrated from history
    ClineProvider.cancelTask()
• This race was easier to hit during reasoning because reasoning chunks are UI-only (persisted to clineMessages) and not added to apiConversationHistory mid-stream, so the Task catch reached rehydrate faster.

Changes

1. Centralize rehydration in the Provider

   • Removed Task-side rehydrate in the streaming error/cancel catch; the Task now:
     • Persists an interruption marker first
     • Sets an explicit abortReason
     • Calls abortTask() and emits TaskAborted
     • Does not call createTaskWithHistoryItem
   • Provider listens for TaskAborted and rehydrates only for streaming failures (not user-cancels)
     Task.recursivelyMakeClineRequests()
     ClineProvider.onTaskAborted

2. Prevent double-create by marking “abandoned” earlier on user-cancel

   • Set task.abortReason = "user_cancelled" and mark the current Task instance abandoned immediately after abortTask(), before waiting for the stream to drain
     ClineProvider.cancelTask()
   • This ensures the Task catch never tries to rehydrate.

3. Provider-side cancel bookkeeping to mirror abortStream for user cancels

   • Because setting abandoned early can skip abortStream on user-cancel, the Provider now fills the same persistence gaps:
     • Update the last say("api_req_started") UI row with cancelReason = "user_cancelled"
       ClineProvider.cancelTask()
     • Append an assistant “Response interrupted by user” marker to apiConversationHistory when appropriate
       ClineProvider.cancelTask()
   • This preserves UI/API consistency and cancellation telemetry without reintroducing the race.

4. Resume reconciliation for UI-only reasoning

   • On resuming from history, remove trailing reasoning-only UI rows that never entered apiConversationHistory (orphan partials)
     Task.resumeTaskFromHistory()

5. Defensive safeguards to avoid rehydrate after rehydrate

   • Before rehydrating on TaskAborted (streaming_failed) or after cancel wait, check if the current instance already changed; skip if so
     ClineProvider.onTaskAborted
     ClineProvider.cancelTask()

Why this approach

• Eliminates the duplicate/overlay by making the Provider the single source of rehydration truth.
• Maintains a coherent timeline when cancelling mid-reasoning by explicitly persisting:
  • cancelReason into the last api_req_started row
  • an assistant “interrupted by user” entry into API history
• Keeps normal success flows unchanged and produces a clean resume prompt consistently.

Behavioral impact

• Cancel during reasoning: one rehydrate, no duplicates; cancelReason and interruption marker preserved.
• Network failure mid-stream: Task emits TaskAborted with abortReason="streaming_failed"; Provider rehydrates once.
• Cancel during text streaming: one rehydrate; no duplicates.
• didFinishAbortingStream may not set on user-cancel (due to early abandoned), but Provider waits on other safe conditions and applies the same persistence updates Provider-side.

Key references

• Removed Task-side rehydrate:
  Task.recursivelyMakeClineRequests()
• Provider-owned rehydrate and cancel bookkeeping:
  ClineProvider.onTaskAborted
  ClineProvider.cancelTask()
• Resume reasoning reconciliation:
  Task.resumeTaskFromHistory()

---

Important

Centralizes task rehydration in ClineProvider.ts to prevent duplicate rehydration during reasoning and updates localization for interruption messages.

• Behavior:
  • Centralizes rehydration in ClineProvider.ts, removing task-side rehydration in Task.ts.
  • ClineProvider.ts now handles rehydration only for streaming failures, not user cancels.
  • Marks tasks as "abandoned" earlier on user-cancel to prevent double rehydration.
  • Updates UI/API consistency by appending interruption markers to apiConversationHistory.
• Files:
  • Task.ts: Removes task-side rehydration logic, adds abortReason property.
  • ClineProvider.ts: Implements centralized rehydration logic, updates cancel bookkeeping.
  • Localization files: Adds interruption messages for user and API error interruptions.
• Misc:
  • Ensures no rehydration occurs if the task instance has already changed.
  • Improves handling of reasoning-only UI rows during task resumption.

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