Bug: ExitPlanMode can present stale plan from a previous task to user for approval

Bug: ExitPlanMode can present stale plan from a previous task

Summary

When plan mode is entered for a new task but the agent determines no implementation is needed (e.g., the issue is already resolved), calling ExitPlanMode presents the stale plan file from a completely different prior task to the user for approval. If the user approves without reading carefully, Claude executes the wrong plan.

Steps to reproduce

1. In a long conversation, complete a multi-step task that uses plan mode (e.g., a cross-repo version bump and publish workflow)
2. Ask Claude to implement a new, unrelated issue
3. Claude enters plan mode, explores the codebase, and determines the issue is already resolved — there is nothing to implement
4. Claude calls ExitPlanMode to exit

Expected behavior

ExitPlanMode should either:

• Present an empty/cleared plan (since no new plan was written)
• Refuse to exit if the plan file hasn't been updated for the current task
• Require the agent to explicitly clear/overwrite the plan file before exiting

Actual behavior

ExitPlanMode presents the previous task's plan to the user. In my case, it showed a detailed plan for a cross-repo version bump workflow when the current task was a simple docs.yml cleanup that was already resolved.

Why this is dangerous

• The stale plan may contain destructive or irreversible actions (publishing releases, merging PRs, closing issues)
• Users who trust the agent and approve quickly will trigger execution of the wrong plan
• The plan content can be entirely unrelated to the user's current request
• There is no visual indicator that the plan is stale

Environment

• Claude Code CLI
• Claude Opus 4.6
• Plan file persists at a fixed path across tasks within the same conversation