[BUG] Plan side panel shows a stale snapshot from the first proposal, never updates #78369

What's Wrong?

In a long session with multiple plan-mode cycles, clicking Open plan opens the Plan side panel showing content from the first plan proposal of the session.

The panel never reflects later revisions, nor a switch to a different plan file.

Steps to Reproduce

1. Enter plan mode.
2. Write plan A to the assigned plan file.
3. Call ExitPlanMode.
4. Revise the plan file several times across further plan-mode cycles, approving/rejecting in between.
5. Re-enter plan mode. The harness assigns a new plan file with a different generated name.
6. Write a completely different plan.
7. Call ExitPlanMode.
8. Click Open plan.

Expected Behavior

The Plan side panel shows the current plan file's current content.

Actual Behavior

The panel shows the content of the very first proposal from hours earlier, including sections that were removed many revisions ago.

Evidence

The underlying pointer appears to be correct. The session transcript's planFilePath field updates correctly:

• First half of the session: plans/9p-85-witty-moth.md
• From the moment plan mode is re-entered: plans/sharded-prancing-pumpkin.md

This suggests the stale content is caused by panel-side caching rather than an incorrect plan-file path.

Impact

The Plan side panel is the primary way to read a plan before approving it. Showing stale content means a user may approve one plan while reading an entirely different, outdated proposal.

Environment

• Claude Code version: 2.1.209
• Operating system: macOS 14.6

Version Note

The issue was reproduced on 2.1.209. At filing time, npm reports 2.1.212 as the latest release, so this report does not claim the bug was re-verified on the latest version.