handle all session conflict scenarios inside claude and giving instructions

[Soph]

We had this implemented for when you run two parallel claude code sessions (without closing the first one first) but there are two more scenarios where this is needed:

• manual-commit is active: when you have a first session which causes changes, close it and start another one without committing the changes we properly warn you now inside the claude code session and give instructions
• worktree is active: if you have two worktree folders and both start changes from the same sha commits would go on the same shared branch (this is actually not unlikely...)

Should fix: https://linear.app/entirehq/issue/ENT-102/error-when-exiting-plan-mode

[Copilot]

Pull request overview

This pull request improves session conflict handling in Claude Code by displaying user-friendly blocking messages instead of returning errors. The changes ensure that when session conflicts occur (from parallel sessions, uncommitted changes, or cross-worktree scenarios), users receive clear instructions within the Claude interface rather than encountering error states.

Changes:

• Modified conflict handlers to output blocking JSON responses with actionable guidance
• Updated test infrastructure to verify blocking behavior via parsed hook responses
• Refined conflict detection tests to validate new response format

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
cmd/entire/cli/integration_test/session_conflict_test.go	Updated test to verify blocking JSON response for session conflicts; removed formatting whitespace
cmd/entire/cli/integration_test/hooks.go	Added HookResponse struct and SimulateUserPromptSubmitWithResponse method to support testing blocking hook behavior
cmd/entire/cli/hooks_claudecode_handlers.go	Changed shadow branch and session ID conflict handlers to output blocking JSON responses instead of returning errors, with cleaner message formatting

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[khaong]

we may want to consider our shadow branch naming to include either branch or cwd hints, and/or using our other session state/metadata to reference it to avoid the worktree problem?

[Soph]

yeah agree, but this is just fixing that it's at least not throwing an error in the face of the user. Let's handle in another PR?