ExitPlanMode rejection/interruption causes session restart, losing all context

Bug Description

When ExitPlanMode is rejected or interrupted by the user, the Claude Code CLI terminates the current session and spawns a new one with just the plan text as the initial prompt. All accumulated in-session context (skill-injected preferences, exploration results, etc.) is lost.

Steps to Reproduce

1. Start a new Claude Code session
2. Invoke a skill (e.g., some-skill) that loads additional context/preferences into the session
3. Enter plan mode and go through codebase exploration
4. Approve the plan — ExitPlanMode is called
5. If ExitPlanMode needs to be called multiple times (e.g., plan revisions), reject/interrupt one of the calls

Expected Behavior

The session should continue in-place after ExitPlanMode rejection. The user should be able to provide feedback and the assistant should retry within the same session, preserving all context.

Actual Behavior

The CLI terminates the old session and starts a new session with only the plan text injected as the initial prompt. Evidence from session transcripts:

• Old session (session A): Ends with ExitPlanMode tool call, followed by a tool_result with is_error: true and message: "The user doesn't want to proceed with this tool use. The tool use was rejected"
• New session (session B): Starts with "[Request interrupted by user for tool use]" followed by "Implement the following plan: ..." containing only the plan text

All context from skills, codebase exploration, and user preferences loaded during the old session was lost.

Impact

• Skill-injected context (from custom skills) is completely lost
• Codebase exploration done during planning must be redone
• User preferences loaded via skills are not applied during execution
• The plan itself includes a transcript file path hint as a workaround, but the assistant may not read it

Environment

• Claude Code version: 2.1.34
• Model: claude-opus-4-6
• Platform: macOS (Darwin 25.2.0)
• Session type: Local terminal (not remote)

Additional Context

The ExitPlanMode tool was called 4 times in the old session (due to plan revisions requested by the user). The final call was rejected, triggering the session restart. The plan file was written to ~/.claude/plans/xyz.md and the new session received its content, but none of the conversational context survived.