refactor(claude-code): simplify session resumption logic for standalone and task mode

[DevelopmentCats]

Description

Brings session resumption up to speed with current claude-code capabilities, and should make session resumption less prone to errors across the board.

I am still testing this further to ensure that all logic path's are verified.

Type of Change

• New module
• New template
• Bug fix
• Feature/enhancement
• Documentation
• Other

Module Information

Path: registry/coder/modules/claude-code
New version: v4.2.5
Breaking change: [ ] Yes [ ] No

Testing & Validation

• Tests pass (bun test)
• Code formatted (bun fmt)
• Changes tested locally

Related Issues

[Copilot]

Pull request overview

This PR refactors the session resumption logic for the claude-code module to simplify and improve reliability across both standalone and task modes. The changes remove the problematic remove-last-session-id.sh script that attempted to manage stale session data, replacing it with more robust session validation and detection functions directly in the start script.

Key changes:

• Introduces three new helper functions (task_session_exists, is_valid_session, has_any_sessions) to improve session state detection
• Simplifies the session resumption decision tree by consolidating conditional logic and removing external script dependencies
• Adds comprehensive test coverage for edge cases like partial initialization, session validation, and mode-specific behavior

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
registry/coder/modules/claude-code/scripts/start.sh	Refactored session resumption logic with new validation functions; removed dependency on external session cleanup script; simplified conditional branches for task vs standalone modes
registry/coder/modules/claude-code/scripts/remove-last-session-id.sh	Removed entirely - session cleanup logic no longer needed with improved validation approach
registry/coder/modules/claude-code/main.tf	Removed references to remove-last-session-id.sh script; updated local variables to remove unused script encoding
registry/coder/modules/claude-code/main.test.ts	Added four new test cases for partial initialization detection, first build scenarios, session continuation, and task mode isolation; updated existing test to create valid JSONL session files with proper content
registry/coder/modules/claude-code/README.md	Updated module version to 4.2.3 across all examples; updated version pins in examples (claude_code_version, agentapi_version, boundary_version); removed cli_app from standalone mode example

[DevelopmentCats]

@matifali @35C4n0r this should solve all of the session resumption issues, if you guys can test this too that would be cool 😸

[35C4n0r]

LGTM!

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

[david-fraley]

Lending a 👍 based on other's approval