Fix: Resolve orphaned processes and keyboard input issues (#422, #423, #424)

[hyacz]

Summary

Fixes Issue #422, #423, and #424 (all related to process and terminal management issues during mode switches).

Issue #422: "Bug: Input handler persists after remote-to-local mode switch" ✅

Problem: Input handler persists after switching from Local → Remote, with orphaned processes continuing to read from stdin and blocking subsequent input.

Root Cause: Child processes spawned with signal: opts.abort were not properly terminated when the parent process exited during Local → Remote switches.

Solution:

• Remove signal: opts.abort from spawn options
• Add HAPPY_SESSION_ID environment variable to track process groups
• Implement pkill-based cleanup in claudeLocal.ts (SIGTERM → SIGKILL)
• Add signal handlers in claude_local_launcher.cjs

Issue #424: "After switching back to local mode, the input is starting to getting incomplete." ✅

Problem: After switching back to local mode, input is incomplete due to orphaned processes competing for stdin.

Root Cause: Same as Issue #422 - orphaned processes from Local mode continue reading from stdin.

Solution: Same fixes as Issue #422.

Issue #423: "Terminal input stuck after exit (raw mode not restored)" ✅

Problem: After exiting happy-cli (via Ctrl+C or normal exit), the terminal input becomes stuck at whitespace. Users need to run stty sane or reset to restore normal terminal behavior.

Root Cause: Manual process.stdin.setRawMode(true) calls bypassed Ink's cleanup mechanism. When SIGINT/SIGTERM was caught, process.exit(0) terminated immediately, skipping the finally block that should restore terminal state.

Solution:

• Remove manual process.stdin.setRawMode() calls from claudeRemoteLauncher.ts
• Let Ink handle all stdin management via stdin.ref()/unref()
• Ink properly restores terminal state on cleanup through its unmount process

Additional Issue: Second Remote Fails to Receive Keyboard Input ✅

Problem: First Remote worked correctly, but after Local → Remote → Local → Remote, the second Remote's keyboard input was buffered (cooked mode behavior).

Root Cause: Orphaned processes (Issues #422/#424) from Local mode modify terminal driver state through stdio: 'inherit'. When Ink calls process.stdin.setRawMode(true), the terminal driver doesn't actually enter raw mode.

Solution:

• Force raw mode toggle in RemoteModeDisplay.tsx component mount
• Wait 100ms for Ink to complete setup
• Toggle sequence: setRawMode(false) → setRawMode(true) with 10ms delay
• Simplify stdin management in claudeRemoteLauncher.ts (let Ink handle everything)

Test Plan

• Test Remote → Local → Remote keyboard input works
• Verify no orphaned processes after mode switches (ps aux | grep -i claude)
• Test multiple mode switches in succession
• Verify input is complete after switching back to local mode
• Verify terminal state is properly restored after exit (no need for stty sane)
• Verify first Remote still works correctly

Files Changed

• src/ui/ink/RemoteModeDisplay.tsx - Raw mode toggle fix
• src/claude/claudeRemoteLauncher.ts - Simplified stdin management, removed manual setRawMode
• src/claude/claudeLocal.ts - Process cleanup logic
• scripts/claude_local_launcher.cjs - Signal handlers
• scripts/claude_version_utils.cjs - Session ID tracking

Note: All existing logger.debug() calls from commit 8691991 have been preserved. Only manual stdin management that was causing issues has been removed.

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