Harden IPC security, async transcription, model label display

[lcoutodemos]

Summary

• Security hardening across 5 IPC boundaries (from PR Security hardening, TS fixes, JS drag, and dynamic window resize #12 analysis — took what was right, rejected what would break reliability):

  • OPEN_IN_TERMINAL: UUID-validate sessionId, single-quote shell escaping to block $() and backtick injection via projectPath
  • LOAD_SESSION: UUID-gate sessionId to prevent path traversal (../../etc/passwd.jsonl)
  • LIST_SESSIONS / LOAD_SESSION: reject null bytes, newlines, non-absolute projectPath
  • OPEN_EXTERNAL: replace regex with new URL() constructor for protocol/hostname validation
  • Marketplace install/uninstall: validate pluginName charset, repo owner/repo format, sourcePath traversal, and resolve() containment check ensuring paths stay under ~/.claude/skills/

• Async transcription — replaced execSync with async execFile wrapper so voice transcription no longer blocks the Electron main thread (fixes macOS loading cursor / app freeze during recording)

• Transcription diagnostics — per-phase timing logs (decode+write_wav, probe_binary_paths, whisperkit_transcribe_report, etc.) written to ~/.clui-debug.log on every transcription

• Conditional fallback — WhisperKit only re-runs transcription if first run produced empty stdout (was unconditional before, causing ~2x latency)

• Model label display — normalizes model IDs with context window hints (e.g. claude-opus-4-6[1m] → Opus 4.6 (1M)) for the status bar picker

Test plan

• npm run build compiles clean
• Voice transcription works (no app freeze / loading cursor)
• tail -f ~/.clui-debug.log shows timing breakdown per transcription
• Model picker displays correct labels for all model variants
• "Open in Terminal" works with normal project paths
• Marketplace install/uninstall works for valid plugin names

Security vectors verified

Attack	Handler	Result
sessionId = '$(curl evil)'	OPEN_IN_TERMINAL	Rejected (UUID check)
projectPath = '/tmp/$(touch pwned)'	OPEN_IN_TERMINAL	Safe (single-quoted)
sessionId = '../../etc/passwd'	LOAD_SESSION	Rejected (UUID check)
pluginName = '../../../tmp/evil'	installPlugin	Rejected (charset + containment)
url = 'javascript:alert(1)'	OPEN_EXTERNAL	Rejected (URL constructor)