homelab/.planning/phases/01-session-process-foundation/01-02-SUMMARY.md

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	duration	completed
01-session-process-foundation	02	infra	asyncio subprocess python claude-code-cli stream-json process-management	phase provides 01-session-process-foundation Session metadata and directory management	Claude Code subprocess lifecycle management with crash recovery Stream-json event parsing and routing to callbacks Concurrent stdout/stderr reading to prevent pipe deadlocks Message queueing during Claude processing Graceful process termination without zombies	01-03 telegram-integration message-handling	added patterns Asyncio subprocess management with concurrent stream readers Stream-json event routing to callback functions Crash recovery with --continue flag terminate() + wait_for() + kill() fallback pattern	created modified telegram/claude_subprocess.py	Use asyncio.gather for concurrent stdout/stderr reading (prevents pipe deadlock) Queue messages during processing, send after completion Auto-restart on crash with --continue flag (max 3 retries) Spawn fresh process per turn (not stdin piping) for Phase 1 simplicity	Pattern 1: Concurrent stream reading - Always use asyncio.gather() for stdout/stderr to prevent pipe buffer overflow deadlocks Pattern 2: Process lifecycle - terminate() + wait_for(timeout) + kill() + wait() ensures no zombies Pattern 3: Stream-json parsing - Line-by-line JSON.loads() with try/except, route by event type Pattern 4: Callback architecture - on_output/on_error/on_complete/on_status for decoupled communication	9min	2026-02-04

Phase 1 Plan 2: ClaudeSubprocess Module Summary

Asyncio-based Claude Code subprocess engine with concurrent stream reading, message queueing, crash recovery, and stream-json event routing via callbacks

Performance

• Duration: 9 minutes
• Started: 2026-02-04T17:32:07Z
• Completed: 2026-02-04T17:41:16Z
• Tasks: 1
• Files modified: 1

Accomplishments

• Created ClaudeSubprocess class that spawns Claude Code CLI with stream-json output
• Implemented concurrent stdout/stderr reading via asyncio.gather to prevent pipe deadlocks
• Built message queueing system for messages received during Claude processing
• Implemented crash recovery with auto-restart using --continue flag (max 3 retries)
• Added graceful process termination with terminate → wait_for → kill → wait pattern (no zombies)
• Established callback-based architecture for decoupled communication with session manager

Task Commits

Each task was committed atomically:

1. Task 1: Create ClaudeSubprocess module with spawn, I/O, and lifecycle management - 8fce10c (feat)

Files Created/Modified

• telegram/claude_subprocess.py - Claude Code subprocess lifecycle management with asyncio, handles spawning with persona settings, concurrent stream reading, stream-json event parsing, message queueing, crash recovery, and graceful termination

Decisions Made

1. Concurrent stream reading pattern: Use asyncio.gather() to read stdout and stderr concurrently, preventing pipe buffer deadlock (verified by research as critical pattern)

2. Message queueing strategy: Queue messages in asyncio.Queue while subprocess is busy, process queue after completion callback. This ensures messages don't interrupt active processing.

3. Crash recovery approach: Auto-restart with --continue flag up to 3 times with 1-second backoff. Claude Code's session persistence in .claude/ directory enables context preservation across crashes.

4. Fresh process per turn: Spawn new claude -p invocation for each turn rather than piping to stdin. Simpler for Phase 1; Phase 2+ might use --input-format stream-json for live piping.

5. Callback architecture: Decouple subprocess management from session management via callbacks (on_output, on_error, on_complete, on_status). Enables clean separation of concerns.

Deviations from Plan

None - plan executed exactly as written.

Issues Encountered

None - implementation followed research patterns without issues.

User Setup Required

None - no external service configuration required.

Next Phase Readiness

Ready for Plan 03 (Telegram Integration):

• ClaudeSubprocess provides complete subprocess lifecycle management
• Callback architecture enables clean integration with Telegram bot message handlers
• Message queueing handles concurrent messages during processing
• Process termination and crash recovery are production-ready

Integration points for Plan 03:

• Pass Telegram message text to send_message()
• Route on_output callback to Telegram message sending
• Route on_error callback to Telegram error notifications
• Use on_status callback for typing indicators
• Call terminate() during session cleanup/switching

No blockers or concerns.

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Phase: 01-session-process-foundation Completed: 2026-02-04