docs(01-04): complete logging infrastructure plan

Tasks completed: 2/2
- Create log directory management
- Create per-process log writer

SUMMARY: .planning/phases/01-core-infrastructure/01-04-SUMMARY.md

.planning/phases/01-core-infrastructure/01-04-SUMMARY.md

@@ -0,0 +1,109 @@
+---
+phase: 01-core-infrastructure
+plan: 04
+subsystem: infra
+tags: [logging, filesystem, node:fs, streams]
+
+# Dependency graph
+requires:
+  - phase: 01-01
+    provides: TypeScript project structure
+provides:
+  - LogManager for directory management
+  - ProcessLogWriter for per-process stdout/stderr capture
+  - createLogger convenience function
+affects: [agent-spawning, process-management, debugging]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - "Per-process log directory structure: ~/.cw/logs/{processId}/"
+    - "Timestamped log entries: [YYYY-MM-DD HH:mm:ss.SSS]"
+    - "WriteStream backpressure handling via drain events"
+
+key-files:
+  created:
+    - src/logging/types.ts
+    - src/logging/manager.ts
+    - src/logging/writer.ts
+    - src/logging/index.ts
+  modified: []
+
+key-decisions:
+  - "Log directory structure: ~/.cw/logs/{processId}/stdout.log and stderr.log"
+  - "Timestamp format: [YYYY-MM-DD HH:mm:ss.SSS] prefix per line"
+  - "Append mode for log files (flags: 'a') to support resumption"
+
+patterns-established:
+  - "Module structure: types.ts, implementation.ts, index.ts"
+  - "Async/await for file operations with node:fs/promises"
+  - "WriteStream backpressure handling pattern"
+
+# Metrics
+duration: 5 min
+completed: 2026-01-30
+---
+
+# Phase 1 Plan 4: File-Based Logging Summary
+
+**Per-process logging infrastructure with timestamped stdout/stderr capture to ~/.cw/logs/{processId}/**
+
+## Performance
+
+- **Duration:** 5 min
+- **Started:** 2026-01-30T12:12:19Z
+- **Completed:** 2026-01-30T12:17:03Z
+- **Tasks:** 2
+- **Files created:** 4
+
+## Accomplishments
+
+- LogManager class for directory creation and path management
+- ProcessLogWriter class for per-process stdout/stderr file capture
+- Timestamp prefixing for each line of output
+- Backpressure handling for write streams
+- cleanOldLogs for log retention management
+- createLogger convenience function for common use case
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Create log directory management** - `e64e243` (feat)
+2. **Task 2: Create per-process log writer** - `fc410e2` (feat)
+
+## Files Created/Modified
+
+- `src/logging/types.ts` - LogLevel, LogEntry, LogConfig, LogStream types
+- `src/logging/manager.ts` - LogManager class for directory/path management
+- `src/logging/writer.ts` - ProcessLogWriter class for file output capture
+- `src/logging/index.ts` - Module exports and createLogger helper
+
+## Decisions Made
+
+1. **Directory structure:** `~/.cw/logs/{processId}/stdout.log` and `stderr.log` - keeps process logs isolated and easy to clean up
+2. **Timestamp format:** `[YYYY-MM-DD HH:mm:ss.SSS]` - readable and sortable, includes milliseconds for debugging
+3. **Append mode:** Files opened with `flags: 'a'` to support process restarts without losing prior logs
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+
+None.
+
+## User Setup Required
+
+None - no external service configuration required.
+
+## Next Phase Readiness
+
+- Logging infrastructure ready for integration with process spawning (01-03)
+- ProcessLogWriter.getStdoutStream()/getStderrStream() ready for direct piping from child processes
+- LogManager can be shared across multiple ProcessLogWriter instances
+
+---
+*Phase: 01-core-infrastructure*
+*Completed: 2026-01-30*