---
phase: 03-execution-pipeline
plan: 02
subsystem: execution
tags: [subprocess, execution, e2e-tests, python]

# Dependency graph
requires:
  - phase: 03-01
    provides: "Multi-file architecture with run_sl stub"
  - phase: 02-e2e-test-infrastructure
    provides: "E2E test harness for validation"
provides:
  - "Working run_sl() with subprocess.run() passthrough"
  - "E2E tests for EXEC-02 through EXEC-05"
  - "Exit code propagation verified"
  - "I/O passthrough verified"
affects: [04-command-translation]

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "subprocess.run() with default I/O inheritance (no PIPE)"
    - "sys.executable for portable Python invocation in tests"

key-files:
  created:
    - tests/test_execution.py
  modified:
    - common.py
    - tests/conftest.py

key-decisions:
  - "Use subprocess.run() defaults for I/O inheritance (real-time passthrough)"
  - "Use sys.executable instead of 'python' for cross-platform test compatibility"

patterns-established:
  - "E2E tests skip gracefully when external tool not installed"
  - "Test with repos that have changes to verify output behavior"

# Metrics
duration: 2min
completed: 2026-01-18
---

# Phase 3 Plan 02: Subprocess Execution Summary

**Implemented run_sl() with subprocess passthrough and E2E tests proving correct exit code and I/O propagation**

## Performance

- **Duration:** 2 min
- **Started:** 2026-01-18T03:18:05Z
- **Completed:** 2026-01-18T03:21:00Z
- **Tasks:** 3
- **Files modified:** 3

## Accomplishments
- Replaced run_sl stub with real subprocess.run() implementation
- Created test_execution.py with 5 E2E tests for execution pipeline
- Verified EXEC-02 through EXEC-05 requirements
- All 40 tests pass (35 existing + 5 new)

## Task Commits

Each task was committed atomically:

1. **Task 1: Implement run_sl() with subprocess passthrough** - `e232dbe` (feat)
2. **Task 2: Create E2E execution tests** - `0187ebd` (test)
3. **Task 3: Verify full integration** - (verification only, no commit)

## Files Created/Modified
- `common.py` - run_sl() now uses subprocess.run() with default I/O inheritance
- `tests/test_execution.py` - E2E tests for exit code and I/O passthrough
- `tests/conftest.py` - Fixed to use sys.executable for portability

## Decisions Made
- **No PIPE, no capture_output:** subprocess.run() defaults ensure real-time I/O passthrough
- **sys.executable:** Tests use same Python interpreter as pytest for portability

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 3 - Blocking] Fixed Python executable portability**
- **Found during:** Task 2
- **Issue:** conftest.py used "python" which doesn't exist on macOS (only python3)
- **Fix:** Changed to use sys.executable for portable Python invocation
- **Files modified:** tests/conftest.py
- **Commit:** 0187ebd (included in Task 2 commit)

**2. [Rule 1 - Bug] Fixed test for empty repo**
- **Found during:** Task 2
- **Issue:** test_status_output_appears expected output from empty repo, but sl status produces no output when clean
- **Fix:** Changed test to use git_repo_with_changes fixture
- **Files modified:** tests/test_execution.py
- **Commit:** 0187ebd (included in Task 2 commit)

## Issues Encountered

None - all blockers resolved inline.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness
- Execution pipeline complete and tested
- run_sl() ready for use by all command handlers
- E2E test pattern established for future command testing
- Phase 03 fully complete, ready for Phase 04 (command translation)

---
*Phase: 03-execution-pipeline*
*Completed: 2026-01-18*
