claw-code/CLAUDE.md
YeonGyu-Kim 932710a626 docs: ERROR_HANDLING.md — unified error handler pattern for orchestration code
Cycle #22 ships documentation that operationalizes cycles #178–#179.

Problem context:
After #178 (parse-error envelope) and #179 (stderr hygiene + real error message),
claws can now build a unified error handler for all 14 clawable commands.
But there was no guide on how to actually do that. Operators had the pieces;
they didn't have the pattern.

This file changes that.

New file: ERROR_HANDLING.md
- Quick reference: exit codes + envelope shapes (0=success, 1=error, 2=timeout)
- One-handler pattern: ~80 lines of Python showing how to parse error.kind,
  check retryable, and decide recovery strategy
- Four practical recovery patterns:
  - Retry on transient errors (filesystem, timeout)
  - Reuse session after timeout (if cancel_observed=true)
  - Validate command syntax before dispatch (dry-run --help)
  - Log errors for observability
- Error kinds enumeration (parse, session_not_found, filesystem, runtime, timeout)
- Common mistakes to avoid (6 patterns with BAD vs GOOD examples)
- Testing your error handler (unit test examples)

Operational impact:
Orchestration code now has a canonical pattern. Claws can:
- Copy-paste the run_claw_command() function (works for all commands)
- Classify errors uniformly (no special cases per command)
- Decide recovery deterministically (error.kind + retryable + cancel_observed)
- Log/monitor/escalate with confidence

Related cycles:
- #178: Parse-error envelope (commands now emit structured JSON on invalid argv)
- #179: Stderr hygiene + real message (JSON mode silences argparse, carries actual error)
- #164 Stage B: cancel_observed field (callers know if session is safe for reuse)

Updated CLAUDE.md:
- Added ERROR_HANDLING.md to 'Related docs' section
- Now documents the one-handler pattern as a guideline

No code changes. No test changes. Pure documentation.

This completes the documentation trail from protocol (SCHEMAS.md) →
governance (OPT_OUT_AUDIT.md, OPT_OUT_DEMAND_LOG.md) → practice (ERROR_HANDLING.md).
2026-04-22 20:42:43 +09:00

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# CLAUDE.md — Python Reference Implementation
**This file guides work on `src/` and `tests/` — the Python reference harness for claw-code protocol.**
The production CLI lives in `rust/`; this directory (`src/`, `tests/`, `.py` files) is a **protocol validation and dogfood surface**.
## What this Python harness does
**Machine-first orchestration layer** — proves that the claw-code JSON protocol is:
- Deterministic and recoverable (every output is reproducible)
- Self-describing (SCHEMAS.md documents every field)
- Clawable (external agents can build ONE error handler for all commands)
## Stack
- **Language:** Python 3.13+
- **Dependencies:** minimal (no frameworks; pure stdlibs + attrs/dataclasses)
- **Test runner:** pytest
- **Protocol contract:** SCHEMAS.md (machine-readable JSON envelope)
## Quick start
```bash
# 1. Install dependencies (if not already in venv)
python3 -m venv .venv && source .venv/bin/activate
# (dependencies minimal; standard library mostly)
# 2. Run tests
python3 -m pytest tests/ -q
# 3. Try a command
python3 -m src.main bootstrap "hello" --output-format json | python3 -m json.tool
```
## Verification workflow
```bash
# Unit tests (fast)
python3 -m pytest tests/ -q 2>&1 | tail -3
# Type checking (optional but recommended)
python3 -m mypy src/ --ignore-missing-imports 2>&1 | tail -5
```
## Repository shape
- **`src/`** — Python reference harness implementing SCHEMAS.md protocol
- `main.py` — CLI entry point; all 14 clawable commands
- `query_engine.py` — core TurnResult / QueryEngineConfig
- `runtime.py` — PortRuntime; turn loop + cancellation (#164 Stage A/B)
- `session_store.py` — session persistence
- `transcript.py` — turn transcript assembly
- `commands.py`, `tools.py` — simulated command/tool trees
- `models.py` — PermissionDenial, UsageSummary, etc.
- **`tests/`** — comprehensive protocol validation (22 baseline → 192 passing as of 2026-04-22)
- `test_cli_parity_audit.py` — proves all 14 clawable commands accept --output-format
- `test_json_envelope_field_consistency.py` — validates SCHEMAS.md contract
- `test_cancel_observed_field.py`#164 Stage B: cancellation observability + safe-to-reuse semantics
- `test_run_turn_loop_*.py` — turn loop behavior (timeout, cancellation, continuation, permissions)
- `test_submit_message_*.py` — budget, cancellation contracts
- `test_*_cli.py` — command-specific JSON output validation
- **`SCHEMAS.md`** — canonical JSON contract
- Common fields (all envelopes): timestamp, command, exit_code, output_format, schema_version
- Error envelope shape
- Not-found envelope shape
- Per-command success schemas (14 commands documented)
- Turn Result fields (including cancel_observed as of #164 Stage B)
- **`.gitignore`** — excludes `.port_sessions/` (dogfood-run state)
## Key concepts
### Clawable surface (14 commands)
Every clawable command **must**:
1. Accept `--output-format {text,json}`
2. Return JSON envelopes matching SCHEMAS.md
3. Use common fields (timestamp, command, exit_code, output_format, schema_version)
4. Exit 0 on success, 1 on error/not-found, 2 on timeout
**Commands:** list-sessions, delete-session, load-session, flush-transcript, show-command, show-tool, exec-command, exec-tool, route, bootstrap, command-graph, tool-pool, bootstrap-graph, turn-loop
**Validation:** `test_cli_parity_audit.py` auto-tests all 14 for --output-format acceptance.
### OPT_OUT surfaces (12 commands)
Explicitly exempt from --output-format requirement (for now):
- Rich-Markdown reports: summary, manifest, parity-audit, setup-report
- List commands with query filters: subsystems, commands, tools
- Simulation/debug: remote-mode, ssh-mode, teleport-mode, direct-connect-mode, deep-link-mode
**Future work:** audit OPT_OUT surfaces for JSON promotion (post-#164).
### Protocol layers
**Coverage (#167#170):** All clawable commands emit JSON
**Enforcement (#171):** Parity CI prevents new commands skipping JSON
**Documentation (#172):** SCHEMAS.md locks field contract
**Alignment (#173):** Test framework validates docs ↔ code match
**Field evolution (#164 Stage B):** cancel_observed proves protocol extensibility
## Testing & coverage
### Run full suite
```bash
python3 -m pytest tests/ -q
```
### Run one test file
```bash
python3 -m pytest tests/test_cancel_observed_field.py -v
```
### Run one test
```bash
python3 -m pytest tests/test_cancel_observed_field.py::TestCancelObservedField::test_default_value_is_false -v
```
### Check coverage (optional)
```bash
python3 -m pip install coverage # if not already installed
python3 -m coverage run -m pytest tests/
python3 -m coverage report --skip-covered
```
Target: >90% line coverage for src/ (currently ~85%).
## Common workflows
### Add a new clawable command
1. Add parser in `main.py` (argparse)
2. Add `--output-format` flag
3. Emit JSON envelope using `wrap_json_envelope(data, command_name)`
4. Add command to CLAWABLE_SURFACES in test_cli_parity_audit.py
5. Document in SCHEMAS.md (schema + example)
6. Write test in tests/test_*_cli.py or tests/test_json_envelope_field_consistency.py
7. Run full suite to confirm parity
### Modify TurnResult or protocol fields
1. Update dataclass in `query_engine.py`
2. Update SCHEMAS.md with new field + rationale
3. Write test in `tests/test_json_envelope_field_consistency.py` that validates field presence
4. Update all places that construct TurnResult (grep for `TurnResult(`)
5. Update bootstrap/turn-loop JSON builders in main.py
6. Run `tests/` to ensure no regressions
### Promote an OPT_OUT surface to CLAWABLE
**Prerequisite:** Real demand signal logged in `OPT_OUT_DEMAND_LOG.md` (threshold: 2+ independent signals per surface). Speculative promotions are not allowed.
Once demand is evidenced:
1. Add --output-format flag to argparse
2. Emit wrap_json_envelope() output in JSON path
3. Move command from OPT_OUT_SURFACES to CLAWABLE_SURFACES
4. Document in SCHEMAS.md
5. Write test for JSON output
6. Run parity audit to confirm no regressions
7. Update `OPT_OUT_DEMAND_LOG.md` to mark signal as resolved
### File a demand signal (when a claw actually needs JSON from an OPT_OUT surface)
1. Open `OPT_OUT_DEMAND_LOG.md`
2. Find the surface's entry under Group A/B/C
3. Append a dated entry with Source, Use Case, and Markdown-alternative-checked explanation
4. If this is the 2nd signal for the same surface, file a promotion pinpoint in ROADMAP.md
## Dogfood principles
The Python harness is continuously dogfood-tested:
- Every cycle ships to `main` with detailed commit messages
- New tests are written before/alongside implementation
- Test suite must pass before pushing (zero-regression principle)
- Commits grouped by pinpoint (#159, #160, ..., #174)
- Failure modes classified per exit code: 0=success, 1=error, 2=timeout
## Protocol governance
- **SCHEMAS.md is the source of truth** — any implementation must match field-for-field
- **Tests enforce the contract** — drift is caught by test suite
- **Field additions are forward-compatible** — new fields get defaults, old clients ignore them
- **Exit codes are signals** — claws use them for conditional logic (0→continue, 1→escalate, 2→timeout)
- **Timestamps are audit trails** — every envelope includes ISO 8601 UTC time for chronological ordering
## Related docs
- **`ERROR_HANDLING.md`** — Unified error-handling pattern for claws (one handler for all 14 clawable commands)
- **`SCHEMAS.md`** — JSON protocol specification (read before implementing)
- **`OPT_OUT_AUDIT.md`** — Governance for the 12 non-clawable surfaces
- **`OPT_OUT_DEMAND_LOG.md`** — Active survey recording real demand signals (evidence base for decisions)
- **`ROADMAP.md`** — macro roadmap and macro pain points
- **`PHILOSOPHY.md`** — system design intent
- **`PARITY.md`** — status of Python ↔ Rust protocol equivalence