feat: add harness skill with hooks install/uninstall support (#156)

Add multi-session autonomous agent harness with progress checkpointing,
failure recovery, task dependencies, and post-completion self-reflection.

- Add harness module to config.json (copy_dir with hooks.json)
- Add 7 hook scripts: stop, sessionstart, teammateidle, subagentstop,
  claim, renew, self-reflect-stop + shared _harness_common.py
- Fix self-reflect-stop: only triggers when harness was initialized
  (checks harness-tasks.json existence), not on every session
- Add unmerge_hooks_from_settings() to uninstall.py for clean hook removal
- Add unit tests (57 tests) and E2E test (100 tasks + 5 self-reflect)

Generated with SWE-Agent.ai

Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>

skills/harness/hooks/harness-subagentstop.py

@@ -0,0 +1,137 @@
+#!/usr/bin/env python3
+"""Harness SubagentStop hook — blocks subagents from stopping when they
+have assigned harness tasks still in progress.
+
+Uses the same decision format as Stop hooks:
+  {"decision": "block", "reason": "..."}
+"""
+from __future__ import annotations
+
+import json
+import os
+import sys
+from pathlib import Path
+from typing import Any, Optional
+
+
+def _read_hook_payload() -> dict[str, Any]:
+    raw = sys.stdin.read()
+    if not raw.strip():
+        return {}
+    try:
+        data = json.loads(raw)
+        return data if isinstance(data, dict) else {}
+    except Exception:
+        return {}
+
+
+def _find_harness_root(payload: dict[str, Any]) -> Optional[Path]:
+    state_root = os.environ.get("HARNESS_STATE_ROOT")
+    if state_root:
+        p = Path(state_root)
+        if (p / "harness-tasks.json").is_file():
+            try:
+                return p.resolve()
+            except Exception:
+                return p
+    candidates: list[Path] = []
+    env_dir = os.environ.get("CLAUDE_PROJECT_DIR")
+    if env_dir:
+        candidates.append(Path(env_dir))
+    cwd = payload.get("cwd") or os.getcwd()
+    candidates.append(Path(cwd))
+    seen: set[str] = set()
+    for base in candidates:
+        try:
+            base = base.resolve()
+        except Exception:
+            continue
+        if str(base) in seen:
+            continue
+        seen.add(str(base))
+        for parent in [base, *list(base.parents)[:8]]:
+            if (parent / "harness-tasks.json").is_file():
+                return parent
+    return None
+
+
+def _load_json(path: Path) -> dict[str, Any]:
+    with path.open("r", encoding="utf-8") as f:
+        data = json.load(f)
+    if not isinstance(data, dict):
+        raise ValueError(f"{path.name} must be a JSON object")
+    return data
+
+
+def _is_harness_active(root: Path) -> bool:
+    """Check if harness skill is actively running (marker file exists)."""
+    return (root / ".harness-active").is_file()
+
+
+def main() -> int:
+    payload = _read_hook_payload()
+
+    # Safety: respect stop_hook_active to prevent infinite loops
+    if payload.get("stop_hook_active", False):
+        return 0
+
+    root = _find_harness_root(payload)
+    if root is None:
+        return 0  # no harness project, allow stop
+
+    # Guard: only active when harness skill is triggered
+    if not _is_harness_active(root):
+        return 0
+
+    tasks_path = root / "harness-tasks.json"
+    try:
+        state = _load_json(tasks_path)
+        session_config = state.get("session_config") or {}
+        if not isinstance(session_config, dict):
+            session_config = {}
+        is_concurrent = str(session_config.get("concurrency_mode") or "exclusive") == "concurrent"
+        tasks_raw = state.get("tasks") or []
+        if not isinstance(tasks_raw, list):
+            return 0
+        tasks = [t for t in tasks_raw if isinstance(t, dict)]
+    except Exception:
+        return 0
+
+    in_progress = [t for t in tasks if str(t.get("status", "")) == "in_progress"]
+    worker_id = str(os.environ.get("HARNESS_WORKER_ID") or "").strip()
+    agent_id = str(payload.get("agent_id") or "").strip()
+    teammate_name = str(payload.get("teammate_name") or "").strip()
+    identities = {x for x in (worker_id, agent_id, teammate_name) if x}
+
+    if is_concurrent and in_progress and not identities:
+        reason = (
+            "HARNESS: concurrent 模式缺少 worker identity（HARNESS_WORKER_ID/agent_id）。"
+            "为避免误停导致任务悬空，本次阻止停止。"
+        )
+        print(json.dumps({"decision": "block", "reason": reason}, ensure_ascii=False))
+        return 0
+
+    if is_concurrent:
+        owned = [
+            t for t in in_progress
+            if str(t.get("claimed_by") or "") in identities
+        ] if identities else []
+    else:
+        owned = in_progress
+
+    # Only block when this subagent still owns in-progress work.
+    if owned:
+        tid = str(owned[0].get("id") or "")
+        title = str(owned[0].get("title") or "")
+        reason = (
+            f"HARNESS: 子代理仍有进行中的任务 [{tid}] {title}。"
+            "请完成当前任务的验证和记录后再停止。"
+        )
+        print(json.dumps({"decision": "block", "reason": reason}, ensure_ascii=False))
+        return 0
+
+    return 0  # all done, allow stop
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())