feat(worktree): git worktree per task to isolate shared /repos (ORCH-2 / S-4)

- add src/git_worktree.py: ensure/remove/get_worktree_path
- config: worktrees_dir=/repos/_wt
- launcher: agent runs in per-branch worktree; task-file + commit/push in worktree; no shared checkout
- qg/checks: read artifacts + run make test from worktree (branch arg, backward-compatible)
- webhooks/plane: pass branch into QG dispatch; review fallback from worktree
- webhooks/gitea: keep read-only branch --contains in main clone (documented)
- tests: test_git_worktree.py (isolation) + update test_launcher write-task-file
- docs: ARCHITECTURE worktree section + BUGFIXES_2026-06-02_ORCH2

Preserves B-1/B-2/S-1/S-5 fixes (paths now point at worktree).

docs/ARCHITECTURE.md

@@ -39,7 +39,7 @@ STAGE_TRANSITIONS = {
 |-------|---------------|
 | check_analysis_approved | Filesystem: 4 файла + :approved: comment в Plane |
 | check_architecture_done | Filesystem: ADR dir или infra-requirements.md |
-| check_tests_local | Оркестратор сам гоняет `make test` в `/repos/<repo>` (judge по exit-code). Заменил check_ci_green: Gitea CI не сконфигурирован. |
+| check_tests_local | Оркестратор сам гоняет `make test` в **worktree задачи** `/repos/_wt/<repo>/<branch>` (judge по exit-code). Заменил check_ci_green: Gitea CI не сконфигурирован. Worktree-изоляция → безопасно при параллельных задачах (ORCH-2 / S-4). |
 | check_reviewer_verdict | Filesystem: читает `verdict: APPROVED\|REQUEST_CHANGES` из YAML-frontmatter `12-review.md` (только машиночитаемое поле, не подстроки в тексте) |
 | check_tests_passed | Filesystem: test-report.md содержит "PASS" |
 | check_ci_green | (legacy) Gitea API: GET /commits/{branch}/status — больше не используется как QG развития |
@@ -188,7 +188,7 @@ services:
 
 Каждый агент — Claude CLI с:
 - **System prompt**: `.openclaw/agents/{role}.md` (в репозитории)
-- **Task file**: `.task-{suffix}.md` — генерируется orchestrator **прямой записью в смонтированный volume `/repos/<repo>/`** (B-1, без docker). В `.gitignore` репозитория проекта (рантайм-артефакт, не коммитится).
+- **Task file**: `.task-{suffix}.md` — генерируется orchestrator **прямой записью в worktree задачи** `/repos/_wt/<repo>/<branch>/` (B-1, без docker; ORCH-2 — в изолированную рабочую копию, не в shared `/repos/<repo>`). В `.gitignore` репозитория проекта (рантайм-артефакт, не коммитится).
 - **Tools**: Read, Write, Edit, Bash
 - **Output**: `--print` mode (весь вывод в stdout после завершения)
 
@@ -201,13 +201,39 @@ services:
 | tester | test-report.md, e2e results | 10-25 мин |
 | deployer | merge PR + SSH deploy-hook + smoke | 5-10 мин |
 
+## Изоляция через git worktree (ORCH-2 / S-4)
+
+Каждая задача (= одна git-ветка) работает в **изолированной git worktree**, а не в общем
+`/repos/<repo>`. Это убирает гонки `git checkout`, когда две задачи активны одновременно.
+
+```
+/repos/<repo>                      ← основной clone (fetch / управление worktree, read-only запросы)
+/repos/_wt/<repo>/<safe-branch>    ← worktree конкретной задачи (рабочая копия агента)
+```
+
+Модуль `src/git_worktree.py`:
+- `get_worktree_path(repo, branch)` — путь worktree (не создаёт).
+- `ensure_worktree(repo, branch)` — создаёт (или переиспользует) worktree на нужной ветке;
+  для новой ветки создаёт её от `origin/main`. Возвращает путь.
+- `remove_worktree(repo, branch)` — опциональная очистка при `done`.
+
+Где используется worktree:
+- **launcher**: агент запускается с `cd <worktree>` (без `git checkout` в cmd); task-файл
+  пишется в worktree; commit/push в `_monitor_agent` идут в worktree.
+- **qg/checks**: чтение артефактов агента (`check_analysis_complete`, `check_architecture_done`,
+  `check_tests_passed`, `check_reviewer_verdict`) и `check_tests_local` (`make test`) — из worktree.
+  Артефакт-функции принимают опциональный `branch`; без него падают на shared `/repos/<repo>`
+  (обратная совместимость).
+- **webhooks/gitea**: `git branch -r --contains <sha>` оставлен в основном clone — это
+  **read-only** запрос (нет checkout/мутации), гонок не создаёт.
+
+> Один branch может быть checked out только в одной worktree одновременно —
+> это и есть нужное свойство: одна задача = одна ветка = одна worktree.
+
 ## Известные ограничения
 
-- **Shared `/repos` checkout (гонки при параллельных задачах).** Все агенты и
-  `check_tests_local` делают `git checkout` в одном `/repos/<repo>`. При двух
-  одновременно активных задачах checkout одной перетрёт рабочую копию другой.
-  Пока приемлемо (задачи идут последовательно). **Исправление — git worktree per task/branch
-  (запланировано отдельной задачей S-4).**
+- ~~Shared `/repos` checkout (гонки при параллельных задачах).~~ **РЕШЕНО (ORCH-2 / S-4):**
+  git worktree per task/branch — см. раздел «Изоляция через git worktree» ниже.
 - **In-process daemon-потоки.** Агенты запускаются в daemon-потоках uvicorn. При
   рестарте uvicorn запущенные агенты осиротевают → ловит orphan-recovery (M-1).
   Целевая архитектура — очередь задач (F-2b, отдельно).

docs/BUGFIXES_2026-06-02_ORCH2.md

@@ -0,0 +1,81 @@
+# ORCH-2 / S-4 — git worktree per task (изоляция shared /repos)
+
+**Дата:** 2026-06-02
+**Ветка:** `feature/ORCH-2-worktree`
+**Источник:** `AUDIT_2026-06-02.md` (SERIOUS S-4), `DEV_TASK_ORCH2_WORKTREE.md`
+**Исполнитель:** Dev (Opus 4.8 Tokenator)
+
+## Проблема (S-4)
+
+Все git-операции (`launcher.launch` cmd, `_monitor_agent` commit/push, `check_tests_local`)
+делали `git checkout <branch>` в одном общем `/repos/<repo>`. При двух активных задачах
+checkout одной перетирал рабочую копию другой → гонки (на ET-009 это дало «два коллектора»
+и путаницу веток).
+
+## Решение
+
+**git worktree per branch.** Каждая задача (ветка) работает в изолированной рабочей копии:
+
+```
+/repos/<repo>                      ← основной clone (fetch / worktree mgmt / read-only)
+/repos/_wt/<repo>/<safe-branch>    ← worktree задачи (рабочая копия агента)
+```
+
+## Изменения
+
+| Файл | Что |
+|------|-----|
+| `src/config.py` | + `worktrees_dir: str = "/repos/_wt"` |
+| `src/git_worktree.py` (новый) | `_safe`, `get_worktree_path`, `ensure_worktree`, `remove_worktree` |
+| `src/agents/launcher.py` | `launch()`: ветка резолвится заранее → `ensure_worktree`; cmd = `cd <worktree>` без `git checkout`; `_write_task_file(repo, branch, ...)` пишет в worktree; `_monitor_agent` commit/push в worktree (checkout убран); чтение `01-questions.md`/`10-conflict.md` из worktree; QG-диспетчер прокидывает `branch` |
+| `src/qg/checks.py` | `_repo_path(repo, branch)` helper (worktree если есть, иначе shared); артефакт-чеки получили опциональный `branch`; `check_tests_local` → `ensure_worktree` + `make test` в worktree (TODO про S-4 удалён) |
+| `src/webhooks/plane.py` | QG-диспетчер прокидывает `branch`; review-файл fallback читается из worktree |
+| `src/webhooks/gitea.py` | `git branch -r --contains <sha>` — подтверждено read-only, оставлено в main clone (+ комментарий) |
+| `tests/test_git_worktree.py` (новый) | покрытие `_safe`/`get_worktree_path`/`ensure_worktree`/`remove_worktree` + изоляция двух веток (реальные локальные git-репо в tmp, без сети) |
+| `tests/test_launcher.py` | `TestWriteTaskFile` обновлён под новую сигнатуру (запись в worktree) |
+| `docs/ARCHITECTURE.md` | раздел «Изоляция через git worktree»; убран пункт про shared-checkout гонки |
+
+## Совместимость с прежними фиксами
+
+- **B-1** (запись task-файла без docker, прямой `open()`): сохранена — теперь путь = worktree.
+- **B-2** (Popen stdout → файл, monitor `proc.wait()` без зомби): не тронут.
+- **S-5** (`check_reviewer_verdict` — только YAML-frontmatter): не тронут, добавлен лишь worktree-путь.
+- **S-1** (`check_tests_local` — свой `make test` вместо Gitea CI): сохранён, тесты теперь в worktree.
+
+Обратная совместимость QG-диспетчеризации: артефакт-чеки принимают `branch` опционально
+(default `None` → shared `/repos/<repo>`), поэтому существующие 2-арг вызовы/тесты не сломаны.
+
+## Проверка
+
+```bash
+# Тесты (в контейнере через образ — хостовый .venv сломан):
+IMG=$(docker inspect orchestrator --format '{{.Config.Image}}')
+docker run --rm -v /home/slin/repos/orchestrator:/code -w /code --entrypoint python3 $IMG -m pytest tests/ -q
+# → 37 passed, 9 failed (pre-existing test_webhooks 401/signature — НЕ относятся к ORCH-2,
+#   идентичны baseline на main).
+
+# test_git_worktree.py изолированно → 9 passed.
+```
+
+### Тест изоляции (в работающем контейнере)
+
+```bash
+docker exec orchestrator python3 -c "
+import sys; sys.path.insert(0,'/app')
+from src.git_worktree import ensure_worktree
+import subprocess
+p1 = ensure_worktree('enduro-trails','feature/wt-test-A')
+p2 = ensure_worktree('enduro-trails','feature/wt-test-B')
+b1 = subprocess.run(['git','-C',p1,'branch','--show-current'],capture_output=True,text=True).stdout.strip()
+b2 = subprocess.run(['git','-C',p2,'branch','--show-current'],capture_output=True,text=True).stdout.strip()
+assert p1!=p2 and b1!=b2, 'NOT ISOLATED'
+print('ISOLATION OK', p1, p2, b1, b2)
+"
+```
+
+(Результат прогона на сервере — см. ниже / в отчёте Стрим.)
+
+## Ограничения / заметки
+
+- Очередь задач (ORCH-1 / F-2b) **не** входит в эту задачу.
+- `remove_worktree` существует, но автоматический вызов при `done` не подключён (опционально, отдельным шагом).

src/agents/launcher.py

@@ -6,6 +6,7 @@ import signal
 from ..config import settings
 from ..db import get_db, get_task_by_repo_branch, update_task_stage
 from ..stages import get_next_stage, get_qg_for_stage, get_agent_for_stage
+from ..git_worktree import ensure_worktree, get_worktree_path
 from ..qg.checks import QG_CHECKS
 from ..notifications import notify_stage_change, notify_qg_failure, notify_agent_started, notify_agent_finished, notify_approve_requested
 from ..plane_sync import notify_stage_change as plane_notify_stage, add_comment as plane_add_comment
@@ -71,15 +72,22 @@ class AgentLauncher:
         if not config:
             raise ValueError(f"Unknown agent: {agent}")
 
-        # Container-local path (repos mounted at /repos)
+        # Main clone lives at /repos/<repo>; the agent works in an isolated worktree
+        # (ORCH-2 / S-4) so concurrent tasks never fight over a shared checkout.
         local_repo_path = os.path.join(settings.repos_dir, repo)
-
         if not os.path.isdir(local_repo_path):
             raise FileNotFoundError(f"Repo not found: {local_repo_path}")
 
-        # Write task file if content provided (B-1: direct write to mounted /repos, no docker)
+        # Determine branch (needed before we touch the worktree / task file).
+        _br_row = get_db().execute("SELECT branch FROM tasks WHERE id=?", (task_id,)).fetchone() if task_id else None
+        agent_branch = _br_row[0] if _br_row else "main"
+
+        # Ensure the per-branch worktree exists and is on the right branch.
+        work_path = ensure_worktree(repo, agent_branch)
+
+        # Write task file if content provided (B-1: direct write; now into the worktree).
         if task_content:
-            self._write_task_file(repo, config["task_file"], task_content)
+            self._write_task_file(repo, agent_branch, config["task_file"], task_content)
 
         # Record run in DB
         conn = get_db()
@@ -99,15 +107,13 @@ class AgentLauncher:
         system_prompt = config["system_prompt"]
         allowed_tools = config["allowed_tools"]
 
-        # Determine branch for checkout
-        _br_row = get_db().execute("SELECT branch FROM tasks WHERE id=?", (task_id,)).fetchone() if task_id else None
-        agent_branch = _br_row[0] if _br_row else "main"
-
         model = config.get("model", "")
         model_flag = f"--model {model} " if model else ""
 
+        # No git fetch/checkout here: ensure_worktree() already put the worktree on
+        # the right branch. The agent simply runs inside its isolated work_path.
         cmd = (
-            f'cd {local_repo_path} && git fetch origin 2>/dev/null; git checkout {agent_branch} 2>/dev/null || git checkout -b {agent_branch} origin/{agent_branch} 2>/dev/null; '
+            f'cd {work_path} && '
             f'{self.CLAUDE_BIN} --print '
             f'{model_flag}'
             f'"$(cat {task_file})" '
@@ -219,8 +225,10 @@ class AgentLauncher:
 
         notify_agent_finished(run_id, agent, exit_code, task_id=_task_id, duration_s=_duration_s)
 
-        # Commit and push any changes
-        repo_path = os.path.join(settings.repos_dir, repo)
+        # Commit and push any changes — in the per-branch worktree (ORCH-2 / S-4),
+        # NOT in the shared /repos/<repo>. The worktree is already on `branch`
+        # (ensure_worktree did the checkout), so no checkout is needed here.
+        repo_path = get_worktree_path(repo, branch)
         try:
             git_env = {
                 **os.environ,
@@ -230,20 +238,6 @@ class AgentLauncher:
                 "GIT_COMMITTER_NAME": "claude-bot",
                 "GIT_COMMITTER_EMAIL": "claude-bot@mva154.local",
             }
-            # Checkout feature branch before committing
-            subprocess.run(
-                ["git", "-C", repo_path, "fetch", "origin"],
-                capture_output=True, text=True, timeout=30, env=git_env
-            )
-            checkout_result = subprocess.run(
-                ["git", "-C", repo_path, "checkout", branch],
-                capture_output=True, text=True, timeout=30, env=git_env
-            )
-            if checkout_result.returncode != 0:
-                subprocess.run(
-                    ["git", "-C", repo_path, "checkout", "-b", branch, f"origin/{branch}"],
-                    capture_output=True, text=True, timeout=30, env=git_env
-            )
             result = subprocess.run(
                 ["git", "-C", repo_path, "status", "--porcelain"],
                 capture_output=True, text=True, timeout=10, env=git_env
@@ -351,7 +345,7 @@ class AgentLauncher:
                     if agent == "analyst" and qg_name == "check_analysis_approved" and work_item_id:
                         files_check = QG_CHECKS.get("check_analysis_complete")
                         if files_check:
-                            files_ok, _ = files_check(repo, work_item_id)
+                            files_ok, _ = files_check(repo, work_item_id, branch)
                             if files_ok:
                                 # Full artifacts ready -> In Review
                                 from ..plane_sync import set_issue_in_review
@@ -364,10 +358,10 @@ class AgentLauncher:
                                 notify_approve_requested(task_id)
                                 logger.info(f"Task {task_id}: analyst finished, requested :approved: in Plane")
                             else:
-                                # Check if questions file exists
+                                # Check if questions file exists (in the task worktree)
                                 import os as _os
                                 questions_path = _os.path.join(
-                                    settings.repos_dir, repo,
+                                    get_worktree_path(repo, branch),
                                     f"docs/work-items/{work_item_id}/01-questions.md"
                                 )
                                 if _os.path.isfile(questions_path):
@@ -392,11 +386,14 @@ class AgentLauncher:
                                     )
                     return
                 elif qg_name in ("check_ci_green", "check_tests_local"):
+                    # (repo, branch) signature — already worktree-aware.
                     passed, reason = check_fn(repo, branch)
                 elif qg_name == "check_tests_passed":
-                    passed, reason = check_fn(repo, work_item_id or "")
+                    # Artifact check — pass branch so it reads from the worktree.
+                    passed, reason = check_fn(repo, work_item_id or "", branch)
                 else:
-                    passed, reason = check_fn(repo, work_item_id or "")
+                    # Other artifact checks (check_architecture_done, etc.) — worktree-aware.
+                    passed, reason = check_fn(repo, work_item_id or "", branch)
 
                 if not passed:
                     logger.info(f"Task {task_id}: QG '{qg_name}' not passed after {agent}: {reason}")
@@ -461,7 +458,7 @@ class AgentLauncher:
                     if agent == "architect" and qg_name == "check_architecture_done" and not passed:
                         import os as _os
                         conflict_path = _os.path.join(
-                            settings.repos_dir, repo,
+                            get_worktree_path(repo, branch),
                             f"docs/work-items/{work_item_id}/10-conflict.md"
                         )
                         if _os.path.isfile(conflict_path):
@@ -578,15 +575,16 @@ class AgentLauncher:
             logger.error(f"Auto-merge failed for {branch}: {e}")
             return False
 
-    def _write_task_file(self, repo: str, task_file: str, content: str):
-        """Write task file directly to the mounted repo volume (/repos).
+    def _write_task_file(self, repo: str, branch: str, task_file: str, content: str):
+        """Write task file directly into the task's worktree.
 
-        B-1 fix: no docker. The repos directory is mounted RW at settings.repos_dir
-        (/repos inside the container), so write straight to /repos/<repo>/<task_file>.
+        B-1 fix: no docker (direct open()). ORCH-2/S-4: the target is the per-branch
+        worktree (/repos/_wt/<repo>/<branch>), not the shared /repos/<repo>, so the
+        agent reads the task ZADANIE from its own isolated working copy.
         Raise on failure instead of silently swallowing errors.
         """
-        container_repo_path = os.path.join(settings.repos_dir, repo)  # /repos/<repo>
-        full_path = os.path.join(container_repo_path, task_file)
+        work_path = get_worktree_path(repo, branch)  # /repos/_wt/<repo>/<branch>
+        full_path = os.path.join(work_path, task_file)
         try:
             with open(full_path, "w", encoding="utf-8") as f:
                 f.write(content)

src/config.py

@@ -20,6 +20,7 @@ class Settings(BaseSettings):
     claude_bin: str = "/opt/claude-code/bin/claude.exe"
     repos_dir: str = "/repos"
     host_repos_dir: str = "/home/slin/repos"
+    worktrees_dir: str = "/repos/_wt"  # ORCH-2 / S-4: isolated worktree per task/branch
 
     # DB
     db_path: str = "/app/data/orchestrator.db"

src/git_worktree.py

@@ -0,0 +1,107 @@
+"""Git worktree management — isolated working copy per task/branch (ORCH-2 / S-4).
+
+Background
+----------
+Previously every git operation (checkout/commit/push/test) ran in the single shared
+clone ``/repos/<repo>``. With two active tasks a ``git checkout`` of one branch would
+overwrite the working copy of the other -> races (see AUDIT S-4 / ET-009 "two collectors").
+
+Solution
+--------
+Each task (branch) gets an isolated git worktree::
+
+    /repos/<repo>                      <- main clone (fetch / worktree management)
+    /repos/_wt/<repo>/<safe-branch>    <- worktree for one task/branch (agent works here)
+
+A branch can only be checked out in ONE worktree at a time, which is exactly the
+property we want: one task = one branch = one worktree.
+"""
+import os
+import re
+import subprocess
+import logging
+from .config import settings
+
+logger = logging.getLogger("orchestrator.git_worktree")
+
+
+def _safe(branch: str) -> str:
+    """Filesystem-safe branch name for use in a path component."""
+    return re.sub(r"[^A-Za-z0-9._-]", "_", branch)
+
+
+def get_worktree_path(repo: str, branch: str) -> str:
+    """Path of the worktree for (repo, branch). Does NOT create it."""
+    return os.path.join(settings.worktrees_dir, repo, _safe(branch))
+
+
+def _main_repo(repo: str) -> str:
+    return os.path.join(settings.repos_dir, repo)
+
+
+def ensure_worktree(repo: str, branch: str) -> str:
+    """Create (or reuse) an isolated worktree for ``branch``. Returns its path.
+
+    Main clone stays at ``/repos/<repo>``. Worktree lives at
+    ``/repos/_wt/<repo>/<safe-branch>``.
+
+    - If the worktree already exists, it is fetched + fast-aligned to the branch
+      (and to ``origin/<branch>`` when that remote branch exists).
+    - If the branch exists (locally or on origin) it is checked out into a fresh
+      worktree; otherwise a new branch is created from ``origin/main``.
+    """
+    main_repo = _main_repo(repo)
+    wt = get_worktree_path(repo, branch)
+
+    if not os.path.isdir(main_repo):
+        raise FileNotFoundError(f"Main repo not found: {main_repo}")
+
+    # Always refresh refs in the main clone first.
+    subprocess.run(["git", "-C", main_repo, "fetch", "origin"],
+                   capture_output=True, timeout=60)
+
+    # Reuse existing worktree (.git may be a dir or a file pointer for worktrees).
+    if os.path.isdir(os.path.join(wt, ".git")) or os.path.isfile(os.path.join(wt, ".git")):
+        subprocess.run(["git", "-C", wt, "fetch", "origin"], capture_output=True, timeout=60)
+        subprocess.run(["git", "-C", wt, "checkout", branch], capture_output=True, timeout=30)
+        # Align to remote only if the remote branch exists (avoid wiping local-only work).
+        rb = subprocess.run(
+            ["git", "-C", wt, "rev-parse", "--verify", "--quiet", f"origin/{branch}"],
+            capture_output=True,
+        )
+        if rb.returncode == 0:
+            subprocess.run(["git", "-C", wt, "reset", "--hard", f"origin/{branch}"],
+                           capture_output=True, timeout=30)
+        logger.info(f"Worktree reused: {wt} (branch {branch})")
+        return wt
+
+    os.makedirs(os.path.dirname(wt), exist_ok=True)
+
+    # Try to attach an existing branch (local or remote-tracking) to the new worktree.
+    r = subprocess.run(["git", "-C", main_repo, "worktree", "add", wt, branch],
+                       capture_output=True, text=True, timeout=60)
+    if r.returncode != 0:
+        # Branch doesn't exist yet — create it from origin/main.
+        r2 = subprocess.run(
+            ["git", "-C", main_repo, "worktree", "add", "-b", branch, wt, "origin/main"],
+            capture_output=True, text=True, timeout=60,
+        )
+        if r2.returncode != 0:
+            raise RuntimeError(
+                f"git worktree add failed for {repo}:{branch}: "
+                f"{r.stderr.strip()} | {r2.stderr.strip()}"
+            )
+    logger.info(f"Worktree ready: {wt} (branch {branch})")
+    return wt
+
+
+def remove_worktree(repo: str, branch: str):
+    """Remove the worktree for (repo, branch) — optional cleanup when a task is done."""
+    main_repo = _main_repo(repo)
+    wt = get_worktree_path(repo, branch)
+    subprocess.run(["git", "-C", main_repo, "worktree", "remove", "--force", wt],
+                   capture_output=True, timeout=30)
+    # Prune dangling administrative entries.
+    subprocess.run(["git", "-C", main_repo, "worktree", "prune"],
+                   capture_output=True, timeout=30)
+    logger.info(f"Worktree removed: {wt}")

src/qg/checks.py

@@ -7,12 +7,28 @@ from ..config import settings
 
 logger = logging.getLogger("orchestrator.qg")
 
+from ..git_worktree import get_worktree_path, ensure_worktree
+
+
+def _repo_path(repo: str, branch: str | None = None) -> str:
+    """Resolve the working path to read agent artifacts from.
+
+    ORCH-2 / S-4: artifacts now live in the per-branch worktree. When a branch is
+    given and its worktree exists on disk, read from there; otherwise fall back to
+    the shared /repos/<repo> clone (keeps backward-compat for 2-arg callers/tests).
+    """
+    if branch:
+        wt = get_worktree_path(repo, branch)
+        if os.path.isdir(wt):
+            return wt
+    return os.path.join(settings.repos_dir, repo)
+
 # Shared httpx client config
 GITEA_HEADERS = {"Authorization": f"token {settings.gitea_token}"}
 GITEA_BASE = f"{settings.gitea_url}/api/v1"
 
 
-def check_analysis_complete(repo: str, work_item_id: str) -> tuple[bool, str]:
+def check_analysis_complete(repo: str, work_item_id: str, branch: str | None = None) -> tuple[bool, str]:
     """
     Check if analysis artifacts exist in the repo branch.
     Required files:
@@ -28,7 +44,7 @@ def check_analysis_complete(repo: str, work_item_id: str) -> tuple[bool, str]:
         f"docs/work-items/{work_item_id}/04-test-plan.yaml",
     ]
 
-    repo_path = os.path.join(settings.repos_dir, repo)
+    repo_path = _repo_path(repo, branch)
     missing = []
 
     for f in required_files:
@@ -41,13 +57,13 @@ def check_analysis_complete(repo: str, work_item_id: str) -> tuple[bool, str]:
     return True, "All analysis artifacts present"
 
 
-def check_architecture_done(repo: str, work_item_id: str) -> tuple[bool, str]:
+def check_architecture_done(repo: str, work_item_id: str, branch: str | None = None) -> tuple[bool, str]:
     """
     Check if architecture artifacts exist.
     Required: docs/work-items/<work_item_id>/06-adr/ (at least 1 file)
     OR: docs/work-items/<work_item_id>/07-infra-requirements.md
     """
-    repo_path = os.path.join(settings.repos_dir, repo)
+    repo_path = _repo_path(repo, branch)
 
     adr_dir = os.path.join(repo_path, f"docs/work-items/{work_item_id}/06-adr")
     infra_file = os.path.join(repo_path, f"docs/work-items/{work_item_id}/07-infra-requirements.md")
@@ -119,12 +135,12 @@ def check_review_approved(repo: str, pr_number: int) -> tuple[bool, str]:
         return False, f"API error: {e}"
 
 
-def check_tests_passed(repo: str, work_item_id: str) -> tuple[bool, str]:
+def check_tests_passed(repo: str, work_item_id: str, branch: str | None = None) -> tuple[bool, str]:
     """
     Check if test report exists and contains PASS indicator.
     File: docs/work-items/<work_item_id>/13-test-report.md
     """
-    repo_path = os.path.join(settings.repos_dir, repo)
+    repo_path = _repo_path(repo, branch)
     report_path = os.path.join(repo_path, f"docs/work-items/{work_item_id}/13-test-report.md")
 
     if not os.path.isfile(report_path):
@@ -141,7 +157,7 @@ def check_tests_passed(repo: str, work_item_id: str) -> tuple[bool, str]:
 
 
 
-def check_analysis_approved(repo: str, work_item_id: str) -> tuple[bool, str]:
+def check_analysis_approved(repo: str, work_item_id: str, branch: str | None = None) -> tuple[bool, str]:
     """
     Check if analysis is complete AND approved by stakeholder.
     Requirements:
@@ -152,7 +168,7 @@ def check_analysis_approved(repo: str, work_item_id: str) -> tuple[bool, str]:
     so the approval check verifies file completeness as a safety gate.
     """
     # First check files
-    files_ok, files_reason = check_analysis_complete(repo, work_item_id)
+    files_ok, files_reason = check_analysis_complete(repo, work_item_id, branch)
     if not files_ok:
         return False, files_reason
 
@@ -187,7 +203,7 @@ def check_analysis_approved(repo: str, work_item_id: str) -> tuple[bool, str]:
 
 
 
-def check_reviewer_verdict(repo: str, work_item_id: str) -> tuple[bool, str]:
+def check_reviewer_verdict(repo: str, work_item_id: str, branch: str | None = None) -> tuple[bool, str]:
     """
     Check reviewer agent verdict from 12-review.md (S-5 fix).
 
@@ -198,7 +214,7 @@ def check_reviewer_verdict(repo: str, work_item_id: str) -> tuple[bool, str]:
       (False, ...) -> verdict: REQUEST_CHANGES, missing verdict, or no frontmatter
     """
     import yaml
-    repo_path = os.path.join(settings.repos_dir, repo)
+    repo_path = _repo_path(repo, branch)
     review_path = os.path.join(repo_path, f"docs/work-items/{work_item_id}/12-review.md")
 
     if not os.path.isfile(review_path):
@@ -229,26 +245,15 @@ def check_reviewer_verdict(repo: str, work_item_id: str) -> tuple[bool, str]:
 
 def check_tests_local(repo: str, branch: str) -> tuple[bool, str]:
     """
-    S-1 fix: run the project test suite locally in /repos/<repo> and judge by exit
-    code, instead of depending on Gitea CI (which is not configured -> always false).
+    S-1 fix: run the project test suite locally and judge by exit code, instead of
+    depending on Gitea CI (which is not configured -> always false).
 
-    Checks out `branch` in the shared /repos checkout and runs `make test`.
-    NOTE (known limitation): the shared /repos checkout means this is not safe for
-    concurrent active tasks. git-worktree-per-task is a separate task (S-4).
+    ORCH-2 / S-4: tests run inside the per-branch worktree (ensure_worktree), so this
+    is safe for concurrent active tasks — no shared /repos checkout race.
     """
     import subprocess
-    repo_path = os.path.join(settings.repos_dir, repo)
     try:
-        subprocess.run(
-            ["git", "-C", repo_path, "fetch", "origin"],
-            capture_output=True, timeout=30,
-        )
-        co = subprocess.run(
-            ["git", "-C", repo_path, "checkout", branch],
-            capture_output=True, text=True, timeout=30,
-        )
-        if co.returncode != 0:
-            return False, f"Cannot checkout branch '{branch}': {co.stderr.strip()[-200:]}"
+        repo_path = ensure_worktree(repo, branch)
         r = subprocess.run(
             ["make", "test"], cwd=repo_path,
             capture_output=True, text=True, timeout=600,

src/webhooks/gitea.py

@@ -146,7 +146,9 @@ async def handle_ci_status(payload: dict):
     if not branch:
         sha = payload.get("sha", "")
         repo_name = payload.get("repository", {}).get("name", settings.default_repo)
-        # Try to find task by checking git branch containing this SHA
+        # Try to find task by checking git branch containing this SHA.
+        # ORCH-2 / S-4: this is a READ-ONLY query of remote-tracking refs in the main
+        # clone (no checkout / no mutation), so it is safe to keep on /repos/<repo>.
         try:
             result = subprocess.run(
                 ["git", "-C", os.path.join(settings.repos_dir, repo_name),

src/webhooks/plane.py

@@ -304,7 +304,8 @@ async def _try_advance_stage(
 
         # Determine args based on QG function
         if qg_name in ("check_analysis_approved", "check_analysis_complete", "check_architecture_done", "check_tests_passed", "check_reviewer_verdict"):
-            passed, reason = qg_func(repo, work_item_id)
+            # ORCH-2 / S-4: pass branch so artifacts are read from the task worktree.
+            passed, reason = qg_func(repo, work_item_id, branch)
         elif qg_name in ("check_ci_green", "check_tests_local"):
             passed, reason = qg_func(repo, branch)
         elif qg_name == "check_review_approved":
@@ -327,8 +328,10 @@ async def _try_advance_stage(
                 else:
                     # No open PR but review file exists — check file-based
                     import os
-                    _review_path = os.path.join(_s.repos_dir, repo, f"docs/work-items/{work_item_id}/12-review.md")
-                    _review_path2 = os.path.join(_s.repos_dir, repo, f"docs/work-items/{work_item_id}/09-review.md")
+                    from ..git_worktree import get_worktree_path as _gwp
+                    _wt = _gwp(repo, branch) if os.path.isdir(_gwp(repo, branch)) else os.path.join(_s.repos_dir, repo)
+                    _review_path = os.path.join(_wt, f"docs/work-items/{work_item_id}/12-review.md")
+                    _review_path2 = os.path.join(_wt, f"docs/work-items/{work_item_id}/09-review.md")
                     if os.path.isfile(_review_path) or os.path.isfile(_review_path2):
                         passed, reason = True, "Review file exists (file-based approval)"
                     else:

tests/test_git_worktree.py

@@ -0,0 +1,152 @@
+"""Tests for src/git_worktree (ORCH-2 / S-4): isolated worktree per task/branch.
+
+Uses real local git repos in tmp (a bare 'origin' + a working main clone) so that
+`git fetch origin`, `git worktree add`, branch creation from origin/main, reuse and
+removal are all exercised without network access.
+"""
+import os
+import subprocess
+import tempfile
+
+import pytest
+
+# Env must be set before importing app modules (same convention as the other suites).
+_test_db = os.path.join(tempfile.gettempdir(), "test_orchestrator_wt.db")
+os.environ["ORCH_DB_PATH"] = _test_db
+os.environ["ORCH_REPOS_DIR"] = tempfile.gettempdir()
+os.environ["ORCH_GITEA_TOKEN"] = "test-token"
+os.environ["ORCH_PLANE_API_TOKEN"] = "test-token"
+
+from src import git_worktree
+from src.git_worktree import (
+    _safe,
+    get_worktree_path,
+    ensure_worktree,
+    remove_worktree,
+)
+
+
+def _git(cwd, *args):
+    return subprocess.run(["git", "-C", cwd, *args], capture_output=True, text=True)
+
+
+@pytest.fixture
+def repos(tmp_path, monkeypatch):
+    """Build a bare 'origin' with main + a feature branch, plus a main clone at repos_dir/<repo>.
+
+    Returns the repo name. settings.repos_dir / worktrees_dir are pointed at tmp.
+    """
+    repo = "enduro-trails"
+    repos_dir = tmp_path / "repos"
+    wt_dir = tmp_path / "repos" / "_wt"
+    repos_dir.mkdir(parents=True)
+
+    monkeypatch.setattr(git_worktree.settings, "repos_dir", str(repos_dir))
+    monkeypatch.setattr(git_worktree.settings, "worktrees_dir", str(wt_dir))
+
+    # Bare origin
+    origin = tmp_path / "origin.git"
+    subprocess.run(["git", "init", "--bare", "-b", "main", str(origin)], capture_output=True)
+
+    # Seed repo
+    seed = tmp_path / "seed"
+    seed.mkdir()
+    _git(str(seed), "init", "-b", "main")
+    _git(str(seed), "config", "user.email", "t@t")
+    _git(str(seed), "config", "user.name", "t")
+    (seed / "README.md").write_text("# seed\n")
+    _git(str(seed), "add", ".")
+    _git(str(seed), "commit", "-m", "init")
+    _git(str(seed), "remote", "add", "origin", str(origin))
+    _git(str(seed), "push", "origin", "main")
+    # An existing feature branch on origin
+    _git(str(seed), "checkout", "-b", "feature/existing")
+    (seed / "f.txt").write_text("feature\n")
+    _git(str(seed), "add", ".")
+    _git(str(seed), "commit", "-m", "feat")
+    _git(str(seed), "push", "origin", "feature/existing")
+
+    # Main clone at repos_dir/<repo>
+    main_clone = repos_dir / repo
+    subprocess.run(["git", "clone", str(origin), str(main_clone)], capture_output=True)
+    _git(str(main_clone), "config", "user.email", "t@t")
+    _git(str(main_clone), "config", "user.name", "t")
+    return repo
+
+
+# ---------------------------------------------------------------------------
+# _safe / get_worktree_path
+# ---------------------------------------------------------------------------
+class TestSafeAndPath:
+    def test_safe_replaces_slashes_and_specials(self):
+        assert _safe("feature/ET-001-x") == "feature_ET-001-x"
+        assert _safe("a b/c:d") == "a_b_c_d"
+        assert _safe("keep.dots-and_underscores") == "keep.dots-and_underscores"
+
+    def test_get_worktree_path(self, monkeypatch):
+        monkeypatch.setattr(git_worktree.settings, "worktrees_dir", "/repos/_wt")
+        assert get_worktree_path("repo", "feature/x") == "/repos/_wt/repo/feature_x"
+
+
+# ---------------------------------------------------------------------------
+# ensure_worktree
+# ---------------------------------------------------------------------------
+class TestEnsureWorktree:
+    def test_missing_main_repo_raises(self, tmp_path, monkeypatch):
+        monkeypatch.setattr(git_worktree.settings, "repos_dir", str(tmp_path / "nope"))
+        monkeypatch.setattr(git_worktree.settings, "worktrees_dir", str(tmp_path / "_wt"))
+        with pytest.raises(FileNotFoundError):
+            ensure_worktree("enduro-trails", "main")
+
+    def test_creates_worktree_for_existing_branch(self, repos):
+        wt = ensure_worktree(repos, "feature/existing")
+        assert os.path.isdir(wt)
+        assert wt == get_worktree_path(repos, "feature/existing")
+        # On the right branch
+        cur = _git(wt, "branch", "--show-current").stdout.strip()
+        assert cur == "feature/existing"
+        # Feature file from that branch is present (proves correct checkout)
+        assert os.path.isfile(os.path.join(wt, "f.txt"))
+
+    def test_creates_new_branch_from_origin_main(self, repos):
+        wt = ensure_worktree(repos, "feature/brand-new")
+        assert os.path.isdir(wt)
+        cur = _git(wt, "branch", "--show-current").stdout.strip()
+        assert cur == "feature/brand-new"
+        # Based on main -> README present, no feature file
+        assert os.path.isfile(os.path.join(wt, "README.md"))
+        assert not os.path.isfile(os.path.join(wt, "f.txt"))
+
+    def test_reuse_returns_same_path(self, repos):
+        wt1 = ensure_worktree(repos, "feature/existing")
+        wt2 = ensure_worktree(repos, "feature/existing")
+        assert wt1 == wt2
+        assert os.path.isdir(wt2)
+
+    def test_two_branches_are_isolated(self, repos):
+        a = ensure_worktree(repos, "feature/wt-A")
+        b = ensure_worktree(repos, "feature/wt-B")
+        assert a != b
+        ba = _git(a, "branch", "--show-current").stdout.strip()
+        bb = _git(b, "branch", "--show-current").stdout.strip()
+        assert ba == "feature/wt-A"
+        assert bb == "feature/wt-B"
+        # Writing in A must not affect B
+        with open(os.path.join(a, "only-a.txt"), "w") as f:
+            f.write("a")
+        assert not os.path.isfile(os.path.join(b, "only-a.txt"))
+
+
+# ---------------------------------------------------------------------------
+# remove_worktree
+# ---------------------------------------------------------------------------
+class TestRemoveWorktree:
+    def test_remove_deletes_worktree_dir(self, repos):
+        wt = ensure_worktree(repos, "feature/to-remove")
+        assert os.path.isdir(wt)
+        remove_worktree(repos, "feature/to-remove")
+        assert not os.path.isdir(wt)
+
+    def test_remove_nonexistent_is_noop(self, repos):
+        # Should not raise even if the worktree was never created.
+        remove_worktree(repos, "feature/never-made")

tests/test_launcher.py

@@ -26,24 +26,34 @@ from src.qg.checks import check_reviewer_verdict
 # B-1: _write_task_file
 # ---------------------------------------------------------------------------
 class TestWriteTaskFile:
-    def test_writes_to_repos_volume_path(self, tmp_path, monkeypatch):
-        """Task file is written to <repos_dir>/<repo>/<task_file>, content matches."""
-        monkeypatch.setattr("src.agents.launcher.settings.repos_dir", str(tmp_path))
-        repo_dir = tmp_path / "enduro-trails"
-        repo_dir.mkdir()
+    """B-1 fix preserved + ORCH-2/S-4: task file now lands in the per-branch worktree.
+
+    _write_task_file(repo, branch, task_file, content) writes to
+    <worktrees_dir>/<repo>/<safe-branch>/<task_file> with a plain open() (no docker).
+    """
+
+    def _wt_dir(self, tmp_path, repo, branch):
+        from src.git_worktree import _safe
+        d = tmp_path / "_wt" / repo / _safe(branch)
+        d.mkdir(parents=True)
+        return d
+
+    def test_writes_to_worktree_path(self, tmp_path, monkeypatch):
+        """Task file is written to the worktree path, content matches (B-1 + S-4)."""
+        monkeypatch.setattr("src.git_worktree.settings.worktrees_dir", str(tmp_path / "_wt"))
+        wt = self._wt_dir(tmp_path, "enduro-trails", "feature/ET-001-x")
 
         launcher = AgentLauncher()
-        launcher._write_task_file("enduro-trails", ".task-dev.md", "hello-content")
+        launcher._write_task_file("enduro-trails", "feature/ET-001-x", ".task-dev.md", "hello-content")
 
-        written = repo_dir / ".task-dev.md"
+        written = wt / ".task-dev.md"
         assert written.is_file()
         assert written.read_text() == "hello-content"
 
     def test_does_not_use_docker(self, tmp_path, monkeypatch):
         """No subprocess/docker call: if subprocess.run were used it would error here."""
-        monkeypatch.setattr("src.agents.launcher.settings.repos_dir", str(tmp_path))
-        repo_dir = tmp_path / "enduro-trails"
-        repo_dir.mkdir()
+        monkeypatch.setattr("src.git_worktree.settings.worktrees_dir", str(tmp_path / "_wt"))
+        self._wt_dir(tmp_path, "enduro-trails", "main")
 
         called = {"run": False}
 
@@ -54,17 +64,17 @@ class TestWriteTaskFile:
         monkeypatch.setattr("src.agents.launcher.subprocess.run", _fail_run)
 
         launcher = AgentLauncher()
-        launcher._write_task_file("enduro-trails", ".task.md", "x")
+        launcher._write_task_file("enduro-trails", "main", ".task.md", "x")
         assert called["run"] is False
 
     def test_raises_on_write_failure(self, tmp_path, monkeypatch):
-        """If the target dir does not exist, raise RuntimeError (do not fail silently)."""
-        monkeypatch.setattr("src.agents.launcher.settings.repos_dir", str(tmp_path))
-        # repo dir intentionally NOT created -> open() raises OSError
+        """If the target worktree dir does not exist, raise RuntimeError (no silent fail)."""
+        monkeypatch.setattr("src.git_worktree.settings.worktrees_dir", str(tmp_path / "_wt"))
+        # worktree dir intentionally NOT created -> open() raises OSError
 
         launcher = AgentLauncher()
         with pytest.raises(RuntimeError):
-            launcher._write_task_file("nonexistent-repo", ".task.md", "x")
+            launcher._write_task_file("nonexistent-repo", "main", ".task.md", "x")
 
 
 # ---------------------------------------------------------------------------