chore: import upstream snapshot with attribution

s12_task_system/code.py

@@ -0,0 +1,378 @@
+#!/usr/bin/env python3
+"""
+s12: Task System — file-persisted task graph with blockedBy dependencies.
+
+Run:  python s12_task_system/code.py
+Need: pip install anthropic python-dotenv + .env with ANTHROPIC_API_KEY
+
+Changes from s11:
+  - Task dataclass (id, subject, description, status, owner, blockedBy)
+  - TASKS_DIR = .tasks/ for persistent JSON storage
+  - create_task / save_task / load_task / list_tasks / get_task
+  - can_start: checks blockedBy all completed (missing deps = blocked)
+  - claim_task: set owner + pending -> in_progress
+  - complete_task: set completed + report unblocked downstream
+  - 5 new tools: create_task, list_tasks, get_task, claim_task, complete_task
+
+Note: Teaching code keeps a basic agent loop to stay focused on the task
+system. S11's full error recovery (RecoveryState, backoff, escalation,
+reactive compact, fallback model) is omitted — in real CC, tasks.ts and
+withRetry are independent layers that compose naturally.
+"""
+
+import os, subprocess, json, time, random
+from pathlib import Path
+from dataclasses import dataclass, asdict
+
+try:
+    import readline
+    readline.parse_and_bind('set bind-tty-special-chars off')
+except ImportError:
+    pass
+
+from anthropic import Anthropic
+from dotenv import load_dotenv
+
+load_dotenv(override=True)
+if os.getenv("ANTHROPIC_BASE_URL"):
+    os.environ.pop("ANTHROPIC_AUTH_TOKEN", None)
+
+WORKDIR = Path.cwd()
+MEMORY_DIR = WORKDIR / ".memory"
+MEMORY_INDEX = MEMORY_DIR / "MEMORY.md"
+client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
+MODEL = os.environ["MODEL_ID"]
+
+# ── Task System ──
+
+TASKS_DIR = WORKDIR / ".tasks"
+TASKS_DIR.mkdir(exist_ok=True)
+
+
+@dataclass
+class Task:
+    id: str
+    subject: str
+    description: str
+    status: str          # pending | in_progress | completed
+    owner: str | None    # Agent name (multi-agent scenarios)
+    blockedBy: list[str] # Dependency task IDs
+
+
+def _task_path(task_id: str) -> Path:
+    return TASKS_DIR / f"{task_id}.json"
+
+
+def create_task(subject: str, description: str = "",
+                blockedBy: list[str] | None = None) -> Task:
+    task = Task(
+        id=f"task_{int(time.time())}_{random.randint(0, 9999):04d}",
+        subject=subject,
+        description=description,
+        status="pending",
+        owner=None,
+        blockedBy=blockedBy or [],
+    )
+    save_task(task)
+    return task
+
+
+def save_task(task: Task):
+    _task_path(task.id).write_text(json.dumps(asdict(task), indent=2))
+
+
+def load_task(task_id: str) -> Task:
+    return Task(**json.loads(_task_path(task_id).read_text()))
+
+
+def list_tasks() -> list[Task]:
+    return [Task(**json.loads(p.read_text()))
+            for p in sorted(TASKS_DIR.glob("task_*.json"))]
+
+
+def get_task(task_id: str) -> str:
+    """Return full task details as JSON."""
+    task = load_task(task_id)
+    return json.dumps(asdict(task), indent=2)
+
+
+def can_start(task_id: str) -> bool:
+    """Check if all blockedBy dependencies are completed.
+    Missing dependencies are treated as blocked."""
+    task = load_task(task_id)
+    for dep_id in task.blockedBy:
+        if not _task_path(dep_id).exists():
+            return False
+        if load_task(dep_id).status != "completed":
+            return False
+    return True
+
+
+def claim_task(task_id: str, owner: str = "agent") -> str:
+    task = load_task(task_id)
+    if task.status != "pending":
+        return f"Task {task_id} is {task.status}, cannot claim"
+    if not can_start(task_id):
+        deps = [d for d in task.blockedBy
+                if not _task_path(d).exists() or load_task(d).status != "completed"]
+        return f"Blocked by: {deps}"
+    task.owner = owner
+    task.status = "in_progress"
+    save_task(task)
+    print(f"  \033[36m[claim] {task.subject} → in_progress (owner: {owner})\033[0m")
+    return f"Claimed {task.id} ({task.subject})"
+
+
+def complete_task(task_id: str) -> str:
+    task = load_task(task_id)
+    if task.status != "in_progress":
+        return f"Task {task_id} is {task.status}, cannot complete"
+    task.status = "completed"
+    save_task(task)
+    unblocked = [t.subject for t in list_tasks()
+                 if t.status == "pending" and t.blockedBy and can_start(t.id)]
+    print(f"  \033[32m[complete] {task.subject} ✓\033[0m")
+    msg = f"Completed {task.id} ({task.subject})"
+    if unblocked:
+        msg += f"\nUnblocked: {', '.join(unblocked)}"
+        print(f"  \033[33m[unblocked] {', '.join(unblocked)}\033[0m")
+    return msg
+
+
+# ── Prompt Assembly (from s10, synced) ──
+
+PROMPT_SECTIONS = {
+    "identity": "You are a coding agent. Act, don't explain.",
+    "tools": "Available tools: bash, read_file, write_file, "
+             "create_task, list_tasks, get_task, claim_task, complete_task.",
+    "workspace": f"Working directory: {WORKDIR}",
+    "memory": "Relevant memories are injected below when available.",
+}
+
+
+def assemble_system_prompt(context: dict) -> str:
+    sections = [PROMPT_SECTIONS["identity"],
+                PROMPT_SECTIONS["tools"],
+                PROMPT_SECTIONS["workspace"]]
+    memories = context.get("memories", "")
+    if memories:
+        sections.append(f"Relevant memories:\n{memories}")
+    return "\n\n".join(sections)
+
+
+_last_context_key, _last_prompt = None, None
+
+
+def get_system_prompt(context: dict) -> str:
+    global _last_context_key, _last_prompt
+    key = json.dumps(context, sort_keys=True, ensure_ascii=False, default=str)
+    if key == _last_context_key and _last_prompt:
+        return _last_prompt
+    _last_context_key = key
+    _last_prompt = assemble_system_prompt(context)
+    return _last_prompt
+
+
+# ── Tools ──
+
+def safe_path(p: str) -> Path:
+    path = (WORKDIR / p).resolve()
+    if not path.is_relative_to(WORKDIR):
+        raise ValueError(f"Path escapes workspace: {p}")
+    return path
+
+
+def run_bash(command: str) -> str:
+    try:
+        r = subprocess.run(command, shell=True, cwd=WORKDIR,
+                           capture_output=True, text=True, timeout=120)
+        out = (r.stdout + r.stderr).strip()
+        return out[:50000] if out else "(no output)"
+    except subprocess.TimeoutExpired:
+        return "Error: Timeout (120s)"
+
+
+def run_read(path: str, limit: int | None = None) -> str:
+    try:
+        lines = safe_path(path).read_text().splitlines()
+        if limit and limit < len(lines):
+            lines = lines[:limit] + [f"... ({len(lines) - limit} more lines)"]
+        return "\n".join(lines)
+    except Exception as e:
+        return f"Error: {e}"
+
+
+def run_write(path: str, content: str) -> str:
+    try:
+        fp = safe_path(path)
+        fp.parent.mkdir(parents=True, exist_ok=True)
+        fp.write_text(content)
+        return f"Wrote {len(content)} bytes to {path}"
+    except Exception as e:
+        return f"Error: {e}"
+
+
+# Task tools
+
+def run_create_task(subject: str, description: str = "",
+                    blockedBy: list[str] | None = None) -> str:
+    task = create_task(subject, description, blockedBy)
+    deps = f" (blockedBy: {', '.join(blockedBy)})" if blockedBy else ""
+    print(f"  \033[34m[create] {task.subject}{deps}\033[0m")
+    return f"Created {task.id}: {task.subject}{deps}"
+
+
+def run_list_tasks() -> str:
+    tasks = list_tasks()
+    if not tasks:
+        return "No tasks. Use create_task to add some."
+    lines = []
+    for t in tasks:
+        icon = {"pending": "○", "in_progress": "●",
+                "completed": "✓"}.get(t.status, "?")
+        deps = f" (blockedBy: {', '.join(t.blockedBy)})" if t.blockedBy else ""
+        owner = f" [{t.owner}]" if t.owner else ""
+        lines.append(f"  {icon} {t.id}: {t.subject} "
+                     f"[{t.status}]{owner}{deps}")
+    return "\n".join(lines)
+
+
+def run_get_task(task_id: str) -> str:
+    try:
+        return get_task(task_id)
+    except FileNotFoundError:
+        return f"Error: Task {task_id} not found"
+
+
+def run_claim_task(task_id: str) -> str:
+    return claim_task(task_id, owner="agent")
+
+
+def run_complete_task(task_id: str) -> str:
+    return complete_task(task_id)
+
+
+TOOLS = [
+    {"name": "bash", "description": "Run a shell command.",
+     "input_schema": {"type": "object",
+                      "properties": {"command": {"type": "string"}},
+                      "required": ["command"]}},
+    {"name": "read_file", "description": "Read file contents.",
+     "input_schema": {"type": "object",
+                      "properties": {"path": {"type": "string"},
+                                     "limit": {"type": "integer"}},
+                      "required": ["path"]}},
+    {"name": "write_file", "description": "Write content to a file.",
+     "input_schema": {"type": "object",
+                      "properties": {"path": {"type": "string"},
+                                     "content": {"type": "string"}},
+                      "required": ["path", "content"]}},
+    {"name": "create_task",
+     "description": "Create a new task with optional blockedBy dependencies.",
+     "input_schema": {"type": "object",
+                      "properties": {
+                          "subject": {"type": "string"},
+                          "description": {"type": "string"},
+                          "blockedBy": {"type": "array",
+                                        "items": {"type": "string"}}},
+                      "required": ["subject"]}},
+    {"name": "list_tasks",
+     "description": "List all tasks with status, owner, and dependencies.",
+     "input_schema": {"type": "object", "properties": {},
+                      "required": []}},
+    {"name": "get_task",
+     "description": "Get full details of a specific task by ID.",
+     "input_schema": {"type": "object",
+                      "properties": {"task_id": {"type": "string"}},
+                      "required": ["task_id"]}},
+    {"name": "claim_task",
+     "description": "Claim a pending task. Sets owner, changes status to in_progress.",
+     "input_schema": {"type": "object",
+                      "properties": {"task_id": {"type": "string"}},
+                      "required": ["task_id"]}},
+    {"name": "complete_task",
+     "description": "Complete an in-progress task. Reports unblocked downstream tasks.",
+     "input_schema": {"type": "object",
+                      "properties": {"task_id": {"type": "string"}},
+                      "required": ["task_id"]}},
+]
+
+TOOL_HANDLERS = {
+    "bash": run_bash, "read_file": run_read, "write_file": run_write,
+    "create_task": run_create_task, "list_tasks": run_list_tasks,
+    "get_task": run_get_task, "claim_task": run_claim_task,
+    "complete_task": run_complete_task,
+}
+
+
+# ── Context ──
+
+def update_context(context: dict, messages: list) -> dict:
+    """Derive context from real state."""
+    memories = ""
+    if MEMORY_INDEX.exists():
+        content = MEMORY_INDEX.read_text().strip()
+        if content:
+            memories = content
+    return {
+        "enabled_tools": list(TOOL_HANDLERS.keys()),
+        "workspace": str(WORKDIR),
+        "memories": memories,
+    }
+
+
+# ── Agent Loop (simplified, focused on task system) ──
+
+def agent_loop(messages: list, context: dict):
+    system = get_system_prompt(context)
+    while True:
+        try:
+            response = client.messages.create(
+                model=MODEL, system=system, messages=messages,
+                tools=TOOLS, max_tokens=8000)
+        except Exception as e:
+            messages.append({"role": "assistant", "content": [
+                {"type": "text",
+                 "text": f"[Error] {type(e).__name__}: {e}"}]})
+            return
+
+        messages.append({"role": "assistant", "content": response.content})
+        if response.stop_reason != "tool_use":
+            return
+
+        results = []
+        for block in response.content:
+            if block.type != "tool_use":
+                continue
+            print(f"\033[36m> {block.name}\033[0m")
+            handler = TOOL_HANDLERS.get(block.name)
+            output = handler(**block.input) if handler else f"Unknown: {block.name}"
+            print(str(output)[:300])
+            results.append({"type": "tool_result",
+                            "tool_use_id": block.id, "content": output})
+        messages.append({"role": "user", "content": results})
+        context = update_context(context, messages)
+        system = get_system_prompt(context)
+
+
+if __name__ == "__main__":
+    print("s12: task system")
+    print("Enter a question, press Enter to send. Type q to quit.\n")
+    history = []
+    context = update_context({}, [])
+    while True:
+        try:
+            query = input("\033[36ms12 >> \033[0m")
+        except (EOFError, KeyboardInterrupt):
+            break
+        if query.strip().lower() in ("q", "exit", ""):
+            break
+        history.append({"role": "user", "content": query})
+        agent_loop(history, context)
+        context = update_context(context, history)
+        for block in history[-1]["content"]:
+            if getattr(block, "type", None) == "text":
+                print(block.text)
+            elif isinstance(block, dict) and block.get("type") == "text":
+                print(block.get("text", ""))
+        print()