MosswartOverlord/agent/claude_wrapper.py

"""Subprocess wrapper around `claude -p` (Claude Code in headless JSON mode).

Run from cwd=/home/erik/MosswartOverlord so:
  • Sessions persist at ~/.claude/projects/-home-erik-MosswartOverlord/<uuid>.jsonl
  • Project-level .mcp.json is auto-loaded
  • CLAUDE.md in the repo root briefs the agent

The `--session-id` flag both creates a new session (first call) and resumes
an existing one (subsequent calls), so we don't need separate code paths.
"""

from __future__ import annotations

import asyncio
import json
import logging
import os
from dataclasses import dataclass
from pathlib import Path
from typing import Any

logger = logging.getLogger(__name__)

# These can be overridden via env vars for non-prod testing.
CLAUDE_BIN = os.getenv("CLAUDE_BIN", "/home/erik/.local/bin/claude")
CLAUDE_CWD = os.getenv("CLAUDE_CWD", "/home/erik/MosswartOverlord")
# Hard cap on how long a single agent turn may take. Claude Code can spin a
# while when chaining many tool calls; we don't want to leave a zombie
# subprocess if something gets stuck.
CLAUDE_TIMEOUT_S = int(os.getenv("CLAUDE_TIMEOUT_S", "120"))


@dataclass
class ClaudeResult:
    result: str
    session_id: str
    duration_ms: int
    num_turns: int
    is_error: bool
    raw: dict[str, Any]


class ClaudeError(RuntimeError):
    """Raised when the claude CLI returns a non-zero exit or unparseable output."""


async def ask_claude(message: str, session_id: str) -> ClaudeResult:
    """Send `message` to `claude -p` resuming session_id; return parsed result.

    Raises ClaudeError on subprocess failure, JSON parse failure, or timeout.
    """
    if not Path(CLAUDE_BIN).exists():
        raise ClaudeError(f"claude binary not found at {CLAUDE_BIN}")
    if not Path(CLAUDE_CWD).is_dir():
        raise ClaudeError(f"CLAUDE_CWD does not exist: {CLAUDE_CWD}")

    args = [
        CLAUDE_BIN,
        "-p",
        "--session-id",
        session_id,
        "--output-format",
        "json",
    ]

    logger.info(
        "claude exec: session=%s msg_len=%d cwd=%s", session_id, len(message), CLAUDE_CWD
    )

    proc = await asyncio.create_subprocess_exec(
        *args,
        stdin=asyncio.subprocess.PIPE,
        stdout=asyncio.subprocess.PIPE,
        stderr=asyncio.subprocess.PIPE,
        cwd=CLAUDE_CWD,
    )

    try:
        stdout, stderr = await asyncio.wait_for(
            proc.communicate(input=message.encode("utf-8")),
            timeout=CLAUDE_TIMEOUT_S,
        )
    except asyncio.TimeoutError:
        try:
            proc.kill()
        except ProcessLookupError:
            pass
        raise ClaudeError(f"claude timed out after {CLAUDE_TIMEOUT_S}s")

    if proc.returncode != 0:
        raise ClaudeError(
            f"claude exited {proc.returncode}: {stderr.decode('utf-8', 'replace')[:500]}"
        )

    raw_text = stdout.decode("utf-8", "replace").strip()
    if not raw_text:
        raise ClaudeError("claude produced empty stdout")

    # In --output-format json mode the LAST line is the JSON envelope; some
    # earlier lines may be progress. Be tolerant.
    try:
        envelope = json.loads(raw_text)
    except json.JSONDecodeError:
        # Try the last non-empty line
        last = next(
            (line for line in reversed(raw_text.splitlines()) if line.strip()),
            "",
        )
        try:
            envelope = json.loads(last)
        except json.JSONDecodeError as e:
            raise ClaudeError(
                f"claude stdout was not JSON: {raw_text[:500]}"
            ) from e

    return ClaudeResult(
        result=envelope.get("result", ""),
        session_id=envelope.get("session_id", session_id),
        duration_ms=int(envelope.get("duration_ms", 0)),
        num_turns=int(envelope.get("num_turns", 0)),
        is_error=bool(envelope.get("is_error", False)),
        raw=envelope,
    )