coord/hook.py

#!/usr/bin/env python3
"""Fail-open recognized-write guard and transactional peer-message delivery."""

from __future__ import annotations

import importlib.util
import importlib.machinery
import hashlib
import json
import os
import pathlib
import re
import socket
import sys
import uuid

HERE = pathlib.Path(__file__).resolve().parent
CLI_SPEC = importlib.util.spec_from_loader(
    "coord_cli",
    importlib.machinery.SourceFileLoader("coord_cli", str(HERE / "coord")),
)
try:
    cli = importlib.util.module_from_spec(CLI_SPEC)
    assert CLI_SPEC.loader is not None
    CLI_SPEC.loader.exec_module(cli)
except Exception as exc:  # the hook boundary must fail open, including import
    print(f"coord-hook: cannot load coordinator; failing open: {exc}", file=sys.stderr)
    raise SystemExit(0)

PATCH_PATH = re.compile(
    r"^\*\*\* (?:Add|Update|Delete) File: (.+)$|^\*\*\* Move to: (.+)$",
    re.MULTILINE,
)
MAX_MESSAGES = 5


def allow() -> None:
    raise SystemExit(0)


def runtime_for(db: object, event: dict) -> str:
    agent_id = str(event.get("agent_id") or "")
    conversation = str(event.get("session_id") or "")
    if agent_id and conversation:
        sub_conversation = f"{conversation}:agent:{agent_id}"
        exact = str(
            uuid.uuid5(
                uuid.NAMESPACE_URL, f"fleet-agent-coord:{sub_conversation}"
            )
        )
        try:
            return db.resolve_runtime(exact)
        except KeyError:
            return db.register_instance(
                sub_conversation,
                runtime_id=exact,
                harness="claude-code-subagent",
                host=socket.gethostname(),
                cwd=str(project_root()),
                label=f"subagent:{agent_id}",
            )
    exact = os.environ.get("COORD_INSTANCE_ID", "")
    return db.resolve_runtime(exact or event.get("session_id", ""))


def project_root() -> pathlib.Path:
    """Return the checkout root; the override exists for packaged tests/tools."""
    override = os.environ.get("COORD_PROJECT_ROOT", "")
    return pathlib.Path(override).resolve() if override else cli.ROOT


def relative_path(raw: str, cwd: pathlib.Path, root: pathlib.Path) -> str | None:
    candidate = pathlib.Path(raw)
    if not candidate.is_absolute():
        candidate = cwd / candidate
    try:
        return candidate.resolve(strict=False).relative_to(root).as_posix()
    except ValueError:
        return None


def paths_from(event: dict) -> list[str]:
    tool_input = event.get("tool_input") or {}
    cwd = pathlib.Path(event.get("cwd") or os.getcwd()).resolve()
    root = project_root()
    raw_paths: list[str] = []
    direct = tool_input.get("file_path") or tool_input.get("path")
    if isinstance(direct, str):
        raw_paths.append(direct)
    body = tool_input.get("command") or tool_input.get("input") or ""
    if isinstance(body, str):
        for match in PATCH_PATH.finditer(body):
            raw_paths.append(match.group(1) or match.group(2))
    normalized = (relative_path(path.strip(), cwd, root) for path in raw_paths)
    return list(dict.fromkeys(path for path in normalized if path))


def output_context(messages: list[object]) -> None:
    lines = []
    for item in messages:
        sender = cli.runtime_handle(item.sender_runtime_id)
        if item.state == "delivered":
            digest = hashlib.sha256(item.body.encode("utf-8")).hexdigest()[:10]
            lines.append(
                f"[{item.message_id}] {sender} pending again "
                f"({item.kind}, sha256:{digest}); read with `coord inbox --peek`"
            )
        else:
            lines.append(
                f"[{item.message_id}] {sender} ({item.kind}): {item.body}"
            )
    print(
        json.dumps(
            {
                "hookSpecificOutput": {
                    "hookEventName": "PreToolUse",
                    "additionalContext": (
                        "Messages from peer agent runtimes:\n"
                        + "\n".join(lines)
                        + "\nDelivery repeats until explicitly acknowledged with "
                        "`coord ack <message-id>`."
                    ),
                }
            }
        )
    )


def main() -> None:
    try:
        event = json.loads(sys.stdin.read())
    except Exception:
        allow()
    db = cli.store()
    owner = runtime_for(db, event)
    db.heartbeat(
        owner,
        ttl_seconds=cli.storelib.DEFAULT_INSTANCE_TTL,
        renew_lease_ttl_seconds=cli.storelib.DEFAULT_LEASE_TTL,
    )

    managed_workspace = db.is_managed_workspace(project_root())
    leases = db.active_leases()
    for path in paths_from(event):
        owner_has_lease = False
        for lease in leases:
            if (
                lease["runtime_id"] == owner
                and lease["mode"] == "exclusive"
                and db.resources_overlap(path, lease["path"])
            ):
                owner_has_lease = True
            if lease["runtime_id"] == owner or lease["mode"] != "exclusive":
                continue
            if not db.resources_overlap(path, lease["path"]):
                continue
            print(
                json.dumps(
                    {
                        "hookSpecificOutput": {
                            "hookEventName": "PreToolUse",
                            "permissionDecision": "deny",
                            "permissionDecisionReason": (
                                f"{path} is leased exclusively by "
                                f"{cli.runtime_handle(lease['runtime_id'])} for "
                                f"{lease['purpose'] or 'unstated'}. Coordinate before editing."
                            ),
                        }
                    }
                )
            )
            return
        if not managed_workspace and not owner_has_lease:
            print(
                json.dumps(
                    {
                        "hookSpecificOutput": {
                            "hookEventName": "PreToolUse",
                            "permissionDecision": "deny",
                            "permissionDecisionReason": (
                                f"{path} is in the canonical integration checkout. "
                                "Writable work must use a managed isolated clone, or "
                                "the integration owner must claim this exact resource."
                            ),
                        }
                    }
                )
            )
            return

    pending = db.inbox(owner, limit=MAX_MESSAGES, mark_delivered=True)
    if pending:
        output_context(pending)


if __name__ == "__main__":
    try:
        main()
    except SystemExit:
        raise
    except Exception as exc:  # fail open is load-bearing
        print(f"coord-hook: failing open: {exc}", file=sys.stderr)
    raise SystemExit(0)