hermes-agent/hermes_cli/backup.py

"""
Backup and import commands for hermes CLI.

`hermes backup` creates a zip archive of the entire ~/.hermes/ directory
(excluding the hermes-agent repo and transient files).

`hermes import` restores from a backup zip, overlaying onto the current
HERMES_HOME root.
"""

import json
import logging
import os
import shutil
import sqlite3
import sys
import tempfile
import time
import zipfile
from datetime import datetime, timezone
from pathlib import Path
from typing import Any, Dict, List, Optional

from hermes_constants import get_default_hermes_root, get_hermes_home, display_hermes_home

logger = logging.getLogger(__name__)


# ---------------------------------------------------------------------------
# Exclusion rules
# ---------------------------------------------------------------------------

# Directory names to skip entirely (matched against each path component)
# ``hermes-agent`` is special-cased to root level only in ``_should_exclude``
# so that skill directories like ``skills/autonomous-ai-agents/hermes-agent/``
# are not accidentally excluded.
_EXCLUDED_DIRS = {
    "hermes-agent",     # the codebase repo — re-clone instead
    "__pycache__",      # bytecode caches — regenerated on import
    ".git",             # nested git dirs (profiles shouldn't have these, but safety)
    "node_modules",     # js deps if website/ somehow leaks in
    "backups",          # prior auto-backups — don't nest backups exponentially
    "checkpoints",      # session-local trajectory caches — regenerated per-session,
                        # session-hash-keyed so they don't port to another machine anyway
}

# File-name suffixes to skip
_EXCLUDED_SUFFIXES = (
    ".pyc",
    ".pyo",
    # SQLite sidecar files — the backup takes a consistent snapshot of ``*.db``
    # via ``sqlite3.backup()``, so shipping the live WAL / shared-memory /
    # rollback-journal alongside would pair a fresh snapshot with stale sidecar
    # state and produce a torn restore on the next open. They're transient and
    # regenerated on first connection anyway.
    ".db-wal",
    ".db-shm",
    ".db-journal",
)

# File names to skip (runtime state that's meaningless on another machine)
_EXCLUDED_NAMES = {
    "gateway.pid",
    "cron.pid",
}

# File names that ``hermes import`` must never overwrite, matched by basename so
# they're caught for the root profile (``gateway_state.json``) and for named
# profiles alike (``profiles/<name>/gateway_state.json``).
#
# These hold *volatile gateway/process runtime state that is namespaced to the
# machine or container the backup was taken on* — PIDs in a dead process
# namespace, a runtime lock, the process registry, and the gateway's last
# recorded run/desired state. Restoring them onto a different host (or a hosted
# container) is at best meaningless and at worst actively harmful:
#
#   - ``gateway_state.json`` drives the container-boot reconciler
#     (``container_boot._read_desired_state``), which only auto-starts a
#     gateway whose recorded state is ``running``. A backup taken from a
#     machine where the gateway was stopped (or carrying a stale/foreign
#     value) overwrites the container's own state and leaves the gateway
#     stuck "starting"/"cooking", disconnecting it from the Nous portal
#     (NS-508 / the second half of NS-501).
#   - ``gateway.pid`` / ``cron.pid`` / ``gateway.lock`` / ``processes.json``
#     reference PIDs and locks in the *source* machine's process namespace; a
#     numerically-equal PID in the new environment is a different process.
#     These mirror exactly what ``container_boot._STALE_RUNTIME_FILES`` already
#     sweeps on every container boot.
#
# Older backups predate the backup-side exclusions, so we filter on import too
# rather than trusting the archive's contents.
_IMPORT_SKIP_NAMES = {
    "gateway_state.json",
    "gateway.pid",
    "cron.pid",
    "gateway.lock",
    "processes.json",
}

# zipfile.open() drops Unix mode bits on extract; restore tightens these to 0600.
_SECRET_FILE_NAMES = {".env", "auth.json", "state.db"}


def _should_exclude(rel_path: Path) -> bool:
    """Return True if *rel_path* (relative to hermes root) should be skipped."""
    parts = rel_path.parts

    for part in parts:
        if part not in _EXCLUDED_DIRS:
            continue
        # ``hermes-agent`` only matches at the root level (first component).
        # Nested directories with the same name — e.g.
        # ``skills/autonomous-ai-agents/hermes-agent/`` — must be preserved.
        if part == "hermes-agent" and part != parts[0]:
            continue
        return True

    name = rel_path.name

    if name in _EXCLUDED_NAMES:
        return True

    if name.endswith(_EXCLUDED_SUFFIXES):
        return True

    return False


def _should_skip_backup_file(abs_path: Path, rel_path: Path, out_path: Path) -> bool:
    """Return True when a candidate file should not be written to a backup zip."""
    if _should_exclude(rel_path):
        return True

    # zipfile.write() follows file symlinks, so skip links before any archive
    # write can copy data from outside HERMES_HOME.
    if abs_path.is_symlink():
        return True

    try:
        return abs_path.resolve() == out_path.resolve()
    except (OSError, ValueError):
        return False


# ---------------------------------------------------------------------------
# SQLite safe copy
# ---------------------------------------------------------------------------

def _safe_copy_db(src: Path, dst: Path) -> bool:
    """Copy a SQLite database safely using the backup() API.

    Handles WAL mode — produces a consistent snapshot even while
    the DB is being written to.  Falls back to raw copy on failure.
    """
    try:
        conn = sqlite3.connect(f"file:{src}?mode=ro", uri=True)
        backup_conn = sqlite3.connect(str(dst))
        conn.backup(backup_conn)
        backup_conn.close()
        conn.close()
        return True
    except Exception as exc:
        logger.warning("SQLite safe copy failed for %s: %s", src, exc)
        try:
            shutil.copy2(src, dst)
            return True
        except Exception as exc2:
            logger.error("Raw copy also failed for %s: %s", src, exc2)
            return False


# ---------------------------------------------------------------------------
# Backup
# ---------------------------------------------------------------------------

def _format_size(nbytes: int) -> str:
    """Human-readable file size."""
    for unit in ("B", "KB", "MB", "GB"):
        if nbytes < 1024:
            return f"{nbytes:.1f} {unit}" if unit != "B" else f"{nbytes} {unit}"
        nbytes /= 1024
    return f"{nbytes:.1f} TB"


def run_backup(args) -> None:
    """Create a zip backup of the Hermes home directory."""
    hermes_root = get_default_hermes_root()

    if not hermes_root.is_dir():
        print(f"Error: Hermes home directory not found at {hermes_root}")
        sys.exit(1)

    # Determine output path
    if args.output:
        out_path = Path(args.output).expanduser().resolve()
        # If user gave a directory, put the zip inside it
        if out_path.is_dir():
            stamp = datetime.now().strftime("%Y-%m-%d-%H%M%S")
            out_path = out_path / f"hermes-backup-{stamp}.zip"
    else:
        stamp = datetime.now().strftime("%Y-%m-%d-%H%M%S")
        out_path = Path.home() / f"hermes-backup-{stamp}.zip"

    # Ensure the suffix is .zip
    if out_path.suffix.lower() != ".zip":
        out_path = out_path.with_suffix(out_path.suffix + ".zip")

    # Ensure parent directory exists
    out_path.parent.mkdir(parents=True, exist_ok=True)

    # Collect files
    print(f"Scanning {display_hermes_home()} ...")
    files_to_add: list[tuple[Path, Path]] = []  # (absolute, relative)
    skipped_dirs = set()

    for dirpath, dirnames, filenames in os.walk(hermes_root, followlinks=False):
        dp = Path(dirpath)
        rel_dir = dp.relative_to(hermes_root)

        # Prune excluded directories in-place so os.walk doesn't descend
        # ``hermes-agent`` is only pruned at the root level; nested dirs
        # with the same name (e.g. in skills/) must be preserved.
        is_root = rel_dir == Path(".")
        orig_dirnames = dirnames[:]
        dirnames[:] = [
            d for d in dirnames
            if d not in _EXCLUDED_DIRS or (d == "hermes-agent" and not is_root)
        ]
        for removed in set(orig_dirnames) - set(dirnames):
            skipped_dirs.add(str(rel_dir / removed))

        for fname in filenames:
            fpath = dp / fname
            rel = fpath.relative_to(hermes_root)

            if _should_skip_backup_file(fpath, rel, out_path):
                continue

            files_to_add.append((fpath, rel))

    if not files_to_add:
        print("No files to back up.")
        return

    # Create the zip
    file_count = len(files_to_add)
    print(f"Backing up {file_count} files ...")

    total_bytes = 0
    errors = []
    t0 = time.monotonic()

    with zipfile.ZipFile(out_path, "w", zipfile.ZIP_DEFLATED, compresslevel=6) as zf:
        for i, (abs_path, rel_path) in enumerate(files_to_add, 1):
            try:
                # Safe copy for SQLite databases (handles WAL mode)
                if abs_path.suffix == ".db":
                    # Stage the snapshot alongside the output zip so that the
                    # temp file lives on the same filesystem.  The system
                    # default (/tmp) may be a small tmpfs that cannot hold
                    # large databases, causing silent backup incompleteness.
                    with tempfile.NamedTemporaryFile(
                        suffix=".db", delete=False, dir=str(out_path.parent)
                    ) as tmp:
                        tmp_db = Path(tmp.name)
                    if _safe_copy_db(abs_path, tmp_db):
                        zf.write(tmp_db, arcname=str(rel_path))
                        total_bytes += tmp_db.stat().st_size
                        tmp_db.unlink(missing_ok=True)
                    else:
                        tmp_db.unlink(missing_ok=True)
                        errors.append(f"  {rel_path}: SQLite safe copy failed")
                        continue
                else:
                    zf.write(abs_path, arcname=str(rel_path))
                    total_bytes += abs_path.stat().st_size
            except (PermissionError, OSError, ValueError) as exc:
                errors.append(f"  {rel_path}: {exc}")
                continue

            # Progress every 500 files
            if i % 500 == 0:
                print(f"  {i}/{file_count} files ...")

    elapsed = time.monotonic() - t0
    zip_size = out_path.stat().st_size

    # Summary
    print()
    print(f"Backup complete: {out_path}")
    print(f"  Files:       {file_count}")
    print(f"  Original:    {_format_size(total_bytes)}")
    print(f"  Compressed:  {_format_size(zip_size)}")
    print(f"  Time:        {elapsed:.1f}s")

    if skipped_dirs:
        print(f"\n  Excluded directories:")
        for d in sorted(skipped_dirs):
            print(f"    {d}/")

    if errors:
        print(f"\n  Warnings ({len(errors)} files skipped):")
        for e in errors[:10]:
            print(e)
        if len(errors) > 10:
            print(f"  ... and {len(errors) - 10} more")

    print(f"\nRestore with: hermes import {out_path.name}")


# ---------------------------------------------------------------------------
# Import
# ---------------------------------------------------------------------------

def _validate_backup_zip(zf: zipfile.ZipFile) -> tuple[bool, str]:
    """Check that a zip looks like a Hermes backup.

    Returns (ok, reason).
    """
    names = zf.namelist()
    if not names:
        return False, "zip archive is empty"

    # Look for telltale files that a hermes home would have
    markers = {"config.yaml", ".env", "state.db"}
    found = set()
    for n in names:
        # Could be at the root or one level deep (if someone zipped the directory)
        basename = Path(n).name
        if basename in markers:
            found.add(basename)

    if not found:
        return False, (
            "zip does not appear to be a Hermes backup "
            "(no config.yaml, .env, or state databases found)"
        )

    return True, ""


def _detect_prefix(zf: zipfile.ZipFile) -> str:
    """Detect if the zip has a common directory prefix wrapping all entries.

    Some tools zip as `.hermes/config.yaml` instead of `config.yaml`.
    Returns the prefix to strip (empty string if none).
    """
    names = [n for n in zf.namelist() if not n.endswith("/")]
    if not names:
        return ""

    # Find common prefix
    parts_list = [Path(n).parts for n in names]

    # Check if all entries share a common first directory
    first_parts = {p[0] for p in parts_list if len(p) > 1}
    if len(first_parts) == 1:
        prefix = first_parts.pop()
        # Only strip if it looks like a hermes dir name
        if prefix in {".hermes", "hermes"}:
            return prefix + "/"

    return ""


def run_import(args) -> None:
    """Restore a Hermes backup from a zip file."""
    zip_path = Path(args.zipfile).expanduser().resolve()

    if not zip_path.is_file():
        print(f"Error: File not found: {zip_path}")
        sys.exit(1)

    if not zipfile.is_zipfile(zip_path):
        print(f"Error: Not a valid zip file: {zip_path}")
        sys.exit(1)

    hermes_root = get_default_hermes_root()

    with zipfile.ZipFile(zip_path, "r") as zf:
        # Validate
        ok, reason = _validate_backup_zip(zf)
        if not ok:
            print(f"Error: {reason}")
            sys.exit(1)

        prefix = _detect_prefix(zf)
        members = [n for n in zf.namelist() if not n.endswith("/")]
        file_count = len(members)

        print(f"Backup contains {file_count} files")
        print(f"Target: {display_hermes_home()}")

        if prefix:
            print(f"Detected archive prefix: {prefix!r} (will be stripped)")

        # Check for existing installation
        has_config = (hermes_root / "config.yaml").exists()
        has_env = (hermes_root / ".env").exists()

        if (has_config or has_env) and not args.force:
            print()
            print("Warning: Target directory already has Hermes configuration.")
            print("Importing will overwrite existing files with backup contents.")
            print()
            try:
                answer = input("Continue? [y/N] ").strip().lower()
            except (EOFError, KeyboardInterrupt):
                print("\nAborted.")
                sys.exit(1)
            if answer not in {"y", "yes"}:
                print("Aborted.")
                return

        # Extract
        print(f"\nImporting {file_count} files ...")
        hermes_root.mkdir(parents=True, exist_ok=True)

        errors = []
        restored = 0
        skipped_runtime: list[str] = []
        t0 = time.monotonic()

        for member in members:
            # Strip prefix if detected
            if prefix and member.startswith(prefix):
                rel = member[len(prefix):]
            else:
                rel = member

            if not rel:
                continue

            # Never overwrite volatile gateway/process runtime state. These are
            # namespaced to the machine/container the backup was taken on;
            # clobbering them (especially gateway_state.json) breaks the gateway
            # reconciler on the target and disconnects hosted instances from the
            # Nous portal. Matched by basename so both the root profile and
            # named profiles (profiles/<name>/gateway_state.json) are covered.
            if Path(rel).name in _IMPORT_SKIP_NAMES:
                skipped_runtime.append(rel)
                continue

            target = hermes_root / rel

            # Security: reject absolute paths and traversals
            try:
                target.resolve().relative_to(hermes_root.resolve())
            except ValueError:
                errors.append(f"  {rel}: path traversal blocked")
                continue

            try:
                target.parent.mkdir(parents=True, exist_ok=True)
                with zf.open(member) as src, open(target, "wb") as dst:
                    dst.write(src.read())
                if target.name in _SECRET_FILE_NAMES:
                    os.chmod(target, 0o600)
                restored += 1
            except (PermissionError, OSError) as exc:
                errors.append(f"  {rel}: {exc}")

            if restored % 500 == 0:
                print(f"  {restored}/{file_count} files ...")

        elapsed = time.monotonic() - t0

        # Summary
        print()
        print(f"Import complete: {restored} files restored in {elapsed:.1f}s")
        print(f"  Target: {display_hermes_home()}")

        if errors:
            print(f"\n  Warnings ({len(errors)} files skipped):")
            for e in errors[:10]:
                print(e)
            if len(errors) > 10:
                print(f"  ... and {len(errors) - 10} more")

        if skipped_runtime:
            print(
                f"\n  Preserved {len(skipped_runtime)} runtime state "
                f"file(s) (kept this machine's, not the backup's):"
            )
            for rel in sorted(skipped_runtime)[:10]:
                print(f"    {rel}")
            if len(skipped_runtime) > 10:
                print(f"    ... and {len(skipped_runtime) - 10} more")

        # Post-import: restore profile wrapper scripts
        profiles_dir = hermes_root / "profiles"
        restored_profiles = []
        if profiles_dir.is_dir():
            try:
                from hermes_cli.profiles import (
                    create_wrapper_script, check_alias_collision,
                    _is_wrapper_dir_in_path, _get_wrapper_dir,
                )
                for entry in sorted(profiles_dir.iterdir()):
                    if not entry.is_dir():
                        continue
                    profile_name = entry.name
                    # Only create wrappers for directories with config
                    if not (entry / "config.yaml").exists() and not (entry / ".env").exists():
                        continue
                    collision = check_alias_collision(profile_name)
                    if collision:
                        print(f"  Skipped alias '{profile_name}': {collision}")
                        restored_profiles.append((profile_name, False))
                    else:
                        wrapper = create_wrapper_script(profile_name)
                        restored_profiles.append((profile_name, wrapper is not None))

                if restored_profiles:
                    created = [n for n, ok in restored_profiles if ok]
                    skipped = [n for n, ok in restored_profiles if not ok]
                    if created:
                        print(f"\n  Profile aliases restored: {', '.join(created)}")
                    if skipped:
                        print(f"  Profile aliases skipped:  {', '.join(skipped)}")
                    if not _is_wrapper_dir_in_path():
                        print(f"\n  Note: {_get_wrapper_dir()} is not in your PATH.")
                        print('  Add to your shell config (~/.bashrc or ~/.zshrc):')
                        print('    export PATH="$HOME/.local/bin:$PATH"')
            except ImportError:
                # hermes_cli.profiles might not be available (fresh install)
                if any(profiles_dir.iterdir()):
                    print(f"\n  Profiles detected but aliases could not be created.")
                    print(f"  Run: hermes profile list  (after installing hermes)")

        # Guidance
        print()
        if not (hermes_root / "hermes-agent").is_dir():
            print("Note: The hermes-agent codebase was not included in the backup.")
            print("  If this is a fresh install, run: hermes update")

        if restored_profiles:
            gw_profiles = [n for n, _ in restored_profiles]
            print("\nTo re-enable gateway services for profiles:")
            for pname in gw_profiles:
                print(f"  hermes -p {pname} gateway install")

        print("Done. Your Hermes configuration has been restored.")


# ---------------------------------------------------------------------------
# Quick state snapshots (used by /snapshot slash command and hermes backup --quick)
# ---------------------------------------------------------------------------

# Critical state files to include in quick snapshots (relative to HERMES_HOME).
# Everything else is either regeneratable (logs, cache) or managed separately
# (skills, repo, sessions/).
#
# Entries may be individual files OR directories.  Directories are captured
# recursively; missing entries are silently skipped.  Pairing data lives in
# platform-specific JSON blobs outside state.db, so it's listed here explicitly
# — `hermes update` snapshots this set before pulling so approved-user lists
# are recoverable if anything goes wrong (issue #15733).
_QUICK_STATE_FILES = (
    "state.db",
    "config.yaml",
    ".env",
    "auth.json",
    "cron/jobs.json",
    "gateway_state.json",
    "channel_directory.json",
    "channel_aliases.json",
    "processes.json",
    # Pairing stores (generic + per-platform JSONs outside state.db)
    "pairing",                          # legacy location (gateway/pairing.py)
    "platforms/pairing",                # new location (gateway/pairing.py)
    "feishu_comment_pairing.json",      # Feishu comment subscription pairings
)

_QUICK_SNAPSHOTS_DIR = "state-snapshots"
_QUICK_DEFAULT_KEEP = 20


def _quick_snapshot_root(hermes_home: Optional[Path] = None) -> Path:
    home = hermes_home or get_hermes_home()
    return home / _QUICK_SNAPSHOTS_DIR


def create_quick_snapshot(
    label: Optional[str] = None,
    hermes_home: Optional[Path] = None,
    keep: Optional[int] = None,
) -> Optional[str]:
    """Create a quick state snapshot of critical files.

    Copies STATE_FILES to a timestamped directory under state-snapshots/.
    Auto-prunes old snapshots beyond the keep limit.

    Returns:
        Snapshot ID (timestamp-based), or None if no files found.
    """
    home = hermes_home or get_hermes_home()
    root = _quick_snapshot_root(home)

    ts = datetime.now(timezone.utc).strftime("%Y%m%d-%H%M%S")
    snap_id = f"{ts}-{label}" if label else ts
    snap_dir = root / snap_id
    snap_dir.mkdir(parents=True, exist_ok=True)

    manifest: Dict[str, int] = {}  # rel_path -> file size

    for rel in _QUICK_STATE_FILES:
        src = home / rel
        if not src.exists():
            continue

        if src.is_dir():
            # Walk the directory and record each file individually in the
            # manifest so restore can treat them uniformly.  Empty dirs are
            # skipped (nothing to snapshot).
            for sub in src.rglob("*"):
                if not sub.is_file():
                    continue
                sub_rel = sub.relative_to(home).as_posix()
                dst = snap_dir / sub_rel
                dst.parent.mkdir(parents=True, exist_ok=True)
                try:
                    shutil.copy2(sub, dst)
                    manifest[sub_rel] = dst.stat().st_size
                except (OSError, PermissionError) as exc:
                    logger.warning("Could not snapshot %s: %s", sub_rel, exc)
            continue

        if not src.is_file():
            continue

        dst = snap_dir / rel
        dst.parent.mkdir(parents=True, exist_ok=True)

        try:
            if src.suffix == ".db":
                if not _safe_copy_db(src, dst):
                    continue
            else:
                shutil.copy2(src, dst)
            manifest[rel] = dst.stat().st_size
        except (OSError, PermissionError) as exc:
            logger.warning("Could not snapshot %s: %s", rel, exc)

    if not manifest:
        shutil.rmtree(snap_dir, ignore_errors=True)
        return None

    # Write manifest
    meta = {
        "id": snap_id,
        "timestamp": ts,
        "label": label,
        "file_count": len(manifest),
        "total_size": sum(manifest.values()),
        "files": manifest,
    }
    with open(snap_dir / "manifest.json", "w", encoding="utf-8") as f:
        json.dump(meta, f, indent=2)

    # Auto-prune. Defaults preserve historical manual /snapshot behavior; callers
    # with known high-churn safety snapshots (for example pre-update) can pass a
    # smaller keep value so large state.db copies do not accumulate indefinitely.
    _prune_quick_snapshots(root, keep=_QUICK_DEFAULT_KEEP if keep is None else keep)

    logger.info("State snapshot created: %s (%d files)", snap_id, len(manifest))
    return snap_id


def list_quick_snapshots(
    limit: int = 20,
    hermes_home: Optional[Path] = None,
) -> List[Dict[str, Any]]:
    """List existing quick state snapshots, most recent first."""
    root = _quick_snapshot_root(hermes_home)
    if not root.exists():
        return []

    results = []
    for d in sorted(root.iterdir(), reverse=True):
        if not d.is_dir():
            continue
        manifest_path = d / "manifest.json"
        if manifest_path.exists():
            try:
                with open(manifest_path, encoding="utf-8") as f:
                    results.append(json.load(f))
            except (json.JSONDecodeError, OSError):
                results.append({"id": d.name, "file_count": 0, "total_size": 0})
        if len(results) >= limit:
            break

    return results


def restore_quick_snapshot(
    snapshot_id: str,
    hermes_home: Optional[Path] = None,
) -> bool:
    """Restore state from a quick snapshot.

    Overwrites current state files with the snapshot's copies.
    Returns True if at least one file was restored.
    """
    home = hermes_home or get_hermes_home()
    root = _quick_snapshot_root(home)
    snap_dir = root / snapshot_id

    if not snap_dir.is_dir():
        return False

    manifest_path = snap_dir / "manifest.json"
    if not manifest_path.exists():
        return False

    with open(manifest_path, encoding="utf-8") as f:
        meta = json.load(f)

    restored = 0
    for rel in meta.get("files", {}):
        src = snap_dir / rel
        if not src.exists():
            continue

        dst = home / rel
        dst.parent.mkdir(parents=True, exist_ok=True)

        try:
            if dst.suffix == ".db":
                # Atomic-ish replace for databases
                tmp = dst.parent / f".{dst.name}.snap_restore"
                shutil.copy2(src, tmp)
                dst.unlink(missing_ok=True)
                shutil.move(str(tmp), str(dst))
            else:
                shutil.copy2(src, dst)
            restored += 1
        except (OSError, PermissionError) as exc:
            logger.error("Failed to restore %s: %s", rel, exc)

    logger.info("Restored %d files from snapshot %s", restored, snapshot_id)
    return restored > 0


# Relative path of the cron job database inside HERMES_HOME. Kept in sync with
# the entry in ``_QUICK_STATE_FILES`` and with ``cron/jobs.py``'s ``JOBS_FILE``.
_CRON_JOBS_REL = "cron/jobs.json"


def _count_cron_jobs(path: Path) -> Optional[int]:
    """Return the number of cron jobs stored in ``path``.

    The canonical on-disk shape is ``{"jobs": [...]}`` (see ``cron/jobs.py``).
    A legacy bare-list shape (``[...]``) is also honoured.

    Returns:
        The job count for any *valid, readable* JSON document, or ``None`` if
        the file is missing or cannot be parsed. ``None`` means "unknown" —
        callers must not treat it as "zero jobs", because acting on an
        unreadable file could mask a real corruption the user needs to see.
    """
    if not path.is_file():
        return None
    try:
        with open(path, "r", encoding="utf-8") as f:
            data = json.load(f)
    except (OSError, json.JSONDecodeError):
        return None
    if isinstance(data, dict):
        jobs = data.get("jobs", [])
        return len(jobs) if isinstance(jobs, list) else None
    if isinstance(data, list):
        return len(data)
    return None


def restore_cron_jobs_if_emptied(
    snapshot_id: str,
    hermes_home: Optional[Path] = None,
) -> Optional[Dict[str, Any]]:
    """Safety net for silent cron-job loss across ``hermes update``.

    Config-version migrations have been observed to leave ``cron/jobs.json``
    valid-but-empty after an update, silently dropping every scheduled job
    (issue #34600). The existing malformed-shape guards in ``cron/jobs.py``
    don't catch this case because ``{"jobs": []}`` is perfectly valid JSON.

    This compares the *current* job count against the pre-update snapshot. If
    the live file now has **zero** jobs while the snapshot captured **one or
    more**, the snapshot copy of ``cron/jobs.json`` is restored in place.

    The check is deliberately conservative — it only ever restores when there
    is unambiguous evidence of loss (snapshot had jobs, live file has none),
    so a user who genuinely deleted all their jobs during/after the update is
    never second-guessed, and an unreadable live file (count ``None``) is left
    untouched so real corruption still surfaces.

    Args:
        snapshot_id: The pre-update quick-snapshot id (from
            :func:`create_quick_snapshot`).
        hermes_home: Override for the Hermes home directory (tests).

    Returns:
        ``None`` when no action was taken (the common, healthy path). On a
        successful restore, a dict ``{"restored": True, "job_count": N,
        "snapshot_id": ...}`` so the caller can warn the user.
    """
    if not snapshot_id:
        return None

    home = hermes_home or get_hermes_home()
    live_path = home / _CRON_JOBS_REL

    live_count = _count_cron_jobs(live_path)
    # Only act when the live file is readable AND empty. ``None`` (missing or
    # unparseable) is intentionally left alone — that's a different failure
    # mode the user should see rather than have papered over.
    if live_count is None or live_count > 0:
        return None

    snap_path = _quick_snapshot_root(home) / snapshot_id / _CRON_JOBS_REL
    snap_count = _count_cron_jobs(snap_path)
    if not snap_count:  # None or 0 — nothing worth restoring
        return None

    try:
        live_path.parent.mkdir(parents=True, exist_ok=True)
        shutil.copy2(snap_path, live_path)
    except (OSError, PermissionError) as exc:
        logger.error(
            "Cron jobs were emptied during update but auto-restore failed: %s", exc
        )
        return None

    logger.warning(
        "Restored %d cron job(s) from pre-update snapshot %s "
        "(cron/jobs.json was emptied during migration)",
        snap_count,
        snapshot_id,
    )
    return {"restored": True, "job_count": snap_count, "snapshot_id": snapshot_id}


def _prune_quick_snapshots(root: Path, keep: int = _QUICK_DEFAULT_KEEP) -> int:
    """Remove oldest quick snapshots beyond the keep limit. Returns count deleted."""
    if not root.exists():
        return 0

    dirs = sorted(
        (d for d in root.iterdir() if d.is_dir()),
        key=lambda d: d.name,
        reverse=True,
    )

    deleted = 0
    for d in dirs[keep:]:
        try:
            shutil.rmtree(d)
            deleted += 1
        except OSError as exc:
            logger.warning("Failed to prune snapshot %s: %s", d.name, exc)

    return deleted


def prune_quick_snapshots(
    keep: int = _QUICK_DEFAULT_KEEP,
    hermes_home: Optional[Path] = None,
) -> int:
    """Manually prune quick snapshots. Returns count deleted."""
    return _prune_quick_snapshots(_quick_snapshot_root(hermes_home), keep=keep)


def run_quick_backup(args) -> None:
    """CLI entry point for hermes backup --quick."""
    label = getattr(args, "label", None)
    snap_id = create_quick_snapshot(label=label)
    if snap_id:
        print(f"State snapshot created: {snap_id}")
        snaps = list_quick_snapshots()
        print(f"  {len(snaps)} snapshot(s) stored in {display_hermes_home()}/state-snapshots/")
        print(f"  Restore with: /snapshot restore {snap_id}")
    else:
        print("No state files found to snapshot.")


# ---------------------------------------------------------------------------
# Shared full-zip backup helper
# ---------------------------------------------------------------------------

def _write_full_zip_backup(out_path: Path, hermes_root: Path) -> Optional[Path]:
    """Write a full zip snapshot of ``hermes_root`` to ``out_path``.

    Uses the same exclusion rules and SQLite safe-copy as :func:`run_backup`.
    Returns the output path on success, None on failure (nothing to back up,
    or write error — caller should surface the outcome but not raise).
    """
    files_to_add: list[tuple[Path, Path]] = []
    try:
        for dirpath, dirnames, filenames in os.walk(hermes_root, followlinks=False):
            dp = Path(dirpath)
            # Prune excluded directories in-place so os.walk doesn't descend
            dirnames[:] = [d for d in dirnames if d not in _EXCLUDED_DIRS]

            for fname in filenames:
                fpath = dp / fname
                try:
                    rel = fpath.relative_to(hermes_root)
                except ValueError:
                    continue

                if _should_skip_backup_file(fpath, rel, out_path):
                    continue

                files_to_add.append((fpath, rel))
    except OSError as exc:
        logger.warning("Full-zip backup: walk failed: %s", exc)
        return None

    if not files_to_add:
        return None

    try:
        with zipfile.ZipFile(out_path, "w", zipfile.ZIP_DEFLATED, compresslevel=6) as zf:
            for abs_path, rel_path in files_to_add:
                try:
                    if abs_path.suffix == ".db":
                        # Stage the snapshot alongside the output zip so that the
                        # temp file lives on the same filesystem.  The system
                        # default (/tmp) may be a small tmpfs that cannot hold
                        # large databases, causing silent backup incompleteness.
                        with tempfile.NamedTemporaryFile(
                            suffix=".db", delete=False, dir=str(out_path.parent)
                        ) as tmp:
                            tmp_db = Path(tmp.name)
                        try:
                            if _safe_copy_db(abs_path, tmp_db):
                                zf.write(tmp_db, arcname=str(rel_path))
                        finally:
                            tmp_db.unlink(missing_ok=True)
                    else:
                        zf.write(abs_path, arcname=str(rel_path))
                except (PermissionError, OSError, ValueError) as exc:
                    logger.debug("Skipping %s in zip backup: %s", rel_path, exc)
                    continue
    except OSError as exc:
        logger.warning("Full-zip backup: zip write failed: %s", exc)
        # Best-effort cleanup of partial file
        try:
            out_path.unlink(missing_ok=True)
        except OSError:
            pass
        return None

    return out_path


# ---------------------------------------------------------------------------
# Pre-update auto-backup
# ---------------------------------------------------------------------------

_PRE_UPDATE_BACKUPS_DIR = "backups"
_PRE_UPDATE_PREFIX = "pre-update-"
_PRE_UPDATE_DEFAULT_KEEP = 5


def _pre_update_backup_dir(hermes_home: Optional[Path] = None) -> Path:
    home = hermes_home or get_hermes_home()
    return home / _PRE_UPDATE_BACKUPS_DIR


def _prune_pre_update_backups(backup_dir: Path, keep: int) -> int:
    """Remove oldest pre-update backups beyond the keep limit.

    Returns the number of files deleted.  Only touches files matching
    ``pre-update-*.zip`` so hand-made zips dropped in the same directory
    are never touched.

    ``keep`` is floored to 1 because this helper is only called immediately
    after a fresh backup is written: deleting that backup right after the
    user paid the disk/CPU cost to create it would leave them worse off
    than no backup at all (and the wrapper in ``main.py`` would still print
    a misleading ``Saved: <path>`` line for a file that no longer exists).
    Operators who genuinely don't want a backup should set
    ``updates.pre_update_backup: false`` in config — that gates creation.
    """
    keep = max(keep, 1)
    if not backup_dir.exists():
        return 0

    backups = sorted(
        (p for p in backup_dir.iterdir()
         if p.is_file() and p.name.startswith(_PRE_UPDATE_PREFIX) and p.suffix.lower() == ".zip"),
        key=lambda p: p.name,
        reverse=True,
    )

    deleted = 0
    for p in backups[keep:]:
        try:
            p.unlink()
            deleted += 1
        except OSError as exc:
            logger.warning("Failed to prune backup %s: %s", p.name, exc)

    return deleted


def create_pre_update_backup(
    hermes_home: Optional[Path] = None,
    keep: int = _PRE_UPDATE_DEFAULT_KEEP,
) -> Optional[Path]:
    """Create a full zip backup of HERMES_HOME under ``backups/``.

    Mirrors :func:`run_backup` (same exclusion rules, same SQLite safe-copy)
    but writes to ``<HERMES_HOME>/backups/pre-update-<timestamp>.zip`` and
    auto-prunes old pre-update backups.

    Returns the path to the created zip, or ``None`` if no files were
    found or the backup could not be created.  Never raises — the caller
    (``hermes update``) should continue even if the backup fails.
    """
    hermes_root = hermes_home or get_default_hermes_root()
    if not hermes_root.is_dir():
        return None

    backup_dir = _pre_update_backup_dir(hermes_root)
    try:
        backup_dir.mkdir(parents=True, exist_ok=True)
    except OSError as exc:
        logger.warning("Could not create pre-update backup dir %s: %s", backup_dir, exc)
        return None

    stamp = datetime.now().strftime("%Y-%m-%d-%H%M%S")
    out_path = backup_dir / f"{_PRE_UPDATE_PREFIX}{stamp}.zip"

    result = _write_full_zip_backup(out_path, hermes_root)
    if result is None:
        return None

    _prune_pre_update_backups(backup_dir, keep=keep)
    return out_path


# ---------------------------------------------------------------------------
# Pre-migration auto-backup (used by `hermes claw migrate`)
# ---------------------------------------------------------------------------

_PRE_MIGRATION_PREFIX = "pre-migration-"
_PRE_MIGRATION_DEFAULT_KEEP = 5


def _prune_pre_migration_backups(backup_dir: Path, keep: int) -> int:
    """Remove oldest pre-migration backups beyond the keep limit.

    Only touches files matching ``pre-migration-*.zip`` so other backups in
    the same directory are never touched.
    """
    keep = max(keep, 0)
    if not backup_dir.exists():
        return 0

    backups = sorted(
        (p for p in backup_dir.iterdir()
         if p.is_file() and p.name.startswith(_PRE_MIGRATION_PREFIX) and p.suffix.lower() == ".zip"),
        key=lambda p: p.name,
        reverse=True,
    )

    deleted = 0
    for p in backups[keep:]:
        try:
            p.unlink()
            deleted += 1
        except OSError as exc:
            logger.warning("Failed to prune pre-migration backup %s: %s", p.name, exc)

    return deleted


def create_pre_migration_backup(
    hermes_home: Optional[Path] = None,
    keep: int = _PRE_MIGRATION_DEFAULT_KEEP,
) -> Optional[Path]:
    """Create a full zip backup of HERMES_HOME under ``backups/`` before a
    ``hermes claw migrate`` apply.

    Shares implementation with :func:`create_pre_update_backup` via
    ``_write_full_zip_backup`` — same exclusions, same SQLite safe-copy,
    restorable with ``hermes import <archive>``.  Writes to
    ``<HERMES_HOME>/backups/pre-migration-<timestamp>.zip`` and auto-prunes
    old pre-migration backups.

    Returns the path to the created zip, or ``None`` if nothing was found
    to back up (fresh install) or the write failed.  Never raises — the
    caller decides whether to abort or proceed.
    """
    hermes_root = hermes_home or get_default_hermes_root()
    if not hermes_root.is_dir():
        return None

    # Reuses the shared backups/ directory so `hermes import` and the
    # update-backup listing pick up pre-migration archives too.
    backup_dir = _pre_update_backup_dir(hermes_root)
    try:
        backup_dir.mkdir(parents=True, exist_ok=True)
    except OSError as exc:
        logger.warning("Could not create pre-migration backup dir %s: %s", backup_dir, exc)
        return None

    stamp = datetime.now().strftime("%Y-%m-%d-%H%M%S")
    out_path = backup_dir / f"{_PRE_MIGRATION_PREFIX}{stamp}.zip"

    result = _write_full_zip_backup(out_path, hermes_root)
    if result is None:
        return None

    _prune_pre_migration_backups(backup_dir, keep=keep)
    return out_path