feat(webui): unified session/lease/lock/worktree inventory API (Closes #636)

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

webui/inventory.py

@@ -0,0 +1,952 @@
+"""Unified session/lease/lock/worktree inventory for the web console (#636).
+
+Leases (#433), worktrees (#432), and runtime (#430) each ship their own MVP
+view, each with its own shape and its own idea of what "owned" means. A
+traffic-control or recovery operator has to read all three and correlate them
+by hand, which is exactly the step that goes wrong under collision pressure.
+
+This module aggregates them into one versioned, read-only snapshot so the
+console, and any worker asking "what is safe to do next", read the same
+inventory from the same authority.
+
+Field authority is explicit and never blended. Every section declares where its
+rows came from:
+
+* ``control_plane_db`` — the #613 substrate: sessions, leases, assignments.
+  Authoritative for *exclusive ownership* (#600/#601).
+* ``filesystem`` — durable per-issue lock files (:mod:`issue_lock_store`) and
+  registered git worktrees. Authoritative for *what exists on this machine*.
+* ``gitea`` — remote issue/PR state, reached only through existing loaders.
+
+Safety invariants:
+
+* **Read-only.** The control-plane database is opened through a ``mode=ro``
+  URI. :class:`control_plane_db.ControlPlaneDB` creates directories and runs
+  migrations in its constructor, which an inventory read must never do, so this
+  module talks to sqlite directly rather than through that class.
+* **Fail-soft, never fail-silent.** A subsystem that cannot be read degrades to
+  a section carrying ``status`` and ``reason``. It never raises, and it never
+  produces an empty list that reads like "nothing is there".
+* **Never invent active ownership.** This is the invariant that matters most.
+  A degraded ownership source sets ``ownership_authority_complete`` false, and
+  while that flag is false no work item is reported unowned and no collision is
+  asserted. Absence of evidence is reported as absence of evidence.
+* **Redaction at the boundary.** Absolute paths are collapsed against the home
+  directory, URLs lose userinfo and query strings, and no credential-shaped
+  value is emitted. No session token exists in these sources and none is read.
+
+Phase 1 is read-only. Lease steal/release and worktree deletion are Phase 2+
+and deliberately have no representation here, not even a disabled one.
+"""
+
+from __future__ import annotations
+
+import os
+import re
+import sqlite3
+import time
+from dataclasses import dataclass, field
+from datetime import datetime, timezone
+from typing import Any, Callable
+from urllib.parse import urlparse
+
+import control_plane_db
+import issue_lock_store
+
+SCHEMA_VERSION = 1
+API_VERSION = "v1"
+
+#: Sections whose absence would make an ownership claim unprovable. If any of
+#: these is not ``ok``, the snapshot refuses to describe anything as unowned.
+OWNERSHIP_SECTIONS = ("sessions", "leases", "locks")
+
+SECTION_NAMES = ("sessions", "leases", "locks", "worktrees", "namespaces")
+
+STATUS_OK = "ok"
+STATUS_DEGRADED = "degraded"
+STATUS_UNAVAILABLE = "unavailable"
+
+AUTHORITY_CONTROL_PLANE_DB = "control_plane_db"
+AUTHORITY_FILESYSTEM = "filesystem"
+AUTHORITY_GITEA = "gitea"
+
+_CREDENTIAL_KEY_RE = re.compile(
+    r"(token|secret|password|passwd|api[_-]?key|authorization|bearer|credential)",
+    re.IGNORECASE,
+)
+_REDACTED = "[redacted]"
+
+
+@dataclass(frozen=True)
+class InventorySection:
+    """One subsystem's contribution, with its authority and health."""
+
+    name: str
+    authority: str
+    status: str
+    items: tuple[dict[str, Any], ...] = ()
+    reason: str | None = None
+    scan_ms: float | None = None
+
+    @property
+    def ok(self) -> bool:
+        return self.status == STATUS_OK
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "name": self.name,
+            "authority": self.authority,
+            "status": self.status,
+            "count": len(self.items),
+            "reason": self.reason,
+            "scan_ms": self.scan_ms,
+            "items": [dict(item) for item in self.items],
+        }
+
+
+@dataclass(frozen=True)
+class CollisionSignal:
+    """A detected conflict between two ownership records."""
+
+    kind: str
+    message: str
+    severity: str = "warning"
+    issue_number: int | None = None
+    branch: str | None = None
+    worktree_path: str | None = None
+    session_ids: tuple[str, ...] = ()
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "kind": self.kind,
+            "severity": self.severity,
+            "message": self.message,
+            "issue_number": self.issue_number,
+            "branch": self.branch,
+            "worktree_path": self.worktree_path,
+            "session_ids": list(self.session_ids),
+        }
+
+
+@dataclass(frozen=True)
+class InventorySnapshot:
+    """Versioned aggregate of every inventory section."""
+
+    generated_at: str
+    sections: tuple[InventorySection, ...]
+    collisions: tuple[CollisionSignal, ...] = ()
+    correlations: tuple[dict[str, Any], ...] = ()
+    schema_version: int = SCHEMA_VERSION
+    api_version: str = API_VERSION
+    scan_ms: float | None = None
+    _section_index: dict[str, InventorySection] = field(
+        default_factory=dict, repr=False, compare=False
+    )
+
+    def section(self, name: str) -> InventorySection | None:
+        return self._section_index.get(name)
+
+    @property
+    def degraded_sections(self) -> tuple[str, ...]:
+        return tuple(s.name for s in self.sections if not s.ok)
+
+    @property
+    def ownership_authority_complete(self) -> bool:
+        """True only when every ownership-bearing section read cleanly.
+
+        While this is false the snapshot must not describe any work item as
+        unowned: a lease the reader could not load is not an absent lease.
+        """
+        for name in OWNERSHIP_SECTIONS:
+            section = self._section_index.get(name)
+            if section is None or not section.ok:
+                return False
+        return True
+
+    @property
+    def status(self) -> str:
+        if all(s.ok for s in self.sections):
+            return STATUS_OK
+        return STATUS_DEGRADED
+
+
+# ── redaction ────────────────────────────────────────────────────────────────
+
+
+def redact_path(path: str | None) -> str | None:
+    """Collapse an absolute path against ``$HOME`` for browser display."""
+    if not path:
+        return path
+    text = str(path)
+    home = os.path.expanduser("~")
+    if home and home != "/" and text.startswith(home):
+        return "~" + text[len(home) :]
+    return text
+
+
+def redact_url(value: str | None) -> str | None:
+    """Strip userinfo and query string from a URL."""
+    if not value:
+        return value
+    text = str(value)
+    try:
+        parsed = urlparse(text)
+    except ValueError:
+        return _REDACTED
+    if not parsed.scheme or not parsed.netloc:
+        return text
+    netloc = parsed.hostname or ""
+    if parsed.port:
+        netloc = f"{netloc}:{parsed.port}"
+    rebuilt = f"{parsed.scheme}://{netloc}{parsed.path}"
+    return rebuilt.rstrip("/") or rebuilt
+
+
+def scrub(value: Any, *, key: str | None = None) -> Any:
+    """Recursively drop credential-shaped values and redact paths/URLs.
+
+    Never raises: an unexpected object degrades to its ``repr`` rather than
+    propagating out of a read-only view.
+    """
+    if key and _CREDENTIAL_KEY_RE.search(key):
+        return _REDACTED
+    if isinstance(value, dict):
+        return {str(k): scrub(v, key=str(k)) for k, v in value.items()}
+    if isinstance(value, (list, tuple)):
+        return [scrub(v, key=key) for v in value]
+    if isinstance(value, str):
+        if value.startswith(("http://", "https://")):
+            return redact_url(value)
+        if value.startswith("/") or value.startswith("~"):
+            return redact_path(value)
+        return value
+    if isinstance(value, (int, float, bool)) or value is None:
+        return value
+    return repr(value)
+
+
+# ── control-plane database (read-only) ───────────────────────────────────────
+
+
+def _open_readonly(db_path: str) -> sqlite3.Connection:
+    """Open the control-plane DB without creating or migrating anything."""
+    conn = sqlite3.connect(f"file:{db_path}?mode=ro", uri=True, timeout=5)
+    conn.row_factory = sqlite3.Row
+    return conn
+
+
+def _table_names(conn: sqlite3.Connection) -> set[str]:
+    rows = conn.execute(
+        "SELECT name FROM sqlite_master WHERE type = 'table'"
+    ).fetchall()
+    return {str(row[0]) for row in rows}
+
+
+def _load_cp_db_sections(
+    *,
+    db_path: str | None = None,
+    limit: int = 200,
+) -> tuple[InventorySection, InventorySection]:
+    """Return the ``sessions`` and ``leases`` sections from the #613 DB."""
+    path = (db_path or control_plane_db.default_db_path()).strip()
+
+    def _both_unavailable(reason: str) -> tuple[InventorySection, InventorySection]:
+        return (
+            InventorySection(
+                name="sessions",
+                authority=AUTHORITY_CONTROL_PLANE_DB,
+                status=STATUS_UNAVAILABLE,
+                reason=reason,
+            ),
+            InventorySection(
+                name="leases",
+                authority=AUTHORITY_CONTROL_PLANE_DB,
+                status=STATUS_UNAVAILABLE,
+                reason=reason,
+            ),
+        )
+
+    if not path:
+        return _both_unavailable("control-plane database path is not configured")
+    if not os.path.exists(path):
+        return _both_unavailable(
+            f"control-plane database not present at {redact_path(path)}; "
+            "no session or lease authority available"
+        )
+
+    started = time.perf_counter()
+    try:
+        conn = _open_readonly(path)
+    except sqlite3.Error as exc:
+        return _both_unavailable(f"control-plane database could not be opened: {exc}")
+
+    try:
+        tables = _table_names(conn)
+        if "sessions" not in tables or "leases" not in tables:
+            missing = sorted({"sessions", "leases"} - tables)
+            return _both_unavailable(
+                "control-plane database is missing required tables: "
+                + ", ".join(missing)
+            )
+
+        session_rows = [
+            dict(row)
+            for row in conn.execute(
+                "SELECT session_id, role, profile, namespace, pid, started_at,"
+                " last_heartbeat_at, status FROM sessions"
+                " ORDER BY last_heartbeat_at DESC LIMIT ?",
+                (max(1, int(limit)),),
+            ).fetchall()
+        ]
+
+        has_work_items = "work_items" in tables
+        if has_work_items:
+            lease_sql = (
+                "SELECT l.lease_id, l.session_id, l.role, l.phase, l.status,"
+                " l.expires_at, w.remote, w.org, w.repo, w.kind AS work_kind,"
+                " w.number AS work_number, w.state AS work_state,"
+                " s.pid AS session_pid, s.profile AS session_profile,"
+                " s.namespace AS session_namespace, s.status AS session_status"
+                " FROM leases l"
+                " JOIN work_items w ON w.work_item_id = l.work_item_id"
+                " LEFT JOIN sessions s ON s.session_id = l.session_id"
+                " ORDER BY l.expires_at DESC LIMIT ?"
+            )
+        else:
+            lease_sql = (
+                "SELECT l.lease_id, l.session_id, l.role, l.phase, l.status,"
+                " l.expires_at FROM leases l"
+                " ORDER BY l.expires_at DESC LIMIT ?"
+            )
+        lease_rows = [
+            dict(row)
+            for row in conn.execute(lease_sql, (max(1, int(limit)),)).fetchall()
+        ]
+    except sqlite3.Error as exc:
+        return _both_unavailable(f"control-plane database read failed: {exc}")
+    finally:
+        conn.close()
+
+    elapsed = (time.perf_counter() - started) * 1000.0
+    now = datetime.now(timezone.utc)
+
+    sessions = tuple(
+        scrub(
+            {
+                "session_id": row.get("session_id"),
+                "role": row.get("role"),
+                "profile": row.get("profile"),
+                "namespace": row.get("namespace"),
+                "pid": row.get("pid"),
+                "pid_alive": issue_lock_store.is_process_alive(row.get("pid")),
+                "started_at": row.get("started_at"),
+                "last_heartbeat_at": row.get("last_heartbeat_at"),
+                "status": row.get("status"),
+            }
+        )
+        for row in session_rows
+    )
+
+    leases = tuple(
+        scrub(
+            {
+                "lease_id": row.get("lease_id"),
+                "session_id": row.get("session_id"),
+                "role": row.get("role"),
+                "phase": row.get("phase"),
+                "status": row.get("status"),
+                "expires_at": row.get("expires_at"),
+                "expired": _is_expired(row.get("expires_at"), now=now),
+                "remote": row.get("remote"),
+                "org": row.get("org"),
+                "repo": row.get("repo"),
+                "work_kind": row.get("work_kind"),
+                "work_number": row.get("work_number"),
+                "work_state": row.get("work_state"),
+                "session_pid": row.get("session_pid"),
+                "session_profile": row.get("session_profile"),
+                "session_namespace": row.get("session_namespace"),
+                "session_status": row.get("session_status"),
+            }
+        )
+        for row in lease_rows
+    )
+
+    degraded_reason = (
+        None
+        if has_work_items
+        else "work_items table absent; lease rows carry no work linkage"
+    )
+    lease_status = STATUS_OK if has_work_items else STATUS_DEGRADED
+
+    return (
+        InventorySection(
+            name="sessions",
+            authority=AUTHORITY_CONTROL_PLANE_DB,
+            status=STATUS_OK,
+            items=sessions,
+            scan_ms=round(elapsed, 3),
+        ),
+        InventorySection(
+            name="leases",
+            authority=AUTHORITY_CONTROL_PLANE_DB,
+            status=lease_status,
+            items=leases,
+            reason=degraded_reason,
+            scan_ms=round(elapsed, 3),
+        ),
+    )
+
+
+def _is_expired(expires_at: str | None, *, now: datetime) -> bool | None:
+    if not expires_at:
+        return None
+    text = str(expires_at).strip().replace("Z", "+00:00")
+    try:
+        parsed = datetime.fromisoformat(text)
+    except ValueError:
+        return None
+    if parsed.tzinfo is None:
+        parsed = parsed.replace(tzinfo=timezone.utc)
+    return parsed <= now
+
+
+# ── durable issue locks (filesystem) ─────────────────────────────────────────
+
+
+def _load_locks_section(*, lock_dir: str | None = None) -> InventorySection:
+    started = time.perf_counter()
+    try:
+        paths = issue_lock_store.iter_lock_files(lock_dir)
+    except OSError as exc:
+        return InventorySection(
+            name="locks",
+            authority=AUTHORITY_FILESYSTEM,
+            status=STATUS_UNAVAILABLE,
+            reason=f"issue lock directory could not be listed: {exc}",
+        )
+
+    items: list[dict[str, Any]] = []
+    unreadable = 0
+    for path in paths:
+        try:
+            record = issue_lock_store.read_lock_file(path)
+        except (OSError, ValueError):
+            unreadable += 1
+            continue
+        if not record:
+            unreadable += 1
+            continue
+        try:
+            freshness = issue_lock_store.assess_lock_freshness(record)
+        except Exception:  # noqa: BLE001 — a read-only view never raises
+            freshness = {"status": "unknown", "live": False, "stale": False}
+        claimant = record.get("claimant") or (
+            (record.get("work_lease") or {}).get("claimant") or {}
+        )
+        items.append(
+            scrub(
+                {
+                    "issue_number": record.get("issue_number"),
+                    "branch_name": record.get("branch_name"),
+                    "remote": record.get("remote"),
+                    "org": record.get("org"),
+                    "repo": record.get("repo"),
+                    "worktree_path": record.get("worktree_path"),
+                    "pid": record.get("session_pid") or record.get("pid"),
+                    "pid_alive": issue_lock_store.is_process_alive(
+                        record.get("session_pid") or record.get("pid")
+                    ),
+                    "claimant_username": (claimant or {}).get("username"),
+                    "claimant_profile": (claimant or {}).get("profile"),
+                    "lock_generation": record.get("lock_generation"),
+                    "freshness_status": freshness.get("status"),
+                    "live": bool(freshness.get("live")),
+                    "stale": bool(freshness.get("stale")),
+                    "freshness_reason": freshness.get("reason"),
+                    "lock_path": record.get("lock_file_path") or path,
+                }
+            )
+        )
+
+    elapsed = (time.perf_counter() - started) * 1000.0
+    reason = (
+        f"{unreadable} lock file(s) were unreadable and are not represented"
+        if unreadable
+        else None
+    )
+    return InventorySection(
+        name="locks",
+        authority=AUTHORITY_FILESYSTEM,
+        status=STATUS_DEGRADED if unreadable else STATUS_OK,
+        items=tuple(items),
+        reason=reason,
+        scan_ms=round(elapsed, 3),
+    )
+
+
+# ── worktrees (filesystem, via the #432 scanner) ─────────────────────────────
+
+
+def _load_worktrees_section(
+    *, load_hygiene: Callable[[], Any] | None = None
+) -> InventorySection:
+    started = time.perf_counter()
+    try:
+        loader = load_hygiene
+        if loader is None:
+            from webui.worktree_scanner import load_hygiene_snapshot
+
+            loader = load_hygiene_snapshot
+        snapshot = loader()
+    except Exception as exc:  # noqa: BLE001 — fail soft, never fail the request
+        return InventorySection(
+            name="worktrees",
+            authority=AUTHORITY_FILESYSTEM,
+            status=STATUS_UNAVAILABLE,
+            reason=f"worktree scan failed: {exc}",
+        )
+
+    items = tuple(
+        scrub(
+            {
+                "rel_path": entry.rel_path,
+                "folder_name": entry.folder_name,
+                "classification": entry.classification,
+                "branch": entry.branch,
+                "head_sha": entry.head_sha,
+                "dirty_tracked": entry.dirty_tracked,
+                "dirty_untracked": entry.dirty_untracked,
+                "detached": entry.detached,
+                "registered_worktree": entry.registered_worktree,
+                "notes": entry.notes,
+            }
+        )
+        for entry in snapshot.entries
+    )
+    scan_error = getattr(snapshot, "scan_error", None)
+    elapsed = (time.perf_counter() - started) * 1000.0
+    return InventorySection(
+        name="worktrees",
+        authority=AUTHORITY_FILESYSTEM,
+        status=STATUS_DEGRADED if scan_error else STATUS_OK,
+        items=items,
+        reason=scan_error,
+        scan_ms=round(elapsed, 3),
+    )
+
+
+# ── namespaces / capability summary ──────────────────────────────────────────
+
+
+def _load_namespaces_section() -> InventorySection:
+    started = time.perf_counter()
+    try:
+        from gitea_auth import get_profile
+
+        profile = get_profile() or {}
+    except Exception as exc:  # noqa: BLE001
+        return InventorySection(
+            name="namespaces",
+            authority=AUTHORITY_FILESYSTEM,
+            status=STATUS_UNAVAILABLE,
+            reason=f"active profile could not be resolved: {exc}",
+        )
+
+    allowed = list(profile.get("allowed_operations") or [])
+    forbidden = list(profile.get("forbidden_operations") or [])
+    profile_name = str(profile.get("profile_name") or "")
+
+    namespace = None
+    try:
+        import role_namespace_gate
+
+        namespace = role_namespace_gate.infer_mcp_namespace(profile_name)
+    except Exception:  # noqa: BLE001 — namespace inference is advisory
+        namespace = None
+
+    item = scrub(
+        {
+            "profile_name": profile_name,
+            "role": profile.get("role"),
+            "mcp_namespace": namespace,
+            "allowed_operations": sorted(allowed),
+            "forbidden_operations": sorted(forbidden),
+            "capability_summary": {
+                "can_author": "gitea.pr.create" in allowed,
+                "can_review": "gitea.pr.approve" in allowed,
+                "can_merge": "gitea.pr.merge" in allowed,
+                "can_close_pr": "gitea.pr.close" in allowed,
+            },
+            "active": True,
+        }
+    )
+    elapsed = (time.perf_counter() - started) * 1000.0
+    return InventorySection(
+        name="namespaces",
+        authority=AUTHORITY_FILESYSTEM,
+        status=STATUS_OK,
+        items=(item,),
+        reason=(
+            "only the profile serving this web process is observable; other "
+            "namespaces are not enumerable from here"
+        ),
+        scan_ms=round(elapsed, 3),
+    )
+
+
+# ── correlation and collision detection ──────────────────────────────────────
+
+
+def _issue_from_branch(branch: str | None) -> int | None:
+    match = re.search(r"issue-(\d+)", str(branch or ""), re.IGNORECASE)
+    return int(match.group(1)) if match else None
+
+
+def correlate(
+    *,
+    leases: InventorySection,
+    locks: InventorySection,
+    worktrees: InventorySection,
+    sessions: InventorySection,
+) -> tuple[tuple[dict[str, Any], ...], tuple[CollisionSignal, ...]]:
+    """Join lease owner ↔ lock ↔ worktree ↔ namespace where evidence allows.
+
+    Correlation rows are emitted from whatever sections did load. Collision
+    signals are only emitted from sections that are ``ok``: a conflict inferred
+    from a partially-read source would be a false accusation.
+    """
+    correlations: list[dict[str, Any]] = []
+    collisions: list[CollisionSignal] = []
+
+    worktree_by_branch: dict[str, dict[str, Any]] = {}
+    for entry in worktrees.items:
+        branch = (entry.get("branch") or "").strip()
+        if branch:
+            worktree_by_branch.setdefault(branch, entry)
+
+    session_by_id = {
+        str(s.get("session_id")): s for s in sessions.items if s.get("session_id")
+    }
+
+    # Lock-centred rows: a durable lock names an issue, a branch, and a worktree.
+    for lock in locks.items:
+        branch = (lock.get("branch_name") or "").strip()
+        worktree = worktree_by_branch.get(branch)
+        matching_leases = [
+            lease
+            for lease in leases.items
+            if lease.get("work_kind") == "issue"
+            and lease.get("work_number") == lock.get("issue_number")
+        ]
+        correlations.append(
+            {
+                "issue_number": lock.get("issue_number"),
+                "branch": branch or None,
+                "lock_live": bool(lock.get("live")),
+                "lock_claimant": lock.get("claimant_profile"),
+                "lock_pid": lock.get("pid"),
+                "lock_pid_alive": lock.get("pid_alive"),
+                "worktree_rel_path": (worktree or {}).get("rel_path"),
+                "worktree_classification": (worktree or {}).get("classification"),
+                "worktree_registered": (worktree or {}).get("registered_worktree"),
+                "lease_ids": [
+                    lease.get("lease_id")
+                    for lease in matching_leases
+                    if lease.get("lease_id")
+                ],
+                "lease_sessions": [
+                    lease.get("session_id")
+                    for lease in matching_leases
+                    if lease.get("session_id")
+                ],
+            }
+        )
+
+        if locks.ok and worktrees.ok:
+            # A claim whose lease window is still open but has no registered
+            # worktree is an anomaly regardless of whether its pid is alive; a
+            # fully time-expired lease is on its way out and is not flagged.
+            if (
+                lock.get("freshness_status") != "expired"
+                and branch
+                and worktree is None
+            ):
+                collisions.append(
+                    CollisionSignal(
+                        kind="lock-without-worktree",
+                        severity="warning",
+                        issue_number=lock.get("issue_number"),
+                        branch=branch,
+                        worktree_path=lock.get("worktree_path"),
+                        message=(
+                            f"Live lock on issue #{lock.get('issue_number')} names "
+                            f"branch {branch!r} but no registered worktree carries "
+                            "that branch (#404)"
+                        ),
+                    )
+                )
+
+        if locks.ok:
+            # A lock whose recorded pid is gone is held by nobody: a clean #753
+            # dead-session recovery candidate. Subclassify by the lease window,
+            # because the two cases need different operator urgency. When the
+            # window is still open the lock would read as live to a naive
+            # timestamp check even though the owner is dead — the more dangerous
+            # case — so it is flagged distinctly from a fully time-expired lease.
+            if lock.get("pid_alive") is False and lock.get("stale"):
+                if lock.get("freshness_status") == "expired":
+                    collisions.append(
+                        CollisionSignal(
+                            kind="stale-lock-dead-owner",
+                            severity="warning",
+                            issue_number=lock.get("issue_number"),
+                            branch=branch or None,
+                            message=(
+                                f"Lock on issue #{lock.get('issue_number')} is stale "
+                                f"and its recorded pid {lock.get('pid')} is not running "
+                                "(#753 dead-session recovery candidate)"
+                            ),
+                        )
+                    )
+                else:
+                    collisions.append(
+                        CollisionSignal(
+                            kind="live-lock-dead-owner",
+                            severity="warning",
+                            issue_number=lock.get("issue_number"),
+                            branch=branch or None,
+                            message=(
+                                f"Lock on issue #{lock.get('issue_number')} has an "
+                                "unexpired lease but its recorded pid "
+                                f"{lock.get('pid')} is not running; it would read as "
+                                "live to a timestamp check (#753 dead-session recovery "
+                                "candidate)"
+                            ),
+                        )
+                    )
+            # The #635 trap: the lease has expired but the recorded pid is a
+            # still-running daemon, so neither dead-pid reclaim nor exact-owner
+            # renewal applies. This is the collision an operator must see.
+            elif (
+                lock.get("freshness_status") == "expired"
+                and lock.get("pid_alive") is True
+            ):
+                collisions.append(
+                    CollisionSignal(
+                        kind="expired-lock-live-owner",
+                        severity="error",
+                        issue_number=lock.get("issue_number"),
+                        branch=branch or None,
+                        message=(
+                            f"Lock on issue #{lock.get('issue_number')} has an expired "
+                            f"lease but its recorded pid {lock.get('pid')} is still "
+                            "running (daemon-pid deadlock; needs an operator decision, "
+                            "#635/#760)"
+                        ),
+                    )
+                )
+
+    # Two live locks on one branch, or two active leases on one work item.
+    if locks.ok:
+        by_branch: dict[str, list[dict[str, Any]]] = {}
+        for lock in locks.items:
+            if not lock.get("live"):
+                continue
+            branch = (lock.get("branch_name") or "").strip()
+            if branch:
+                by_branch.setdefault(branch, []).append(lock)
+        for branch, entries in sorted(by_branch.items()):
+            if len(entries) > 1:
+                collisions.append(
+                    CollisionSignal(
+                        kind="duplicate-live-lock",
+                        severity="error",
+                        branch=branch,
+                        message=(
+                            f"{len(entries)} live locks name branch {branch!r}: "
+                            "issues "
+                            + ", ".join(
+                                f"#{e.get('issue_number')}" for e in entries
+                            )
+                        ),
+                    )
+                )
+
+    if leases.ok:
+        by_work: dict[tuple[str, int], list[dict[str, Any]]] = {}
+        for lease in leases.items:
+            if str(lease.get("status") or "").lower() != "active":
+                continue
+            kind = str(lease.get("work_kind") or "").strip().lower()
+            number = lease.get("work_number")
+            if not kind or number is None:
+                continue
+            by_work.setdefault((kind, int(number)), []).append(lease)
+        for (kind, number), entries in sorted(by_work.items()):
+            sessions_held = {
+                str(e.get("session_id")) for e in entries if e.get("session_id")
+            }
+            if len(sessions_held) > 1:
+                collisions.append(
+                    CollisionSignal(
+                        kind="concurrent-active-lease",
+                        severity="error",
+                        issue_number=number if kind == "issue" else None,
+                        session_ids=tuple(sorted(sessions_held)),
+                        message=(
+                            f"{len(sessions_held)} sessions hold an active lease on "
+                            f"{kind} #{number}"
+                        ),
+                    )
+                )
+            for entry in entries:
+                if entry.get("expired") is True:
+                    collisions.append(
+                        CollisionSignal(
+                            kind="active-lease-past-expiry",
+                            severity="warning",
+                            issue_number=number if kind == "issue" else None,
+                            session_ids=(
+                                (str(entry.get("session_id")),)
+                                if entry.get("session_id")
+                                else ()
+                            ),
+                            message=(
+                                f"Lease {entry.get('lease_id')} on {kind} #{number} "
+                                "is still marked active past its expiry"
+                            ),
+                        )
+                    )
+
+    # A lease whose owning session is gone is an orphan, not free work.
+    if leases.ok and sessions.ok:
+        for lease in leases.items:
+            if str(lease.get("status") or "").lower() != "active":
+                continue
+            session_id = str(lease.get("session_id") or "")
+            if session_id and session_id not in session_by_id:
+                collisions.append(
+                    CollisionSignal(
+                        kind="orphan-lease",
+                        severity="error",
+                        session_ids=(session_id,),
+                        message=(
+                            f"Active lease {lease.get('lease_id')} names session "
+                            f"{session_id}, which has no session record"
+                        ),
+                    )
+                )
+
+    return tuple(correlations), tuple(collisions)
+
+
+# ── snapshot assembly ────────────────────────────────────────────────────────
+
+
+def load_inventory_snapshot(
+    *,
+    db_path: str | None = None,
+    lock_dir: str | None = None,
+    load_hygiene: Callable[[], Any] | None = None,
+    include: tuple[str, ...] | None = None,
+) -> InventorySnapshot:
+    """Build the unified inventory snapshot.
+
+    Every section is loaded independently and fails soft. *include* restricts
+    the sections that are scanned; omitted sections are simply absent rather
+    than reported as empty, so a resource-split request cannot be mistaken for
+    a whole-inventory answer.
+    """
+    started = time.perf_counter()
+    wanted = tuple(include) if include else SECTION_NAMES
+
+    sections: list[InventorySection] = []
+    sessions_section: InventorySection | None = None
+    leases_section: InventorySection | None = None
+
+    if "sessions" in wanted or "leases" in wanted:
+        sessions_section, leases_section = _load_cp_db_sections(db_path=db_path)
+        if "sessions" in wanted:
+            sections.append(sessions_section)
+        if "leases" in wanted:
+            sections.append(leases_section)
+
+    locks_section = (
+        _load_locks_section(lock_dir=lock_dir)
+        if "locks" in wanted
+        else _empty_section("locks", AUTHORITY_FILESYSTEM)
+    )
+    if "locks" in wanted:
+        sections.append(locks_section)
+
+    worktrees_section = (
+        _load_worktrees_section(load_hygiene=load_hygiene)
+        if "worktrees" in wanted
+        else _empty_section("worktrees", AUTHORITY_FILESYSTEM)
+    )
+    if "worktrees" in wanted:
+        sections.append(worktrees_section)
+
+    if "namespaces" in wanted:
+        sections.append(_load_namespaces_section())
+
+    correlations, collisions = correlate(
+        leases=leases_section or _empty_section("leases", AUTHORITY_CONTROL_PLANE_DB),
+        locks=locks_section,
+        worktrees=worktrees_section,
+        sessions=sessions_section
+        or _empty_section("sessions", AUTHORITY_CONTROL_PLANE_DB),
+    )
+
+    elapsed = (time.perf_counter() - started) * 1000.0
+    index = {section.name: section for section in sections}
+    return InventorySnapshot(
+        generated_at=datetime.now(timezone.utc).isoformat(),
+        sections=tuple(sections),
+        collisions=collisions,
+        correlations=correlations,
+        scan_ms=round(elapsed, 3),
+        _section_index=index,
+    )
+
+
+def _empty_section(name: str, authority: str) -> InventorySection:
+    """A section that was not requested — never a claim that it is empty."""
+    return InventorySection(
+        name=name,
+        authority=authority,
+        status=STATUS_UNAVAILABLE,
+        reason="section not requested in this scan",
+    )
+
+
+def snapshot_to_dict(snapshot: InventorySnapshot) -> dict[str, Any]:
+    """Serialize the snapshot for the versioned API."""
+    return {
+        "api_version": snapshot.api_version,
+        "schema_version": snapshot.schema_version,
+        "generated_at": snapshot.generated_at,
+        "status": snapshot.status,
+        "scan_ms": snapshot.scan_ms,
+        "ownership_authority_complete": snapshot.ownership_authority_complete,
+        "ownership_note": (
+            "Every ownership source read cleanly; an item absent from leases "
+            "and locks is genuinely unclaimed."
+            if snapshot.ownership_authority_complete
+            else "One or more ownership sources are degraded; nothing in this "
+            "snapshot may be treated as unowned. Collisions are reported only "
+            "from sections that read cleanly."
+        ),
+        "degraded_sections": list(snapshot.degraded_sections),
+        "field_authority": {
+            "sessions": AUTHORITY_CONTROL_PLANE_DB,
+            "leases": AUTHORITY_CONTROL_PLANE_DB,
+            "locks": AUTHORITY_FILESYSTEM,
+            "worktrees": AUTHORITY_FILESYSTEM,
+            "namespaces": AUTHORITY_FILESYSTEM,
+        },
+        "sections": {section.name: section.to_dict() for section in snapshot.sections},
+        "correlations": [dict(row) for row in snapshot.correlations],
+        "collisions": [signal.to_dict() for signal in snapshot.collisions],
+    }