Merge pull request 'feat(mcp-health): inventory and guard MCP restart/reload/kill paths (Closes #657)' (#870) from feat/issue-657-mcp-restart-path-inventory-guard into master

docs/mcp-restart-path-inventory.md

@@ -0,0 +1,90 @@
+# MCP restart / reload / kill path inventory (#657)
+
+Complete inventory of every code, script, and host path that can **restart,
+reload, reconnect, kill, or force-recreate** an MCP process in this project,
+with each path classified and linked to the guard that constrains it.
+
+This document is the human-readable companion to the machine-readable registry
+in [`mcp_restart_paths.py`](../mcp_restart_paths.py). The two are kept in
+lock-step by [`tests/test_mcp_restart_paths.py`](../tests/test_mcp_restart_paths.py):
+every `path_id` below must appear in this file, and the source guards are run
+against the live tree.
+
+Roadmap linkage: this inventory is the enumeration step of the restart
+governance work — parent **#655**, restart-governance ADR **#656**, vision
+**#652**, roadmap **#653**. Related detection/guard work: master-advance
+staleness **#591**/**#420**, side-effect-free resolver **#685**, transport flap
+**#584**, manual-kill contamination **#630**.
+
+## Classifications
+
+| Classification | Meaning |
+|---|---|
+| `sanctioned_narrow_recovery` | One-shot, safe-by-construction recovery that never targets the running daemon. |
+| `guarded_fail_closed` | Detects a restart-requiring condition, then fails mutations closed and emits reconnect guidance. Never self-restarts. |
+| `forbidden` | A workflow-safety violation; where an LLM tool could invoke it, it is marked contamination. |
+| `removed` | A previously-existing unguarded restart primitive that has been deleted; a regression guard keeps it absent. |
+| `host_residual` | Behavior owned by the host/IDE, outside this process's control. Documented, not code-guarded here. |
+
+## The rule
+
+**No component may perform an unguarded full restart of the MCP daemon.** The
+in-process daemon (`gitea_mcp_server.py`, `mcp_server.py`,
+`role_session_router.py`) must never replace or terminate its own process:
+replacing the process after the host has wired up the stdio pipes desyncs the
+JSON-RPC transport (observed with Antigravity/Cascade hosts). Recovery is owned
+by the host/operator via a client reconnect — the daemon only ever *detects*
+and *fails closed*.
+
+## Inventory
+
+| path_id | Classification | Mechanism | Guard | Refs |
+|---|---|---|---|---|
+| `cli_venv_bootstrap_execv` | sanctioned_narrow_recovery | CLI wrapper scripts re-exec into `venv/bin/python3` via `os.execv`, guarded by `sys.executable != venv_python`. | One-shot pre-import bootstrap; runs before any MCP transport exists and only when not already on the venv interpreter; idempotent guard prevents a re-exec loop. | #657 |
+| `daemon_self_replacement` | forbidden | The daemon replacing/terminating its own process (`os.execv`/`os.kill`/`os._exit`) to reload code. | Forbidden by design; enforced against the source tree by `assert_no_daemon_self_replacement()`. | #657, #584 |
+| `legacy_auto_restart_helper` | removed | A helper (`_trigger_mcp_auto_restart`) that actively restarted the server from the read-only resolver path. | Removed in #685; kept absent by `assert_auto_restart_helper_absent()`. | #685, #657 |
+| `config_touch_reload` | removed | Touching (utime) the MCP client config to make the host reload the server. | Removed from the resolver in #685: stale detection is report-only, never mutating config, spawning threads, or calling `os._exit`. | #685, #657 |
+| `master_advance_auto_restart` | guarded_fail_closed | On-disk master advancing past the running code. | `master_parity_gate` captures startup parity and blocks mutations while stale, emitting restart guidance; the process never self-restarts. | #420, #591, #657 |
+| `stale_runtime_resolver_reconnect` | guarded_fail_closed | The capability resolver detecting a stale serving process. | Report-only (#685): returns `restart_required`/`stop_required` and an exact reconnect action; no restart, thread, config touch, or `os._exit`. | #685, #657 |
+| `manual_daemon_kill` | forbidden | Shell kills of the daemon: `pkill -f mcp_server.py`, `killall`, broad `pkill -f python` sweeps, or `kill <pid>` of a daemon pid. | Forbidden (#630): `runtime_recovery_guard` classifies these as contamination and `gitea_record_daemon_process_kill_attempt` writes a durable marker that fails later mutations closed. Operator maintenance authorization is read only from the environment. | #630, #657 |
+| `conflict_marker_infra_stop` | guarded_fail_closed | The daemon entrypoint scans for unresolved merge-conflict markers at startup and stops (`sys.exit(1)`). | Fail-closed startup stop, not a restart: the process exits and waits for the operator to resolve conflicts and relaunch; never loops. | #657 |
+| `ide_client_reconnect` | host_residual | A manual `/mcp reconnect` (or equivalent host action) that recreates the MCP client connection. | Outside this process's control; the sanctioned recovery the gates point operators toward. No in-process code initiates it. | #584, #656, #657 |
+| `profile_switch_runtime` | sanctioned_narrow_recovery | Switching the active execution profile at runtime (dynamic-profile mode). | In-process and restart-free: `runtime_switching_supported` is true, so a switch rebinds capability without recreating the process. | #656, #657 |
+
+## Guards enforced in CI
+
+`tests/test_mcp_restart_paths.py` asserts, against the live source tree:
+
+1. **Registry well-formedness** — every path has a valid classification, a
+   non-empty guard description, references, and locations; ids are unique; all
+   five classifications are represented.
+2. **Unknown restart attempts fail closed** —
+   `assert_restart_attempt_registered()` raises `UnknownRestartPathError` for
+   any path id not in this inventory, so a novel/unnamed restart primitive
+   cannot slip through silently.
+3. **Daemon never self-replaces** — `assert_no_daemon_self_replacement()` scans
+   the daemon modules for `os.execv`/`os.kill`/`os._exit`/`os.abort` calls
+   (comment/docstring mentions are ignored) and finds none.
+4. **Legacy helper stays removed** — `assert_auto_restart_helper_absent()`
+   confirms `_trigger_mcp_auto_restart` has not returned.
+5. **pkill stays forbidden** — a daemon `pkill` command still classifies as
+   contamination via `runtime_recovery_guard`.
+
+## Residual host behaviors (outside process control)
+
+* `/mcp reconnect` in the IDE/host — the sanctioned recovery for stale-runtime,
+  transport-flap (#584), and worktree-binding conditions. The daemon can only
+  emit guidance toward it.
+* Host-level process management (the operator relaunching the daemon after a
+  fail-closed stop, or after resolving merge conflicts).
+
+These are documented rather than code-guarded because the process cannot
+observe or gate them from inside itself.
+
+## Rollout
+
+Per #657, guards are introduced flag-free as **regression assertions** (they
+codify invariants that already hold) before any hard runtime block is layered
+on. When the restart coordinator (#655/#656) lands, registered paths gain a
+coordinator token/capability check; unregistered attempts already fail closed
+today via `assert_restart_attempt_registered()`.

mcp_restart_paths.py

@@ -0,0 +1,475 @@
+"""Inventory and fail-closed guards for MCP restart/reload/kill paths (#657).
+
+Single source of truth enumerating every code/script/doc path that can
+restart, reload, reconnect, kill, or force-recreate an MCP process. Each path
+is classified and linked to the guard that constrains it. The companion
+human-readable inventory lives in ``docs/mcp-restart-path-inventory.md`` and is
+kept in lock-step with this module by ``tests/test_mcp_restart_paths.py``.
+
+Design intent (aligns with #655 restart-coordinator roadmap):
+
+* **No unguarded full restart.** The in-process MCP daemon
+  (``gitea_mcp_server.py`` / ``mcp_server.py`` / ``role_session_router.py``)
+  must never replace or kill its own process — replacing the process after the
+  host wired up the stdio pipes desyncs the JSON-RPC transport (observed with
+  Antigravity/Cascade hosts). ``assert_no_daemon_self_replacement`` enforces
+  this against the live source tree.
+* **No legacy auto-restart helper.** ``_trigger_mcp_auto_restart`` was removed
+  when the stale-runtime resolver became side-effect free (#685);
+  ``assert_auto_restart_helper_absent`` keeps it removed.
+* **Unknown restart attempts fail closed.** LLM tools must route any restart
+  intent through a *registered* path. ``assert_restart_attempt_registered``
+  raises ``UnknownRestartPathError`` for anything not in this inventory.
+* **pkill stays forbidden (#630).** Manual daemon kills are classified as
+  contamination by :mod:`runtime_recovery_guard`; this module records that path
+  and the test asserts the classification still holds.
+
+This module performs no restarts, spawns no threads, and touches no config or
+process state. It is pure inventory + read-only source assertions.
+"""
+
+from __future__ import annotations
+
+import os
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Iterable
+
+# --- Classifications -------------------------------------------------------
+
+#: A narrow, one-shot recovery that is safe by construction (e.g. a CLI wrapper
+#: re-execing into the venv interpreter before importing anything, or an
+#: in-process profile switch). Never targets the running MCP daemon process.
+CLASS_SANCTIONED_NARROW = "sanctioned_narrow_recovery"
+
+#: The path detects a condition that would require a restart, then *fails
+#: closed* on mutations and emits restart/reconnect guidance. It never restarts
+#: the process itself (recovery is owned by the host/operator).
+CLASS_GUARDED_FAIL_CLOSED = "guarded_fail_closed"
+
+#: The path is forbidden. Attempting it is a workflow-safety violation and,
+#: where an LLM tool could invoke it, is marked as contamination.
+CLASS_FORBIDDEN = "forbidden"
+
+#: A previously-existing unguarded restart primitive that has been deleted. A
+#: regression guard keeps it absent.
+CLASS_REMOVED = "removed"
+
+#: Behavior that lives in the host/IDE and is outside this process's control
+#: (e.g. a manual ``/mcp reconnect``). Documented, not code-guarded here.
+CLASS_HOST_RESIDUAL = "host_residual"
+
+VALID_CLASSIFICATIONS = frozenset(
+    {
+        CLASS_SANCTIONED_NARROW,
+        CLASS_GUARDED_FAIL_CLOSED,
+        CLASS_FORBIDDEN,
+        CLASS_REMOVED,
+        CLASS_HOST_RESIDUAL,
+    }
+)
+
+#: The in-process MCP daemon modules. These must never self-replace/self-kill.
+DAEMON_MODULES = (
+    "gitea_mcp_server.py",
+    "mcp_server.py",
+    "role_session_router.py",
+)
+
+#: The legacy auto-restart helper removed in #685. Must stay removed.
+LEGACY_AUTO_RESTART_HELPER = "_trigger_mcp_auto_restart"
+
+#: Call patterns that would let the daemon replace or terminate its own
+#: process. Matched as calls (trailing ``(``) so prose/docstring mentions such
+#: as "we do NOT os.execv() here" or "never calls ``os._exit``" do not trip the
+#: scanner (comment lines are stripped first regardless).
+DAEMON_SELF_REPLACEMENT_PRIMITIVES = (
+    "os.execv(",
+    "os.execve(",
+    "os.execvp(",
+    "os.execvpe(",
+    "os.kill(",
+    "os.killpg(",
+    "os._exit(",
+    "os.abort(",
+)
+
+
+@dataclass(frozen=True)
+class RestartPath:
+    """One classified restart/reload/kill path in the inventory."""
+
+    path_id: str
+    title: str
+    mechanism: str
+    classification: str
+    guard: str
+    locations: tuple[str, ...]
+    references: tuple[str, ...]
+    residual_host: bool = False
+    notes: str = ""
+
+
+class UnknownRestartPathError(RuntimeError):
+    """Raised when a restart attempt is not a registered, classified path."""
+
+
+# --- The inventory ---------------------------------------------------------
+
+_RESTART_PATHS: tuple[RestartPath, ...] = (
+    RestartPath(
+        path_id="cli_venv_bootstrap_execv",
+        title="CLI wrapper venv re-exec",
+        mechanism=(
+            "Standalone CLI scripts re-exec into venv/bin/python3 via os.execv "
+            "at import top, guarded by `sys.executable != venv_python`."
+        ),
+        classification=CLASS_SANCTIONED_NARROW,
+        guard=(
+            "One-shot, pre-import bootstrap; runs before any MCP transport "
+            "exists and only when not already on the venv interpreter, so it "
+            "cannot desync a live daemon. Idempotent guard condition prevents "
+            "a re-exec loop."
+        ),
+        locations=(
+            "create_pr.py",
+            "create_issue.py",
+            "close_issue.py",
+            "merge_pr.py",
+            "review_pr.py",
+            "edit_pr.py",
+            "delete_branch.py",
+            "mark_issue.py",
+            "manage_labels.py",
+            "list_issues.py",
+            "list_prs.py",
+        ),
+        references=("#657",),
+    ),
+    RestartPath(
+        path_id="daemon_self_replacement",
+        title="MCP daemon self-replacement",
+        mechanism=(
+            "The in-process MCP daemon replacing/terminating its own process "
+            "(os.execv/os.kill/os._exit) to reload code."
+        ),
+        classification=CLASS_FORBIDDEN,
+        guard=(
+            "Forbidden by design: replacing the process after the host wired "
+            "up stdio desyncs JSON-RPC (Antigravity/Cascade). Enforced against "
+            "the source tree by assert_no_daemon_self_replacement()."
+        ),
+        locations=("gitea_mcp_server.py:~155 (decision comment)",) + DAEMON_MODULES,
+        references=("#657", "#584"),
+    ),
+    RestartPath(
+        path_id="legacy_auto_restart_helper",
+        title="Legacy _trigger_mcp_auto_restart helper",
+        mechanism=(
+            "A helper that actively restarted the MCP server from the "
+            "read-only resolver path."
+        ),
+        classification=CLASS_REMOVED,
+        guard=(
+            "Removed in #685 when the resolver became side-effect free. Kept "
+            "absent by assert_auto_restart_helper_absent()."
+        ),
+        locations=("gitea_mcp_server.py", "mcp_server.py"),
+        references=("#685", "#657"),
+    ),
+    RestartPath(
+        path_id="config_touch_reload",
+        title="MCP client config-touch reload",
+        mechanism=(
+            "Touching (utime) the MCP client config file to make the host "
+            "reload/recreate the server process."
+        ),
+        classification=CLASS_REMOVED,
+        guard=(
+            "Removed from the resolver in #685: stale-runtime detection is "
+            "report-only and never mutates client config, spawns threads, or "
+            "calls os._exit."
+        ),
+        locations=("gitea_mcp_server.py (resolve_task_capability)",),
+        references=("#685", "#657"),
+    ),
+    RestartPath(
+        path_id="master_advance_auto_restart",
+        title="Master-advance staleness gate",
+        mechanism=(
+            "On-disk master advancing past the running code. The master-parity "
+            "gate detects it and fails mutations closed with restart guidance."
+        ),
+        classification=CLASS_GUARDED_FAIL_CLOSED,
+        guard=(
+            "Detect + fail closed only; the process never self-restarts. "
+            "master_parity_gate captures startup parity and blocks mutations "
+            "while stale, emitting restart/reconnect guidance."
+        ),
+        locations=(
+            "master_parity_gate.py",
+            "gitea_mcp_server.py (gitea_assess_master_parity)",
+        ),
+        references=("#420", "#591", "#657"),
+    ),
+    RestartPath(
+        path_id="stale_runtime_resolver_reconnect",
+        title="Stale-runtime resolver reconnect guidance",
+        mechanism=(
+            "The capability resolver detecting a stale serving process and "
+            "reporting restart_required/stop_required for a client reconnect."
+        ),
+        classification=CLASS_GUARDED_FAIL_CLOSED,
+        guard=(
+            "Report-only (#685): returns restart_required/stop_required and an "
+            "exact_safe_next_action pointing at IDE/client reconnect; performs "
+            "no restart, thread spawn, config touch, or os._exit."
+        ),
+        locations=("gitea_mcp_server.py (gitea_resolve_task_capability)",),
+        references=("#685", "#657"),
+    ),
+    RestartPath(
+        path_id="manual_daemon_kill",
+        title="Manual daemon kill (pkill/killall/kill)",
+        mechanism=(
+            "Shell kills of the MCP daemon: `pkill -f mcp_server.py`, "
+            "`killall`, broad `pkill -f python` sweeps, or `kill <pid>` of a "
+            "daemon pid."
+        ),
+        classification=CLASS_FORBIDDEN,
+        guard=(
+            "Forbidden (#630): runtime_recovery_guard classifies these as "
+            "contamination and gitea_record_daemon_process_kill_attempt writes "
+            "a durable marker that fails subsequent mutations closed. Operator "
+            "maintenance authorization is read only from the environment, not "
+            "from a tool argument."
+        ),
+        locations=(
+            "runtime_recovery_guard.py",
+            "gitea_mcp_server.py (gitea_record_daemon_process_kill_attempt)",
+        ),
+        references=("#630", "#657"),
+    ),
+    RestartPath(
+        path_id="conflict_marker_infra_stop",
+        title="Startup conflict-marker infra stop",
+        mechanism=(
+            "The daemon entrypoint scans for unresolved merge-conflict markers "
+            "at startup and stops (sys.exit(1)) if found."
+        ),
+        classification=CLASS_GUARDED_FAIL_CLOSED,
+        guard=(
+            "Fail-closed startup stop, not a restart: the process exits and "
+            "waits for the operator to resolve conflicts and relaunch. Never "
+            "self-restarts or loops."
+        ),
+        locations=("mcp_server.py (check_conflict_markers)",),
+        references=("#657",),
+    ),
+    RestartPath(
+        path_id="ide_client_reconnect",
+        title="Host/IDE MCP reconnect",
+        mechanism=(
+            "A manual `/mcp reconnect` (or equivalent host action) that the "
+            "IDE performs to recreate the MCP client connection."
+        ),
+        classification=CLASS_HOST_RESIDUAL,
+        guard=(
+            "Outside this process's control. It is the sanctioned recovery the "
+            "gates point operators toward; documented as residual host "
+            "behavior. No in-process code initiates it."
+        ),
+        locations=("host/IDE",),
+        references=("#584", "#656", "#657"),
+        residual_host=True,
+    ),
+    RestartPath(
+        path_id="profile_switch_runtime",
+        title="Runtime profile switch",
+        mechanism=(
+            "Switching the active execution profile at runtime "
+            "(dynamic-profile mode)."
+        ),
+        classification=CLASS_SANCTIONED_NARROW,
+        guard=(
+            "In-process and restart-free: runtime_switching_supported is true, "
+            "so a profile switch rebinds capability without recreating the "
+            "process. No restart primitive is invoked."
+        ),
+        locations=("gitea_mcp_server.py (gitea_activate_profile)",),
+        references=("#656", "#657"),
+    ),
+)
+
+_BY_ID: dict[str, RestartPath] = {p.path_id: p for p in _RESTART_PATHS}
+
+
+# --- Read-only accessors ---------------------------------------------------
+
+
+def iter_restart_paths() -> tuple[RestartPath, ...]:
+    """Return the full inventory as an immutable tuple."""
+
+    return _RESTART_PATHS
+
+
+def restart_path_ids() -> frozenset[str]:
+    """Return the set of registered path ids."""
+
+    return frozenset(_BY_ID)
+
+
+def get_restart_path(path_id: str) -> RestartPath:
+    """Return the registered path, or raise :class:`UnknownRestartPathError`."""
+
+    try:
+        return _BY_ID[path_id]
+    except KeyError as exc:
+        raise UnknownRestartPathError(
+            f"unknown restart path id {path_id!r}; not in the #657 inventory"
+        ) from exc
+
+
+def paths_by_classification(classification: str) -> tuple[RestartPath, ...]:
+    """Return all registered paths with the given classification."""
+
+    if classification not in VALID_CLASSIFICATIONS:
+        raise ValueError(f"unknown classification {classification!r}")
+    return tuple(p for p in _RESTART_PATHS if p.classification == classification)
+
+
+def assert_restart_attempt_registered(path_id: str) -> RestartPath:
+    """Fail closed unless ``path_id`` is a registered, classified restart path.
+
+    LLM tools that intend to trigger any restart/reload/reconnect must name a
+    registered path so an unknown/novel restart primitive cannot slip through
+    silently. Forbidden and removed paths are registered too — this only
+    asserts the attempt is *known*, not that it is *permitted*; callers must
+    still honor the classification.
+    """
+
+    return get_restart_path(path_id)
+
+
+def assert_registry_wellformed() -> None:
+    """Validate the inventory's own invariants (fail closed on drift)."""
+
+    seen: set[str] = set()
+    for path in _RESTART_PATHS:
+        if path.path_id in seen:
+            raise ValueError(f"duplicate restart path id {path.path_id!r}")
+        seen.add(path.path_id)
+        if path.classification not in VALID_CLASSIFICATIONS:
+            raise ValueError(
+                f"{path.path_id!r} has invalid classification "
+                f"{path.classification!r}"
+            )
+        if not path.guard.strip():
+            raise ValueError(f"{path.path_id!r} is missing a guard description")
+        if not path.references:
+            raise ValueError(f"{path.path_id!r} is missing references")
+        if not path.locations:
+            raise ValueError(f"{path.path_id!r} is missing locations")
+        if path.classification == CLASS_HOST_RESIDUAL and not path.residual_host:
+            raise ValueError(
+                f"{path.path_id!r} is host_residual but residual_host is False"
+            )
+
+
+# --- Source-tree guards ----------------------------------------------------
+
+
+def _repo_root(root: str | os.PathLike[str] | None = None) -> Path:
+    if root is not None:
+        return Path(root)
+    return Path(__file__).resolve().parent
+
+
+def _iter_code_lines(text: str) -> Iterable[tuple[int, str]]:
+    """Yield (1-based lineno, line) for lines that are not full-line comments."""
+
+    for lineno, line in enumerate(text.splitlines(), start=1):
+        if line.lstrip().startswith("#"):
+            continue
+        yield lineno, line
+
+
+def scan_daemon_self_replacement(
+    root: str | os.PathLike[str] | None = None,
+) -> list[dict[str, object]]:
+    """Return violations where a daemon module could self-replace/self-kill.
+
+    Scans :data:`DAEMON_MODULES` for calls in
+    :data:`DAEMON_SELF_REPLACEMENT_PRIMITIVES`. Full-line comments are ignored,
+    and only call forms (with a trailing ``(``) match, so decision comments and
+    docstrings that merely mention the primitives do not produce false hits.
+    """
+
+    repo = _repo_root(root)
+    violations: list[dict[str, object]] = []
+    for module in DAEMON_MODULES:
+        path = repo / module
+        if not path.exists():
+            continue
+        text = path.read_text(encoding="utf-8", errors="replace")
+        for lineno, line in _iter_code_lines(text):
+            for primitive in DAEMON_SELF_REPLACEMENT_PRIMITIVES:
+                if primitive in line:
+                    violations.append(
+                        {
+                            "module": module,
+                            "line": lineno,
+                            "primitive": primitive,
+                            "text": line.strip(),
+                        }
+                    )
+    return violations
+
+
+def assert_no_daemon_self_replacement(
+    root: str | os.PathLike[str] | None = None,
+) -> None:
+    """Fail closed if any daemon module can restart/kill its own process."""
+
+    violations = scan_daemon_self_replacement(root)
+    if violations:
+        rendered = "; ".join(
+            f"{v['module']}:{v['line']} {v['primitive']}" for v in violations
+        )
+        raise AssertionError(
+            "MCP daemon must never self-replace/self-kill (#657); found: "
+            f"{rendered}"
+        )
+
+
+def scan_auto_restart_helper(
+    root: str | os.PathLike[str] | None = None,
+) -> list[dict[str, object]]:
+    """Return occurrences of a *definition* of the legacy auto-restart helper."""
+
+    repo = _repo_root(root)
+    needle = f"def {LEGACY_AUTO_RESTART_HELPER}"
+    hits: list[dict[str, object]] = []
+    for module in DAEMON_MODULES:
+        path = repo / module
+        if not path.exists():
+            continue
+        text = path.read_text(encoding="utf-8", errors="replace")
+        for lineno, line in _iter_code_lines(text):
+            if needle in line:
+                hits.append({"module": module, "line": lineno})
+    return hits
+
+
+def assert_auto_restart_helper_absent(
+    root: str | os.PathLike[str] | None = None,
+) -> None:
+    """Fail closed if the removed ``_trigger_mcp_auto_restart`` reappears."""
+
+    hits = scan_auto_restart_helper(root)
+    if hits:
+        rendered = "; ".join(f"{h['module']}:{h['line']}" for h in hits)
+        raise AssertionError(
+            f"{LEGACY_AUTO_RESTART_HELPER} was removed in #685 and must not "
+            f"return (#657); found definition at: {rendered}"
+        )

tests/test_mcp_restart_paths.py

@@ -0,0 +1,146 @@
+"""Tests for the MCP restart-path inventory and guards (#657).
+
+Covers:
+* the registry is well-formed and every path is classified;
+* unknown restart attempts fail closed (AC "fail closed on unknown restart");
+* the previously-unguarded full-restart primitives stay guarded/absent
+  against the real source tree (AC "tests for at least one previously
+  unguarded path");
+* pkill of the daemon is still classified as contamination (#630, AC3);
+* the inventory doc and module stay in lock-step.
+"""
+
+import os
+import tempfile
+import unittest
+from pathlib import Path
+
+import mcp_restart_paths as rp
+import runtime_recovery_guard
+
+REPO_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+DOC_PATH = os.path.join(REPO_ROOT, "docs", "mcp-restart-path-inventory.md")
+
+
+class TestRegistryWellformed(unittest.TestCase):
+    def test_registry_is_wellformed(self):
+        # Must not raise.
+        rp.assert_registry_wellformed()
+
+    def test_every_path_has_valid_classification(self):
+        for path in rp.iter_restart_paths():
+            self.assertIn(path.classification, rp.VALID_CLASSIFICATIONS)
+            self.assertTrue(path.guard.strip(), path.path_id)
+            self.assertTrue(path.references, path.path_id)
+            self.assertTrue(path.locations, path.path_id)
+
+    def test_ids_are_unique(self):
+        ids = [p.path_id for p in rp.iter_restart_paths()]
+        self.assertEqual(len(ids), len(set(ids)))
+
+    def test_covers_every_classification(self):
+        present = {p.classification for p in rp.iter_restart_paths()}
+        self.assertEqual(present, set(rp.VALID_CLASSIFICATIONS))
+
+
+class TestUnknownAttemptFailsClosed(unittest.TestCase):
+    def test_unknown_path_raises(self):
+        with self.assertRaises(rp.UnknownRestartPathError):
+            rp.assert_restart_attempt_registered("totally_novel_restart_hack")
+
+    def test_get_unknown_raises(self):
+        with self.assertRaises(rp.UnknownRestartPathError):
+            rp.get_restart_path("nope")
+
+    def test_registered_attempt_returns_path(self):
+        path = rp.assert_restart_attempt_registered("manual_daemon_kill")
+        self.assertEqual(path.classification, rp.CLASS_FORBIDDEN)
+
+
+class TestDaemonNeverSelfReplaces(unittest.TestCase):
+    """Previously-unguarded full-restart primitive: daemon self-replacement."""
+
+    def test_no_self_replacement_in_source(self):
+        # The live daemon modules must contain no os.execv/os.kill/os._exit
+        # self-restart call. Must not raise.
+        rp.assert_no_daemon_self_replacement(REPO_ROOT)
+
+    def test_scanner_flags_injected_violation(self):
+        # Guard the guard: prove the scanner catches a real self-replace call.
+        with tempfile.TemporaryDirectory() as tmp:
+            bad = Path(tmp) / "gitea_mcp_server.py"
+            bad.write_text(
+                "import os\n"
+                "def restart():\n"
+                "    os.execv('/usr/bin/python', ['python'])\n",
+                encoding="utf-8",
+            )
+            found = rp.scan_daemon_self_replacement(tmp)
+            self.assertTrue(found)
+            with self.assertRaises(AssertionError):
+                rp.assert_no_daemon_self_replacement(tmp)
+
+    def test_scanner_ignores_comment_and_docstring_mentions(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            ok = Path(tmp) / "gitea_mcp_server.py"
+            ok.write_text(
+                "import os\n"
+                "# NOT os.execv() to re-point the interpreter here.\n"
+                '"""Never calls os._exit to restart."""\n'
+                "value = 1\n",
+                encoding="utf-8",
+            )
+            self.assertEqual(rp.scan_daemon_self_replacement(tmp), [])
+
+
+class TestLegacyAutoRestartHelperRemoved(unittest.TestCase):
+    """Previously-unguarded full-restart path: _trigger_mcp_auto_restart."""
+
+    def test_helper_absent_in_source(self):
+        # Must not raise: helper was removed in #685.
+        rp.assert_auto_restart_helper_absent(REPO_ROOT)
+
+    def test_scanner_flags_reintroduced_helper(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            bad = Path(tmp) / "mcp_server.py"
+            bad.write_text(
+                "def _trigger_mcp_auto_restart():\n    return True\n",
+                encoding="utf-8",
+            )
+            with self.assertRaises(AssertionError):
+                rp.assert_auto_restart_helper_absent(tmp)
+
+
+class TestPkillStaysForbidden(unittest.TestCase):
+    """AC3: pkill of the daemon remains forbidden/contaminating (#630)."""
+
+    def test_manual_daemon_kill_registered_as_forbidden(self):
+        path = rp.get_restart_path("manual_daemon_kill")
+        self.assertEqual(path.classification, rp.CLASS_FORBIDDEN)
+
+    def test_pkill_classified_as_contamination(self):
+        assessment = runtime_recovery_guard.assess_recovery_command(
+            "pkill -f mcp_server.py"
+        )
+        self.assertTrue(assessment["contaminated"])
+
+    def test_read_only_probe_not_contamination(self):
+        assessment = runtime_recovery_guard.assess_recovery_command(
+            "ps aux | grep mcp_server"
+        )
+        self.assertFalse(assessment["contaminated"])
+
+
+class TestInventoryDocInSync(unittest.TestCase):
+    def test_doc_exists(self):
+        self.assertTrue(os.path.exists(DOC_PATH), DOC_PATH)
+
+    def test_doc_mentions_every_path_id(self):
+        with open(DOC_PATH, encoding="utf-8") as handle:
+            doc = handle.read()
+        for path in rp.iter_restart_paths():
+            self.assertIn(path.path_id, doc, f"doc missing {path.path_id}")
+
+
+if __name__ == "__main__":
+    unittest.main()