Merge master into feat/issue-663-restart-classes (resolve #886 conflict)

Brings PR #886 up to date with master @ 2f4dec8323
(8 commits behind), resolving the single conflicted file.

Conflict: gitea_mcp_server.py, both hunks inside gitea_request_mcp_restart.
Both sides were purely additive to the same tool, so both are kept in full:

- Branch side (#663, restart classes): parameters restart_class,
  target_session_id, target_role, target_connector; payload keys
  controller_approval_authorized, requester_role, requester_permissions.
- Master side (#661 via PR #882, drain-proof hard gate): parameters
  drain_proof_json, request_break_glass; the explanatory comment describing
  the apply-path hard gate and break-glass authorization.

No behaviour from either side was dropped, reordered, or reimplemented. Every
parameter from both sides is already consumed by the auto-merged function body
(restart_class and the three target_* arguments flow into the coordinator call;
drain_proof_json and request_break_glass drive the dry_run=False hard gate), so
the union is the only resolution that keeps the merged function coherent.

Validation on the merged tree:

  python -m pytest tests/test_drain_proof.py tests/test_restart_classes.py \
    tests/test_restart_coordinator.py tests/test_mcp_restart_paths.py \
    tests/test_mcp_restart_governance_docs.py tests/test_webui_sanctioned_restart.py \
    tests/test_issue_662_post_restart_reconcile.py -q
  # 165 passed, 68 subtests passed

py_compile on gitea_mcp_server.py passes and no conflict markers remain.

Closes #663

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

docs/mcp-restart-classes.md

@@ -0,0 +1,53 @@
+# MCP restart classes and blast-radius permissions (#663)
+
+This is the machine-enforced class matrix used by
+`restart_coordinator.RESTART_CLASS_POLICIES`. It implements the narrower-first
+recovery ladder from #655 and the authorization policy from #656, using the
+path inventory from #657 and the impact coordinator from #658. Product and
+delivery lineage: vision #652 and roadmap #653.
+
+Unknown class names are denied. The coordinator requires both the class
+permission and an eligible request role. Approval gates are additional: a
+caller cannot turn a request permission into execution authority.
+
+| Restart class | Required permission | Expected blast radius | Drain requirement | Approval requirement | Audit requirement | Recovery behavior |
+|---|---|---|---|---|---|---|
+| `client_reconnect` | `mcp.reconnect.client` | none | none | self service | class, actor, client namespace, reason, outcome | Reconnect only the caller's client transport. No daemon or peer work changes. |
+| `session_reconnect` | `mcp.reconnect.session` | low | requesting-session safe point | self service | class, actor, session, reason, outcome | Rebind identity, capability, and workspace state for one session. |
+| `worker_restart` | `mcp.restart.worker.request` | low | target worker | controller approval + automated gates | class, actor, worker, approval, scoped drain, outcome | Restart one worker after its own leases and mutations drain. |
+| `role_runtime_restart` | `mcp.restart.role_runtime.request` | medium | target role runtime | controller approval + automated gates | class, actor, role namespace, approval, scoped drain, outcome | Restart and re-probe one role runtime; unrelated roles remain available. |
+| `connector_restart` | `mcp.restart.connector.request` | medium | target connector | controller approval + automated gates | class, actor, connector, approval, scoped drain, outcome | Restart one connector while unrelated runtimes remain available. |
+| `configuration_reload` | `mcp.reload.configuration.request` | low | mutation quiesce | controller approval + automated gates | class, actor, configuration revision, approval, outcome | Gracefully reload configuration without replacing the daemon. |
+| `rolling_mcp_restart` | `mcp.restart.rolling.request` | medium | one instance at a time | controller approval + automated gates | class, actor, instance order, approval, per-instance drains, outcome | Drain, restart, verify, and restore each instance before advancing. |
+| `full_mcp_restart` | `mcp.restart.full.request` | high | all sessions and mutations | controller approval + automated gates | class, actor, full impact, approval, full drain proof, outcome | Replace the complete MCP runtime only after a verified full drain. |
+| `host_restart` | `mcp.restart.host.request` | high | all host work | controller approval + infrastructure operator | class, actor, host/change or incident id, approval, full drain proof, outcome | Hand off to infrastructure ownership and reconcile every runtime afterward. |
+
+## Drain boundary
+
+Only `full_mcp_restart` and `host_restart` set `full_drain_required=true`.
+Reconnects and configuration reloads do not disrupt peer sessions. Worker,
+role-runtime, and connector restarts evaluate only their explicitly named
+target. Rolling restart drains one instance at a time. Missing required target
+scope denies the request rather than silently widening it to a full restart.
+
+## Permission and approval boundary
+
+Author, reviewer, merger, and reconciler roles may self-request reconnects and
+request scoped worker/role/connector/reload recovery. They cannot request
+rolling, full, or host restart classes. Controller/operator/admin roles may
+request the broader classes, while execution remains operator/admin-owned.
+Controller approval is independently required for every class above a session
+reconnect. Host restart additionally requires infrastructure-operator proof.
+
+The MCP request tool derives class permissions from its authenticated runtime
+role. It does not accept caller-supplied permissions. Controller and operator
+authorization are read from the already-running daemon environment, never
+from a request argument.
+
+## Audit and failure behavior
+
+Every impact audit and every console restart/reload audit includes a
+`restart_class` field. The impact audit also includes the exact
+`required_permission`. Unknown classes, missing permissions, ineligible roles,
+missing approval, missing scoped targets, and incomplete inventory all deny
+fail closed. Manual process kills remain forbidden and contaminating (#630).

docs/mcp-restart-coordinator.md

@@ -12,6 +12,12 @@ restart/reload/kill paths). The **mutative apply** path — actually performing
 restart — is a later child gated by a drain proof and is explicitly out of
 scope here.
 
+The coordinator now routes every request through the restart-class policy
+matrix defined for #663. See
+[`mcp-restart-classes.md`](./mcp-restart-classes.md) for permissions, expected
+blast radius, scoped drain and approval requirements, audit fields, and
+recovery behavior for all nine classes.
+
 ## Components
 
 | Piece | Where | Responsibility |
@@ -77,7 +83,10 @@ authorization is present.
 ```text
 gitea_request_mcp_restart(remote, host, org, repo,
                           dry_run=True, request_override=False,
-                          session_id=None, limit=200)
+                          session_id=None, limit=200,
+                          restart_class="full_mcp_restart",
+                          target_session_id=None, target_role=None,
+                          target_connector=None)
 ```
 
 Read-only, dry-run, and it **never restarts anything**. `apply_supported` is
@@ -87,7 +96,8 @@ apply is gated by a drain proof (a separate child).
 ## Audit
 
 Every evaluation carries an `audit_record` (event, coordinator version, verdict,
-allow decision, blast radius, counts, timestamp) so restart decisions are
+restart class, required permission, allow decision, blast radius, counts,
+timestamp) so restart decisions are
 auditable. No secrets flow through the coordinator — session ids, pids, and
 profiles are operational metadata only.
 

gitea_mcp_server.py

@@ -2068,6 +2068,7 @@ import lease_lifecycle  # noqa: E402
 import lease_policy  # noqa: E402
 import workflow_dashboard  # noqa: E402  # #605 live queue/lease dashboard
 import restart_coordinator  # noqa: E402  # #658 MCP restart coordinator/impact
+import drain_proof  # noqa: E402  # #661 pre-restart drain proof and hard gate
 import incident_bridge  # noqa: E402
 import sentry_observability  # noqa: E402  (#606 optional Sentry observability)
 import sentry_incident_bridge  # noqa: E402  (#607 Sentry→Gitea incident bridge)
@@ -22342,19 +22343,31 @@ def gitea_request_mcp_restart(
     request_override: bool = False,
     session_id: str | None = None,
     limit: int = 200,
+    restart_class: str = "full_mcp_restart",
+    target_session_id: str | None = None,
+    target_role: str | None = None,
+    target_connector: str | None = None,
+    drain_proof_json: str | None = None,
+    request_break_glass: bool = False,
 ) -> dict:
     """Evaluate a proposed MCP restart and return an impact preview (#658).
 
-    Central restart coordinator: gathers live control-plane state (sessions,
+    Central restart coordinator: resolves the requested restart class, gathers
+    live control-plane state (sessions,
     leases/locks, in-flight issue/PR work, mutations, worktrees) and returns a
     blast-radius impact report with a ``safe`` / ``unsafe`` / ``override``
     verdict, so the console (#642/#652) and operators can see what a restart
     would disrupt *before* any concurrent LLM work is destroyed.
 
-    This tool is **dry-run and never restarts anything.** The mutative apply
-    path is a separate child gated by a drain proof (non-goal here); calling
-    with ``dry_run=False`` still performs no restart and reports that apply is
-    not yet available.
+    This tool **never restarts a process.** In dry-run (the default) it returns
+    only the impact preview. With ``dry_run=False`` it enforces the #661 hard
+    gate: the apply request must present a valid, unexpired, clean drain proof
+    (``drain_proof_json``) or it is denied and a durable incident descriptor is
+    returned under ``incident``. Break-glass is the only bypass and is honoured
+    only when ``request_break_glass`` is set *and* the environment carries
+    ``GITEA_BREAKGLASS_RESTART_AUTHORIZATION``. Even an authorized gate performs
+    no restart here; actual execution is a further child. The gate outcome is
+    reported under ``apply_gate`` / ``apply_authorized``.
 
     Operator override authority is read from the process environment
     (``GITEA_OPERATOR_RESTART_OVERRIDE_AUTHORIZATION``), never self-asserted by
@@ -22439,6 +22452,9 @@ def gitea_request_mcp_restart(
 
     profile = get_profile()
     profile_name = (profile.get("profile_name") or "").strip() or "session"
+    requester_role = (
+        profile.get("role_kind") or profile.get("role") or ""
+    ).strip().lower()
     sid = (session_id or "").strip() or f"{profile_name}-{os.getpid()}"
 
     # Override authority is read from the environment only — a worker session
@@ -22448,6 +22464,15 @@ def gitea_request_mcp_restart(
         (os.environ.get("GITEA_OPERATOR_RESTART_OVERRIDE_AUTHORIZATION") or "").strip()
     )
     operator_override = bool(request_override and operator_authorized)
+    controller_approved = bool(
+        (
+            os.environ.get("GITEA_CONTROLLER_RESTART_APPROVAL_AUTHORIZATION")
+            or ""
+        ).strip()
+    )
+    requester_permissions = restart_coordinator.permissions_for_role(
+        requester_role
+    )
 
     inventory = {
         "sessions": sessions,
@@ -22462,6 +22487,14 @@ def gitea_request_mcp_restart(
         operator_override=operator_override,
         requesting_session_id=sid,
         dry_run=True,  # coordinator is always analysis-only (#658)
+        restart_class=restart_class,
+        requester_role=requester_role,
+        requester_permissions=requester_permissions,
+        controller_approved=controller_approved,
+        operator_authorized=operator_authorized,
+        target_session_id=target_session_id,
+        target_role=target_role,
+        target_connector=target_connector,
     )
 
     payload = report.as_dict()
@@ -22473,12 +22506,57 @@ def gitea_request_mcp_restart(
     payload["requesting_session_id"] = sid
     payload["operator_override_requested"] = bool(request_override)
     payload["operator_override_authorized"] = operator_authorized
+    payload["controller_approval_authorized"] = controller_approved
+    payload["requester_role"] = requester_role
+    payload["requester_permissions"] = list(requester_permissions)
+    # Actual restart execution remains a further child; this tool never restarts
+    # a process. What #661 adds is the *hard gate*: an apply request (dry_run
+    # False) must present a valid, unexpired, clean drain proof, or it is denied
+    # and a durable incident is raised. Break-glass is the only bypass and its
+    # authorization is read from the environment, never self-asserted.
     payload["apply_supported"] = False
     if not dry_run:
-        payload["reasons"] = list(payload.get("reasons") or []) + [
-            "apply requested but not supported: sanctioned restart apply is "
-            "gated by a drain proof (separate child); no restart performed (#658)"
-        ]
+        proof_obj: dict | None = None
+        proof_parse_error: str | None = None
+        if drain_proof_json:
+            try:
+                parsed = json.loads(drain_proof_json)
+                proof_obj = parsed if isinstance(parsed, dict) else None
+                if proof_obj is None:
+                    proof_parse_error = "drain_proof_json is not a JSON object"
+            except (ValueError, TypeError) as exc:
+                proof_parse_error = f"invalid drain_proof_json: {_redact(str(exc))}"
+
+        break_glass_authorized = bool(
+            (
+                os.environ.get("GITEA_BREAKGLASS_RESTART_AUTHORIZATION") or ""
+            ).strip()
+        )
+        break_glass = bool(request_break_glass and break_glass_authorized)
+
+        expected_fp = drain_proof.impact_fingerprint(report.as_dict())
+        gate = drain_proof.gate_apply_restart(
+            proof=proof_obj,
+            break_glass=break_glass,
+            expected_impact_fingerprint=expected_fp,
+            requesting_session_id=sid,
+        )
+        gate_payload = gate.as_dict()
+        if proof_parse_error and not break_glass:
+            gate_payload["reasons"] = [proof_parse_error] + list(
+                gate_payload.get("reasons") or []
+            )
+        payload["apply_gate"] = gate_payload
+        payload["apply_authorized"] = gate.allow
+        payload["break_glass_requested"] = bool(request_break_glass)
+        payload["break_glass_authorized"] = break_glass_authorized
+        # Even an authorized gate performs no restart here: execution is a later
+        # child. The gate proves the apply path *would* be permitted.
+        payload["reasons"] = list(payload.get("reasons") or []) + list(
+            gate_payload.get("reasons") or []
+        )
+        if not gate.allow and gate.incident is not None:
+            payload["incident"] = gate.incident
     return payload
 
 

restart_coordinator.py

@@ -28,11 +28,12 @@ from __future__ import annotations
 
 from dataclasses import dataclass, field
 from datetime import datetime, timezone
+from enum import Enum
 from typing import Any, Mapping, Sequence
 
 import lease_lifecycle
 
-COORDINATOR_VERSION = "1.0.0-issue-658"
+COORDINATOR_VERSION = "1.1.0-issue-663"
 
 # Restart verdicts. Exactly the three the acceptance criteria name.
 VERDICT_SAFE = "safe"
@@ -54,6 +55,194 @@ LEASE_FRESHNESS_LIVE = "active"
 DEFAULT_SESSION_HEARTBEAT_STALE_SECONDS = 900
 
 
+class RestartClass(str, Enum):
+    """The only restart/recovery classes accepted by the coordinator."""
+
+    CLIENT_RECONNECT = "client_reconnect"
+    SESSION_RECONNECT = "session_reconnect"
+    WORKER_RESTART = "worker_restart"
+    ROLE_RUNTIME_RESTART = "role_runtime_restart"
+    CONNECTOR_RESTART = "connector_restart"
+    CONFIGURATION_RELOAD = "configuration_reload"
+    ROLLING_MCP_RESTART = "rolling_mcp_restart"
+    FULL_MCP_RESTART = "full_mcp_restart"
+    HOST_RESTART = "host_restart"
+
+
+@dataclass(frozen=True)
+class RestartClassPolicy:
+    """Least-privilege policy for one :class:`RestartClass`."""
+
+    restart_class: RestartClass
+    required_permission: str
+    expected_blast_radius: str
+    drain_requirement: str
+    full_drain_required: bool
+    approval_requirement: str
+    audit_requirement: str
+    recovery_behavior: str
+    request_roles: tuple[str, ...]
+    execution_roles: tuple[str, ...]
+
+    def as_dict(self) -> dict[str, Any]:
+        return {
+            "restart_class": self.restart_class.value,
+            "required_permission": self.required_permission,
+            "expected_blast_radius": self.expected_blast_radius,
+            "drain_requirement": self.drain_requirement,
+            "full_drain_required": self.full_drain_required,
+            "approval_requirement": self.approval_requirement,
+            "audit_requirement": self.audit_requirement,
+            "recovery_behavior": self.recovery_behavior,
+            "request_roles": list(self.request_roles),
+            "execution_roles": list(self.execution_roles),
+        }
+
+
+WORKER_ROLES = ("author", "reviewer", "merger", "reconciler")
+CONTROL_ROLES = ("controller", "operator", "admin")
+ALL_REQUEST_ROLES = WORKER_ROLES + CONTROL_ROLES
+
+RESTART_CLASS_POLICIES: dict[RestartClass, RestartClassPolicy] = {
+    RestartClass.CLIENT_RECONNECT: RestartClassPolicy(
+        RestartClass.CLIENT_RECONNECT,
+        "mcp.reconnect.client",
+        BLAST_NONE,
+        "none",
+        False,
+        "self_service",
+        "record class, actor, client namespace, reason, and outcome",
+        "Reconnect only the caller's client transport; no daemon or peer session changes.",
+        ALL_REQUEST_ROLES,
+        ALL_REQUEST_ROLES,
+    ),
+    RestartClass.SESSION_RECONNECT: RestartClassPolicy(
+        RestartClass.SESSION_RECONNECT,
+        "mcp.reconnect.session",
+        BLAST_LOW,
+        "requesting_session_safe_point",
+        False,
+        "self_service",
+        "record class, actor, session id, reason, and outcome",
+        "Rebind identity, capability, and workspace state for one session.",
+        ALL_REQUEST_ROLES,
+        ALL_REQUEST_ROLES,
+    ),
+    RestartClass.WORKER_RESTART: RestartClassPolicy(
+        RestartClass.WORKER_RESTART,
+        "mcp.restart.worker.request",
+        BLAST_LOW,
+        "target_worker",
+        False,
+        "controller_approval_and_automated_gates",
+        "record class, actor, target worker, approval, drain proof, and outcome",
+        "Restart one worker after its own lease and mutation scope is drained.",
+        ALL_REQUEST_ROLES,
+        ("operator", "admin"),
+    ),
+    RestartClass.ROLE_RUNTIME_RESTART: RestartClassPolicy(
+        RestartClass.ROLE_RUNTIME_RESTART,
+        "mcp.restart.role_runtime.request",
+        BLAST_MEDIUM,
+        "target_role_runtime",
+        False,
+        "controller_approval_and_automated_gates",
+        "record class, actor, role namespace, approval, drain proof, and outcome",
+        "Restart only the selected role runtime and then re-probe that namespace.",
+        ALL_REQUEST_ROLES,
+        ("operator", "admin"),
+    ),
+    RestartClass.CONNECTOR_RESTART: RestartClassPolicy(
+        RestartClass.CONNECTOR_RESTART,
+        "mcp.restart.connector.request",
+        BLAST_MEDIUM,
+        "target_connector",
+        False,
+        "controller_approval_and_automated_gates",
+        "record class, actor, connector id, approval, drain proof, and outcome",
+        "Restart one connector while unrelated role runtimes remain available.",
+        ALL_REQUEST_ROLES,
+        ("operator", "admin"),
+    ),
+    RestartClass.CONFIGURATION_RELOAD: RestartClassPolicy(
+        RestartClass.CONFIGURATION_RELOAD,
+        "mcp.reload.configuration.request",
+        BLAST_LOW,
+        "mutation_quiesce",
+        False,
+        "controller_approval_and_automated_gates",
+        "record class, actor, configuration revision, approval, and outcome",
+        "Gracefully reload configuration without replacing the daemon process.",
+        ALL_REQUEST_ROLES,
+        ("operator", "admin"),
+    ),
+    RestartClass.ROLLING_MCP_RESTART: RestartClassPolicy(
+        RestartClass.ROLLING_MCP_RESTART,
+        "mcp.restart.rolling.request",
+        BLAST_MEDIUM,
+        "one_instance_at_a_time",
+        False,
+        "controller_approval_and_automated_gates",
+        "record class, actor, instance order, approval, per-instance drains, and outcome",
+        "Drain, restart, verify, and restore one instance before advancing to the next.",
+        CONTROL_ROLES,
+        ("operator", "admin"),
+    ),
+    RestartClass.FULL_MCP_RESTART: RestartClassPolicy(
+        RestartClass.FULL_MCP_RESTART,
+        "mcp.restart.full.request",
+        BLAST_HIGH,
+        "all_sessions_and_mutations",
+        True,
+        "controller_approval_and_automated_gates",
+        "record class, actor, full impact report, approval, drain proof, and outcome",
+        "Stop and restore the complete MCP runtime only after a verified full drain.",
+        CONTROL_ROLES,
+        ("operator", "admin"),
+    ),
+    RestartClass.HOST_RESTART: RestartClassPolicy(
+        RestartClass.HOST_RESTART,
+        "mcp.restart.host.request",
+        BLAST_HIGH,
+        "all_host_work",
+        True,
+        "controller_approval_plus_infrastructure_operator",
+        "record class, actor, host, incident or change id, approval, drain proof, and outcome",
+        "Hand off to infrastructure ownership; reconcile every runtime after the host returns.",
+        ("controller", "operator", "admin"),
+        ("operator", "admin"),
+    ),
+}
+
+
+def resolve_restart_class(value: RestartClass | str) -> RestartClass:
+    """Resolve a restart class or fail closed for an unknown value."""
+
+    if isinstance(value, RestartClass):
+        return value
+    try:
+        return RestartClass(str(value).strip())
+    except ValueError as exc:
+        raise ValueError(f"unknown restart class {value!r}; deny (fail closed)") from exc
+
+
+def restart_class_policy(value: RestartClass | str) -> RestartClassPolicy:
+    """Return the canonical policy for *value*."""
+
+    return RESTART_CLASS_POLICIES[resolve_restart_class(value)]
+
+
+def permissions_for_role(role: str | None) -> tuple[str, ...]:
+    """Return request permissions granted to a workflow role by this policy."""
+
+    normalized = str(role or "").strip().lower()
+    return tuple(
+        policy.required_permission
+        for policy in RESTART_CLASS_POLICIES.values()
+        if normalized in policy.request_roles
+    )
+
+
 def _utc_now() -> datetime:
     return datetime.now(timezone.utc)
 
@@ -75,6 +264,7 @@ class SessionImpact:
     heartbeat_stale: bool
     is_requester: bool
     live: bool
+    connector: str | None = None
 
     def as_dict(self) -> dict[str, Any]:
         return {
@@ -87,6 +277,7 @@ class SessionImpact:
             "heartbeat_stale": self.heartbeat_stale,
             "is_requester": self.is_requester,
             "live": self.live,
+            "connector": self.connector,
         }
 
 
@@ -105,6 +296,7 @@ class LeaseImpact:
     disruptive: bool
     is_mutation: bool
     is_critical_section: bool
+    connector: str | None = None
 
     def as_dict(self) -> dict[str, Any]:
         return {
@@ -119,6 +311,7 @@ class LeaseImpact:
             "disruptive": self.disruptive,
             "is_mutation": self.is_mutation,
             "is_critical_section": self.is_critical_section,
+            "connector": self.connector,
         }
 
 
@@ -127,6 +320,13 @@ class RestartImpactReport:
     """Impact preview DTO returned to the console / operator (#642/#652)."""
 
     coordinator_version: str
+    restart_class: str
+    restart_policy: dict[str, Any]
+    policy_enforced: bool
+    permission_authorized: bool
+    role_authorized: bool
+    approval_satisfied: bool
+    authorization_reasons: list[str]
     evaluated_at: str
     dry_run: bool
     restart_performed: bool
@@ -153,6 +353,13 @@ class RestartImpactReport:
     def as_dict(self) -> dict[str, Any]:
         return {
             "coordinator_version": self.coordinator_version,
+            "restart_class": self.restart_class,
+            "restart_policy": dict(self.restart_policy),
+            "policy_enforced": self.policy_enforced,
+            "permission_authorized": self.permission_authorized,
+            "role_authorized": self.role_authorized,
+            "approval_satisfied": self.approval_satisfied,
+            "authorization_reasons": list(self.authorization_reasons),
             "evaluated_at": self.evaluated_at,
             "dry_run": self.dry_run,
             "restart_performed": self.restart_performed,
@@ -206,6 +413,7 @@ def _classify_session(
             requesting_session_id and session_id == requesting_session_id
         ),
         live=live,
+        connector=(str(row.get("connector") or "").strip() or None),
     )
 
 
@@ -258,6 +466,7 @@ def _classify_lease(row: Mapping[str, Any]) -> LeaseImpact:
         disruptive=disruptive,
         is_mutation=is_mutation,
         is_critical_section=disruptive,
+        connector=(str(row.get("connector") or "").strip() or None),
     )
 
 
@@ -279,6 +488,14 @@ def evaluate_restart_impact(
     requesting_session_id: str | None = None,
     dry_run: bool = True,
     session_heartbeat_stale_seconds: int = DEFAULT_SESSION_HEARTBEAT_STALE_SECONDS,
+    restart_class: RestartClass | str | None = None,
+    requester_role: str | None = None,
+    requester_permissions: Sequence[str] | None = None,
+    controller_approved: bool = False,
+    operator_authorized: bool = False,
+    target_session_id: str | None = None,
+    target_role: str | None = None,
+    target_connector: str | None = None,
 ) -> RestartImpactReport:
     """Evaluate a proposed MCP restart and return an impact preview.
 
@@ -301,6 +518,61 @@ def evaluate_restart_impact(
     """
     moment = now or _utc_now()
     reasons: list[str] = []
+    authorization_reasons: list[str] = []
+
+    # ``None`` preserves the pre-#663 impact-only API for callers that have not
+    # yet been migrated. All MCP requests pass an explicit class and therefore
+    # take the fail-closed policy path.
+    policy_enforced = restart_class is not None
+    try:
+        resolved_class = resolve_restart_class(
+            restart_class or RestartClass.FULL_MCP_RESTART
+        )
+        policy = RESTART_CLASS_POLICIES[resolved_class]
+        unknown_class = False
+    except ValueError as exc:
+        resolved_class = None
+        policy = None
+        unknown_class = True
+        authorization_reasons.append(str(exc))
+
+    normalized_role = str(requester_role or "").strip().lower()
+    granted = {str(p).strip() for p in (requester_permissions or ())}
+    if policy_enforced and policy is not None:
+        permission_authorized = policy.required_permission in granted
+        role_authorized = normalized_role in policy.request_roles
+        if not permission_authorized:
+            authorization_reasons.append(
+                f"missing required permission {policy.required_permission!r}"
+            )
+        if not role_authorized:
+            authorization_reasons.append(
+                f"role {normalized_role or 'unknown'!r} may not request "
+                f"{policy.restart_class.value}"
+            )
+    elif unknown_class:
+        permission_authorized = False
+        role_authorized = False
+    else:
+        permission_authorized = True
+        role_authorized = True
+
+    if policy_enforced and policy is not None:
+        approval = policy.approval_requirement
+        if approval == "self_service":
+            approval_satisfied = True
+        elif approval == "controller_approval_plus_infrastructure_operator":
+            approval_satisfied = bool(controller_approved and operator_authorized)
+        else:
+            approval_satisfied = bool(controller_approved)
+        if not approval_satisfied:
+            authorization_reasons.append(
+                f"approval requirement not satisfied: {approval}"
+            )
+    elif unknown_class:
+        approval_satisfied = False
+    else:
+        approval_satisfied = True
 
     inventory_complete = bool(inventory.get("inventory_complete", False))
     incomplete_reasons = [str(r) for r in (inventory.get("incomplete_reasons") or [])]
@@ -323,15 +595,67 @@ def evaluate_restart_impact(
     ]
     lease_impacts = [_classify_lease(l) for l in leases_raw]
 
-    # Only *other* live sessions and live leases constitute blast radius: a
-    # restart that would kill only the requesting session with no other work in
-    # flight is safe.
+    # Route impact through the selected class. Narrow classes never inherit a
+    # full-runtime drain merely because unrelated work exists.
+    target_complete = True
+    if resolved_class in {
+        RestartClass.CLIENT_RECONNECT,
+        RestartClass.SESSION_RECONNECT,
+        RestartClass.CONFIGURATION_RELOAD,
+    }:
+        scoped_sessions: list[SessionImpact] = []
+        scoped_leases: list[LeaseImpact] = []
+    elif resolved_class == RestartClass.WORKER_RESTART:
+        selected_session = (target_session_id or "").strip()
+        target_complete = bool(selected_session)
+        scoped_sessions = [
+            s for s in session_impacts if s.session_id == selected_session
+        ]
+        scoped_leases = [
+            l for l in lease_impacts if l.session_id == selected_session
+        ]
+    elif resolved_class == RestartClass.ROLE_RUNTIME_RESTART:
+        selected_role = (target_role or "").strip().lower()
+        target_complete = bool(selected_role)
+        scoped_sessions = [
+            s for s in session_impacts if str(s.role or "").lower() == selected_role
+        ]
+        scoped_leases = [
+            l for l in lease_impacts if str(l.role or "").lower() == selected_role
+        ]
+    elif resolved_class == RestartClass.CONNECTOR_RESTART:
+        selected_connector = (target_connector or "").strip()
+        target_complete = bool(selected_connector)
+        scoped_sessions = [
+            s for s in session_impacts if s.connector == selected_connector
+        ]
+        scoped_leases = [
+            l for l in lease_impacts if l.connector == selected_connector
+        ]
+    else:
+        scoped_sessions = list(session_impacts)
+        scoped_leases = list(lease_impacts)
+
+    if policy_enforced and not target_complete:
+        authorization_reasons.append(
+            f"target required for {resolved_class.value if resolved_class else 'unknown class'}"
+        )
+
     other_live_sessions = [
-        s for s in session_impacts if s.live and not s.is_requester
+        s for s in scoped_sessions if s.live and not s.is_requester
     ]
-    disruptive_leases = [l for l in lease_impacts if l.disruptive]
-    critical_sections = [l for l in lease_impacts if l.is_critical_section]
-    mutations = [l for l in lease_impacts if l.is_mutation]
+    disruptive_leases = [l for l in scoped_leases if l.disruptive]
+    critical_sections = [l for l in scoped_leases if l.is_critical_section]
+    mutations = [l for l in scoped_leases if l.is_mutation]
+    terminal_lock_in_scope = (
+        terminal_lock
+        if resolved_class
+        not in {
+            RestartClass.CLIENT_RECONNECT,
+            RestartClass.SESSION_RECONNECT,
+        }
+        else None
+    )
 
     affected_issues = sorted(
         {
@@ -348,9 +672,24 @@ def evaluate_restart_impact(
         }
     )
 
-    disruptive = bool(disruptive_leases or other_live_sessions or terminal_lock)
+    disruptive = bool(
+        disruptive_leases or other_live_sessions or terminal_lock_in_scope
+    )
 
-    if not inventory_complete:
+    authorization_ok = bool(
+        not unknown_class
+        and permission_authorized
+        and role_authorized
+        and approval_satisfied
+        and target_complete
+    )
+
+    if policy_enforced and not authorization_ok:
+        verdict = VERDICT_UNSAFE
+        allow_restart = False
+        reasons.append("restart class authorization denied (fail closed)")
+        reasons.extend(authorization_reasons)
+    elif not inventory_complete:
         verdict = VERDICT_UNSAFE
         allow_restart = False
         reasons.append(
@@ -381,7 +720,7 @@ def evaluate_restart_impact(
             f"{len(critical_sections)} critical section(s) in flight "
             "(active lease with a live owner)"
         )
-    if terminal_lock:
+    if terminal_lock_in_scope:
         reasons.append("active terminal (merge) lock present")
 
     override_would_allow = bool(inventory_complete and disruptive)
@@ -411,6 +750,12 @@ def evaluate_restart_impact(
     audit_record = {
         "event": "restart_impact_evaluated",
         "coordinator_version": COORDINATOR_VERSION,
+        "restart_class": (
+            resolved_class.value if resolved_class else str(restart_class or "")
+        ),
+        "required_permission": (
+            policy.required_permission if policy is not None else None
+        ),
         "evaluated_at": moment.isoformat(),
         "dry_run": dry_run,
         "operator_override": bool(operator_override),
@@ -424,6 +769,15 @@ def evaluate_restart_impact(
 
     return RestartImpactReport(
         coordinator_version=COORDINATOR_VERSION,
+        restart_class=(
+            resolved_class.value if resolved_class else str(restart_class or "")
+        ),
+        restart_policy=policy.as_dict() if policy is not None else {},
+        policy_enforced=policy_enforced,
+        permission_authorized=permission_authorized,
+        role_authorized=role_authorized,
+        approval_satisfied=approval_satisfied,
+        authorization_reasons=authorization_reasons,
         evaluated_at=moment.isoformat(),
         dry_run=dry_run,
         restart_performed=False,
@@ -440,9 +794,11 @@ def evaluate_restart_impact(
         affected_issues=affected_issues,
         affected_prs=affected_prs,
         mutations=mutations,
-        terminal_lock=dict(terminal_lock)
-        if isinstance(terminal_lock, Mapping)
-        else terminal_lock,
+        terminal_lock=(
+            dict(terminal_lock_in_scope)
+            if isinstance(terminal_lock_in_scope, Mapping)
+            else terminal_lock_in_scope
+        ),
         ack_state=ack_state,
         prior_recovery_attempts=prior_recovery_attempts,
         counts=counts,

tests/test_drain_proof.py

@@ -0,0 +1,907 @@
+"""Tests for the pre-restart drain proof and hard gate (#661).
+
+Covers the acceptance criteria:
+
+1. Restart apply without a proof fails closed.
+2. A successful drain produces a verifiable proof.
+3. An open unsafe mutation makes the proof fail (multi-session fixture).
+4. Pass / fail / expired verification paths.
+
+Plus the security posture: forged/tampered proofs are rejected, break-glass is
+the only bypass and is never silent, a stale blast-radius fingerprint rejects a
+proof, and no per-process secret ever leaks into a serialized artifact.
+"""
+
+from __future__ import annotations
+
+import os
+import unittest
+from datetime import datetime, timedelta, timezone
+
+import drain_proof as dp
+import restart_coordinator as rc
+
+
+NOW = datetime(2026, 7, 24, 6, 0, 0, tzinfo=timezone.utc)
+SECRET = b"unit-test-drain-proof-secret-0123456789abcdef"
+
+
+def _live_pid() -> int:
+    return os.getpid()
+
+
+def _clean_drain_state() -> dict:
+    """Every drain action succeeded, no sessions outstanding."""
+
+    return {
+        "assignments_stopped": True,
+        "checkpoints_complete": True,
+        "handoffs_verified": True,
+        "leases_handled": True,
+        "acks": {},  # no other live sessions to acknowledge
+        "ack_timeout_policy_applied": False,
+    }
+
+
+def _safe_report() -> dict:
+    """Impact report with no other live work: a restart here is safe."""
+
+    report = rc.evaluate_restart_impact(
+        {"sessions": [], "leases": [], "inventory_complete": True},
+        now=NOW,
+        requesting_session_id="prgs-controller-1-req",
+    )
+    return report.as_dict()
+
+
+def _unsafe_mutation_report() -> dict:
+    """Multi-session report: a second session holds a live author mutation."""
+
+    sessions = [
+        {
+            "session_id": "prgs-controller-1-req",
+            "role": "controller",
+            "profile": "prgs-controller",
+            "pid": _live_pid(),
+            "status": "active",
+            "last_heartbeat_at": NOW.isoformat(),
+        },
+        {
+            "session_id": "prgs-author-99",
+            "role": "author",
+            "profile": "prgs-author",
+            "pid": _live_pid(),
+            "status": "active",
+            "last_heartbeat_at": NOW.isoformat(),
+        },
+    ]
+    leases = [
+        {
+            "lease_id": "lease-mut",
+            "session_id": "prgs-author-99",
+            "role": "author",
+            "phase": "implementing",
+            "work_kind": "issue",
+            "work_number": 661,
+            "worktree_path": "branches/issue-661",
+            "freshness": {"freshness": "active"},
+        }
+    ]
+    report = rc.evaluate_restart_impact(
+        {"sessions": sessions, "leases": leases, "inventory_complete": True},
+        now=NOW,
+        requesting_session_id="prgs-controller-1-req",
+    )
+    return report.as_dict()
+
+
+class BuildDrainProofTests(unittest.TestCase):
+    def test_clean_drain_produces_verifiable_clean_proof(self):
+        """AC#2: a successful drain produces a verifiable proof."""
+
+        proof = dp.build_drain_proof(
+            impact_report=_safe_report(),
+            drain_state=_clean_drain_state(),
+            requesting_session_id="prgs-controller-1-req",
+            now=NOW,
+            secret=SECRET,
+        )
+        self.assertTrue(proof.clean)
+        self.assertEqual(proof.failed_checks, [])
+        self.assertEqual(
+            {c.name for c in proof.checks}, set(dp.REQUIRED_CHECKS)
+        )
+        result = dp.verify_drain_proof(
+            proof.as_dict(), now=NOW, secret=SECRET
+        )
+        self.assertTrue(result.valid, result.reasons)
+        self.assertFalse(result.expired)
+        self.assertFalse(result.tampered)
+
+    def test_open_mutation_makes_proof_unclean(self):
+        """AC#3: an unsafe mutation still in flight fails the proof."""
+
+        proof = dp.build_drain_proof(
+            impact_report=_unsafe_mutation_report(),
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        )
+        self.assertFalse(proof.clean)
+        self.assertIn(dp.CHECK_NO_INFLIGHT_MUTATIONS, proof.failed_checks)
+        # Leases-handled also fails: the report still shows a disruptive lease.
+        self.assertIn(dp.CHECK_LEASES_HANDLED, proof.failed_checks)
+        result = dp.verify_drain_proof(proof.as_dict(), now=NOW, secret=SECRET)
+        self.assertFalse(result.valid)
+
+    def test_incomplete_inventory_fails_no_mutations_check(self):
+        proof = dp.build_drain_proof(
+            impact_report={"inventory_complete": False},
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        )
+        self.assertFalse(proof.clean)
+        self.assertIn(dp.CHECK_NO_INFLIGHT_MUTATIONS, proof.failed_checks)
+
+    def test_missing_checkpoint_flag_fails_closed(self):
+        state = _clean_drain_state()
+        del state["checkpoints_complete"]
+        proof = dp.build_drain_proof(
+            impact_report=_safe_report(), drain_state=state, now=NOW, secret=SECRET
+        )
+        self.assertFalse(proof.clean)
+        self.assertIn(dp.CHECK_CHECKPOINTS_COMPLETE, proof.failed_checks)
+
+    def test_non_true_flags_fail_closed(self):
+        """A truthy-but-not-True value (e.g. the string 'yes') must not pass."""
+
+        state = _clean_drain_state()
+        state["assignments_stopped"] = "yes"
+        proof = dp.build_drain_proof(
+            impact_report=_safe_report(), drain_state=state, now=NOW, secret=SECRET
+        )
+        self.assertIn(dp.CHECK_ASSIGNMENTS_STOPPED, proof.failed_checks)
+
+    def test_ack_timeout_policy_satisfies_ack_check(self):
+        state = _clean_drain_state()
+        state["acks"] = {"prgs-author-99": "pending"}
+        state["ack_timeout_policy_applied"] = True
+        proof = dp.build_drain_proof(
+            impact_report=_safe_report(), drain_state=state, now=NOW, secret=SECRET
+        )
+        names = {c.name: c.passed for c in proof.checks}
+        self.assertTrue(names[dp.CHECK_ACKS_OR_TIMEOUT])
+
+    def test_outstanding_acks_without_timeout_fail(self):
+        state = _clean_drain_state()
+        state["acks"] = {"prgs-author-99": "pending"}
+        state["ack_timeout_policy_applied"] = False
+        proof = dp.build_drain_proof(
+            impact_report=_safe_report(), drain_state=state, now=NOW, secret=SECRET
+        )
+        self.assertIn(dp.CHECK_ACKS_OR_TIMEOUT, proof.failed_checks)
+
+    def test_all_acked_satisfies_ack_check(self):
+        state = _clean_drain_state()
+        state["acks"] = {"prgs-author-99": "acked", "prgs-author-2": "acknowledged"}
+        proof = dp.build_drain_proof(
+            impact_report=_safe_report(), drain_state=state, now=NOW, secret=SECRET
+        )
+        names = {c.name: c.passed for c in proof.checks}
+        self.assertTrue(names[dp.CHECK_ACKS_OR_TIMEOUT])
+
+
+class VerifyDrainProofTests(unittest.TestCase):
+    def _clean_proof_dict(self) -> dict:
+        return dp.build_drain_proof(
+            impact_report=_safe_report(),
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        ).as_dict()
+
+    def test_missing_proof_is_invalid(self):
+        result = dp.verify_drain_proof(None, now=NOW, secret=SECRET)
+        self.assertFalse(result.valid)
+        self.assertIsNone(result.proof_id)
+
+    def test_expired_proof_is_invalid(self):
+        """AC#4: an expired proof fails verification."""
+
+        proof = self._clean_proof_dict()
+        later = NOW + timedelta(seconds=dp.DEFAULT_PROOF_TTL_SECONDS + 1)
+        result = dp.verify_drain_proof(proof, now=later, secret=SECRET)
+        self.assertFalse(result.valid)
+        self.assertTrue(result.expired)
+
+    def test_proof_valid_just_before_expiry(self):
+        proof = self._clean_proof_dict()
+        almost = NOW + timedelta(seconds=dp.DEFAULT_PROOF_TTL_SECONDS - 1)
+        result = dp.verify_drain_proof(proof, now=almost, secret=SECRET)
+        self.assertTrue(result.valid, result.reasons)
+
+    def test_wrong_secret_rejected(self):
+        """A proof minted in a prior process (different secret) will not verify."""
+
+        proof = self._clean_proof_dict()
+        result = dp.verify_drain_proof(proof, now=NOW, secret=b"other-secret")
+        self.assertFalse(result.valid)
+        self.assertTrue(result.tampered)
+
+    def test_flipping_clean_flag_is_detected(self):
+        """Forging clean=True on an unclean proof breaks the signature."""
+
+        unclean = dp.build_drain_proof(
+            impact_report=_unsafe_mutation_report(),
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        ).as_dict()
+        self.assertFalse(unclean["clean"])
+        unclean["clean"] = True  # forge
+        result = dp.verify_drain_proof(unclean, now=NOW, secret=SECRET)
+        self.assertFalse(result.valid)
+        self.assertTrue(result.tampered)
+
+    def test_tampering_a_check_is_detected(self):
+        unclean = dp.build_drain_proof(
+            impact_report=_unsafe_mutation_report(),
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        ).as_dict()
+        for c in unclean["checks"]:
+            if c["name"] == dp.CHECK_NO_INFLIGHT_MUTATIONS:
+                c["passed"] = True  # forge the failing check to pass
+        result = dp.verify_drain_proof(unclean, now=NOW, secret=SECRET)
+        self.assertFalse(result.valid)
+        self.assertTrue(result.tampered)
+
+    def test_missing_required_check_rejected(self):
+        proof = self._clean_proof_dict()
+        proof["checks"] = [
+            c for c in proof["checks"] if c["name"] != dp.CHECK_HANDOFFS_OK
+        ]
+        result = dp.verify_drain_proof(proof, now=NOW, secret=SECRET)
+        self.assertFalse(result.valid)
+
+    def test_stale_fingerprint_rejected(self):
+        proof = self._clean_proof_dict()
+        result = dp.verify_drain_proof(
+            proof,
+            now=NOW,
+            secret=SECRET,
+            expected_impact_fingerprint="deadbeef",
+        )
+        self.assertFalse(result.valid)
+
+    def test_matching_fingerprint_accepted(self):
+        report = _safe_report()
+        proof = dp.build_drain_proof(
+            impact_report=report,
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        ).as_dict()
+        fp = dp.impact_fingerprint(report)
+        result = dp.verify_drain_proof(
+            proof, now=NOW, secret=SECRET, expected_impact_fingerprint=fp
+        )
+        self.assertTrue(result.valid, result.reasons)
+
+
+class GateApplyRestartTests(unittest.TestCase):
+    def _clean_proof_dict(self) -> dict:
+        return dp.build_drain_proof(
+            impact_report=_safe_report(),
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        ).as_dict()
+
+    def test_apply_without_proof_denied(self):
+        """AC#1: restart apply without a proof fails closed + raises incident."""
+
+        decision = dp.gate_apply_restart(proof=None, now=NOW, secret=SECRET)
+        self.assertFalse(decision.allow)
+        self.assertEqual(decision.verdict, dp.GATE_DENY)
+        self.assertIsNotNone(decision.incident)
+        self.assertEqual(
+            decision.incident["kind"], "restart_drain_gate_denied"
+        )
+
+    def test_apply_with_valid_proof_allowed(self):
+        decision = dp.gate_apply_restart(
+            proof=self._clean_proof_dict(), now=NOW, secret=SECRET
+        )
+        self.assertTrue(decision.allow)
+        self.assertEqual(decision.verdict, dp.GATE_ALLOW)
+        self.assertIsNone(decision.incident)
+
+    def test_apply_with_expired_proof_denied_with_incident(self):
+        later = NOW + timedelta(seconds=dp.DEFAULT_PROOF_TTL_SECONDS + 5)
+        decision = dp.gate_apply_restart(
+            proof=self._clean_proof_dict(), now=later, secret=SECRET
+        )
+        self.assertFalse(decision.allow)
+        self.assertIsNotNone(decision.incident)
+
+    def test_apply_with_unclean_proof_denied(self):
+        """AC#3 at the gate: an unsafe-mutation proof is denied."""
+
+        unclean = dp.build_drain_proof(
+            impact_report=_unsafe_mutation_report(),
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        ).as_dict()
+        decision = dp.gate_apply_restart(proof=unclean, now=NOW, secret=SECRET)
+        self.assertFalse(decision.allow)
+        self.assertIsNotNone(decision.incident)
+
+    def test_break_glass_allows_without_proof_but_records_bypass(self):
+        decision = dp.gate_apply_restart(
+            proof=None, now=NOW, secret=SECRET, break_glass=True
+        )
+        self.assertTrue(decision.allow)
+        self.assertEqual(decision.verdict, dp.GATE_BREAK_GLASS)
+        self.assertTrue(decision.break_glass)
+        self.assertIsNone(decision.incident)
+        self.assertTrue(decision.audit_record["break_glass"])
+
+    def test_denied_gate_carries_stale_fingerprint_reason(self):
+        decision = dp.gate_apply_restart(
+            proof=self._clean_proof_dict(),
+            now=NOW,
+            secret=SECRET,
+            expected_impact_fingerprint="not-the-fingerprint",
+        )
+        self.assertFalse(decision.allow)
+
+
+class SecretHygieneTests(unittest.TestCase):
+    def test_secret_never_serialized(self):
+        proof = dp.build_drain_proof(
+            impact_report=_safe_report(),
+            drain_state=_clean_drain_state(),
+            now=NOW,
+            secret=SECRET,
+        )
+        blob = dp._canonical(proof.as_dict())
+        self.assertNotIn(SECRET.decode(), blob)
+        # The signature is a hex digest, not the raw secret.
+        self.assertNotIn(SECRET.hex(), blob)
+
+    def test_incident_descriptor_has_no_secret(self):
+        decision = dp.gate_apply_restart(proof=None, now=NOW, secret=SECRET)
+        blob = dp._canonical(decision.incident)
+        self.assertNotIn(SECRET.decode(), blob)
+
+
+def _drained_report_with_live_sessions(count: int) -> dict:
+    """Report with ``count`` other live sessions but nothing in flight.
+
+    Every other checklist item passes against this report, so a failure
+    isolates the acknowledgement check rather than tripping on mutations.
+    """
+
+    sessions = [
+        {
+            "session_id": "prgs-controller-1-req",
+            "role": "controller",
+            "profile": "prgs-controller",
+            "pid": _live_pid(),
+            "status": "active",
+            "last_heartbeat_at": NOW.isoformat(),
+        }
+    ]
+    for index in range(count):
+        sessions.append(
+            {
+                "session_id": f"prgs-author-{index}",
+                "role": "author",
+                "profile": "prgs-author",
+                "pid": _live_pid(),
+                "status": "active",
+                "last_heartbeat_at": NOW.isoformat(),
+            }
+        )
+    report = rc.evaluate_restart_impact(
+        {"sessions": sessions, "leases": [], "inventory_complete": True},
+        now=NOW,
+        requesting_session_id="prgs-controller-1-req",
+    )
+    return report.as_dict()
+
+
+class AcknowledgementFailClosedTests(unittest.TestCase):
+    """Acknowledgement evidence must fail closed unless explicitly verified.
+
+    Regression cover for the reviewed fail-open on PR #882: an absent ``acks``
+    key collapsed to ``{}`` and was read as "no other live sessions required to
+    acknowledge", so a proof minted clean and the restart gate allowed while the
+    impact report still showed other live sessions.
+    """
+
+    def _state(self, **overrides) -> dict:
+        state = _clean_drain_state()
+        state.pop("acks", None)
+        state["ack_timeout_policy_applied"] = False
+        state.update(overrides)
+        return state
+
+    def _acks_check(self, proof) -> dp.DrainCheck:
+        return next(c for c in proof.checks if c.name == dp.CHECK_ACKS_OR_TIMEOUT)
+
+    def _build(self, report: dict, state: dict):
+        return dp.build_drain_proof(
+            impact_report=report, drain_state=state, now=NOW, secret=SECRET
+        )
+
+    def assertAcksFailClosed(self, report: dict, state: dict) -> None:
+        proof = self._build(report, state)
+        self.assertFalse(self._acks_check(proof).passed)
+        self.assertIn(dp.CHECK_ACKS_OR_TIMEOUT, proof.failed_checks)
+        self.assertFalse(proof.clean)
+
+    # --- missing / null / empty / malformed ------------------------------
+
+    def test_missing_acks_key_with_live_sessions_fails_closed(self):
+        """The exact reviewed defect: absent key, three other live sessions."""
+        report = _drained_report_with_live_sessions(3)
+        self.assertEqual(report["counts"]["sessions_live_other"], 3)
+        state = self._state()
+        self.assertNotIn("acks", state)
+        proof = self._build(report, state)
+        check = self._acks_check(proof)
+        self.assertFalse(check.passed)
+        self.assertNotIn("no other live sessions", check.detail)
+        self.assertIn("fail closed", check.detail)
+        self.assertFalse(proof.clean)
+        self.assertEqual(proof.failed_checks, [dp.CHECK_ACKS_OR_TIMEOUT])
+
+    def test_none_acks_with_live_sessions_fails_closed(self):
+        self.assertAcksFailClosed(
+            _drained_report_with_live_sessions(2), self._state(acks=None)
+        )
+
+    def test_empty_acks_with_live_sessions_fails_closed(self):
+        self.assertAcksFailClosed(
+            _drained_report_with_live_sessions(1), self._state(acks={})
+        )
+
+    def test_malformed_acks_fail_closed(self):
+        for malformed in ([], "ack", 7, ("ack",), True):
+            with self.subTest(malformed=malformed):
+                self.assertAcksFailClosed(
+                    _drained_report_with_live_sessions(1),
+                    self._state(acks=malformed),
+                )
+
+    # --- stale / unproven values -----------------------------------------
+
+    def test_stale_or_unproven_ack_values_fail_closed(self):
+        for value in ("pending", "stale", "unknown", "", None, True, 1, NOW):
+            with self.subTest(value=value):
+                self.assertAcksFailClosed(
+                    _drained_report_with_live_sessions(1),
+                    self._state(acks={"prgs-author-0": value}),
+                )
+
+    def test_partial_coverage_fails_closed(self):
+        """Fewer acknowledgements than the report's live-session count."""
+        self.assertAcksFailClosed(
+            _drained_report_with_live_sessions(3),
+            self._state(acks={"prgs-author-0": "ack"}),
+        )
+
+    def test_one_unacked_entry_among_many_fails_closed(self):
+        self.assertAcksFailClosed(
+            _drained_report_with_live_sessions(2),
+            self._state(acks={"prgs-author-0": "ack", "prgs-author-1": "pending"}),
+        )
+
+    def test_unproven_live_session_count_fails_closed(self):
+        """A missing or malformed count cannot prove nobody had to acknowledge."""
+        malformed_counts = (
+            None,
+            {},
+            {"sessions_live_other": None},
+            {"sessions_live_other": "3"},
+            {"sessions_live_other": -1},
+            {"sessions_live_other": True},
+        )
+        for counts in malformed_counts:
+            with self.subTest(counts=counts):
+                report = _drained_report_with_live_sessions(0)
+                if counts is None:
+                    report.pop("counts", None)
+                else:
+                    report["counts"] = counts
+                self.assertAcksFailClosed(report, self._state())
+
+    # --- valid evidence still passes -------------------------------------
+
+    def test_complete_valid_acks_pass(self):
+        report = _drained_report_with_live_sessions(2)
+        state = self._state(
+            acks={"prgs-author-0": "ack", "prgs-author-1": "acknowledged"}
+        )
+        proof = self._build(report, state)
+        self.assertTrue(self._acks_check(proof).passed)
+        self.assertTrue(proof.clean)
+        self.assertEqual(proof.failed_checks, [])
+
+    def test_no_other_live_sessions_still_passes(self):
+        """Intended behavior retained: zero live sessions needs no acks."""
+        report = _drained_report_with_live_sessions(0)
+        self.assertEqual(report["counts"]["sessions_live_other"], 0)
+        proof = self._build(report, self._state())
+        check = self._acks_check(proof)
+        self.assertTrue(check.passed)
+        self.assertIn("sessions_live_other=0", check.detail)
+        self.assertTrue(proof.clean)
+
+    # --- timeout policy cannot become a second fail-open ------------------
+
+    def test_unproven_timeout_policy_cannot_open_the_gate(self):
+        for value in (None, "true", "yes", 1, "True", [], {}):
+            with self.subTest(value=value):
+                self.assertAcksFailClosed(
+                    _drained_report_with_live_sessions(2),
+                    self._state(ack_timeout_policy_applied=value),
+                )
+
+    def test_explicit_timeout_policy_permits(self):
+        proof = self._build(
+            _drained_report_with_live_sessions(2),
+            self._state(ack_timeout_policy_applied=True),
+        )
+        check = self._acks_check(proof)
+        self.assertTrue(check.passed)
+        self.assertIn("timeout policy", check.detail)
+        self.assertTrue(proof.clean)
+
+    # --- the gate itself must deny ---------------------------------------
+
+    def test_failed_ack_check_denies_the_restart_gate(self):
+        report = _drained_report_with_live_sessions(3)
+        proof = self._build(report, self._state())
+        self.assertFalse(proof.clean)
+        decision = dp.gate_apply_restart(
+            proof=proof.as_dict(),
+            now=NOW,
+            secret=SECRET,
+            expected_impact_fingerprint=dp.impact_fingerprint(report),
+        )
+        self.assertFalse(decision.allow)
+        self.assertEqual(decision.verdict, dp.GATE_DENY)
+        self.assertIsNotNone(decision.incident)
+
+    def test_unclean_ack_proof_fails_verification(self):
+        report = _drained_report_with_live_sessions(3)
+        proof = self._build(report, self._state())
+        result = dp.verify_drain_proof(
+            proof.as_dict(),
+            now=NOW,
+            secret=SECRET,
+            expected_impact_fingerprint=dp.impact_fingerprint(report),
+        )
+        self.assertFalse(result.valid)
+        self.assertFalse(result.clean)
+
+
+def _identity_report(*, requester: str, others: tuple[str, ...]) -> dict:
+    """Report with explicitly named requester and other live sessions.
+
+    Unlike :func:`_drained_report_with_live_sessions`, the session ids are
+    chosen by the caller so a test can supply acknowledgements for the *wrong*
+    identities while keeping the count correct.
+    """
+
+    sessions = [
+        {
+            "session_id": requester,
+            "role": "controller",
+            "profile": "prgs-controller",
+            "pid": _live_pid(),
+            "status": "active",
+            "last_heartbeat_at": NOW.isoformat(),
+        }
+    ]
+    for session_id in others:
+        sessions.append(
+            {
+                "session_id": session_id,
+                "role": "author",
+                "profile": "prgs-author",
+                "pid": _live_pid(),
+                "status": "active",
+                "last_heartbeat_at": NOW.isoformat(),
+            }
+        )
+    report = rc.evaluate_restart_impact(
+        {"sessions": sessions, "leases": [], "inventory_complete": True},
+        now=NOW,
+        requesting_session_id=requester,
+    )
+    return report.as_dict()
+
+
+class AcknowledgementIdentityBindingTests(unittest.TestCase):
+    """Acknowledgement coverage must be bound to session identity, not counted.
+
+    Regression cover for the second reviewed fail-open on PR #882 (review 582,
+    blocker B1): coverage compared ``acked_count`` against
+    ``counts.sessions_live_other``, so acknowledgements supplied for the
+    requesting session and for ids that do not exist satisfied the obligations
+    of the live sessions that never answered. The required identities are
+    carried by the report itself — ``ack_state`` keys and ``affected_sessions``
+    filtered on ``live and not is_requester`` — and only an acknowledgement
+    keyed by one of those ids may count for it.
+    """
+
+    def _state(self, **overrides) -> dict:
+        state = _clean_drain_state()
+        state.pop("acks", None)
+        state["ack_timeout_policy_applied"] = False
+        state.update(overrides)
+        return state
+
+    def _acks_check(self, proof) -> dp.DrainCheck:
+        return next(c for c in proof.checks if c.name == dp.CHECK_ACKS_OR_TIMEOUT)
+
+    def _build(self, report: dict, state: dict):
+        return dp.build_drain_proof(
+            impact_report=report, drain_state=state, now=NOW, secret=SECRET
+        )
+
+    def assertAcksFailClosed(self, report: dict, state: dict) -> dp.DrainCheck:
+        """Failure must propagate through the check, the proof, and the gate."""
+
+        proof = self._build(report, state)
+        check = self._acks_check(proof)
+        self.assertFalse(check.passed)
+        self.assertFalse(proof.clean)
+        self.assertIn(dp.CHECK_ACKS_OR_TIMEOUT, proof.failed_checks)
+        decision = dp.gate_apply_restart(
+            proof=proof.as_dict(),
+            now=NOW,
+            secret=SECRET,
+            expected_impact_fingerprint=dp.impact_fingerprint(report),
+        )
+        self.assertEqual(decision.verdict, dp.GATE_DENY)
+        self.assertFalse(decision.allow)
+        return check
+
+    # --- the reviewer's exact reproduction --------------------------------
+
+    def test_requester_plus_unknown_id_cannot_satisfy_two_live_sessions(self):
+        """Review 582 B1 verbatim: requester + a nonexistent session.
+
+        ``sessions_live_other=2`` with ``ack_state`` naming ``other-0`` and
+        ``other-1``; the drain state supplies an acknowledgement from the
+        requesting session itself and from a session that does not exist. The
+        count matches, the identities do not.
+        """
+
+        report = _identity_report(requester="req", others=("other-0", "other-1"))
+        self.assertEqual(report["counts"]["sessions_live_other"], 2)
+        self.assertEqual(
+            report["ack_state"], {"other-0": "pending", "other-1": "pending"}
+        )
+        state = self._state(acks={"req": "ack", "totally-bogus-session": "ack"})
+        check = self.assertAcksFailClosed(report, state)
+        self.assertIn("other-0", check.detail)
+        self.assertIn("other-1", check.detail)
+        self.assertIn("fail closed", check.detail)
+
+    # --- wrong / unknown / requester identities ---------------------------
+
+    def test_sufficient_count_of_wrong_ids_fails_closed(self):
+        """Right cardinality, wrong identities: two acks, neither required."""
+
+        report = _identity_report(requester="req", others=("other-0", "other-1"))
+        state = self._state(acks={"ghost-a": "ack", "ghost-b": "ack"})
+        check = self.assertAcksFailClosed(report, state)
+        self.assertIn("do not count", check.detail)
+
+    def test_more_acks_than_required_still_fails_on_wrong_ids(self):
+        """Coverage cannot be bought with volume: five acks, none required."""
+
+        report = _identity_report(requester="req", others=("other-0", "other-1"))
+        state = self._state(acks={f"ghost-{i}": "acknowledged" for i in range(5)})
+        self.assertAcksFailClosed(report, state)
+
+    def test_partial_identity_match_fails_closed(self):
+        """One required id acknowledged, the rest padded with unknown ids."""
+
+        report = _identity_report(
+            requester="req", others=("other-0", "other-1", "other-2")
+        )
+        state = self._state(
+            acks={"other-0": "ack", "ghost-1": "ack", "ghost-2": "ack"}
+        )
+        check = self.assertAcksFailClosed(report, state)
+        self.assertIn("other-1", check.detail)
+        self.assertIn("other-2", check.detail)
+
+    def test_requester_ack_never_satisfies_another_sessions_obligation(self):
+        """The requester is excluded from the required set and stays excluded."""
+
+        report = _identity_report(requester="req", others=("other-0",))
+        requester_rows = [s for s in report["affected_sessions"] if s["is_requester"]]
+        self.assertEqual([s["session_id"] for s in requester_rows], ["req"])
+        self.assertNotIn("req", report["ack_state"])
+        check = self.assertAcksFailClosed(report, self._state(acks={"req": "ack"}))
+        self.assertIn("other-0", check.detail)
+
+    def test_fabricated_ids_do_not_count_toward_coverage(self):
+        report = _identity_report(requester="req", others=("other-0",))
+        for bogus in ("", " ", "other-0 extra", "OTHER-0", "other-01", "0"):
+            with self.subTest(bogus=bogus):
+                self.assertAcksFailClosed(report, self._state(acks={bogus: "ack"}))
+
+    # --- per-session state must be explicitly valid ------------------------
+
+    def test_unproven_per_session_states_fail_closed(self):
+        """A required id present but not explicitly acknowledged fails closed."""
+
+        report = _identity_report(requester="req", others=("other-0", "other-1"))
+        for value in ("pending", "stale", "unknown", "", None, True, 1, NOW):
+            with self.subTest(value=value):
+                self.assertAcksFailClosed(
+                    report,
+                    self._state(acks={"other-0": "ack", "other-1": value}),
+                )
+
+    def test_report_ack_state_placeholder_is_never_read_as_an_ack(self):
+        """``ack_state`` values are the report's own placeholders, not evidence."""
+
+        report = _identity_report(requester="req", others=("other-0",))
+        report["ack_state"] = {"other-0": "ack"}
+        self.assertAcksFailClosed(report, self._state())
+
+    # --- missing / malformed / contradictory identity evidence -------------
+
+    def test_missing_identity_evidence_fails_closed(self):
+        report = _identity_report(requester="req", others=("other-0",))
+        report.pop("ack_state", None)
+        report.pop("affected_sessions", None)
+        check = self.assertAcksFailClosed(report, self._state(acks={"other-0": "ack"}))
+        self.assertIn("no session-identity evidence", check.detail)
+
+    def test_malformed_ack_state_fails_closed(self):
+        for malformed in ([], "other-0", 7, None, ("other-0",)):
+            with self.subTest(malformed=malformed):
+                report = _identity_report(requester="req", others=("other-0",))
+                report["ack_state"] = malformed
+                self.assertAcksFailClosed(
+                    report, self._state(acks={"other-0": "ack"})
+                )
+
+    def test_non_string_ack_state_key_fails_closed(self):
+        report = _identity_report(requester="req", others=("other-0",))
+        report["ack_state"] = {7: "pending"}
+        self.assertAcksFailClosed(report, self._state(acks={"other-0": "ack"}))
+
+    def test_malformed_affected_sessions_fails_closed(self):
+        for malformed in ("sessions", 7, {"session_id": "other-0"}, [None], [7]):
+            with self.subTest(malformed=malformed):
+                report = _identity_report(requester="req", others=("other-0",))
+                report.pop("ack_state", None)
+                report["affected_sessions"] = malformed
+                self.assertAcksFailClosed(
+                    report, self._state(acks={"other-0": "ack"})
+                )
+
+    def test_affected_sessions_without_explicit_booleans_fails_closed(self):
+        """``live``/``is_requester`` must be real booleans, never inferred."""
+
+        report = _identity_report(requester="req", others=("other-0",))
+        report.pop("ack_state", None)
+        for row in report["affected_sessions"]:
+            if row["session_id"] == "other-0":
+                row["is_requester"] = "false"
+        self.assertAcksFailClosed(report, self._state(acks={"other-0": "ack"}))
+
+    def test_affected_sessions_missing_live_flag_fails_closed(self):
+        report = _identity_report(requester="req", others=("other-0",))
+        report.pop("ack_state", None)
+        for row in report["affected_sessions"]:
+            row.pop("live", None)
+        self.assertAcksFailClosed(report, self._state(acks={"other-0": "ack"}))
+
+    def test_contradictory_ack_state_and_affected_sessions_fails_closed(self):
+        """Both views present and disagreeing is unresolvable, not a tie-break."""
+
+        report = _identity_report(requester="req", others=("other-0", "other-1"))
+        report["ack_state"] = {"other-0": "pending", "other-9": "pending"}
+        check = self.assertAcksFailClosed(
+            report, self._state(acks={"other-0": "ack", "other-9": "ack"})
+        )
+        self.assertIn("contradicts itself", check.detail)
+
+    def test_identity_count_mismatch_fails_closed(self):
+        """Identity evidence that cannot be reconciled with the count denies."""
+
+        report = _identity_report(requester="req", others=("other-0", "other-1"))
+        report["counts"] = dict(report["counts"], sessions_live_other=1)
+        check = self.assertAcksFailClosed(
+            report, self._state(acks={"other-0": "ack", "other-1": "ack"})
+        )
+        self.assertIn("cannot be reconciled", check.detail)
+
+    def test_broken_identity_evidence_outranks_timeout_policy(self):
+        """The sanctioned timeout path cannot paper over an unreadable report."""
+
+        report = _identity_report(requester="req", others=("other-0",))
+        report["ack_state"] = "not-a-mapping"
+        self.assertAcksFailClosed(report, self._state(ack_timeout_policy_applied=True))
+
+    # --- legitimate success is preserved -----------------------------------
+
+    def test_every_required_session_acknowledged_passes(self):
+        report = _identity_report(
+            requester="req", others=("other-0", "other-1", "other-2")
+        )
+        state = self._state(
+            acks={
+                "other-0": "ack",
+                "other-1": "acked",
+                "other-2": "acknowledged",
+            }
+        )
+        proof = self._build(report, state)
+        check = self._acks_check(proof)
+        self.assertTrue(check.passed)
+        self.assertTrue(proof.clean)
+        self.assertEqual(proof.failed_checks, [])
+        self.assertIn("acknowledged by identity", check.detail)
+        decision = dp.gate_apply_restart(
+            proof=proof.as_dict(),
+            now=NOW,
+            secret=SECRET,
+            expected_impact_fingerprint=dp.impact_fingerprint(report),
+        )
+        self.assertEqual(decision.verdict, dp.GATE_ALLOW)
+        self.assertTrue(decision.allow)
+
+    def test_required_session_ack_tolerates_surrounding_whitespace(self):
+        report = _identity_report(requester="req", others=("other-0",))
+        proof = self._build(report, self._state(acks={" other-0 ": " ACK "}))
+        self.assertTrue(self._acks_check(proof).passed)
+        self.assertTrue(proof.clean)
+
+    def test_no_other_live_sessions_still_passes_with_identity_evidence(self):
+        report = _identity_report(requester="req", others=())
+        self.assertEqual(report["counts"]["sessions_live_other"], 0)
+        self.assertEqual(report["ack_state"], {})
+        proof = self._build(report, self._state())
+        check = self._acks_check(proof)
+        self.assertTrue(check.passed)
+        self.assertIn("sessions_live_other=0", check.detail)
+        self.assertTrue(proof.clean)
+
+    def test_explicit_timeout_policy_retains_intended_behavior(self):
+        """Valid, correctly typed timeout evidence still permits the check."""
+
+        report = _identity_report(requester="req", others=("other-0", "other-1"))
+        proof = self._build(report, self._state(ack_timeout_policy_applied=True))
+        check = self._acks_check(proof)
+        self.assertTrue(check.passed)
+        self.assertIn("timeout policy", check.detail)
+        self.assertTrue(proof.clean)
+
+    def test_timeout_policy_still_strictly_typed_under_identity_binding(self):
+        report = _identity_report(requester="req", others=("other-0",))
+        for value in (None, "true", "True", 1, [], {}):
+            with self.subTest(value=value):
+                self.assertAcksFailClosed(
+                    report, self._state(ack_timeout_policy_applied=value)
+                )
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_restart_classes.py

@@ -0,0 +1,232 @@
+"""Permission, drain, routing, and audit matrix for restart classes (#663)."""
+
+from __future__ import annotations
+
+import os
+from datetime import datetime, timezone
+
+import restart_coordinator as rc
+
+NOW = datetime(2026, 7, 24, 20, 0, tzinfo=timezone.utc)
+
+
+def _inventory() -> dict:
+    return {
+        "inventory_complete": True,
+        "sessions": [
+            {
+                "session_id": "requester",
+                "role": "author",
+                "profile": "prgs-author",
+                "pid": os.getpid(),
+                "status": "active",
+                "last_heartbeat_at": NOW.isoformat(),
+            },
+            {
+                "session_id": "reviewer",
+                "role": "reviewer",
+                "profile": "prgs-reviewer",
+                "pid": os.getpid(),
+                "status": "active",
+                "last_heartbeat_at": NOW.isoformat(),
+            },
+        ],
+        "leases": [
+            {
+                "lease_id": "review-lease",
+                "session_id": "reviewer",
+                "role": "reviewer",
+                "phase": "reviewing",
+                "work_kind": "pr",
+                "work_number": 900,
+                "worktree_path": "/tmp/review-900",
+                "freshness": {"freshness": "active"},
+            }
+        ],
+    }
+
+
+def _evaluate(
+    restart_class: rc.RestartClass,
+    *,
+    role: str = "controller",
+    permissions: tuple[str, ...] | None = None,
+    approved: bool = True,
+    operator: bool = True,
+    **targets,
+):
+    return rc.evaluate_restart_impact(
+        _inventory(),
+        now=NOW,
+        requesting_session_id="requester",
+        restart_class=restart_class,
+        requester_role=role,
+        requester_permissions=(
+            permissions if permissions is not None
+            else rc.permissions_for_role(role)
+        ),
+        controller_approved=approved,
+        operator_authorized=operator,
+        **targets,
+    )
+
+
+def test_policy_table_covers_exactly_all_nine_classes():
+    assert set(rc.RESTART_CLASS_POLICIES) == set(rc.RestartClass)
+    assert len(rc.RESTART_CLASS_POLICIES) == 9
+    for restart_class, policy in rc.RESTART_CLASS_POLICIES.items():
+        assert policy.restart_class is restart_class
+        assert policy.required_permission
+        assert policy.expected_blast_radius in {
+            rc.BLAST_NONE, rc.BLAST_LOW, rc.BLAST_MEDIUM, rc.BLAST_HIGH
+        }
+        assert policy.drain_requirement
+        assert policy.approval_requirement
+        assert policy.audit_requirement
+        assert policy.recovery_behavior
+
+
+def test_permission_matrix_allows_each_class_with_exact_permission():
+    targets = {
+        rc.RestartClass.WORKER_RESTART: {"target_session_id": "reviewer"},
+        rc.RestartClass.ROLE_RUNTIME_RESTART: {"target_role": "reviewer"},
+        rc.RestartClass.CONNECTOR_RESTART: {"target_connector": "github"},
+    }
+    for restart_class, policy in rc.RESTART_CLASS_POLICIES.items():
+        report = _evaluate(
+            restart_class,
+            permissions=(policy.required_permission,),
+            **targets.get(restart_class, {}),
+        )
+        assert report.permission_authorized, restart_class
+        assert report.role_authorized, restart_class
+        assert report.approval_satisfied, restart_class
+        assert report.audit_record["restart_class"] == restart_class.value
+        assert (
+            report.audit_record["required_permission"]
+            == policy.required_permission
+        )
+
+
+def test_missing_or_nearby_permission_denies():
+    report = _evaluate(
+        rc.RestartClass.ROLE_RUNTIME_RESTART,
+        permissions=("mcp.restart.worker.request",),
+        target_role="reviewer",
+    )
+    assert report.verdict == rc.VERDICT_UNSAFE
+    assert not report.allow_restart
+    assert not report.permission_authorized
+    assert any("missing required permission" in r for r in report.reasons)
+
+
+def test_unknown_restart_class_denies_fail_closed():
+    report = rc.evaluate_restart_impact(
+        _inventory(),
+        now=NOW,
+        restart_class="surprise_reboot",
+        requester_role="admin",
+        requester_permissions=("mcp.restart.host.request",),
+        controller_approved=True,
+        operator_authorized=True,
+    )
+    assert report.verdict == rc.VERDICT_UNSAFE
+    assert not report.allow_restart
+    assert report.restart_policy == {}
+    assert any("unknown restart class" in r for r in report.reasons)
+
+
+def test_worker_roles_cannot_request_full_or_host_restart():
+    for role in rc.WORKER_ROLES:
+        granted = rc.permissions_for_role(role)
+        assert "mcp.restart.full.request" not in granted
+        assert "mcp.restart.host.request" not in granted
+        report = _evaluate(
+            rc.RestartClass.FULL_MCP_RESTART,
+            role=role,
+            permissions=granted,
+        )
+        assert not report.role_authorized
+        assert not report.allow_restart
+
+
+def test_controller_approval_is_independent_of_permission():
+    report = _evaluate(
+        rc.RestartClass.WORKER_RESTART,
+        approved=False,
+        target_session_id="reviewer",
+    )
+    assert report.permission_authorized
+    assert not report.approval_satisfied
+    assert not report.allow_restart
+
+
+def test_narrow_classes_do_not_inherit_full_drain_or_peer_lease_block():
+    for restart_class in (
+        rc.RestartClass.CLIENT_RECONNECT,
+        rc.RestartClass.SESSION_RECONNECT,
+        rc.RestartClass.CONFIGURATION_RELOAD,
+    ):
+        report = _evaluate(restart_class)
+        assert not report.restart_policy["full_drain_required"]
+        assert report.counts["leases_disruptive"] == 0
+        assert report.counts["sessions_live_other"] == 0
+        assert report.counts["critical_sections"] == 0
+        assert report.counts["mutations"] == 0
+        assert report.allow_restart, (restart_class, report.reasons)
+
+
+def test_client_reconnect_does_not_wait_for_unrelated_terminal_lock():
+    inventory = _inventory()
+    inventory["terminal_lock"] = {"terminal_pr": 901}
+    report = rc.evaluate_restart_impact(
+        inventory,
+        now=NOW,
+        requesting_session_id="requester",
+        restart_class=rc.RestartClass.CLIENT_RECONNECT,
+        requester_role="author",
+        requester_permissions=rc.permissions_for_role("author"),
+    )
+    assert report.allow_restart
+    assert report.terminal_lock is None
+
+
+def test_scoped_restart_only_counts_named_target():
+    report = _evaluate(
+        rc.RestartClass.ROLE_RUNTIME_RESTART,
+        target_role="author",
+    )
+    assert report.counts["leases_disruptive"] == 0
+    assert report.affected_prs == []
+    assert report.allow_restart
+
+    reviewer = _evaluate(
+        rc.RestartClass.ROLE_RUNTIME_RESTART,
+        target_role="reviewer",
+    )
+    assert reviewer.counts["leases_disruptive"] == 1
+    assert reviewer.affected_prs == [900]
+    assert not reviewer.allow_restart
+
+
+def test_missing_scoped_target_denies_instead_of_widening():
+    for restart_class in (
+        rc.RestartClass.WORKER_RESTART,
+        rc.RestartClass.ROLE_RUNTIME_RESTART,
+        rc.RestartClass.CONNECTOR_RESTART,
+    ):
+        report = _evaluate(restart_class)
+        assert not report.allow_restart
+        assert any("target required" in r for r in report.reasons)
+
+
+def test_only_full_and_host_classes_require_full_drain():
+    requiring_full = {
+        restart_class
+        for restart_class, policy in rc.RESTART_CLASS_POLICIES.items()
+        if policy.full_drain_required
+    }
+    assert requiring_full == {
+        rc.RestartClass.FULL_MCP_RESTART,
+        rc.RestartClass.HOST_RESTART,
+    }

tests/test_webui_sanctioned_restart.py

@@ -444,6 +444,12 @@ class TestAuditEmission(unittest.TestCase):
         )
         self.assertEqual(record["target"]["namespace"], NAMESPACE)
         self.assertEqual(record["target"]["mode"], "restart")
+        self.assertEqual(
+            record["target"]["restart_class"], "role_runtime_restart"
+        )
+        self.assertEqual(
+            record["metadata"]["restart_class"], "role_runtime_restart"
+        )
         self.assertEqual(record["result"], console_audit.RESULT_ALLOWED)
         self.assertEqual(record["actor"]["subject"], "[email protected]")
         self.assertFalse(record["metadata"]["process_kill_executed"])

webui/sanctioned_restart.py

@@ -38,6 +38,7 @@ from dataclasses import asdict, dataclass
 from typing import Any
 
 import mcp_namespace_health
+import restart_coordinator
 import runtime_recovery_guard
 from webui import console_audit, console_authz
 
@@ -99,6 +100,14 @@ def _clean(value: Any) -> str:
     return str(value or "").strip()
 
 
+def restart_class_for_mode(mode: str) -> str:
+    """Map the existing namespace controls onto the #663 class taxonomy."""
+
+    if _clean(mode) == MODE_RELOAD:
+        return restart_coordinator.RestartClass.CONFIGURATION_RELOAD.value
+    return restart_coordinator.RestartClass.ROLE_RUNTIME_RESTART.value
+
+
 # --- Mutation ledger --------------------------------------------------------
 
 
@@ -256,6 +265,7 @@ def build_restart_preview(
 
     return {
         "action_id": action_id,
+        "restart_class": restart_class_for_mode(md),
         "namespace": ns,
         "mode": md,
         "scope_valid": scope_error is None,
@@ -309,6 +319,7 @@ def assess_restart_request(
             "reason_code": reason_code,
             "detail": detail,
             "action_id": action_id,
+            "restart_class": restart_class_for_mode(md),
             "namespace": ns,
             "mode": md,
             "preview": preview,
@@ -393,6 +404,7 @@ def assess_restart_request(
             "process."
         ),
         "action_id": action_id,
+        "restart_class": restart_class_for_mode(md),
         "namespace": ns,
         "mode": md,
         "preview": preview,
@@ -441,7 +453,11 @@ def execute_restart(
             else console_audit.RESULT_DENIED
         ),
         principal=principal,
-        target={"namespace": assessment["namespace"], "mode": assessment["mode"]},
+        target={
+            "namespace": assessment["namespace"],
+            "mode": assessment["mode"],
+            "restart_class": assessment["restart_class"],
+        },
         reason_code=assessment["reason_code"],
         detail=assessment["detail"],
         request_id=request_id,
@@ -450,6 +466,7 @@ def execute_restart(
             "gates_passed": assessment["gates_passed"],
             "process_kill_executed": False,
             "post_restart_verification_required": True,
+            "restart_class": assessment["restart_class"],
         },
     )
 
@@ -463,6 +480,7 @@ def execute_restart(
         "namespace": assessment["namespace"],
         "mode": assessment["mode"],
         "action_id": action_id,
+        "restart_class": assessment["restart_class"],
         "process_kill_executed": False,
         "host_hook": assessment["preview"]["restart_hook"],
         "next_action": (