diff --git a/branch_cleanup_guard.py b/branch_cleanup_guard.py
index 64db84a..e91ea02 100644
--- a/branch_cleanup_guard.py
+++ b/branch_cleanup_guard.py
@@ -525,6 +525,90 @@ def assess_ownership_record_activity(record: dict[str, Any]) -> dict[str, Any]:
     }
 
 
+# Reviewer-lease reclaim is only reachable from a non-live (expired/stale) lease.
+_RECLAIMABLE_REVIEWER_STATUSES = _EXPIRED_STATUSES | _STALE_STATUSES
+
+
+def is_active_ownership_status(status: str | None) -> bool:
+    """True when *status* denotes live/active ownership of a branch (#855).
+
+    Used to decide whether a *competing* active claimant still uses a branch
+    when weighing an expired reviewer lease for reclaim. Expired, stale,
+    released, and terminal statuses are not active.
+    """
+    return _norm_str(status).lower() in _ACTIVE_OWNERSHIP_STATUSES
+
+
+def assess_expired_reviewer_lease_reclaim(
+    *,
+    role: str,
+    status: str,
+    pr_merged: bool | None,
+    owner_pid_alive: bool | None,
+    competing_active_claimant: bool | None,
+) -> dict[str, Any]:
+    """Decide, explicitly and fail-closed, whether an expired reviewer lease
+    may stop protecting an already-merged branch (#855 AC4).
+
+    An expired reviewer lease should not protect a merged branch forever once
+    its work is done and no live claimant remains. Reclaim is permitted only
+    when **every** condition below is provably satisfied; any unknown
+    (``None``) or contrary value keeps the lease protective:
+
+    - the lease is a ``reviewer`` lease (author/merger/controller/reconciler
+      leases are out of scope and always keep protecting);
+    - its status is expired or stale (never an active/live lease);
+    - the PR is proven merged (``pr_merged is True``);
+    - the lease owner process is proven dead (``owner_pid_alive is False``);
+    - no competing active claimant uses the branch
+      (``competing_active_claimant is False``).
+
+    Returns a decision dict with ``reclaim_allowed`` and, when refused, the
+    fail-closed ``reasons``. The reasons never contain secrets — only the
+    role, the status, and which condition was unproven.
+    """
+    reasons: list[str] = []
+    normalized_role = _norm_str(role).lower()
+    normalized_status = _norm_str(status).lower()
+
+    if normalized_role != "reviewer":
+        reasons.append(
+            f"lease role '{normalized_role or 'unknown'}' is not a reviewer "
+            "lease; expired-reviewer reclaim does not apply"
+        )
+    if normalized_status not in _RECLAIMABLE_REVIEWER_STATUSES:
+        reasons.append(
+            f"lease status '{normalized_status or 'unknown'}' is not expired "
+            "or stale; only a non-live reviewer lease may be reclaimed"
+        )
+    if pr_merged is not True:
+        reasons.append(
+            "PR merged state is not proven true; reclaim requires an "
+            "already-merged PR (fail closed)"
+        )
+    if owner_pid_alive is not False:
+        reasons.append(
+            "lease owner process liveness is not proven dead; a live owner "
+            "still protects the branch (fail closed)"
+        )
+    if competing_active_claimant is not False:
+        reasons.append(
+            "a competing active claimant may still use the branch; reclaim "
+            "requires no other active ownership (fail closed)"
+        )
+
+    allowed = not reasons
+    return {
+        "reclaim_allowed": allowed,
+        "role": normalized_role,
+        "status": normalized_status,
+        "decision": (
+            "reclaim_expired_reviewer_lease" if allowed else "keep_protecting"
+        ),
+        "reasons": [] if allowed else reasons,
+    }
+
+
 def assess_active_branch_ownership(
     *,
     remote: str,
diff --git a/docs/architecture/mcp-restart-governance.md b/docs/architecture/mcp-restart-governance.md
new file mode 100644
index 0000000..2931d10
--- /dev/null
+++ b/docs/architecture/mcp-restart-governance.md
@@ -0,0 +1,223 @@
+# ADR: MCP restart governance and authorization policy
+
+- **Status:** Accepted (policy effective immediately for LLM and operator sessions; enforcement tooling may lag)
+- **Date:** 2026-07-23
+- **Tracking issue:** [#656](https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/issues/656)
+- **Policy version:** `restart-governance/v1`
+- **Related:**
+  - Umbrella: [#655](https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/issues/655) — governed MCP restart coordination and zero-disruption recovery
+  - Vision: [#652](https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/issues/652) — MCP Control Plane Web Console product vision (§A system health and process control)
+  - Roadmap: [#653](https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/issues/653) — Control Plane Web Console phased delivery (Phase 2 restart controls)
+  - Contamination guard: [#630](https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/issues/630) — blocks manual process-kill recovery
+  - Console restart UX: [#642](https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/issues/642) — sanctioned restart and graceful reload
+  - Existing restart / reconnect paths to inventory: [#591](https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/issues/591) — auto-restart on master advance (closed); [#584](https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/issues/584) — host auto-reconnect on transport flap
+  - Stable-control runtime split: `docs/architecture/mcp-stable-control-runtime-policy-adr.md` (#615)
+  - Client-namespace health: `docs/mcp-namespace-health.md` (#543)
+  - Reconnect-only EOF recovery: `docs/mcp-namespace-eof-recovery.md`
+
+## 1. Context
+
+The Gitea MCP server is the **control plane** for real issue and PR mutations
+(create, comment, lock, review, merge, reconcile). The same process serves every
+role namespace (`gitea-author`, `gitea-reviewer`, `gitea-merger`,
+`gitea-reconciler`, `gitea-controller`) and holds the in-memory capability-gate
+code loaded at startup.
+
+Restarting that process is destructive to concurrent work:
+
+- It resets every session's identity, preflight, and capability-lease binding.
+- It can interrupt a mutation mid-critical-section (a lock acquire, a review
+  submit, a merge), leaving durable state half-written.
+- Relaunching from the wrong checkout or worktree silently changes which code
+  the control plane runs, defeating master-parity gates (#420 / #615).
+
+Today there is **no durable written policy** stating who may restart MCP, under
+what conditions, that restart is a last resort, and how controller approval,
+automated safety gates, and break-glass interact. Operators and LLM sessions
+therefore invent restart behavior ad hoc, which makes concurrent multi-role work
+unsafe. #630 and #642 need this policy as their backbone.
+
+This ADR defines that policy. It does **not** implement coordinator code or HA
+multi-instance restart (those are later children of #655).
+
+## 2. Decision
+
+### 2.1 v1 decision (recorded)
+
+**Restart authority in v1 is `controller approval + automated safety gates`.**
+
+A restart of the stable control runtime is authorized only when **both** hold:
+
+1. A **controller** role explicitly approves the restart, recording an audit
+   entry (who, why, scope, affected sessions), **and**
+2. The **automated safety gates** pass: a completed drain acknowledgement (no
+   affected session is mid-critical-section) or a declared break-glass incident
+   (§2.5).
+
+Quorum among multiple controllers is **not** required day-one. It is deferred
+unless a later investigation (tracked under #653) proves single-controller
+approval is insufficient. This ADR records the v1 decision so enforcement code
+(#630) has a fixed target; changing it requires a superseding ADR.
+
+### 2.2 Restart is a last resort — the recovery ladder
+
+Restart is the **last** rung. Before any restart, exhaust the narrower
+recoveries, in order:
+
+1. **Reconnect** the IDE/client MCP namespace (transport EOF, `client is
+   closing: EOF`, transient `#584` flap). No process change. See
+   `docs/mcp-namespace-eof-recovery.md`.
+2. **Refresh / rebind** the session workspace: re-run `gitea_whoami`,
+   `gitea_resolve_task_capability`, and pass an explicit validated
+   `worktree_path`. Fixes stale session context without touching the process.
+3. **Scoped restart** of a single misbehaving namespace/service (where the
+   deployment supports per-service restart) rather than the whole control plane.
+4. **Full restart** of the stable control runtime process — operator-owned,
+   controller-approved, drained.
+5. **Host / infrastructure restart** — the broadest action; same authorization
+   as a full restart plus infrastructure ownership.
+
+A session **must** try rungs 1–2 and record why they were insufficient before
+requesting a restart at rung 3 or above. Skipping straight to restart is a
+policy violation.
+
+### 2.3 Authorization matrix
+
+| Role | Reconnect (1) | Refresh/rebind (2) | Scoped restart (3) | Full restart (4) | Host restart (5) |
+|---|---|---|---|---|---|
+| **author** | self | self | request only | **forbidden** | forbidden |
+| **reviewer** | self | self | request only | **forbidden** | forbidden |
+| **merger** | self | self | request only | **forbidden** | forbidden |
+| **reconciler** | self | self | request only | **forbidden** | forbidden |
+| **controller** | self | self | **approve** (+gates) | **approve** (+gates) | request to operator |
+| **operator** | self | self | execute (controller-approved) | execute (controller-approved) | execute (controller-approved) |
+| **admin** | self | self | execute | execute | execute (break-glass) |
+
+Legend: *self* = may perform for its own client session; *request only* = may
+raise a restart request but not authorize or execute it; *approve* = may
+authorize under §2.1 gates; *execute* = may perform the process action after the
+authorization is recorded.
+
+Key invariants:
+
+- **No LLM worker role (author/reviewer/merger/reconciler) may perform or
+  authorize a full or host restart.** They may only reconnect/rebind their own
+  client and file a restart request.
+- **Controller approval authorizes; operator/admin executes.** The approving
+  controller and the executing operator may be the same human, but both the
+  approval and the execution are audited.
+- Privileged process actions (full restart, host restart) are reserved to
+  **operator/admin**, never to an automated worker.
+
+### 2.4 Approved conditions
+
+A restart at rung 3+ is approved only under one of these recorded conditions:
+
+- **No affected sessions:** the control plane has no live session that would be
+  interrupted (verified, not assumed).
+- **Full drain acknowledged:** every affected session has drained
+  (no open critical section — no held mutation lease mid-write) and the drain is
+  acknowledged in the audit record.
+- **Controller + gates:** controller approval plus passing automated safety
+  gates (§2.1), the standard v1 path.
+- **Quorum:** not required in v1; reserved for a future superseding ADR.
+- **Break-glass:** an incident-backed emergency exception (§2.5).
+
+Restart **never** bypasses mutation gates mid-critical-section. Drain before
+restart is mandatory except under break-glass with a declared incident.
+
+### 2.5 Break-glass
+
+Break-glass is a **separate, narrower** authorization path for emergencies where
+the normal drain-and-approve path cannot complete (e.g. the control plane is
+wedged and cannot drain).
+
+Break-glass conditions:
+
+- A declared incident record exists (id, timestamp, declarer) **before** the
+  action.
+- The action is taken by **operator or admin** authority only — never by an LLM
+  worker role, and never unilaterally by an operator with active peers when a
+  controller is reachable.
+- The scope is the minimum necessary rung of the ladder.
+- A **mandatory post-hoc audit** entry is filed: what was restarted, why the
+  normal path was impossible, which sessions were affected, and the incident id.
+
+Break-glass suspends the drain requirement, not the audit requirement.
+
+### 2.6 Explicit prohibitions
+
+- **A unilateral LLM or operator full restart while active peer sessions
+  exist is forbidden.** An LLM worker role must not kill, restart, or relaunch
+  the MCP process; a lone operator must not full-restart over live peer work
+  without controller approval or a break-glass incident.
+- Process-kill recovery is forbidden as a routine tool (#630). This ADR does not
+  introduce a kill path.
+- Ambiguous policy state **denies** restart (§4).
+
+## 3. Security requirements
+
+- Full restart and host restart are **privileged**; only operator/admin execute
+  them, only after a controller approval or break-glass incident is recorded.
+- Break-glass is a distinct authorization path with its own audit mandate; it is
+  never the default and never silent.
+- **Every approval and every restart action is audited** (who approved, who
+  executed, scope, affected sessions, condition, policy version). No restart is
+  authorized without a durable audit entry.
+
+## 4. Failure behavior
+
+**Ambiguous policy → deny restart.** If it cannot be established that a
+restart is authorized under §2 — unknown affected-session state, missing
+controller approval, absent break-glass incident, or an unclassifiable request —
+the safe action is to **refuse** the restart and stop with a recovery report,
+never to restart on assumption.
+
+## 5. Policy IDs (for enforcement code)
+
+Enforcement code — the restart coordinator (a later child of #655), the #630
+contamination guard, and the #642 console restart UX — binds to these stable
+policy identifiers rather than to prose:
+
+| Policy ID | Statement |
+|---|---|
+| `RG-01` | Restart is last resort; rungs 1–2 must be tried and recorded first (§2.2). |
+| `RG-02` | v1 authority = controller approval + automated safety gates (§2.1). |
+| `RG-03` | No LLM worker role performs or authorizes full/host restart (§2.3). |
+| `RG-04` | Full/host restart executed by operator/admin only, post approval (§2.3). |
+| `RG-05` | Drain before restart is mandatory except break-glass with incident (§2.4). |
+| `RG-06` | Break-glass requires a pre-declared incident and post-hoc audit (§2.5). |
+| `RG-07` | Unilateral LLM/operator full restart with active peers is forbidden (§2.6). |
+| `RG-08` | Ambiguous policy state denies restart (§4). |
+
+The `restart-governance/v1` **policy version** field is emitted on future
+restart audit events so approvals can be reconciled against the policy revision
+in force.
+
+## 6. Dogfooding
+
+Gitea-Tools governs its own MCP control plane by this policy. Author, reviewer,
+merger, and reconciler sessions operating on this repository use the recovery
+ladder (§2.2) — reconnect and rebind, never self-restart — and any real restart
+of the Gitea-Tools stable control runtime follows the controller-approval +
+drain path defined here.
+
+## 7. Acceptance and cross-links
+
+This ADR is the authoritative restart-governance policy. It **must** stay
+cross-linked from the safety model and the web-console deployment boundary:
+
+- `docs/safety-model.md` § Process restart governance references this ADR.
+- `docs/webui-deployment.md` references this ADR for restart/reload disposition.
+
+It is linked to its issue lineage — umbrella **#655**, vision **#652**, roadmap
+**#653**, contamination guard **#630**, and console restart UX **#642** — in
+§ Related above.
+
+## 8. Non-goals
+
+- Implementing the restart coordinator or approval state machine (#630, later
+  children of #655).
+- Implementing HA multi-instance restart or quorum machinery.
+- Introducing any process-kill or auto-restart tool; existing auto-restart
+  behavior must be inventoried before any new restart tool is enabled.
diff --git a/docs/mcp-restart-path-inventory.md b/docs/mcp-restart-path-inventory.md
new file mode 100644
index 0000000..c880269
--- /dev/null
+++ b/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()`.
diff --git a/docs/safety-model.md b/docs/safety-model.md
index 31c740a..bbab241 100644
--- a/docs/safety-model.md
+++ b/docs/safety-model.md
@@ -46,3 +46,17 @@ If shell helpers are unavailable and MCP commit cannot run, stop with a recovery
 report (restart session, clear hung terminals, use MCP-native commit). See
 [`llm-workflow-runbooks.md`](llm-workflow-runbooks.md) § MCP-native commit path
 (#260) and agent temp artifact cleanup (#261).
+
+## 7. Process restart governance
+
+Restarting the MCP control-plane process is destructive to concurrent multi-role
+work and is governed by a dedicated policy. Restart is a **last resort** behind
+narrower recoveries (reconnect, rebind), full/host restart is reserved to
+operator/admin under **controller approval + automated safety gates**, a
+unilateral LLM or operator full restart with active peers is **forbidden**, and
+ambiguous policy state **denies** restart. Break-glass is a separate,
+incident-backed path with a mandatory audit.
+
+See [`architecture/mcp-restart-governance.md`](architecture/mcp-restart-governance.md)
+(#656) for the authorization matrix, the recovery ladder, break-glass
+conditions, and the `RG-01`–`RG-08` policy IDs.
diff --git a/docs/webui-deployment.md b/docs/webui-deployment.md
index fa754ad..2ad46ab 100644
--- a/docs/webui-deployment.md
+++ b/docs/webui-deployment.md
@@ -55,6 +55,15 @@ shipped to the browser.
 assumption paths, and the client-secret policy. Use it to verify an instance is
 configured for internal-only operation.
 
+## Process restart / reload disposition
+
+The console never exposes a restart or reload control; process restart of the
+MCP control-plane runtime is governed separately. Restart is a last resort behind
+reconnect/rebind, full restart is operator/admin-only under controller approval
+plus safety gates, and break-glass is an incident-backed path. See
+[`architecture/mcp-restart-governance.md`](architecture/mcp-restart-governance.md)
+(#656).
+
 ## Non-goals (MVP)
 
 - Full SSO or session login in the UI
diff --git a/gitea_mcp_server.py b/gitea_mcp_server.py
index ed5fc11..e5272e0 100644
--- a/gitea_mcp_server.py
+++ b/gitea_mcp_server.py
@@ -2446,6 +2446,20 @@ def _evaluate_issue_lock_recovery(
             descendant_sha=local_head,
         )
 
+    # #871: the inverse of the #768 descendant relation — the *remote* head may
+    # have advanced past the local/recorded head via a sanctioned merge-based
+    # branch sync (``gitea_update_pr_branch_by_merge``) while the local worktree
+    # stayed put. Observe that provenance server-side so the assessor can prove
+    # it and nothing else. Probed only when the heads differ; never from any
+    # caller-supplied value.
+    sync_provenance: dict | None = None
+    if remote_head and local_head and remote_head != local_head:
+        sync_provenance = issue_lock_worktree.read_merge_sync_provenance(
+            worktree_path,
+            prior_head_sha=local_head,
+            synced_head_sha=remote_head,
+        )
+
     # #772: with no remote branch there is no head to measure against, so the
     # base the branch was cut from is observed instead. Probed only in that
     # case, so the published path's evidence is untouched (#772 AC8).
@@ -2488,6 +2502,7 @@ def _evaluate_issue_lock_recovery(
         remote_branch_exists=remote_branch_exists,
         recorded_base_sha=recorded_base,
         base_ancestry=base_ancestry,
+        sync_provenance=sync_provenance,
     )
 
 
@@ -11117,6 +11132,9 @@ def _collect_branch_ownership_records(
     """
     records: list[dict] = []
     inventory_error = False
+    # #855 AC4: expired/stale reviewer-lease records eligible for an explicit
+    # reclaim decision, evaluated after the full ownership inventory is built.
+    reviewer_reclaim_candidates: list[tuple[dict, bool | None]] = []
     target_branch = (branch or "").strip()
     if not target_branch:
         return {"records": records, "inventory_error": False}
@@ -11265,15 +11283,28 @@ def _collect_branch_ownership_records(
                 else:
                     status = freshness_status
                     reclaim_allowed = False
-                records.append(
-                    _base_rec(
-                        category=category,
-                        status=status,
-                        reclaim_allowed=reclaim_allowed,
-                        role=role,
-                        host=lease_host or host_n or host,
-                    )
+                rec = _base_rec(
+                    category=category,
+                    status=status,
+                    reclaim_allowed=reclaim_allowed,
+                    role=role,
+                    host=lease_host or host_n or host,
                 )
+                records.append(rec)
+                # #855 AC4: a reviewer lease that is expired/stale (its owner
+                # gone) becomes a candidate for an explicit, fail-closed
+                # reclaim decision made once the full inventory is known.
+                if (
+                    role == "reviewer"
+                    and status
+                    in branch_cleanup_guard._RECLAIMABLE_REVIEWER_STATUSES
+                ):
+                    owner_alive = (
+                        fr.get("owner_pid_alive") if isinstance(fr, dict) else None
+                    )
+                    reviewer_reclaim_candidates.append(
+                        (rec, owner_alive if isinstance(owner_alive, bool) else None)
+                    )
     except Exception:
         # O1: fail closed on control-plane inventory errors.
         inventory_error = True
@@ -11344,6 +11375,44 @@ def _collect_branch_ownership_records(
             )
         )
 
+    # #855 AC4: decide, explicitly and fail-closed, whether any expired/stale
+    # reviewer lease may stop protecting an already-merged branch. This runs
+    # only after the full ownership inventory is built, so a competing active
+    # claimant (an active lease, author session, worktree binding, or active
+    # reviewer comment lease) is visible. An inventory failure keeps every
+    # reclaim candidate protective (reclaim_allowed stays False).
+    if reviewer_reclaim_candidates and not inventory_error:
+        pr_merged_state: bool | None = None
+        if pr_number is not None and auth and base_api:
+            try:
+                pr_live = api_request(
+                    "GET", f"{base_api}/pulls/{int(pr_number)}", auth
+                )
+                if isinstance(pr_live, dict) and pr_live:
+                    pr_merged_state = bool(
+                        pr_live.get("merged") or pr_live.get("merged_at")
+                    )
+            except Exception:
+                # Unknown merged state fails closed (candidate stays protective).
+                pr_merged_state = None
+        for cand_rec, owner_alive in reviewer_reclaim_candidates:
+            competing = any(
+                other is not cand_rec
+                and branch_cleanup_guard.is_active_ownership_status(
+                    other.get("status")
+                )
+                for other in records
+            )
+            decision = branch_cleanup_guard.assess_expired_reviewer_lease_reclaim(
+                role=str(cand_rec.get("role")),
+                status=str(cand_rec.get("status")),
+                pr_merged=pr_merged_state,
+                owner_pid_alive=owner_alive,
+                competing_active_claimant=competing,
+            )
+            cand_rec["reclaim_allowed"] = decision["reclaim_allowed"]
+            cand_rec["reclaim_decision"] = decision["decision"]
+
     return {"records": records, "inventory_error": inventory_error}
 
 
@@ -11406,6 +11475,7 @@ def gitea_reconcile_merged_cleanups(
     dry_run: bool = True,
     execute_confirmed: bool = False,
     limit: int = 50,
+    pr_number: int | None = None,
     remote: str = "dadeschools",
     host: str | None = None,
     org: str | None = None,
@@ -11416,7 +11486,11 @@ def gitea_reconcile_merged_cleanups(
     Args:
         dry_run: Defaults to True. When True, only builds the reconciliation report.
         execute_confirmed: Must be True when dry_run=False.
-        limit: Max number of closed PRs to inspect.
+        limit: Max number of closed PRs to inspect (batch mode only; ignored when
+            ``pr_number`` is set).
+        pr_number: Optional exact merged PR selector (#855). When set, only that
+            PR is assessed/acted on (fail closed if missing, unmerged, or
+            ambiguous). When omitted, existing batch behaviour is preserved.
         remote: Known Gitea instance ('dadeschools' or 'prgs').
         host: Override the Gitea host.
         org: Override the owner/organization.
@@ -11451,11 +11525,120 @@ def gitea_reconcile_merged_cleanups(
                 "audit_phase": audit_reconciliation_mode.current_phase(),
             }
 
+    # #855: optional exact PR pin. Fail closed before any inventory mutation.
+    exact_pr: int | None = None
+    if pr_number is not None:
+        try:
+            exact_pr = int(pr_number)
+        except (TypeError, ValueError):
+            return {
+                "success": False,
+                "performed": False,
+                "executed": False,
+                "dry_run": bool(dry_run),
+                "selection_mode": "exact_pr",
+                "selected_pr_number": pr_number,
+                "reasons": [
+                    f"pr_number={pr_number!r} is not a valid integer "
+                    "(fail closed; no mutation)"
+                ],
+                "blocker_kind": "invalid_pr_number",
+            }
+        if exact_pr <= 0:
+            return {
+                "success": False,
+                "performed": False,
+                "executed": False,
+                "dry_run": bool(dry_run),
+                "selection_mode": "exact_pr",
+                "selected_pr_number": exact_pr,
+                "reasons": [
+                    f"pr_number={exact_pr} must be a positive integer "
+                    "(fail closed; no mutation)"
+                ],
+                "blocker_kind": "invalid_pr_number",
+            }
+
     h, o, r = _resolve(remote, host, org, repo)
     auth = _auth(h)
     base = repo_api_url(h, o, r)
-    closed_prs = api_get_all(f"{base}/pulls?state=closed", auth, limit=limit)
-    open_prs = api_get_all(f"{base}/pulls?state=open", auth)
+
+    selection_mode = "batch"
+    closed_prs: list[dict] = []
+    open_prs: list[dict] = []
+    if exact_pr is not None:
+        selection_mode = "exact_pr"
+        try:
+            pr_live = api_request("GET", f"{base}/pulls/{exact_pr}", auth)
+        except Exception as exc:
+            return {
+                "success": False,
+                "performed": False,
+                "executed": False,
+                "dry_run": bool(dry_run),
+                "selection_mode": selection_mode,
+                "selected_pr_number": exact_pr,
+                "reasons": [
+                    f"PR #{exact_pr} could not be uniquely resolved "
+                    f"(fail closed; no mutation): {_redact(str(exc))}"
+                ],
+                "blocker_kind": "pr_unresolvable",
+            }
+        if not isinstance(pr_live, dict) or not pr_live:
+            return {
+                "success": False,
+                "performed": False,
+                "executed": False,
+                "dry_run": bool(dry_run),
+                "selection_mode": selection_mode,
+                "selected_pr_number": exact_pr,
+                "reasons": [
+                    f"PR #{exact_pr} could not be uniquely resolved "
+                    "(empty response; fail closed; no mutation)"
+                ],
+                "blocker_kind": "pr_unresolvable",
+            }
+        live_number = pr_live.get("number")
+        try:
+            live_number_int = int(live_number) if live_number is not None else None
+        except (TypeError, ValueError):
+            live_number_int = None
+        if live_number_int != exact_pr:
+            return {
+                "success": False,
+                "performed": False,
+                "executed": False,
+                "dry_run": bool(dry_run),
+                "selection_mode": selection_mode,
+                "selected_pr_number": exact_pr,
+                "reasons": [
+                    f"PR #{exact_pr} resolution is ambiguous or mismatched "
+                    f"(live number={live_number!r}; fail closed; no mutation)"
+                ],
+                "blocker_kind": "pr_ambiguous",
+            }
+        if not (pr_live.get("merged") or pr_live.get("merged_at")):
+            return {
+                "success": False,
+                "performed": False,
+                "executed": False,
+                "dry_run": bool(dry_run),
+                "selection_mode": selection_mode,
+                "selected_pr_number": exact_pr,
+                "reasons": [
+                    f"PR #{exact_pr} is not merged "
+                    "(exact-target cleanup requires a merged PR; "
+                    "fail closed; no mutation)"
+                ],
+                "blocker_kind": "pr_not_merged",
+            }
+        closed_prs = [pr_live]
+        # Exact mode still needs open heads for remote-delete safety gates.
+        open_prs = api_get_all(f"{base}/pulls?state=open", auth)
+    else:
+        # Preserve historical call order (closed then open) for batch callers/tests.
+        closed_prs = api_get_all(f"{base}/pulls?state=closed", auth, limit=limit)
+        open_prs = api_get_all(f"{base}/pulls?state=open", auth)
 
     merged_closed: list[dict] = []
     remote_branch_exists: dict[str, bool] = {}
@@ -11482,6 +11665,13 @@ def gitea_reconcile_merged_cleanups(
     scratch_candidates = merged_cleanup_reconcile.discover_reviewer_scratch_worktrees(
         _canonical_local_git_root()
     )
+    # #855: exact-target never inventories or mutates foreign PR scratch trees.
+    if exact_pr is not None:
+        scratch_candidates = [
+            s
+            for s in scratch_candidates
+            if int(s.get("pr_number") or 0) == int(exact_pr)
+        ]
     active_reviewer_leases: dict[int, bool] = {}
     pr_states: dict[int, dict] = {}
     for scratch in scratch_candidates:
@@ -11516,6 +11706,33 @@ def gitea_reconcile_merged_cleanups(
         active_reviewer_leases=active_reviewer_leases,
         pr_states=pr_states,
     )
+    report["selection_mode"] = selection_mode
+    if exact_pr is not None:
+        report["selected_pr_number"] = exact_pr
+        # Fail closed if exact pin somehow produced other or zero entries.
+        entries = list(report.get("entries") or [])
+        entry_numbers = []
+        for entry in entries:
+            try:
+                entry_numbers.append(int(entry.get("pr_number")))
+            except (TypeError, ValueError):
+                entry_numbers.append(entry.get("pr_number"))
+        if entry_numbers != [exact_pr]:
+            return {
+                "success": False,
+                "performed": False,
+                "executed": False,
+                "dry_run": bool(dry_run),
+                "selection_mode": selection_mode,
+                "selected_pr_number": exact_pr,
+                "reasons": [
+                    f"exact PR #{exact_pr} selection produced unexpected "
+                    f"candidate set {entry_numbers!r} "
+                    "(fail closed; no mutation)"
+                ],
+                "blocker_kind": "exact_selection_mismatch",
+                "entries": entries,
+            }
 
     if dry_run:
         report["dry_run"] = True
@@ -18890,10 +19107,59 @@ def gitea_update_pr_branch_by_merge(
         prepared_verdict_head_sha=live_pr_head,
     )
 
-    return {
-        "success": True,
+    # #871: the remote head is now advanced; the durable linked-issue lock must
+    # be advanced with it, or a later dead-session recovery can never prove
+    # ownership at the new head. This runs AFTER the successful remote update, so
+    # a failure here is a *partial* lifecycle failure — the remote moved but the
+    # durable state did not — and must never be reported as a full success.
+    claimant = _work_lease_claimant(h)
+    matched_issue = ownership.get("matched_issue")
+    synced_at = datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
+    lock_refresh: dict = {
+        "refreshed": False,
+        "reasons": ["durable lock head refresh was not attempted"],
+    }
+    if new_head and matched_issue and source_branch and (wt or None):
+        try:
+            lock_refresh = issue_lock_store.apply_durable_lock_head_refresh(
+                remote=remote,
+                org=o,
+                repo=r,
+                issue_number=int(matched_issue),
+                branch_name=source_branch,
+                worktree_path=wt,
+                pr_number=pr_number,
+                identity=claimant.get("username"),
+                profile=claimant.get("profile"),
+                current_pid=os.getpid(),
+                expected_old_head=live_pr_head,
+                new_head=new_head,
+                synced_at=synced_at,
+                base_head=live_base_head,
+            )
+        except Exception as exc:
+            lock_refresh = {
+                "refreshed": False,
+                "reasons": [
+                    f"durable lock head refresh raised (fail closed): {_redact(str(exc))}"
+                ],
+            }
+    else:
+        lock_refresh = {
+            "refreshed": False,
+            "reasons": [
+                "durable lock head refresh could not run: missing new head, "
+                "linked issue, source branch, or worktree binding"
+            ],
+        }
+
+    durable_refreshed = bool(lock_refresh.get("refreshed"))
+    base_result = {
         "performed": True,
         "mutation_allowed": True,
+        "durable_lock_refreshed": durable_refreshed,
+        "durable_lock_refresh": lock_refresh,
+        "fully_synchronized": durable_refreshed,
         "style": "merge",
         "force_push": False,
         "rebase": False,
@@ -18915,19 +19181,37 @@ def gitea_update_pr_branch_by_merge(
         "prepared_verdict_invalidated": transition.get(
             "prepared_verdict_invalidated"
         ),
-        "recommended_next_action": transition.get(
-            "recommended_next_action",
-            pr_sync_status.ACTION_FRESH_REVIEW_REQUIRED,
-        ),
         "transition": transition,
         "role_kind": role,
         "profile_name": profile.get("profile_name"),
         "worktree_path": wt or None,
-        "reasons": list(transition.get("reasons") or []) + [
-            "update-by-merge completed via native Gitea API (style=merge only)"
-        ],
     }
 
+    if durable_refreshed:
+        base_result["success"] = True
+        base_result["recommended_next_action"] = transition.get(
+            "recommended_next_action",
+            pr_sync_status.ACTION_FRESH_REVIEW_REQUIRED,
+        )
+        base_result["reasons"] = list(transition.get("reasons") or []) + [
+            "update-by-merge completed via native Gitea API (style=merge only)",
+            f"durable linked-issue lock #{matched_issue} head refreshed to "
+            f"{new_head} (verified by read-after-write)",
+        ]
+        return base_result
+
+    # Partial lifecycle failure: the remote advanced but the durable lock did
+    # not. Do NOT report a fully successful synchronization (#871).
+    base_result["success"] = False
+    base_result["partial_lifecycle_failure"] = True
+    base_result["recommended_next_action"] = pr_sync_status.ACTION_BLOCKED
+    base_result["reasons"] = list(lock_refresh.get("reasons") or []) + [
+        f"PARTIAL LIFECYCLE FAILURE: PR #{pr_number} remote head advanced to "
+        f"{new_head} but the durable linked-issue lock head was not refreshed; "
+        "the synchronization is NOT complete",
+    ]
+    return base_result
+
 
 @mcp.tool()
 def gitea_assess_conflict_fix_push(
diff --git a/issue_lock_recovery.py b/issue_lock_recovery.py
index ecc99c6..ae0cc35 100644
--- a/issue_lock_recovery.py
+++ b/issue_lock_recovery.py
@@ -85,6 +85,12 @@ HEAD_RELATION_STRICT_DESCENDANT = "strict_descendant"
 # #772: an unpublished claim has no recorded head to compare against at all, so
 # its head is measured against the base the branch was cut from instead.
 HEAD_RELATION_DESCENDS_FROM_BASE = "descends_from_recorded_base"
+# #871: the remote/PR head advanced *past* the recorded head via a sanctioned
+# merge-based branch synchronization (``gitea_update_pr_branch_by_merge``) while
+# the local worktree stayed at the recorded head. This is the inverse of the
+# #768 descendant relation — here the *remote* strictly descends the local head,
+# and only because a base was merged into the branch, proven server-side.
+HEAD_RELATION_REMOTE_MERGE_SYNCED = "remote_merge_synced"
 
 # Which body of evidence a recovery was decided on (#772 AC10). These are not
 # interchangeable: a published claim proves ownership against a remote/PR head,
@@ -266,6 +272,70 @@ def _assess_base_descendancy(
     ]
 
 
+def _assess_remote_merge_synced(
+    sync_provenance: Mapping[str, Any] | None,
+    *,
+    recorded_head: str,
+    remote_head: str,
+) -> tuple[bool, list[str]]:
+    """Did ``remote_head`` advance past ``recorded_head`` via a sanctioned
+    merge-based branch sync (#871)?
+
+    ``sync_provenance`` is the server-side git observation from
+    ``issue_lock_worktree.read_merge_sync_provenance``. Its own
+    ``prior_head_sha`` / ``synced_head_sha`` are re-checked against the heads
+    this assessment is actually reasoning about, so an observation taken for some
+    other pair of commits — stale, mismatched, or hand-built — can never
+    authorize recovery. This is the inverse of ``_assess_strict_descendant``: the
+    recorded head is the ancestor and the *remote* head is the descendant, and it
+    is accepted only because the remote head is a base-into-branch merge that
+    preserved the branch mainline back to the recorded head.
+
+    Returns ``(proven, notes)``. Notes name the exact missing element so a
+    refused caller sees why, never a bare "unproven".
+    """
+    if not isinstance(sync_provenance, Mapping):
+        return False, [
+            "no server-derived merge-sync provenance observation was available; a "
+            "remote head ahead of the recorded head cannot be accepted"
+        ]
+
+    probe_prior = _text(sync_provenance.get("prior_head_sha"))
+    probe_synced = _text(sync_provenance.get("synced_head_sha"))
+    if probe_prior != recorded_head or probe_synced != remote_head:
+        return False, [
+            f"merge-sync observation covers {probe_prior or 'unknown'} -> "
+            f"{probe_synced or 'unknown'}, not the heads under assessment "
+            f"({recorded_head} -> {remote_head})"
+        ]
+    if not sync_provenance.get("probe_ok"):
+        return False, (
+            list(sync_provenance.get("reasons") or [])
+            or ["merge-sync provenance probe did not complete; provenance unproven"]
+        )
+    if not sync_provenance.get("prior_is_ancestor"):
+        return False, [
+            f"recorded head {recorded_head} is not an ancestor of remote head "
+            f"{remote_head}; a rewritten or force-moved head cannot be recovered"
+        ]
+    if not sync_provenance.get("is_merge_sync"):
+        return False, (
+            list(sync_provenance.get("reasons") or [])
+            or [
+                f"remote head {remote_head} is not a sanctioned merge-based sync "
+                f"of the base into the branch above {recorded_head}"
+            ]
+        )
+
+    proof = _text(sync_provenance.get("proof")) or (
+        f"{remote_head} merged the base into the branch above {recorded_head}"
+    )
+    return True, [
+        f"remote head {remote_head} advanced past recorded head {recorded_head} "
+        f"via a sanctioned merge-based branch sync ({proof})"
+    ]
+
+
 def assess_dead_session_lock_recovery(
     existing_lock: Mapping[str, Any] | None,
     *,
@@ -290,6 +360,7 @@ def assess_dead_session_lock_recovery(
     remote_branch_exists: bool | None = None,
     recorded_base_sha: str | None = None,
     base_ancestry: Mapping[str, Any] | None = None,
+    sync_provenance: Mapping[str, Any] | None = None,
 ) -> dict[str, Any]:
     """Decide whether a dead-session author lock may be natively recovered.
 
@@ -469,19 +540,39 @@ def assess_dead_session_lock_recovery(
                     head_relation = HEAD_RELATION_STRICT_DESCENDANT
                     ancestry_proof = notes[0] if notes else None
                 else:
-                    reasons.append(
-                        f"local head {local_head} does not match remote branch head "
-                        f"{remote_head}"
+                    # #871: the reverse relation — the remote head advanced past
+                    # the recorded/local head via a sanctioned merge-based branch
+                    # sync while the local worktree stayed put. Accepted only on
+                    # server-proven merge-sync provenance, never a caller claim.
+                    synced, sync_notes = _assess_remote_merge_synced(
+                        sync_provenance,
+                        recorded_head=local_head,
+                        remote_head=remote_head,
                     )
-                    reasons.extend(notes)
+                    if synced:
+                        head_relation = HEAD_RELATION_REMOTE_MERGE_SYNCED
+                        ancestry_proof = sync_notes[0] if sync_notes else None
+                    else:
+                        reasons.append(
+                            f"local head {local_head} does not match remote branch "
+                            f"head {remote_head}"
+                        )
+                        reasons.extend(notes)
+                        reasons.extend(sync_notes)
     evidence["recorded_base"] = recorded_base or None
     evidence["local_head"] = local_head or None
     evidence["remote_head"] = remote_head or None
     # ``recorded_head`` is the head recovery is being measured against;
     # ``accepted_head`` is the head this recovery actually adopts. They differ
     # only in the descendant case, and downstream gates need both (#768 AC2/AC7).
+    # #871: in the merge-sync case the branch/PR already carries the synced
+    # remote head, so that is the head recovery adopts; the local worktree stays
+    # at the ancestor recorded head.
     evidence["recorded_head"] = remote_head or None
-    evidence["accepted_head"] = local_head or None
+    if head_relation == HEAD_RELATION_REMOTE_MERGE_SYNCED:
+        evidence["accepted_head"] = remote_head or None
+    else:
+        evidence["accepted_head"] = local_head or None
     evidence["head_relation"] = head_relation
     evidence["ancestry_proof"] = ancestry_proof
 
@@ -493,12 +584,17 @@ def assess_dead_session_lock_recovery(
         # contradictory; re-stating it as a head mismatch would only obscure why.
         if not unpublished and local_head and pr_head != local_head:
             # A descendant recovery has not been published yet, so the open PR
-            # legitimately still points at the recorded head. Any other
-            # disagreement is a real mismatch.
+            # legitimately still points at the recorded head. A merge-sync
+            # recovery's PR legitimately sits at the advanced remote head. Any
+            # other disagreement is a real mismatch.
             if not (
                 head_relation == HEAD_RELATION_STRICT_DESCENDANT
                 and remote_head
                 and pr_head == remote_head
+            ) and not (
+                head_relation == HEAD_RELATION_REMOTE_MERGE_SYNCED
+                and remote_head
+                and pr_head == remote_head
             ):
                 reasons.append(
                     f"open PR #{pr_number} head {pr_head} does not match local head "
@@ -619,7 +715,11 @@ def assess_dead_session_lock_recovery(
         )
     if (
         head_relation
-        in (HEAD_RELATION_STRICT_DESCENDANT, HEAD_RELATION_DESCENDS_FROM_BASE)
+        in (
+            HEAD_RELATION_STRICT_DESCENDANT,
+            HEAD_RELATION_DESCENDS_FROM_BASE,
+            HEAD_RELATION_REMOTE_MERGE_SYNCED,
+        )
         and ancestry_proof
     ):
         proof.append(ancestry_proof)
@@ -697,6 +797,16 @@ def owning_pr_recovery_evidence(
             return None
         if accepted_head != local_head:
             return None
+    elif relation == HEAD_RELATION_REMOTE_MERGE_SYNCED:
+        # #871: the PR already sits at the advanced remote head; the local
+        # worktree is the ancestor the merge preserved. The head the open PR
+        # shows and the head recovery adopts are both the synced remote head.
+        if not remote_head or pr_head != remote_head:
+            return None
+        if accepted_head != remote_head:
+            return None
+        if not local_head or local_head == remote_head:
+            return None
     else:
         return None
     try:
@@ -765,6 +875,18 @@ def recovered_owning_pr_from_lock(
             return None
         if not accepted_head or accepted_head == recorded_head:
             return None
+    elif relation == HEAD_RELATION_REMOTE_MERGE_SYNCED:
+        # #871: PR sits at the advanced remote head, which is both the recorded
+        # measured-against head and the adopted head; the local worktree is the
+        # ancestor the merge preserved.
+        remote_head = _text(record.get("remote_head"))
+        local_head = _text(record.get("local_head"))
+        if not remote_head or pr_head != remote_head:
+            return None
+        if accepted_head and accepted_head != remote_head:
+            return None
+        if not local_head or local_head == remote_head:
+            return None
     else:
         return None
     try:
diff --git a/issue_lock_store.py b/issue_lock_store.py
index 713fa2a..a963174 100644
--- a/issue_lock_store.py
+++ b/issue_lock_store.py
@@ -737,4 +737,308 @@ def format_lock_proof(
         parts.append("lock released")
     elif released is False:
         parts.append("lock retained")
-    return "; ".join(parts)
\ No newline at end of file
+    return "; ".join(parts)
+
+
+# ── #871: durable linked-issue lock head refresh after branch synchronization ──
+_FULL_SHA_RE = re.compile(r"^[0-9a-f]{40}$", re.IGNORECASE)
+
+# Provenance recorded on the lock when the head is refreshed by a sanctioned
+# merge-based branch synchronization (``gitea_update_pr_branch_by_merge``).
+LOCK_HEAD_REFRESH_PROVENANCE_MERGE_SYNC = "gitea_update_pr_branch_by_merge"
+
+
+def _norm_sha(value: Any) -> str | None:
+    text = str(value or "").strip().lower()
+    return text if _FULL_SHA_RE.match(text) else None
+
+
+def _lock_claimant_view(lock: dict[str, Any] | None) -> dict[str, Any]:
+    if not isinstance(lock, dict):
+        return {}
+    claimant = lock.get("claimant")
+    if not isinstance(claimant, dict):
+        lease = lock.get("work_lease")
+        claimant = lease.get("claimant") if isinstance(lease, dict) else None
+    return dict(claimant) if isinstance(claimant, dict) else {}
+
+
+def assess_durable_lock_head_refresh(
+    existing_lock: dict[str, Any] | None,
+    *,
+    remote: str,
+    org: str,
+    repo: str,
+    issue_number: int,
+    branch_name: str,
+    worktree_path: str,
+    pr_number: int | None,
+    identity: str | None,
+    profile: str | None,
+    current_pid: int | None,
+    expected_old_head: str | None,
+    new_head: str | None,
+    base_head: str | None = None,
+) -> dict[str, Any]:
+    """Fail-closed assessment for refreshing a durable lock's recorded head (#871).
+
+    A successful ``gitea_update_pr_branch_by_merge`` advances the *remote* PR head
+    but must also advance the durable linked-issue lock so a later dead-session
+    recovery can prove ownership. This decides whether that refresh is permitted;
+    it mutates nothing.
+
+    Every element of durable ownership is re-verified against the persisted lock —
+    repository, issue, branch, worktree, claimant identity/profile, and the live
+    owning session — and the recorded head is compare-and-swapped: the lock's
+    currently recorded synced head (if any) must equal ``expected_old_head``, so a
+    lock whose head or provenance changed concurrently is never overwritten.
+    """
+    reasons: list[str] = []
+    old = _norm_sha(expected_old_head)
+    new = _norm_sha(new_head)
+    evidence: dict[str, Any] = {
+        "issue_number": issue_number,
+        "branch_name": branch_name,
+        "worktree_path": worktree_path,
+        "pr_number": pr_number,
+        "expected_old_head": old,
+        "new_head": new,
+        "base_head": _norm_sha(base_head),
+    }
+
+    if not isinstance(existing_lock, dict) or not existing_lock:
+        reasons.append("no durable lock exists for this issue; nothing to refresh")
+        return {"allowed": False, "reasons": reasons, "evidence": evidence,
+                "expected_generation": 0}
+
+    lock = dict(existing_lock)
+    evidence["current_generation"] = lock_generation(lock)
+
+    if lock.get("issue_number") != issue_number:
+        reasons.append(
+            f"durable lock targets issue #{lock.get('issue_number')}, not "
+            f"#{issue_number}; refusing head refresh"
+        )
+
+    for field, expected in (("remote", remote), ("org", org), ("repo", repo)):
+        actual = str(lock.get(field) or "").strip()
+        if actual != str(expected or "").strip():
+            reasons.append(
+                f"lock {field} '{actual}' does not match requested "
+                f"'{str(expected or '').strip()}'"
+            )
+
+    locked_branch = str(lock.get("branch_name") or "").strip()
+    if locked_branch != str(branch_name or "").strip():
+        reasons.append(
+            f"lock branch '{locked_branch}' does not match requested "
+            f"'{str(branch_name or '').strip()}'"
+        )
+
+    locked_worktree = str(lock.get("worktree_path") or "").strip()
+    try:
+        same_wt = bool(locked_worktree) and bool(worktree_path) and (
+            os.path.realpath(locked_worktree) == os.path.realpath(worktree_path)
+        )
+    except OSError:
+        same_wt = locked_worktree == (worktree_path or "")
+    if not same_wt:
+        reasons.append(
+            f"lock worktree '{locked_worktree}' does not match declared "
+            f"'{str(worktree_path or '').strip()}'"
+        )
+
+    claimant = _lock_claimant_view(lock)
+    locked_identity = str(claimant.get("username") or "").strip()
+    locked_profile = str(claimant.get("profile") or "").strip()
+    if not locked_identity or not locked_profile:
+        reasons.append(
+            "durable lock does not record a claimant identity/profile; "
+            "ownership could not be proven for head refresh"
+        )
+    if not str(identity or "").strip() or not str(profile or "").strip():
+        reasons.append(
+            "active session identity/profile is unknown; ownership could not be "
+            "proven for head refresh"
+        )
+    if locked_identity and str(identity or "").strip() and locked_identity != str(identity).strip():
+        reasons.append(
+            f"lock claimant '{locked_identity}' does not match active identity "
+            f"'{str(identity).strip()}'"
+        )
+    if locked_profile and str(profile or "").strip() and locked_profile != str(profile).strip():
+        reasons.append(
+            f"lock profile '{locked_profile}' does not match active profile "
+            f"'{str(profile).strip()}'"
+        )
+
+    # The refresh is written by the LIVE owning author session. A refresh is not
+    # a recovery: the current process must be the recorded owner.
+    recorded_pid = lock.get("session_pid")
+    if recorded_pid is None:
+        recorded_pid = lock.get("pid")
+    evidence["recorded_pid"] = recorded_pid
+    evidence["current_pid"] = current_pid
+    if current_pid is None:
+        reasons.append("current session pid is unknown; cannot prove live ownership")
+    else:
+        try:
+            if recorded_pid is None or int(recorded_pid) != int(current_pid):
+                reasons.append(
+                    f"durable lock is owned by pid {recorded_pid}, not the current "
+                    f"session pid {current_pid}; head refresh requires the live owner"
+                )
+        except (TypeError, ValueError):
+            reasons.append(
+                "durable lock owner pid is malformed; cannot prove live ownership"
+            )
+
+    if not old:
+        reasons.append("expected_old_head is not a full 40-char hex SHA (fail closed)")
+    if not new:
+        reasons.append("new_head is not a full 40-char hex SHA (fail closed)")
+    if old and new and old == new:
+        reasons.append(
+            "new head equals the expected old head; a sync must advance the head"
+        )
+
+    # Compare-and-swap on the recorded head: if the lock already records a synced
+    # head it must be exactly the expected old head, else another sync moved it.
+    recorded_synced = _norm_sha(lock.get("synced_pr_head"))
+    evidence["recorded_synced_pr_head"] = recorded_synced
+    if recorded_synced is not None and old is not None and recorded_synced != old:
+        reasons.append(
+            f"durable lock already records synced head {recorded_synced}, not the "
+            f"expected old head {old}; a concurrent sync changed it (CAS fail closed)"
+        )
+
+    if reasons:
+        return {"allowed": False, "reasons": reasons, "evidence": evidence,
+                "expected_generation": lock_generation(lock)}
+
+    return {
+        "allowed": True,
+        "reasons": [
+            f"durable lock for issue #{issue_number} branch '{locked_branch}' is "
+            f"owned by the live session; refresh recorded head {old} -> {new}"
+        ],
+        "evidence": evidence,
+        "expected_generation": lock_generation(lock),
+    }
+
+
+def apply_durable_lock_head_refresh(
+    *,
+    remote: str,
+    org: str,
+    repo: str,
+    issue_number: int,
+    branch_name: str,
+    worktree_path: str,
+    pr_number: int | None,
+    identity: str | None,
+    profile: str | None,
+    current_pid: int | None,
+    expected_old_head: str | None,
+    new_head: str | None,
+    synced_at: str,
+    base_head: str | None = None,
+    provenance: str = LOCK_HEAD_REFRESH_PROVENANCE_MERGE_SYNC,
+    lock_dir: str | None = None,
+) -> dict[str, Any]:
+    """CAS-refresh the durable lock's recorded head after a branch sync (#871).
+
+    Reads the durable lock from disk, re-asserts ownership via
+    ``assess_durable_lock_head_refresh``, and — only when permitted — writes the
+    new synced head through ``bind_session_lock`` with a generation compare-and-
+    swap. Then re-reads the lock and proves it records the complete new head
+    (read-after-write). Any failure at any step returns ``refreshed=False`` with
+    reasons; the caller must treat that as a partial lifecycle failure and never
+    report a fully successful synchronization.
+    """
+    existing = load_issue_lock(
+        remote=remote, org=org, repo=repo, issue_number=issue_number, lock_dir=lock_dir
+    )
+    assessment = assess_durable_lock_head_refresh(
+        existing,
+        remote=remote,
+        org=org,
+        repo=repo,
+        issue_number=issue_number,
+        branch_name=branch_name,
+        worktree_path=worktree_path,
+        pr_number=pr_number,
+        identity=identity,
+        profile=profile,
+        current_pid=current_pid,
+        expected_old_head=expected_old_head,
+        new_head=new_head,
+        base_head=base_head,
+    )
+    result: dict[str, Any] = {
+        "refreshed": False,
+        "read_after_write_ok": False,
+        "prior_head": _norm_sha(expected_old_head),
+        "new_head": _norm_sha(new_head),
+        "reasons": list(assessment.get("reasons") or []),
+        "evidence": assessment.get("evidence"),
+    }
+    if not assessment.get("allowed"):
+        return result
+
+    new = _norm_sha(new_head)
+    old = _norm_sha(expected_old_head)
+    record = dict(existing or {})
+    sync_block = {
+        "last_synced_pr_head": new,
+        "prior_pr_head": old,
+        "base_head": _norm_sha(base_head),
+        "pr_number": pr_number,
+        "provenance": provenance,
+        "synced_at": synced_at,
+        "synced_by_pid": current_pid,
+        "synced_by": {
+            "username": str(identity or "").strip() or None,
+            "profile": str(profile or "").strip() or None,
+        },
+    }
+    record["synced_pr_head"] = new
+    record["branch_sync"] = sync_block
+    history = record.get("branch_sync_history")
+    if not isinstance(history, list):
+        history = []
+    history = list(history)
+    history.append(sync_block)
+    record["branch_sync_history"] = history
+
+    try:
+        bind_session_lock(
+            record,
+            lock_dir=lock_dir,
+            expected_generation=assessment.get("expected_generation"),
+            renewal_sanctioned=True,
+        )
+    except Exception as exc:  # CAS miss or write failure — partial lifecycle failure
+        result["reasons"].append(
+            f"durable lock head refresh write failed (fail closed): {exc}"
+        )
+        return result
+
+    after = load_issue_lock(
+        remote=remote, org=org, repo=repo, issue_number=issue_number, lock_dir=lock_dir
+    )
+    after_head = _norm_sha((after or {}).get("synced_pr_head"))
+    result["lock_generation_after"] = lock_generation(after)
+    if after_head == new and new is not None:
+        result["refreshed"] = True
+        result["read_after_write_ok"] = True
+        result["reasons"].append(
+            f"durable lock recorded head refreshed to {new} and verified by "
+            "read-after-write"
+        )
+    else:
+        result["reasons"].append(
+            "read-after-write verification failed: durable lock does not record "
+            f"the new head {new} (found {after_head}); partial lifecycle failure"
+        )
+    return result
\ No newline at end of file
diff --git a/issue_lock_worktree.py b/issue_lock_worktree.py
index de52ff7..8188536 100644
--- a/issue_lock_worktree.py
+++ b/issue_lock_worktree.py
@@ -145,6 +145,175 @@ def read_head_ancestry(
     return result
 
 
+def read_merge_sync_provenance(
+    worktree_path: str,
+    *,
+    prior_head_sha: str | None,
+    synced_head_sha: str | None,
+) -> dict:
+    """Observe whether ``synced_head_sha`` is a sanctioned merge-based branch sync
+    that advanced the PR branch past ``prior_head_sha`` (#871).
+
+    ``gitea_update_pr_branch_by_merge`` advances a PR branch by merging the base
+    branch *into* the branch (``POST /pulls/{n}/update?style=merge``). The result
+    is a merge commit ``M`` on the branch whose **first** parent is the prior
+    branch head and whose second parent is the base tip. When the owning session
+    then dies without the durable lock's recorded head being refreshed, the local
+    worktree still sits at ``prior_head_sha`` while the live PR head is ``M``.
+
+    Recovering that drift safely requires proving the remote head is *exactly*
+    such a merge-sync — not a rewrite, rebase, force-push, or an unrelated
+    commit. This is that server-side observation. It reports facts only; the
+    disposition lives in ``issue_lock_recovery``. Every field is read from git in
+    the declared worktree — nothing is supplied by, or reachable from, an MCP
+    caller (#871).
+
+    Provenance is proven only when ALL hold:
+
+    * both commits are present (a rewritten/force-moved prior head leaves the
+      object graph and fails closed);
+    * ``prior_head_sha`` is a strict ancestor of ``synced_head_sha`` (the branch
+      history is preserved, never replaced);
+    * ``synced_head_sha`` is a merge commit (two or more parents), i.e. a base
+      merged in — a plain fast-forward of new direct commits is not a sync;
+    * ``prior_head_sha`` is an ancestor of the merge's **first** parent, so the
+      branch mainline (first-parent lineage) still reaches the prior head — a
+      rebase/force-push that re-authored the branch side fails this.
+    """
+    path = (worktree_path or "").strip()
+    prior = (prior_head_sha or "").strip()
+    synced = (synced_head_sha or "").strip()
+    result: dict = {
+        "prior_head_sha": prior or None,
+        "synced_head_sha": synced or None,
+        "probe_ok": False,
+        "prior_present": False,
+        "synced_present": False,
+        "prior_is_ancestor": False,
+        "synced_is_merge": False,
+        "first_parent_reaches_prior": False,
+        "is_merge_sync": False,
+        "first_parent_sha": None,
+        "parent_count": None,
+        "proof": None,
+        "reasons": [],
+    }
+    if not path or not prior or not synced:
+        result["reasons"].append(
+            "merge-sync provenance probe requires a worktree path and both "
+            "commit SHAs"
+        )
+        return result
+    if prior == synced:
+        result["reasons"].append(
+            "prior and synced heads are identical; no branch sync occurred"
+        )
+        return result
+
+    def _present(sha: str) -> bool:
+        res = subprocess.run(
+            ["git", "-C", path, "rev-parse", "--verify", "--quiet", f"{sha}^{{commit}}"],
+            capture_output=True,
+            text=True,
+            check=False,
+        )
+        return res.returncode == 0
+
+    def _is_ancestor(ancestor: str, descendant: str) -> bool | None:
+        res = subprocess.run(
+            ["git", "-C", path, "merge-base", "--is-ancestor", ancestor, descendant],
+            capture_output=True,
+            text=True,
+            check=False,
+        )
+        if res.returncode == 0:
+            return True
+        if res.returncode == 1:
+            return False
+        return None  # failed probe — never a silent "no"
+
+    try:
+        result["prior_present"] = _present(prior)
+        result["synced_present"] = _present(synced)
+    except OSError as exc:  # git unavailable — fail closed, never assume
+        result["reasons"].append(f"merge-sync provenance probe could not run: {exc}")
+        return result
+
+    if not result["prior_present"]:
+        result["reasons"].append(
+            f"prior head {prior} is not reachable in '{path}'; history may have "
+            "been rewritten or force-moved"
+        )
+    if not result["synced_present"]:
+        result["reasons"].append(
+            f"synced head {synced} is not reachable in '{path}'"
+        )
+    if not (result["prior_present"] and result["synced_present"]):
+        return result
+
+    ancestor = _is_ancestor(prior, synced)
+    if ancestor is None:
+        result["reasons"].append(
+            "ancestry probe failed; merge-sync provenance unproven"
+        )
+        return result
+    result["prior_is_ancestor"] = bool(ancestor)
+    if not ancestor:
+        result["reasons"].append(
+            f"prior head {prior} is not an ancestor of synced head {synced}; "
+            "the branch history was not preserved (not a merge-based sync)"
+        )
+        return result
+
+    parents_res = subprocess.run(
+        ["git", "-C", path, "rev-list", "--parents", "-n", "1", synced],
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    if parents_res.returncode != 0:
+        result["reasons"].append(
+            f"could not read parents of {synced}; merge-sync provenance unproven"
+        )
+        return result
+    tokens = (parents_res.stdout or "").split()
+    # tokens[0] is the commit itself; the rest are its parents.
+    parents = tokens[1:]
+    result["parent_count"] = len(parents)
+    result["synced_is_merge"] = len(parents) >= 2
+    if not result["synced_is_merge"]:
+        result["probe_ok"] = True
+        result["reasons"].append(
+            f"synced head {synced} has {len(parents)} parent(s); a merge-based "
+            "branch sync produces a merge commit (two or more parents)"
+        )
+        return result
+    first_parent = parents[0]
+    result["first_parent_sha"] = first_parent
+
+    fp_reaches = _is_ancestor(prior, first_parent) if prior != first_parent else True
+    if fp_reaches is None:
+        result["reasons"].append(
+            "first-parent ancestry probe failed; merge-sync provenance unproven"
+        )
+        return result
+    result["first_parent_reaches_prior"] = bool(fp_reaches)
+    result["probe_ok"] = True
+    if not fp_reaches:
+        result["reasons"].append(
+            f"merge first parent {first_parent} does not reach prior head "
+            f"{prior}; the branch mainline was re-authored (not a sanctioned sync)"
+        )
+        return result
+
+    result["is_merge_sync"] = True
+    result["proof"] = (
+        f"synced head {synced} is a merge commit (parents={len(parents)}) whose "
+        f"first-parent lineage reaches prior head {prior}; base merged into branch"
+    )
+    return result
+
+
 def read_recorded_base(
     worktree_path: str,
     *,
diff --git a/mcp_restart_paths.py b/mcp_restart_paths.py
new file mode 100644
index 0000000..087fe72
--- /dev/null
+++ b/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}"
+        )
diff --git a/tests/test_branch_cleanup_guard.py b/tests/test_branch_cleanup_guard.py
index 0bd1fda..fddb534 100644
--- a/tests/test_branch_cleanup_guard.py
+++ b/tests/test_branch_cleanup_guard.py
@@ -1639,6 +1639,358 @@ class TestSecondRemediationIntegration(unittest.TestCase):
         self.assertTrue(ownership_calls)
 
 
+class TestIssue855ExactPrSelector(unittest.TestCase):
+    """#855: exact pr_number pin for reconcile_merged_cleanups (#851 lifecycle)."""
+
+    def setUp(self):
+        self._remotes = patch.dict(
+            mcp_server.REMOTES,
+            {
+                "prgs": {
+                    "host": "gitea.example.com",
+                    "org": "Scaled-Tech-Consulting",
+                    "repo": "Gitea-Tools",
+                }
+            },
+        )
+        self._remotes.start()
+        patch("gitea_audit.audit_enabled", return_value=False).start()
+        self.mock_api = patch("mcp_server.api_request").start()
+        self.mock_all = patch("mcp_server.api_get_all", return_value=[]).start()
+        patch("mcp_server.get_auth_header", return_value=FAKE_AUTH).start()
+        patch(
+            "mcp_server.merged_cleanup_reconcile.is_head_ancestor_of_ref",
+            return_value=True,
+        ).start()
+        patch(
+            "mcp_server.get_profile",
+            return_value=dict(RECONCILER_WITH_DELETE),
+        ).start()
+        patch(
+            "mcp_server._profile_operation_gate",
+            return_value=[],
+        ).start()
+        patch(
+            "mcp_server._collect_branch_ownership_records",
+            return_value={"records": [], "inventory_error": False},
+        ).start()
+        patch(
+            "mcp_server.merged_cleanup_reconcile.discover_reviewer_scratch_worktrees",
+            return_value=[],
+        ).start()
+        patch("mcp_server.verify_preflight_purity", return_value=None).start()
+        patch(
+            "mcp_server.audit_reconciliation_mode.check_cleanup_execution_allowed",
+            return_value=(True, []),
+        ).start()
+
+    def tearDown(self):
+        patch.stopall()
+
+    def _merged_pr(self, number, branch, sha="c" * 40):
+        return {
+            "number": number,
+            "title": f"PR {number}",
+            "body": f"Closes #{number - 4}",
+            "merged": True,
+            "merged_at": "2026-07-23T12:00:00Z",
+            "merge_commit_sha": "f" * 40,
+            "state": "closed",
+            "head": {"ref": branch, "sha": sha},
+            "base": {"ref": "master"},
+        }
+
+    def test_exact_pr_848_ignores_newer_852_in_batch_queue(self):
+        """pr_number=848 selects only #848 even when #852 is newer/first."""
+        from mcp_server import gitea_reconcile_merged_cleanups
+
+        pr_848 = self._merged_pr(
+            848, "fix/issue-844-exclude-epic-containers", sha="c3f282ba" + "0" * 32
+        )
+        # Closed list would rank #852 first in batch mode; exact pin must ignore it.
+        closed_batch = [
+            self._merged_pr(852, "fix/issue-851-cleanup-worktree-before-remote-delete"),
+            pr_848,
+            self._merged_pr(849, "fix/issue-849-other"),
+            self._merged_pr(846, "fix/issue-846-other"),
+            self._merged_pr(845, "fix/issue-845-other"),
+        ]
+        batch_fetch_calls = []
+
+        def fake_api(method, url, *args, **kwargs):
+            if method == "GET" and url.rstrip("/").endswith("/pulls/848"):
+                return dict(pr_848)
+            if method == "GET" and "/pulls/" in url:
+                raise AssertionError(f"unexpected PR fetch: {url}")
+            if method == "GET" and "/branches/" in url:
+                return {"name": "present"}
+            return {}
+
+        def fake_all(url, auth, limit=None):
+            batch_fetch_calls.append((url, limit))
+            if "state=open" in url:
+                return []
+            if "state=closed" in url:
+                # Exact mode must not use the closed batch list.
+                raise AssertionError(
+                    "exact pr_number mode must not page closed PRs: " + url
+                )
+            return []
+
+        self.mock_api.side_effect = fake_api
+        self.mock_all.side_effect = fake_all
+        patch(
+            "mcp_server._remote_branch_exists",
+            return_value=True,
+        ).start()
+        patch(
+            "mcp_server.merged_cleanup_reconcile.build_reconciliation_report",
+            side_effect=lambda **kwargs: {
+                "entries": [
+                    {
+                        "pr_number": int(pr["number"]),
+                        "head_branch": (pr.get("head") or {}).get("ref"),
+                        "issue_number": 844,
+                        "remote_branch": {
+                            "safe_to_delete_remote": True,
+                            "head_branch": (pr.get("head") or {}).get("ref"),
+                        },
+                        "local_worktree": {
+                            "safe_to_remove_worktree": True,
+                            "worktree_path": (
+                                "/tmp/branches/fix-issue-844-exclude-epic-containers"
+                            ),
+                        },
+                        "planned_execution_order": (
+                            mcp_server.merged_cleanup_reconcile.plan_cleanup_execution_order(
+                                remote_assessment={"safe_to_delete_remote": True},
+                                local_assessment={"safe_to_remove_worktree": True},
+                            )
+                        ),
+                    }
+                    for pr in kwargs.get("closed_prs") or []
+                    if pr.get("merged_at") or pr.get("merged")
+                ],
+                "reviewer_scratch_entries": [],
+                "merged_pr_count": len(kwargs.get("closed_prs") or []),
+            },
+        ).start()
+
+        res = gitea_reconcile_merged_cleanups(
+            dry_run=True,
+            pr_number=848,
+            remote="prgs",
+            org="Scaled-Tech-Consulting",
+            repo="Gitea-Tools",
+        )
+        self.assertTrue(res.get("success"))
+        self.assertFalse(res.get("performed"))
+        self.assertEqual(res.get("selection_mode"), "exact_pr")
+        self.assertEqual(res.get("selected_pr_number"), 848)
+        entries = res.get("entries") or []
+        self.assertEqual(len(entries), 1, entries)
+        self.assertEqual(entries[0].get("pr_number"), 848)
+        self.assertEqual(
+            entries[0].get("head_branch"),
+            "fix/issue-844-exclude-epic-containers",
+        )
+        # No other PR appears in plan.
+        self.assertEqual(list((res.get("planned_execution_orders") or {}).keys()), ["848"])
+        plan = (res.get("planned_execution_orders") or {}).get("848") or []
+        actions = [s.get("action") for s in plan]
+        self.assertEqual(
+            actions,
+            [
+                "remove_local_worktree",
+                "reassess_branch_ownership",
+                "delete_remote_branch",
+            ],
+        )
+        # Prove we never scanned the multi-PR closed batch.
+        self.assertFalse(any("state=closed" in (u or "") for u, _ in batch_fetch_calls))
+        # closed_batch fixture must remain unused (sanity).
+        self.assertEqual(closed_batch[0]["number"], 852)
+
+    def test_exact_pr_execute_only_mutates_selected_pr(self):
+        """Execute with pr_number must never touch #845/#846/#849/#852."""
+        from mcp_server import gitea_reconcile_merged_cleanups
+
+        pr_848 = self._merged_pr(848, "fix/issue-844-exclude-epic-containers")
+        worktree_path = "/tmp/branches/fix-issue-844-exclude-epic-containers"
+        remove_calls = []
+        delete_api_calls = []
+        ownership_branches = []
+
+        def fake_api(method, url, *args, **kwargs):
+            if method == "GET" and url.rstrip("/").endswith("/pulls/848"):
+                return dict(pr_848)
+            if method == "DELETE":
+                delete_api_calls.append(url)
+                # Forbid foreign PR branch deletion by URL content.
+                for forbidden in ("845", "846", "849", "852"):
+                    self.assertNotIn(forbidden, url)
+            return {}
+
+        def fake_remove(project_root, branch, worktree_path=None):
+            remove_calls.append({"branch": branch, "worktree_path": worktree_path})
+            return {
+                "success": True,
+                "performed": True,
+                "message": f"removed {worktree_path}",
+                "worktree_path": worktree_path,
+            }
+
+        def fake_collect(**kwargs):
+            ownership_branches.append(kwargs.get("branch"))
+            return {"records": [], "inventory_error": False}
+
+        def fake_probe(h, o, r, auth, br):
+            return guard.classify_branch_readback_http_status(
+                404, not_found_scope=guard.NOT_FOUND_SCOPE_BRANCH
+            )
+
+        self.mock_api.side_effect = fake_api
+        self.mock_all.side_effect = lambda url, auth, limit=None: []
+        patch("mcp_server._remote_branch_exists", return_value=True).start()
+        patch(
+            "mcp_server.merged_cleanup_reconcile.build_reconciliation_report",
+            return_value={
+                "entries": [
+                    {
+                        "pr_number": 848,
+                        "head_branch": "fix/issue-844-exclude-epic-containers",
+                        "remote_branch": {"safe_to_delete_remote": True},
+                        "local_worktree": {
+                            "safe_to_remove_worktree": True,
+                            "worktree_path": worktree_path,
+                        },
+                        "planned_execution_order": [
+                            {"action": "remove_local_worktree", "phase": 1},
+                            {"action": "reassess_branch_ownership", "phase": 2},
+                            {"action": "delete_remote_branch", "phase": 3},
+                        ],
+                    }
+                ],
+                "reviewer_scratch_entries": [
+                    # Foreign scratch must be filtered before report execute loop;
+                    # if present here it would still be a test failure if acted on.
+                ],
+                "merged_pr_count": 1,
+            },
+        ).start()
+        patch(
+            "mcp_server.merged_cleanup_reconcile.remove_local_worktree",
+            side_effect=fake_remove,
+        ).start()
+        patch(
+            "mcp_server._collect_branch_ownership_records",
+            side_effect=fake_collect,
+        ).start()
+        patch("mcp_server._probe_remote_branch", side_effect=fake_probe).start()
+
+        res = gitea_reconcile_merged_cleanups(
+            dry_run=False,
+            execute_confirmed=True,
+            pr_number=848,
+            remote="prgs",
+            org="Scaled-Tech-Consulting",
+            repo="Gitea-Tools",
+        )
+        self.assertTrue(res.get("performed") or res.get("executed"))
+        self.assertEqual(res.get("selection_mode"), "exact_pr")
+        self.assertEqual(res.get("selected_pr_number"), 848)
+        actions = res.get("actions") or []
+        pr_numbers_touched = {
+            a.get("pr_number") for a in actions if a.get("pr_number") is not None
+        }
+        self.assertTrue(pr_numbers_touched.issubset({None, 848}) or not pr_numbers_touched)
+        removes = [a for a in actions if a.get("action") == "remove_local_worktree"]
+        deletes = [a for a in actions if a.get("action") == "delete_remote_branch"]
+        self.assertEqual(len(removes), 1)
+        self.assertEqual(remove_calls[0]["branch"], "fix/issue-844-exclude-epic-containers")
+        self.assertEqual(len(deletes), 1)
+        self.assertTrue(deletes[0].get("success"))
+        self.assertTrue(deletes[0].get("after_worktree_removal"))
+        self.assertEqual(len(delete_api_calls), 1)
+        self.assertEqual(
+            ownership_branches, ["fix/issue-844-exclude-epic-containers"]
+        )
+
+    def test_exact_pr_unknown_fails_closed_without_mutation(self):
+        from mcp_server import gitea_reconcile_merged_cleanups
+
+        def fake_api(method, url, *args, **kwargs):
+            if method == "GET" and "/pulls/99999" in url:
+                raise RuntimeError("HTTP 404 Not Found")
+            raise AssertionError(f"unexpected API call {method} {url}")
+
+        self.mock_api.side_effect = fake_api
+        res = gitea_reconcile_merged_cleanups(
+            dry_run=True,
+            pr_number=99999,
+            remote="prgs",
+        )
+        self.assertFalse(res.get("success"))
+        self.assertFalse(res.get("performed"))
+        self.assertEqual(res.get("blocker_kind"), "pr_unresolvable")
+        self.assertIn("99999", " ".join(res.get("reasons") or []))
+
+    def test_exact_pr_not_merged_fails_closed(self):
+        from mcp_server import gitea_reconcile_merged_cleanups
+
+        def fake_api(method, url, *args, **kwargs):
+            if method == "GET" and url.rstrip("/").endswith("/pulls/900"):
+                return {
+                    "number": 900,
+                    "merged": False,
+                    "merged_at": None,
+                    "state": "open",
+                    "head": {"ref": "feat/x", "sha": "a" * 40},
+                }
+            raise AssertionError(f"unexpected {method} {url}")
+
+        self.mock_api.side_effect = fake_api
+        res = gitea_reconcile_merged_cleanups(
+            dry_run=False,
+            execute_confirmed=True,
+            pr_number=900,
+            remote="prgs",
+        )
+        self.assertFalse(res.get("success"))
+        self.assertFalse(res.get("performed"))
+        self.assertEqual(res.get("blocker_kind"), "pr_not_merged")
+
+    def test_exact_pr_invalid_number_fails_closed(self):
+        from mcp_server import gitea_reconcile_merged_cleanups
+
+        res = gitea_reconcile_merged_cleanups(
+            dry_run=True,
+            pr_number=0,
+            remote="prgs",
+        )
+        self.assertFalse(res.get("success"))
+        self.assertEqual(res.get("blocker_kind"), "invalid_pr_number")
+        self.mock_api.assert_not_called()
+
+    def test_batch_mode_still_works_without_pr_number(self):
+        """Unfiltered batch path remains backward compatible."""
+        from mcp_server import gitea_reconcile_merged_cleanups
+
+        self.mock_all.side_effect = lambda url, auth, limit=None: []
+        self.mock_api.side_effect = lambda *a, **k: {}
+        patch(
+            "mcp_server.merged_cleanup_reconcile.build_reconciliation_report",
+            return_value={
+                "entries": [],
+                "reviewer_scratch_entries": [],
+                "merged_pr_count": 0,
+            },
+        ).start()
+        res = gitea_reconcile_merged_cleanups(dry_run=True, remote="prgs", limit=10)
+        self.assertTrue(res.get("success"))
+        self.assertEqual(res.get("selection_mode"), "batch")
+        self.assertIsNone(res.get("selected_pr_number"))
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/test_issue_855_expired_reviewer_reclaim.py b/tests/test_issue_855_expired_reviewer_reclaim.py
new file mode 100644
index 0000000..288b7f7
--- /dev/null
+++ b/tests/test_issue_855_expired_reviewer_reclaim.py
@@ -0,0 +1,244 @@
+"""#855 AC4: an expired reviewer lease must not indefinitely protect an
+already-merged branch when no live claimant exists.
+
+Two layers are covered:
+
+* ``branch_cleanup_guard.assess_expired_reviewer_lease_reclaim`` — the pure,
+  fail-closed reclaim decision. Every condition must be provably satisfied or
+  the lease keeps protecting the branch.
+* ``gitea_mcp_server._collect_branch_ownership_records`` — the wiring that
+  supplies authoritative evidence (PR merged state, owner-process liveness,
+  competing ownership) to that decision, and flips an expired reviewer lease
+  to reclaimable only under the full policy.
+
+All inputs are fabricated; no real repository, lease, or credential is used.
+"""
+
+import importlib
+import unittest
+from unittest.mock import patch
+
+import branch_cleanup_guard
+
+mcp_server = importlib.import_module("gitea_mcp_server")
+
+FAKE_AUTH = "token fake"
+REMOTE = "prgs"
+ORG = "Scaled-Tech-Consulting"
+REPO = "Gitea-Tools"
+HOST = "gitea.prgs.cc"
+BRANCH = "feat/issue-638-webui-app-shell-phase1"
+PR_NUMBER = 818
+
+
+class TestAssessExpiredReviewerLeaseReclaim(unittest.TestCase):
+    """Pure fail-closed reclaim decision (#855 AC4)."""
+
+    def _call(self, **overrides):
+        base = dict(
+            role="reviewer",
+            status="expired",
+            pr_merged=True,
+            owner_pid_alive=False,
+            competing_active_claimant=False,
+        )
+        base.update(overrides)
+        return branch_cleanup_guard.assess_expired_reviewer_lease_reclaim(**base)
+
+    def test_full_policy_satisfied_allows_reclaim(self):
+        out = self._call()
+        self.assertTrue(out["reclaim_allowed"])
+        self.assertEqual(out["reasons"], [])
+        self.assertEqual(out["decision"], "reclaim_expired_reviewer_lease")
+
+    def test_stale_dead_process_reviewer_also_reclaimable(self):
+        out = self._call(status="stale_dead_process")
+        self.assertTrue(out["reclaim_allowed"])
+
+    def test_non_reviewer_role_never_reclaims(self):
+        for role in ("author", "merger", "controller", "reconciler", "unknown"):
+            with self.subTest(role=role):
+                out = self._call(role=role)
+                self.assertFalse(out["reclaim_allowed"])
+                self.assertTrue(out["reasons"])
+                self.assertEqual(out["decision"], "keep_protecting")
+
+    def test_active_status_never_reclaims(self):
+        out = self._call(status="active")
+        self.assertFalse(out["reclaim_allowed"])
+
+    def test_pr_not_merged_blocks_reclaim(self):
+        out = self._call(pr_merged=False)
+        self.assertFalse(out["reclaim_allowed"])
+
+    def test_pr_merged_unknown_fails_closed(self):
+        out = self._call(pr_merged=None)
+        self.assertFalse(out["reclaim_allowed"])
+
+    def test_owner_process_alive_blocks_reclaim(self):
+        out = self._call(owner_pid_alive=True)
+        self.assertFalse(out["reclaim_allowed"])
+
+    def test_owner_liveness_unknown_fails_closed(self):
+        out = self._call(owner_pid_alive=None)
+        self.assertFalse(out["reclaim_allowed"])
+
+    def test_competing_active_claimant_blocks_reclaim(self):
+        out = self._call(competing_active_claimant=True)
+        self.assertFalse(out["reclaim_allowed"])
+
+    def test_competing_claimant_unknown_fails_closed(self):
+        out = self._call(competing_active_claimant=None)
+        self.assertFalse(out["reclaim_allowed"])
+
+    def test_reasons_never_leak_secrets(self):
+        out = self._call(role="author")
+        blob = " ".join(out["reasons"]).lower()
+        self.assertNotIn("token", blob)
+        self.assertNotIn("password", blob)
+
+
+class _FakeLease(dict):
+    pass
+
+
+class TestCollectorExpiredReviewerReclaimWiring(unittest.TestCase):
+    """`_collect_branch_ownership_records` supplies authoritative evidence and
+    flips an expired reviewer lease to reclaimable only under the full policy."""
+
+    def _run(
+        self,
+        *,
+        lease_role="reviewer",
+        lease_freshness="stale_dead_process",
+        owner_pid_alive=False,
+        pr_merged=True,
+        extra_leases=None,
+        worktree_on_branch=False,
+    ):
+        lease = _FakeLease(
+            role=lease_role,
+            work_kind="pr",
+            work_number=PR_NUMBER,
+            branch=BRANCH,
+            status="active",
+            owner_pid=999999,
+            remote=REMOTE,
+            org=ORG,
+            repo=REPO,
+            host=HOST,
+            freshness={
+                "freshness": lease_freshness,
+                "owner_pid": 999999,
+                "owner_pid_alive": owner_pid_alive,
+                "expired_by_time": lease_freshness == "expired",
+            },
+        )
+        leases = [lease] + list(extra_leases or [])
+
+        pr_payload = {
+            "number": PR_NUMBER,
+            "merged": pr_merged,
+            "merged_at": "2026-07-23T00:00:00Z" if pr_merged else None,
+            "head": {"ref": BRANCH},
+        }
+
+        def fake_api_request(method, url, *a, **k):
+            if method == "GET" and f"/pulls/{PR_NUMBER}" in url:
+                return pr_payload
+            raise AssertionError(f"unexpected api_request {method} {url}")
+
+        wt_entries = []
+        if worktree_on_branch:
+            wt_entries = [{"branch": BRANCH, "path": f"/x/branches/{BRANCH}"}]
+
+        with patch.object(
+            mcp_server.lease_lifecycle,
+            "list_active_leases",
+            return_value={"leases": leases},
+        ), patch.object(
+            mcp_server.control_plane_db, "get_db", return_value=object(), create=True
+        ), patch.object(
+            mcp_server.issue_lock_store, "iter_lock_files", return_value=[]
+        ), patch.object(
+            mcp_server.worktree_cleanup_audit,
+            "list_worktrees",
+            return_value=wt_entries,
+        ), patch.object(
+            mcp_server, "api_get_all", return_value=[]
+        ), patch.object(
+            mcp_server, "api_request", side_effect=fake_api_request
+        ):
+            return mcp_server._collect_branch_ownership_records(
+                remote=REMOTE,
+                host=HOST,
+                org=ORG,
+                repo=REPO,
+                branch=BRANCH,
+                pr_number=PR_NUMBER,
+                project_root="/x",
+                auth=FAKE_AUTH,
+                base_api="https://gitea.prgs.cc/api/v1/repos/x/y",
+            )
+
+    def _reviewer_records(self, bundle):
+        return [
+            rec
+            for rec in bundle["records"]
+            if rec.get("category")
+            == branch_cleanup_guard.OWNERSHIP_CATEGORY_REVIEWER_LEASE
+        ]
+
+    def test_merged_dead_uncontested_reviewer_lease_is_reclaimable(self):
+        bundle = self._run()
+        self.assertFalse(bundle["inventory_error"])
+        recs = self._reviewer_records(bundle)
+        self.assertEqual(len(recs), 1)
+        self.assertTrue(recs[0]["reclaim_allowed"])
+        # And the guard consequently does not block deletion on it.
+        ownership = branch_cleanup_guard.assess_active_branch_ownership(
+            remote=REMOTE, org=ORG, repo=REPO, branch=BRANCH, host=HOST,
+            records=bundle["records"],
+        )
+        self.assertFalse(ownership["block"])
+
+    def test_unmerged_pr_keeps_reviewer_lease_protective(self):
+        bundle = self._run(pr_merged=False)
+        recs = self._reviewer_records(bundle)
+        self.assertEqual(len(recs), 1)
+        self.assertFalse(recs[0]["reclaim_allowed"])
+        ownership = branch_cleanup_guard.assess_active_branch_ownership(
+            remote=REMOTE, org=ORG, repo=REPO, branch=BRANCH, host=HOST,
+            records=bundle["records"],
+        )
+        self.assertTrue(ownership["block"])
+
+    def test_owner_process_alive_keeps_reviewer_lease_protective(self):
+        bundle = self._run(owner_pid_alive=True, lease_freshness="expired")
+        recs = self._reviewer_records(bundle)
+        self.assertFalse(recs[0]["reclaim_allowed"])
+
+    def test_competing_worktree_binding_keeps_reviewer_lease_protective(self):
+        bundle = self._run(worktree_on_branch=True)
+        recs = self._reviewer_records(bundle)
+        self.assertFalse(recs[0]["reclaim_allowed"])
+        ownership = branch_cleanup_guard.assess_active_branch_ownership(
+            remote=REMOTE, org=ORG, repo=REPO, branch=BRANCH, host=HOST,
+            records=bundle["records"],
+        )
+        self.assertTrue(ownership["block"])
+
+    def test_expired_author_lease_never_reclaimed_by_reviewer_policy(self):
+        bundle = self._run(lease_role="author")
+        author_recs = [
+            rec
+            for rec in bundle["records"]
+            if rec.get("category")
+            == branch_cleanup_guard.OWNERSHIP_CATEGORY_AUTHOR_LEASE
+        ]
+        self.assertEqual(len(author_recs), 1)
+        self.assertFalse(author_recs[0]["reclaim_allowed"])
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/test_issue_871_durable_lock_head_refresh.py b/tests/test_issue_871_durable_lock_head_refresh.py
new file mode 100644
index 0000000..37851b1
--- /dev/null
+++ b/tests/test_issue_871_durable_lock_head_refresh.py
@@ -0,0 +1,630 @@
+"""Durable linked-issue lock head refresh + merge-sync dead-session recovery (#871).
+
+``gitea_update_pr_branch_by_merge`` advances a PR's *remote* head but historically
+never advanced the linked durable issue lock's recorded head. After the owning
+session died the drifted lock became unrecoverable and no further synchronization
+was possible (PR #866 / issue #855).
+
+Two halves are covered:
+
+* the write-side refresh (``issue_lock_store.assess/apply_durable_lock_head_refresh``)
+  that records the new synced head under compare-and-swap with read-after-write; and
+* the read-side recovery relation (``issue_lock_recovery`` +
+  ``issue_lock_worktree.read_merge_sync_provenance``) that lets a dead-session lock
+  whose recorded head is a merge-sync *ancestor* of the live PR head be recovered —
+  and nothing else.
+"""
+
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+import tempfile
+import unittest
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+import issue_lock_recovery  # noqa: E402
+import issue_lock_store  # noqa: E402
+import issue_lock_worktree  # noqa: E402
+
+ISSUE = 8710
+PR_NUMBER = 8711
+BRANCH = f"fix/issue-{ISSUE}-durable-lock-head-refresh"
+IDENTITY = "example-user"
+PROFILE = "example-author"
+OLD = "a" * 40
+NEW1 = "b" * 40
+NEW2 = "c" * 40
+BASE = "d" * 40
+REMOTE = "prgs"
+ORG = "ExampleOrg"
+REPO = "ExampleRepo"
+
+
+def dead_pid() -> int:
+    proc = subprocess.Popen([sys.executable, "-c", "pass"])
+    proc.wait()
+    return proc.pid
+
+
+def future_ts(hours: int = 4) -> str:
+    return (
+        (datetime.now(timezone.utc) + timedelta(hours=hours))
+        .isoformat()
+        .replace("+00:00", "Z")
+    )
+
+
+def _git(cwd, *args):
+    return subprocess.run(
+        ["git", "-C", cwd, *args],
+        capture_output=True,
+        text=True,
+        check=True,
+    )
+
+
+def _rev(cwd, ref="HEAD") -> str:
+    return _git(cwd, "rev-parse", ref).stdout.strip()
+
+
+def build_merge_sync_repo(tmp: str) -> dict:
+    """Build a repo where a feature branch was synced by merging master in.
+
+    Returns a dict with the prior (branch) head, the synced merge-commit head,
+    the master tip, plus a rebase-style linear descendant and an unrelated head.
+    """
+    _git(tmp, "init", "-q", "-b", "master")
+    _git(tmp, "config", "user.email", "t@example.com")
+    _git(tmp, "config", "user.name", "T")
+    Path(tmp, "base.txt").write_text("base\n")
+    _git(tmp, "add", "-A")
+    _git(tmp, "commit", "-q", "-m", "root")
+
+    # Feature branch cut from root, one commit — this is the PRIOR/recorded head.
+    _git(tmp, "checkout", "-q", "-b", BRANCH)
+    Path(tmp, "feature.txt").write_text("feature\n")
+    _git(tmp, "add", "-A")
+    _git(tmp, "commit", "-q", "-m", "feature work")
+    prior = _rev(tmp)
+
+    # Master advances (the base the sync will merge in).
+    _git(tmp, "checkout", "-q", "master")
+    Path(tmp, "base.txt").write_text("base\nmore\n")
+    _git(tmp, "add", "-A")
+    _git(tmp, "commit", "-q", "-m", "master advance")
+    master_tip = _rev(tmp)
+
+    # Sync: merge master INTO the feature branch → merge commit, first parent = prior.
+    _git(tmp, "checkout", "-q", BRANCH)
+    _git(tmp, "merge", "-q", "--no-ff", "-m", "Merge master into feature", "master")
+    synced = _rev(tmp)
+
+    # A plain linear descendant of prior (NOT a merge) — a rebase/extra-commit shape.
+    _git(tmp, "checkout", "-q", "-b", "linear-branch", prior)
+    Path(tmp, "extra.txt").write_text("extra\n")
+    _git(tmp, "add", "-A")
+    _git(tmp, "commit", "-q", "-m", "extra linear commit")
+    linear = _rev(tmp)
+
+    # An unrelated root (force-push / rewritten history shape).
+    unrelated_dir = tempfile.mkdtemp()
+    _git(unrelated_dir, "init", "-q", "-b", "x")
+    _git(unrelated_dir, "config", "user.email", "t@example.com")
+    _git(unrelated_dir, "config", "user.name", "T")
+    Path(unrelated_dir, "z.txt").write_text("z\n")
+    _git(unrelated_dir, "add", "-A")
+    _git(unrelated_dir, "commit", "-q", "-m", "unrelated")
+    unrelated = _rev(unrelated_dir)
+
+    # Leave the worktree checked out on the feature branch at the PRIOR head, as
+    # a dead author session that never advanced would have left it.
+    _git(tmp, "checkout", "-q", BRANCH)
+    _git(tmp, "reset", "-q", "--hard", prior)
+
+    return {
+        "prior": prior,
+        "master_tip": master_tip,
+        "synced": synced,
+        "linear": linear,
+        "unrelated": unrelated,
+    }
+
+
+# ─────────────────────────── write-side refresh ───────────────────────────
+
+
+class TestDurableLockHeadRefresh(unittest.TestCase):
+    def setUp(self):
+        self.lock_dir = tempfile.mkdtemp()
+        self.wt = tempfile.mkdtemp()
+        lock_data = {
+            "issue_number": ISSUE,
+            "branch_name": BRANCH,
+            "worktree_path": self.wt,
+            "remote": REMOTE,
+            "org": ORG,
+            "repo": REPO,
+            "claimant": {"username": IDENTITY, "profile": PROFILE},
+            "work_lease": {
+                "operation_type": issue_lock_store.AUTHOR_ISSUE_WORK_LEASE,
+                "issue_number": ISSUE,
+                "branch": BRANCH,
+                "worktree_path": self.wt,
+                "claimant": {"username": IDENTITY, "profile": PROFILE},
+                "expires_at": future_ts(),
+            },
+        }
+        issue_lock_store.bind_session_lock(lock_data, lock_dir=self.lock_dir)
+
+    def _apply(self, **over):
+        kw = dict(
+            remote=REMOTE, org=ORG, repo=REPO, issue_number=ISSUE,
+            branch_name=BRANCH, worktree_path=self.wt, pr_number=PR_NUMBER,
+            identity=IDENTITY, profile=PROFILE, current_pid=os.getpid(),
+            expected_old_head=OLD, new_head=NEW1, synced_at=future_ts(0),
+            base_head=BASE, lock_dir=self.lock_dir,
+        )
+        kw.update(over)
+        return issue_lock_store.apply_durable_lock_head_refresh(**kw)
+
+    def _load(self):
+        return issue_lock_store.load_issue_lock(
+            remote=REMOTE, org=ORG, repo=REPO, issue_number=ISSUE,
+            lock_dir=self.lock_dir,
+        )
+
+    def test_first_sync_updates_recorded_head(self):
+        """AC1: first base sync writes the resulting head to the durable lock."""
+        res = self._apply()
+        self.assertTrue(res["refreshed"], res["reasons"])
+        self.assertTrue(res["read_after_write_ok"])
+        self.assertEqual(self._load().get("synced_pr_head"), NEW1)
+
+    def test_second_sync_after_master_advance(self):
+        """AC2: a later master advance permits a second sanctioned sync."""
+        self.assertTrue(self._apply()["refreshed"])
+        res2 = self._apply(expected_old_head=NEW1, new_head=NEW2)
+        self.assertTrue(res2["refreshed"], res2["reasons"])
+        self.assertEqual(self._load().get("synced_pr_head"), NEW2)
+        history = self._load().get("branch_sync_history")
+        self.assertEqual(len(history), 2)
+        self.assertEqual(history[0]["last_synced_pr_head"], NEW1)
+        self.assertEqual(history[1]["prior_pr_head"], NEW1)
+
+    def test_cas_detects_concurrent_head_change(self):
+        """AC6: CAS refuses when the recorded synced head is not the old head."""
+        self.assertTrue(self._apply()["refreshed"])  # recorded head now NEW1
+        # A second sync claiming the old head is still OLD must fail closed.
+        res = self._apply(expected_old_head=OLD, new_head=NEW2)
+        self.assertFalse(res["refreshed"])
+        self.assertTrue(any("CAS" in r or "concurrent" in r for r in res["reasons"]))
+        self.assertEqual(self._load().get("synced_pr_head"), NEW1)
+
+    def test_wrong_issue_fails_closed(self):
+        res = self._apply(issue_number=999999)
+        self.assertFalse(res["refreshed"])
+
+    def test_wrong_branch_fails_closed(self):
+        res = self._apply(branch_name="fix/issue-8710-wrong")
+        self.assertFalse(res["refreshed"])
+
+    def test_wrong_repo_fails_closed(self):
+        res = self._apply(repo="OtherRepo")
+        self.assertFalse(res["refreshed"])
+
+    def test_wrong_identity_fails_closed(self):
+        res = self._apply(identity="intruder")
+        self.assertFalse(res["refreshed"])
+
+    def test_wrong_profile_fails_closed(self):
+        res = self._apply(profile="prgs-reviewer")
+        self.assertFalse(res["refreshed"])
+
+    def test_foreign_session_fails_closed(self):
+        """A refresh is not a recovery: the current process must own the lock."""
+        path = issue_lock_store.lock_file_path(
+            remote=REMOTE, org=ORG, repo=REPO, issue_number=ISSUE,
+            lock_dir=self.lock_dir,
+        )
+        rec = issue_lock_store.read_lock_file(path)
+        rec["session_pid"] = dead_pid()
+        rec["pid"] = rec["session_pid"]
+        issue_lock_store.save_lock_file(path, rec)
+        res = self._apply()
+        self.assertFalse(res["refreshed"])
+        self.assertTrue(any("current session" in r or "live owner" in r for r in res["reasons"]))
+
+    def test_new_equals_old_fails_closed(self):
+        res = self._apply(expected_old_head=OLD, new_head=OLD)
+        self.assertFalse(res["refreshed"])
+
+    def test_non_full_sha_fails_closed(self):
+        self.assertFalse(self._apply(new_head="deadbeef")["refreshed"])
+        self.assertFalse(self._apply(expected_old_head="xyz")["refreshed"])
+
+    def test_no_lock_fails_closed(self):
+        assessment = issue_lock_store.assess_durable_lock_head_refresh(
+            None, remote=REMOTE, org=ORG, repo=REPO, issue_number=ISSUE,
+            branch_name=BRANCH, worktree_path=self.wt, pr_number=PR_NUMBER,
+            identity=IDENTITY, profile=PROFILE, current_pid=os.getpid(),
+            expected_old_head=OLD, new_head=NEW1,
+        )
+        self.assertFalse(assessment["allowed"])
+
+
+# ─────────────────────── merge-sync provenance (real git) ───────────────────
+
+
+class TestMergeSyncProvenanceObservation(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.mkdtemp()
+        self.shas = build_merge_sync_repo(self.tmp)
+
+    def test_merge_sync_is_recognized(self):
+        obs = issue_lock_worktree.read_merge_sync_provenance(
+            self.tmp, prior_head_sha=self.shas["prior"],
+            synced_head_sha=self.shas["synced"],
+        )
+        self.assertTrue(obs["is_merge_sync"], obs["reasons"])
+        self.assertTrue(obs["prior_is_ancestor"])
+        self.assertTrue(obs["synced_is_merge"])
+        self.assertTrue(obs["first_parent_reaches_prior"])
+
+    def test_linear_descendant_is_not_a_merge_sync(self):
+        """A plain non-merge descendant (rebase/extra commit) is not a sync."""
+        obs = issue_lock_worktree.read_merge_sync_provenance(
+            self.tmp, prior_head_sha=self.shas["prior"],
+            synced_head_sha=self.shas["linear"],
+        )
+        self.assertTrue(obs["probe_ok"])
+        self.assertFalse(obs["is_merge_sync"])
+        self.assertFalse(obs["synced_is_merge"])
+
+    def test_unrelated_history_fails_closed(self):
+        """A rewritten/force-pushed head where prior is unreachable fails closed."""
+        obs = issue_lock_worktree.read_merge_sync_provenance(
+            self.tmp, prior_head_sha=self.shas["prior"],
+            synced_head_sha=self.shas["unrelated"],
+        )
+        self.assertFalse(obs["is_merge_sync"])
+
+    def test_missing_args_fail_closed(self):
+        obs = issue_lock_worktree.read_merge_sync_provenance(
+            self.tmp, prior_head_sha=None, synced_head_sha=self.shas["synced"],
+        )
+        self.assertFalse(obs["is_merge_sync"])
+
+
+# ──────────────────── merge-sync dead-session recovery ──────────────────────
+
+
+def make_dead_lock(worktree, **over):
+    pid = dead_pid()
+    lock = {
+        "issue_number": ISSUE,
+        "branch_name": BRANCH,
+        "worktree_path": worktree,
+        "remote": REMOTE,
+        "org": ORG,
+        "repo": REPO,
+        "session_pid": pid,
+        "pid": pid,
+        "claimant": {"username": IDENTITY, "profile": PROFILE},
+        "work_lease": {
+            "operation_type": issue_lock_store.AUTHOR_ISSUE_WORK_LEASE,
+            "issue_number": ISSUE,
+            "branch": BRANCH,
+            "worktree_path": worktree,
+            "claimant": {"username": IDENTITY, "profile": PROFILE},
+            "expires_at": future_ts(),
+        },
+    }
+    lock.update(over)
+    return lock
+
+
+def sync_prov(prior, synced, **over):
+    d = {
+        "prior_head_sha": prior,
+        "synced_head_sha": synced,
+        "probe_ok": True,
+        "prior_present": True,
+        "synced_present": True,
+        "prior_is_ancestor": True,
+        "synced_is_merge": True,
+        "first_parent_reaches_prior": True,
+        "is_merge_sync": True,
+        "first_parent_sha": prior,
+        "parent_count": 2,
+        "proof": f"{synced} merged base into branch above {prior}",
+        "reasons": [],
+    }
+    d.update(over)
+    return d
+
+
+class TestMergeSyncRecovery(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.mkdtemp()
+        self.shas = build_merge_sync_repo(self.tmp)
+        self.prior = self.shas["prior"]
+        self.synced = self.shas["synced"]
+
+    def _assess(self, **over):
+        lock = over.pop("_lock", None) or make_dead_lock(self.tmp)
+        kw = dict(
+            issue_number=ISSUE, branch_name=BRANCH, worktree_path=self.tmp,
+            remote=REMOTE, org=ORG, repo=REPO, identity=IDENTITY, profile=PROFILE,
+            current_branch=BRANCH, porcelain_status="",
+            head_sha=self.prior, remote_head_sha=self.synced,
+            pr_head_sha=self.synced, pr_number=PR_NUMBER,
+            competing_live_locks=[], candidate_branches=[BRANCH],
+            current_pid=os.getpid(),
+            remote_branch_exists=True,
+            sync_provenance=sync_prov(self.prior, self.synced),
+        )
+        kw.update(over)
+        return issue_lock_recovery.assess_dead_session_lock_recovery(lock, **kw)
+
+    def test_merge_sync_drift_is_recoverable(self):
+        """AC3/AC4: dead session, recorded head is a merge-sync ancestor of PR head."""
+        res = self._assess()
+        self.assertEqual(res["outcome"], issue_lock_recovery.RECOVERY_SANCTIONED, res["reasons"])
+        self.assertEqual(
+            res["evidence"]["head_relation"],
+            issue_lock_recovery.HEAD_RELATION_REMOTE_MERGE_SYNCED,
+        )
+        self.assertEqual(res["evidence"]["accepted_head"], self.synced)
+
+    def test_missing_provenance_fails_closed(self):
+        """No server-derived provenance → cannot accept a remote ahead of local."""
+        res = self._assess(sync_provenance=None)
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_non_ancestor_recorded_head_fails_closed(self):
+        """AC7: provenance that does not prove ancestry is rejected."""
+        res = self._assess(
+            sync_provenance=sync_prov(
+                self.prior, self.synced, prior_is_ancestor=False, is_merge_sync=False,
+                reasons=["prior head is not an ancestor"],
+            )
+        )
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_force_pushed_history_fails_closed(self):
+        """AC8: a rewritten head (not a merge sync) stays protected."""
+        res = self._assess(
+            sync_provenance=sync_prov(
+                self.prior, self.synced, is_merge_sync=False, synced_is_merge=False,
+                reasons=["not a merge-based sync"],
+            )
+        )
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_provenance_for_other_commits_fails_closed(self):
+        """Provenance whose endpoints differ from the heads under assessment is rejected."""
+        res = self._assess(
+            sync_provenance=sync_prov("f" * 40, self.synced),
+        )
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_dirty_worktree_fails_closed(self):
+        """AC11: dirty worktrees remain protected."""
+        res = self._assess(porcelain_status=" M feature.txt\n")
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_live_owner_fails_closed(self):
+        """AC10: a live recorded owner is not a dead-session recovery."""
+        lock = make_dead_lock(self.tmp, session_pid=os.getpid(), pid=os.getpid())
+        res = self._assess(_lock=lock)
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_competing_claimant_fails_closed(self):
+        """AC13: a competing live lock blocks recovery."""
+        res = self._assess(
+            competing_live_locks=[{
+                "issue_number": ISSUE, "branch_name": BRANCH,
+                "worktree_path": "/some/other/wt", "pid": os.getpid(),
+            }]
+        )
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_wrong_branch_fails_closed(self):
+        """AC9: worktree on a different branch fails closed."""
+        res = self._assess(current_branch="fix/issue-8710-other")
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_wrong_identity_fails_closed(self):
+        res = self._assess(identity="intruder")
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_pr_head_mismatch_fails_closed(self):
+        """The open PR must sit at the synced remote head."""
+        res = self._assess(pr_head_sha="e" * 40)
+        self.assertEqual(res["outcome"], issue_lock_recovery.REFUSED)
+
+    def test_owning_pr_evidence_for_merge_sync(self):
+        res = self._assess()
+        ev = issue_lock_recovery.owning_pr_recovery_evidence(res)
+        self.assertIsNotNone(ev)
+        self.assertEqual(ev["pr_number"], PR_NUMBER)
+        self.assertEqual(ev["head_sha"], self.synced)
+        self.assertEqual(
+            ev["head_relation"],
+            issue_lock_recovery.HEAD_RELATION_REMOTE_MERGE_SYNCED,
+        )
+
+    def test_recovered_owning_pr_from_persisted_record(self):
+        res = self._assess()
+        record = issue_lock_recovery.build_recovery_record(res, recovered_at=future_ts(0))
+        lock = {"issue_number": ISSUE, "branch_name": BRANCH,
+                "dead_session_recovery": record}
+        rebuilt = issue_lock_recovery.recovered_owning_pr_from_lock(lock)
+        self.assertIsNotNone(rebuilt)
+        self.assertEqual(rebuilt["head_sha"], self.synced)
+        self.assertEqual(
+            rebuilt["head_relation"],
+            issue_lock_recovery.HEAD_RELATION_REMOTE_MERGE_SYNCED,
+        )
+
+
+class TestExistingRelationsUnchanged(unittest.TestCase):
+    """AC14/AC15: equal-head recovery still works; merge-sync did not weaken it."""
+
+    def setUp(self):
+        self.tmp = tempfile.mkdtemp()
+        self.shas = build_merge_sync_repo(self.tmp)
+
+    def test_equal_head_recovery_still_sanctioned(self):
+        # Worktree at prior head; remote also at prior head → the #753 equal case.
+        prior = self.shas["prior"]
+        lock = make_dead_lock(self.tmp)
+        res = issue_lock_recovery.assess_dead_session_lock_recovery(
+            lock, issue_number=ISSUE, branch_name=BRANCH, worktree_path=self.tmp,
+            remote=REMOTE, org=ORG, repo=REPO, identity=IDENTITY, profile=PROFILE,
+            current_branch=BRANCH, porcelain_status="",
+            head_sha=prior, remote_head_sha=prior,
+            pr_head_sha=prior, pr_number=PR_NUMBER,
+            competing_live_locks=[], candidate_branches=[BRANCH],
+            current_pid=os.getpid(), remote_branch_exists=True,
+        )
+        self.assertEqual(res["outcome"], issue_lock_recovery.RECOVERY_SANCTIONED, res["reasons"])
+        self.assertEqual(
+            res["evidence"]["head_relation"], issue_lock_recovery.HEAD_RELATION_EQUAL,
+        )
+
+
+class TestUpdatePrWrapperPartialFailure(unittest.TestCase):
+    """AC5/AC16: the tool advances the remote head then refreshes the durable lock.
+
+    When the durable refresh fails after the remote advance, the tool must report a
+    partial lifecycle failure and NOT a fully successful synchronization. Exact PR-
+    head / base-head pinning is preserved (delegated to the real preflight, stubbed
+    here only to isolate the post-update lifecycle branch).
+    """
+
+    def setUp(self):
+        import gitea_mcp_server as gms  # noqa: E402
+        self.gms = gms
+        self._orig = {}
+
+        def _patch(name, value):
+            self._orig[name] = getattr(gms, name)
+            setattr(gms, name, value)
+
+        _patch("get_profile", lambda *a, **k: {
+            "allowed_operations": ["gitea.branch.push"],
+            "forbidden_operations": [],
+            "profile_name": "prgs-author",
+        })
+        _patch("_role_kind", lambda *a, **k: "author")
+        _patch("_profile_operation_gate", lambda *a, **k: None)
+        _patch("_permission_block_report", lambda *a, **k: {})
+        _patch("_resolve", lambda *a, **k: ("gitea.prgs.cc", ORG, REPO))
+        _patch("_verify_role_mutation_workspace", lambda *a, **k: None)
+        _patch("_get_workspace_porcelain", lambda *a, **k: "")
+        _patch("_canonical_local_git_root", lambda *a, **k: "/x")
+        _patch("_master_parity_block", lambda *a, **k: None)
+        _patch("_auth", lambda *a, **k: {"token": "x"})
+        _patch("repo_api_url", lambda *a, **k: "http://api")
+        _patch("_redact", lambda s: s)
+        _patch("_work_lease_claimant", lambda *a, **k: {
+            "username": IDENTITY, "profile": PROFILE,
+        })
+        _patch("_prove_author_ownership_for_pr", lambda *a, **k: {
+            "has_author_lock": True, "matched_issue": ISSUE,
+            "matched_via": "branch", "linked_issues": [ISSUE],
+            "recovered_owning_pr": None, "reasons": [],
+        })
+
+        # Real preflight is unit-tested elsewhere; stub it to isolate the
+        # post-update durable-lock lifecycle branch under test.
+        orig_pf = gms.pr_sync_status.assess_update_pr_branch_preflight
+        self._orig_pf = orig_pf
+        gms.pr_sync_status.assess_update_pr_branch_preflight = (
+            lambda *a, **k: {"mutation_allowed": True, "reasons": [], "performed": False}
+        )
+
+        # Sequence the two GET /pulls calls: OLD before update, NEW after.
+        self._pull_calls = {"n": 0}
+
+        def fake_api_request(method, url, auth, *a, **k):
+            m = method.upper()
+            if m == "GET" and url.endswith(f"/pulls/{PR_NUMBER}"):
+                self._pull_calls["n"] += 1
+                head = OLD if self._pull_calls["n"] == 1 else NEW1
+                return {
+                    "state": "open",
+                    "head": {"sha": head, "ref": BRANCH},
+                    "base": {"sha": BASE, "ref": "master"},
+                    "mergeable": True, "title": "t", "body": "b",
+                }
+            if m == "GET" and "/branches/" in url:
+                return {"commit": {"id": BASE}}
+            if m == "POST" and "/update" in url:
+                return {}
+            return {}
+
+        _patch("api_request", fake_api_request)
+
+    def tearDown(self):
+        for name, value in self._orig.items():
+            setattr(self.gms, name, value)
+        self.gms.pr_sync_status.assess_update_pr_branch_preflight = self._orig_pf
+
+    def _run(self):
+        return self.gms.gitea_update_pr_branch_by_merge(
+            pr_number=PR_NUMBER,
+            expected_pr_head_sha=OLD,
+            expected_base_head_sha=BASE,
+            remote=REMOTE,
+            worktree_path="/tmp/branches/wt-871",
+        )
+
+    def test_partial_failure_when_refresh_fails(self):
+        self._orig["apply_durable_lock_head_refresh"] = (
+            self.gms.issue_lock_store.apply_durable_lock_head_refresh
+        )
+        self.gms.issue_lock_store.apply_durable_lock_head_refresh = (
+            lambda **k: {"refreshed": False, "reasons": ["forced refresh failure"]}
+        )
+        try:
+            res = self._run()
+        finally:
+            self.gms.issue_lock_store.apply_durable_lock_head_refresh = (
+                self._orig["apply_durable_lock_head_refresh"]
+            )
+        self.assertTrue(res["performed"])
+        self.assertEqual(res["new_pr_head_sha"], NEW1)
+        self.assertFalse(res["success"])
+        self.assertTrue(res["partial_lifecycle_failure"])
+        self.assertFalse(res["durable_lock_refreshed"])
+
+    def test_full_success_when_refresh_succeeds(self):
+        self._orig["apply_durable_lock_head_refresh"] = (
+            self.gms.issue_lock_store.apply_durable_lock_head_refresh
+        )
+        self.gms.issue_lock_store.apply_durable_lock_head_refresh = (
+            lambda **k: {"refreshed": True, "read_after_write_ok": True,
+                         "new_head": NEW1, "reasons": ["ok"]}
+        )
+        try:
+            res = self._run()
+        finally:
+            self.gms.issue_lock_store.apply_durable_lock_head_refresh = (
+                self._orig["apply_durable_lock_head_refresh"]
+            )
+        self.assertTrue(res["success"])
+        self.assertTrue(res["performed"])
+        self.assertTrue(res["durable_lock_refreshed"])
+        self.assertTrue(res["fully_synchronized"])
+        self.assertEqual(res["new_pr_head_sha"], NEW1)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/test_mcp_restart_governance_docs.py b/tests/test_mcp_restart_governance_docs.py
new file mode 100644
index 0000000..5b12e50
--- /dev/null
+++ b/tests/test_mcp_restart_governance_docs.py
@@ -0,0 +1,107 @@
+"""Documentation acceptance for the MCP restart governance ADR (#656).
+
+Enforces issue #656 acceptance criteria:
+
+* AC1 — policy document exists with an authorization matrix and the recorded
+  v1 decision (controller approval + automated safety gates).
+* AC2 — restart is stated as a last resort with enumerated narrower recoveries.
+* AC3 — a unilateral LLM full restart with affected sessions is forbidden.
+* AC4 — break-glass conditions are listed.
+* AC5 — the ADR is linked to #655, #652, #653, #630, #642, and is cross-linked
+  from the safety model and the web-console deployment boundary docs.
+"""
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+ADR = REPO_ROOT / "docs" / "architecture" / "mcp-restart-governance.md"
+ADR_BASENAME = "mcp-restart-governance.md"
+
+CROSS_LINK_DOCS = (
+    REPO_ROOT / "docs" / "safety-model.md",
+    REPO_ROOT / "docs" / "webui-deployment.md",
+)
+
+LINKED_ISSUES = ("#655", "#652", "#653", "#630", "#642")
+POLICY_IDS = ("RG-01", "RG-02", "RG-03", "RG-04", "RG-05", "RG-06", "RG-07", "RG-08")
+
+
+def _read(path: Path) -> str:
+    assert path.is_file(), f"missing {path.relative_to(REPO_ROOT)}"
+    return path.read_text(encoding="utf-8")
+
+
+def test_ac1_adr_exists_with_matrix_and_v1_decision():
+    text = _read(ADR)
+    lower = text.lower()
+    assert text.lstrip().startswith("#"), "ADR lacks a title"
+    assert "#656" in text
+    assert "authorization matrix" in lower
+    # The matrix is a real table with the worker and privileged roles.
+    for role in ("author", "reviewer", "merger", "reconciler", "controller",
+                 "operator", "admin"):
+        assert role in lower, f"authorization matrix missing role {role!r}"
+    # Recorded v1 decision.
+    assert "restart-governance/v1" in text
+    assert "controller approval" in lower and "automated safety gates" in lower
+
+
+def test_ac2_restart_is_last_resort_with_narrower_recoveries():
+    text = _read(ADR)
+    lower = text.lower()
+    assert "last resort" in lower
+    # Enumerated narrower recoveries precede full restart on the ladder.
+    for rung in ("reconnect", "rebind", "scoped restart", "full restart",
+                 "host"):
+        assert rung in lower, f"recovery ladder missing rung {rung!r}"
+
+
+def test_ac3_forbids_unilateral_llm_full_restart_with_affected_sessions():
+    text = _read(ADR)
+    lower = text.lower()
+    assert "forbidden" in lower
+    assert "llm" in lower and "restart" in lower
+    assert "unilateral" in lower
+    # A worker role must not perform or authorize full/host restart.
+    assert "must not" in lower
+
+
+def test_ac4_break_glass_conditions_listed():
+    text = _read(ADR)
+    lower = text.lower()
+    assert "break-glass" in lower
+    assert "incident" in lower
+    assert "audit" in lower
+
+
+def test_ac5_adr_links_issue_lineage():
+    text = _read(ADR)
+    for issue in LINKED_ISSUES:
+        assert issue in text, f"ADR must link issue {issue}"
+
+
+def test_ac5_safety_model_and_deployment_cross_link_adr():
+    for path in CROSS_LINK_DOCS:
+        text = _read(path)
+        assert ADR_BASENAME in text, (
+            f"{path.relative_to(REPO_ROOT)} must cross-link {ADR_BASENAME} "
+            f"(issue #656 acceptance criterion 5)"
+        )
+
+
+def test_policy_ids_present_for_enforcement_code():
+    text = _read(ADR)
+    for pid in POLICY_IDS:
+        assert pid in text, f"policy id {pid} missing from ADR"
+
+
+def test_failure_behavior_denies_on_ambiguity():
+    text = _read(ADR)
+    lower = text.lower()
+    assert "ambiguous" in lower and "deny" in lower
+
+
+def test_cross_links_do_not_embed_secrets():
+    for path in (ADR,) + CROSS_LINK_DOCS:
+        text = _read(path)
+        for marker in ("ghp_", "BEGIN PRIVATE KEY", "Authorization: Bearer"):
+            assert marker not in text, f"{path} contains {marker!r}"
diff --git a/tests/test_mcp_restart_paths.py b/tests/test_mcp_restart_paths.py
new file mode 100644
index 0000000..cf0c5eb
--- /dev/null
+++ b/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()