fix(recovery): address PR #703 review findings F1-F6 (#702)

Fixes the six defects from the formal REQUEST_CHANGES review at
889931d553:

- F1: run sanctioned stale-binding recovery in
  gitea_resolve_task_capability BEFORE the terminal launcher probe, so a
  worktree removed mid-session can no longer wedge mutation resolution on
  'missing cwd' before recovery runs. The fail-closed probe block now also
  carries the binding classification evidence.
- F2: _resolve_preflight_workspace_path resolves with the same
  verify_paths existence checks as the canonical mutation context, and
  _get_workspace_porcelain returns a synthetic tracked-dirty sentinel when
  the workspace is missing or git fails — an uninspectable workspace can
  never read as clean/empty porcelain.
- F3: the orphaned_expired_superseded_head cleanup matrix now requires
  affirmative safe worktree evidence (worktree_clean=true or
  worktree_exists=false), aligned with the sibling orphaned_owner_missing
  gate and the diagnosis path; unknown evidence fails closed.
- F4: reviewer-session-lease shadows and stale-binding audit records are
  recovery-critical kinds exempt from the 4h session-state TTL; they
  persist until a sanctioned clear terminally reconciles them.
- F5: session-lease shadows are keyed by lease session id (collision-safe
  identity) with a list_states enumeration API; concurrent same-profile
  sessions can no longer overwrite or misattribute each other's crash
  evidence. Legacy single-slot records remain readable.
- F6: the durable audit record is persisted (status=pending) BEFORE the
  environment binding is cleared; if audit persistence fails the clear
  does not happen and the failure is reported explicitly.

30 new regression tests cover deleted-worktree recovery ordering, missing/
deleted/symlinked/mid-evaluation path changes, unknown-evidence cleanup,
TTL boundary (before/at/after), interleaved and reconnected concurrent
sessions, and audit-write failure/retry/idempotence/ordering.

Issue #704 dotenv load-path prevention is intentionally NOT included.

Full suite: 2695 passed, 6 skipped, 161 subtests passed.

Co-Authored-By: Claude Fable 5 <[email protected]>

reviewer_pr_lease.py

@@ -413,30 +413,48 @@ def record_session_lease(
 
 def clear_session_lease() -> None:
     global _SESSION_LEASE
+    prior = _SESSION_LEASE
     _SESSION_LEASE = None
-    _persist_session_lease_shadow(None)
+    _persist_session_lease_shadow(None, prior=prior)
 
 
 def get_session_lease() -> dict[str, Any] | None:
     return dict(_SESSION_LEASE) if _SESSION_LEASE else None
 
 
-def _persist_session_lease_shadow(lease: dict[str, Any] | None) -> None:
+def _persist_session_lease_shadow(
+    lease: dict[str, Any] | None,
+    *,
+    prior: dict[str, Any] | None = None,
+) -> None:
     """Best-effort durable shadow of the in-session lease (#702).
 
     A daemon that dies without teardown leaves this record behind, giving a
     later process provable orphan evidence (owner pid + session id) for the
     guarded cleanup path. Observability only — mutation gates never read it,
     and failures here must never block lease operations.
+
+    Shadows are keyed by lease session id (#702 F5): concurrent same-profile
+    sessions each own a distinct record, so one session's heartbeat can never
+    overwrite or misattribute another's crash evidence. A sanctioned clear is
+    the terminal reconciliation of that record's lifecycle.
     """
     try:
         import mcp_session_state as mss
 
         if lease is None:
+            sid = ((prior or {}).get("session_id") or "").strip() or None
+            if sid:
+                mss.clear_state(
+                    kind=mss.KIND_REVIEWER_SESSION_LEASE, instance_id=sid
+                )
+            # Legacy single-slot record from pre-F5 code: clearing it is safe
+            # because collision-safe writes never target that key again.
             mss.clear_state(kind=mss.KIND_REVIEWER_SESSION_LEASE)
             return
         mss.save_state(
             kind=mss.KIND_REVIEWER_SESSION_LEASE,
+            instance_id=((lease.get("session_id") or "").strip() or None),
             payload={
                 "pr_number": lease.get("pr_number"),
                 "session_id": lease.get("session_id"),
@@ -454,12 +472,38 @@ def _persist_session_lease_shadow(lease: dict[str, Any] | None) -> None:
         pass
 
 
-def load_session_lease_shadow() -> dict[str, Any] | None:
-    """Load the durable session-lease shadow left by this profile identity."""
+def load_session_lease_shadow(
+    session_id: str | None = None,
+) -> dict[str, Any] | None:
+    """Load the durable session-lease shadow left by this profile identity.
+
+    With *session_id*, load that session's collision-safe record (#702 F5),
+    falling back to the legacy single-slot record only when its payload names
+    the same session. Without *session_id*, return the legacy record or the
+    sole surviving instance record — ambiguity (multiple candidates) returns
+    ``None`` because a shadow that cannot be attributed proves nothing.
+    """
     try:
         import mcp_session_state as mss
 
-        return mss.load_state(kind=mss.KIND_REVIEWER_SESSION_LEASE)
+        sid = (session_id or "").strip()
+        if sid:
+            record = mss.load_state(
+                kind=mss.KIND_REVIEWER_SESSION_LEASE, instance_id=sid
+            )
+            if record is not None:
+                return record
+            legacy = mss.load_state(kind=mss.KIND_REVIEWER_SESSION_LEASE)
+            if legacy and (legacy.get("session_id") or "").strip() == sid:
+                return legacy
+            return None
+        legacy = mss.load_state(kind=mss.KIND_REVIEWER_SESSION_LEASE)
+        if legacy is not None:
+            return legacy
+        records = mss.list_states(kind=mss.KIND_REVIEWER_SESSION_LEASE)
+        if len(records) == 1:
+            return records[0]
+        return None
     except Exception:
         return None
 
@@ -1006,6 +1050,15 @@ def assess_obsolete_reviewer_comment_lease_cleanup(
                 fail_closed_reasons.append(
                     "owner process absent but worktree dirty; cleanup denied"
                 )
+            elif not (worktree_clean is True or worktree_exists is False):
+                # #702 F3: unknown worktree evidence must fail closed, exactly
+                # like the sibling orphaned_owner_missing gate and the
+                # diagnosis path — cleanup needs affirmative safe evidence.
+                fail_closed_reasons.append(
+                    "owner process absent but worktree evidence is unknown; "
+                    "cleanup requires affirmative safe evidence "
+                    "(worktree_clean=true or worktree_exists=false)"
+                )
         elif head_superseded and not has_terminal:
             classification = "ambiguous_conflicting_evidence"
             fail_closed_reasons.append(