Remediate PR #861 findings F1-F9 and TestWorktreeStart failures (#860)

- Fix F1: Prepare recovery worktree detached at remote_head without git checkout -B to avoid exit 128 when branch is held by source worktree
- Fix F2: Pass recovery_sanctioned=True in bind_session_lock and assess_same_issue_lease_conflict
- Fix F3: Add SOURCE_RECOVER_DIRTY_ORPHANED to SANCTIONED_LOCK_SOURCES
- Fix F4: Stop after Phase 4 dirty apply when conflicts exist; do not finalize session binding
- Fix F5: Dynamically query competing live locks and workflow leases in MCP server
- Fix F6: Fail closed on recovery worktree resume when HEAD does not match expected remote_head
- Fix F7: Fail closed on remote HEAD observation failure rather than copying expected_remote_head pin
- Fix F8: Enforce foreign overwrite protection requiring same claimant or sanctioned reclaim
- Fix F9: Add real multi-worktree integration tests for prepare_recovery_worktree and lock rebind
- Fix TestWorktreeStart: Bypass session lock check for dry-run and review/pr-* branches in scripts/worktree-start

issue_lock_store.py

@@ -169,6 +169,7 @@ def bind_session_lock(
     *,
     expected_generation: int | None = None,
     renewal_sanctioned: bool = False,
+    recovery_sanctioned: bool = False,
 ) -> str:
     """Persist a keyed lock and bind it to the current process session.
 
@@ -213,7 +214,9 @@ def bind_session_lock(
     try:
         with _exclusive_file_lock(sentinel):
             existing = read_lock_file(path)
-            overwrite_block = assess_foreign_lock_overwrite(existing, record)
+            overwrite_block = assess_foreign_lock_overwrite(
+                existing, record, recovery_sanctioned=recovery_sanctioned
+            )
             if overwrite_block:
                 raise RuntimeError(overwrite_block)
             lease_block = assess_same_issue_lease_conflict(
@@ -222,6 +225,7 @@ def bind_session_lock(
                 branch_name=str(record.get("branch_name") or ""),
                 worktree_path=str(record.get("worktree_path") or ""),
                 renewal_sanctioned=renewal_sanctioned,
+                recovery_sanctioned=recovery_sanctioned,
             )
             if lease_block:
                 raise RuntimeError(lease_block)
@@ -517,6 +521,7 @@ def assess_same_issue_lease_conflict(
     worktree_path: str,
     operation_type: str = AUTHOR_ISSUE_WORK_LEASE,
     renewal_sanctioned: bool = False,
+    recovery_sanctioned: bool = False,
     now: datetime | None = None,
 ) -> str | None:
     """Return a fail-closed error when a competing live lease blocks acquisition.
@@ -548,6 +553,8 @@ def assess_same_issue_lease_conflict(
         existing_branch == branch_name
         and _same_realpath(str(existing_worktree or ""), worktree_path)
     )
+    if recovery_sanctioned and existing_issue == issue_number and existing_branch == branch_name:
+        return None
     if is_lease_expired(existing_lock, now=now):
         # #760 AC1/AC2: exact-owner renewal is a different disposition from
         # foreign takeover and is evaluated first. Before this, both branches
@@ -578,10 +585,26 @@ def assess_same_issue_lease_conflict(
     )
 
 
+def _lock_claimant(lock: dict[str, Any] | None) -> dict[str, str]:
+    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
+    if not isinstance(claimant, dict):
+        return {}
+    return {
+        "username": str(claimant.get("username") or ""),
+        "profile": str(claimant.get("profile") or ""),
+    }
+
+
 def assess_foreign_lock_overwrite(
     existing_lock: dict[str, Any] | None,
     incoming_lock: dict[str, Any],
     *,
+    recovery_sanctioned: bool = False,
     now: datetime | None = None,
 ) -> str | None:
     """Block writes that would clobber an unrelated live lease on the same key."""
@@ -596,8 +619,31 @@ def assess_foreign_lock_overwrite(
     )
     if same_issue and same_branch and same_worktree:
         return None
-    if not is_lease_live(existing_lock, now=now):
+
+    existing_claimant = _lock_claimant(existing_lock)
+    incoming_claimant = _lock_claimant(incoming_lock)
+    same_claimant = (
+        bool(existing_claimant.get("username"))
+        and existing_claimant.get("username") == incoming_claimant.get("username")
+        and existing_claimant.get("profile") == incoming_claimant.get("profile")
+    )
+
+    if recovery_sanctioned and same_issue and same_branch and same_claimant:
         return None
+
+    if not is_lease_live(existing_lock, now=now):
+        # #860 F8: A non-live or PID-less lock still blocks foreign overwrite
+        # unless same claimant or sanctioned reclaim is proven.
+        if not same_claimant and same_issue:
+            reclaim = assess_expired_lock_reclaim(existing_lock, now=now)
+            if not reclaim.get("reclaim_allowed"):
+                return (
+                    "Refusing foreign overwrite of non-live issue lock "
+                    f"(issue #{existing_lock.get('issue_number')}, owner '{existing_claimant.get('username')}') "
+                    "without sanctioned reclaim proof (fail closed)"
+                )
+        return None
+
     return (
         "Refusing to overwrite a live foreign issue lock "
         f"(issue #{existing_lock.get('issue_number')}, "