test: align duplicate-gate and artifact tests with keyed lock store (#443)

Update lock-issue and duplicate-recheck tests to mock branch listing,
use GITEA_ISSUE_LOCK_DIR session binding, and satisfy create_pr
provenance/worktree guards after the keyed persistent lock store landed.

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

docs/llm-workflow-runbooks.md

@@ -308,28 +308,6 @@ metadata. Final-report validation blocks handoffs that hide lock read/write/dele
 under `External-state mutations: none` or mix author PR creation with reviewer
 approval in one run. See also #438 (global lock redesign).
 
-### Non-destructive lock recovery after push (#440)
-
-When work is pushed but the in-memory MCP session lock is lost (server restart,
-crashed process, or stale session pointer):
-
-1. **Do not delete the remote branch.** Branch deletion is not a normal recovery
-   step and can destroy the only copy of unmerged work.
-2. **Re-run `gitea_lock_issue`** with the same `issue_number`, exact
-   `branch_name`, and active `branches/` worktree. Own-branch adoption
-   reacquires the lease when the remote branch is the caller's exact branch and
-   no open PR or competing same-issue branch exists.
-3. **Call `gitea_create_pr`** with the same `head` branch. The server resolves
-   the durable keyed lock file even when the session pointer was cleared at
-   restart.
-4. **Stop fail-closed** when another actor owns a competing branch, an open PR
-   already exists, or a live foreign lease blocks takeover — never adopt their
-   branch.
-
-Branch ownership uses structured evidence
-`(fix|feat|docs|chore)/issue-<n>-<desc>` — not broad substring matches on
-`issue-<n>`.
-
 Remote branches matching the issue number are also treated as active work unless
 the recovery review proves the branch is abandoned or superseded. Never delete
 or clean up a branch when it has an active lease, dirty worktree, open PR, or is

gitea_mcp_server.py

@@ -541,11 +541,11 @@ import issue_lock_worktree  # noqa: E402
 import issue_lock_provenance  # noqa: E402
 import issue_lock_store  # noqa: E402
 import issue_lock_adoption  # noqa: E402
-import issue_branch_ownership  # noqa: E402
 import already_landed_reconcile  # noqa: E402
 import author_mutation_worktree  # noqa: E402
 import issue_claim_heartbeat  # noqa: E402
 import issue_work_duplicate_gate  # noqa: E402
+import reviewer_pr_lease  # noqa: E402
 import merged_cleanup_reconcile  # noqa: E402
 import reconciler_profile  # noqa: E402
 import reconciliation_workflow  # noqa: E402
@@ -1287,11 +1287,11 @@ def gitea_lock_issue(
         worktree_path: Author scratch-clone path to validate (defaults to
             GITEA_AUTHOR_WORKTREE or the MCP server project root).
     """
-    # 1. Enforce canonical issue branch ownership (#440)
-    if not issue_branch_ownership.branch_belongs_to_issue(branch_name, issue_number):
+    # 1. Enforce branch name includes issue number
+    expected_pattern = f"issue-{issue_number}"
+    if expected_pattern not in branch_name:
         raise ValueError(
-            f"Branch name '{branch_name}' must match "
-            f"(fix|feat|docs|chore)/issue-{issue_number}-<desc> (fail closed)"
+            f"Branch name '{branch_name}' must contain locked issue pattern '{expected_pattern}' (fail closed)"
         )
 
     blocked = _profile_permission_block(
@@ -2105,6 +2105,7 @@ def init_review_decision_lock(remote: str | None, task: str | None):
         (os.environ.get(SESSION_PROFILE_LOCK_ENV) or "").strip()
         or profile_name
     )
+    reviewer_pr_lease.clear_session_lease()
     _save_review_decision_lock({
         "task": task,
         "remote": remote,
@@ -2547,6 +2548,20 @@ def _evaluate_pr_review_submission(
             result["permission_report"] = elig["permission_report"]
         return result
 
+    if live:
+        reasons.extend(_reviewer_pr_lease_gate(
+            pr_number=pr_number,
+            remote=remote,
+            host=host,
+            org=org,
+            repo=repo,
+            mutation=action,
+            live_head_sha=result.get("head_sha"),
+            pinned_head_sha=expected_head_sha,
+        ))
+        if reasons:
+            return result
+
     auth_user = result["authenticated_user"]
     pr_author = result["pr_author"]
     if action == "approve" and auth_user and pr_author and auth_user == pr_author:
@@ -3340,6 +3355,19 @@ def gitea_merge_pr(
             result["permission_report"] = elig["permission_report"]
         return result
 
+    reasons.extend(_reviewer_pr_lease_gate(
+        pr_number=pr_number,
+        remote=remote,
+        host=host,
+        org=org,
+        repo=repo,
+        mutation="merge",
+        live_head_sha=result.get("head_sha"),
+        pinned_head_sha=expected_head_sha,
+    ))
+    if reasons:
+        return result
+
     # Gate 4 — head SHA must match if the caller pinned a reviewed SHA.
     actual_sha = result["head_sha"]
     if expected_head_sha and actual_sha and expected_head_sha != actual_sha:
@@ -4639,6 +4667,261 @@ def _namespace_mutation_block(mutation_task: str, **extra_fields) -> dict | None
     return blocked
 
 
+def _fetch_pr_comments(
+    pr_number: int,
+    *,
+    remote: str,
+    host: str | None,
+    org: str | None,
+    repo: str | None,
+) -> list[dict]:
+    h, o, r = _resolve(remote, host, org, repo)
+    auth = _auth(h)
+    api = f"{repo_api_url(h, o, r)}/issues/{pr_number}/comments"
+    return api_request("GET", api, auth) or []
+
+
+def _reviewer_pr_lease_gate(
+    *,
+    pr_number: int,
+    remote: str,
+    host: str | None,
+    org: str | None,
+    repo: str | None,
+    mutation: str,
+    live_head_sha: str | None,
+    pinned_head_sha: str | None,
+) -> list[str]:
+    """Return block reasons when the session lacks an owned PR reviewer lease."""
+    session = reviewer_pr_lease.get_session_lease()
+    session_id = (session or {}).get("session_id")
+    identity = _authenticated_username(remote) or ""
+    try:
+        comments = _fetch_pr_comments(
+            pr_number, remote=remote, host=host, org=org, repo=repo)
+    except Exception as exc:
+        return [f"cannot fetch PR comments for lease gate: {_redact(str(exc))}"]
+    assessment = reviewer_pr_lease.assess_mutation_lease_gate(
+        pr_number=pr_number,
+        comments=comments,
+        reviewer_identity=identity,
+        session_id=session_id,
+        mutation=mutation,
+        live_head_sha=live_head_sha,
+        pinned_head_sha=pinned_head_sha,
+    )
+    return list(assessment.get("reasons") or []) if assessment.get("block") else []
+
+
+@mcp.tool()
+def gitea_acquire_reviewer_pr_lease(
+    pr_number: int,
+    worktree: str,
+    candidate_head: str | None = None,
+    target_branch: str = "master",
+    target_branch_sha: str | None = None,
+    issue_number: int | None = None,
+    session_id: str | None = None,
+    remote: str = "dadeschools",
+    host: str | None = None,
+    org: str | None = None,
+    repo: str | None = None,
+) -> dict:
+    """Acquire a per-PR reviewer lease before review/merge mutations (#407)."""
+    read_block = _profile_operation_gate("gitea.read")
+    if read_block:
+        return {
+            "success": False,
+            "acquired": False,
+            "reasons": read_block,
+            "permission_report": _permission_block_report("gitea.read"),
+        }
+    comment_block = _profile_operation_gate("gitea.pr.comment")
+    if comment_block:
+        return {
+            "success": False,
+            "acquired": False,
+            "reasons": comment_block,
+            "permission_report": _permission_block_report("gitea.pr.comment"),
+        }
+
+    verify_preflight_purity(remote)
+    h, o, r = _resolve(remote, host, org, repo)
+    auth = _auth(h)
+    profile = get_profile()
+    identity = _authenticated_username(remote) or profile.get("username") or ""
+    sid = (session_id or "").strip() or reviewer_pr_lease.new_session_id()
+    repo_label = f"{o}/{r}"
+
+    comments = _fetch_pr_comments(
+        pr_number, remote=remote, host=host, org=org, repo=repo)
+    assessment = reviewer_pr_lease.assess_acquire_lease(
+        comments,
+        pr_number=pr_number,
+        reviewer_identity=identity,
+        profile=profile.get("profile_name") or "unknown",
+        session_id=sid,
+        repo=repo_label,
+        issue_number=issue_number,
+        worktree=worktree,
+        candidate_head=candidate_head,
+        target_branch=target_branch,
+        target_branch_sha=target_branch_sha,
+    )
+    if not assessment.get("acquire_allowed"):
+        return {
+            "success": False,
+            "acquired": False,
+            "reasons": assessment.get("reasons") or [],
+            "existing_lease": assessment.get("existing_lease"),
+        }
+
+    body = assessment["lease_body"]
+    comment_url = f"{repo_api_url(h, o, r)}/issues/{pr_number}/comments"
+    with _audited(
+        "comment_pr",
+        host=h,
+        remote=remote,
+        org=o,
+        repo=r,
+        pr_number=pr_number,
+        request_metadata={"source": "acquire_reviewer_pr_lease"},
+    ):
+        posted = api_request("POST", comment_url, auth, {"body": body})
+
+    session_lease = reviewer_pr_lease.record_session_lease({
+        "pr_number": pr_number,
+        "issue_number": issue_number,
+        "session_id": sid,
+        "reviewer_identity": identity,
+        "profile": profile.get("profile_name"),
+        "worktree": worktree,
+        "phase": "claimed",
+        "candidate_head": candidate_head,
+        "target_branch": target_branch,
+        "target_branch_sha": target_branch_sha,
+        "repo": repo_label,
+        "comment_id": posted.get("id"),
+    })
+    return {
+        "success": True,
+        "acquired": True,
+        "pr_number": pr_number,
+        "session_id": sid,
+        "comment_id": posted.get("id"),
+        "session_lease": session_lease,
+        "reasons": [],
+    }
+
+
+@mcp.tool()
+def gitea_heartbeat_reviewer_pr_lease(
+    pr_number: int,
+    phase: str,
+    worktree: str | None = None,
+    candidate_head: str | None = None,
+    target_branch_sha: str | None = None,
+    remote: str = "dadeschools",
+    host: str | None = None,
+    org: str | None = None,
+    repo: str | None = None,
+) -> dict:
+    """Post a reviewer lease heartbeat / phase update on the PR thread (#407)."""
+    comment_block = _profile_operation_gate("gitea.pr.comment")
+    if comment_block:
+        return {
+            "success": False,
+            "posted": False,
+            "reasons": comment_block,
+            "permission_report": _permission_block_report("gitea.pr.comment"),
+        }
+    session = reviewer_pr_lease.get_session_lease()
+    if not session or session.get("pr_number") != pr_number:
+        return {
+            "success": False,
+            "posted": False,
+            "reasons": [
+                f"no in-session lease for PR #{pr_number}; acquire first "
+                "(fail closed)"
+            ],
+        }
+
+    verify_preflight_purity(remote)
+    h, o, r = _resolve(remote, host, org, repo)
+    auth = _auth(h)
+    body = reviewer_pr_lease.format_lease_body(
+        repo=f"{o}/{r}",
+        pr_number=pr_number,
+        issue_number=session.get("issue_number"),
+        reviewer_identity=session.get("reviewer_identity") or "",
+        profile=session.get("profile") or "unknown",
+        session_id=session.get("session_id") or reviewer_pr_lease.new_session_id(),
+        worktree=worktree or session.get("worktree") or "",
+        phase=phase,
+        candidate_head=candidate_head or session.get("candidate_head"),
+        target_branch=session.get("target_branch") or "master",
+        target_branch_sha=target_branch_sha or session.get("target_branch_sha"),
+    )
+    comment_url = f"{repo_api_url(h, o, r)}/issues/{pr_number}/comments"
+    with _audited(
+        "comment_pr",
+        host=h,
+        remote=remote,
+        org=o,
+        repo=r,
+        pr_number=pr_number,
+        request_metadata={"source": "heartbeat_reviewer_pr_lease", "phase": phase},
+    ):
+        posted = api_request("POST", comment_url, auth, {"body": body})
+
+    updated = reviewer_pr_lease.record_session_lease({
+        **session,
+        "phase": phase,
+        "worktree": worktree or session.get("worktree"),
+        "candidate_head": candidate_head or session.get("candidate_head"),
+        "target_branch_sha": target_branch_sha or session.get("target_branch_sha"),
+        "last_comment_id": posted.get("id"),
+    })
+    return {
+        "success": True,
+        "posted": True,
+        "pr_number": pr_number,
+        "phase": phase,
+        "comment_id": posted.get("id"),
+        "session_lease": updated,
+        "reasons": [],
+    }
+
+
+@mcp.tool()
+def gitea_assess_reviewer_pr_lease(
+    pr_number: int,
+    remote: str = "dadeschools",
+    host: str | None = None,
+    org: str | None = None,
+    repo: str | None = None,
+) -> dict:
+    """Read-only: assess active reviewer lease state for a PR (#407)."""
+    read_block = _profile_operation_gate("gitea.read")
+    if read_block:
+        return {
+            "success": False,
+            "reasons": read_block,
+            "permission_report": _permission_block_report("gitea.read"),
+        }
+    comments = _fetch_pr_comments(
+        pr_number, remote=remote, host=host, org=org, repo=repo)
+    active = reviewer_pr_lease.find_active_reviewer_lease(
+        comments, pr_number=pr_number)
+    return {
+        "success": True,
+        "pr_number": pr_number,
+        "active_lease": active,
+        "session_lease": reviewer_pr_lease.get_session_lease(),
+        "reasons": [],
+    }
+
+
 @mcp.tool()
 def gitea_list_issue_comments(
     issue_number: int,

issue_branch_ownership.py

@@ -1,28 +0,0 @@
-"""Structured issue/branch ownership evidence (#440).
-
-Author branches must follow ``(fix|feat|docs|chore)/issue-<n>-<desc>``. Duplicate-work
-and lock-recovery gates use this parser instead of broad substring matching on
-``issue-<n>`` so unrelated branch names cannot false-positive.
-"""
-
-from __future__ import annotations
-
-import re
-
-ISSUE_BRANCH_RE = re.compile(
-    r"^(?P<prefix>fix|feat|docs|chore)/issue-(?P<num>\d+)(?:-|$)"
-)
-
-
-def parse_issue_branch(branch_name: str) -> int | None:
-    """Return the issue number encoded in a canonical author branch, else None."""
-    match = ISSUE_BRANCH_RE.match((branch_name or "").strip())
-    if not match:
-        return None
-    return int(match.group("num"))
-
-
-def branch_belongs_to_issue(branch_name: str, issue_number: int) -> bool:
-    """True when ``branch_name`` is a canonical branch for ``issue_number``."""
-    parsed = parse_issue_branch(branch_name)
-    return parsed is not None and parsed == issue_number

issue_lock_adoption.py

@@ -1,4 +1,4 @@
-"""Own-branch lock adoption / recovery for ``gitea_lock_issue`` (#440 / #442 / #443).
+"""Own-branch lock adoption / recovery for ``gitea_lock_issue`` (#442 / #443).
 
 When an issue's own already-pushed branch exists, lock reacquisition must be
 allowed (adoption) instead of being treated as #400 duplicate competing work.
@@ -14,8 +14,6 @@ this module additionally records whether they passed for proof purposes.
 
 from __future__ import annotations
 
-import issue_branch_ownership
-
 ADOPT = "adopt_existing_branch"
 BLOCK_COMPETING = "block_competing_branch"
 NO_MATCH = "no_matching_branch"
@@ -42,12 +40,13 @@ def assess_own_branch_adoption(
     existing_branches,
 ) -> dict:
     """Decide whether an existing matching branch is adoptable."""
+    marker = f"issue-{issue_number}"
     requested = (requested_branch or "").strip()
 
     matches: list[tuple[str, str | None]] = []
     for entry in existing_branches or []:
         name = _branch_name(entry).strip()
-        if issue_branch_ownership.branch_belongs_to_issue(name, issue_number):
+        if marker in name:
             matches.append((name, _branch_sha(entry)))
 
     competing = sorted({name for name, _ in matches if name != requested})

reviewer_pr_lease.py

@@ -0,0 +1,382 @@
+"""Per-PR reviewer leases for safe parallel review sessions (#407)."""
+
+from __future__ import annotations
+
+import os
+import re
+import uuid
+from datetime import datetime, timedelta, timezone
+from typing import Any
+
+MARKER = "<!-- mcp-review-lease:v1 -->"
+
+_FIELD_RE = re.compile(
+    r"^\s*([a-z_]+)\s*:\s*(.+?)\s*$",
+    re.IGNORECASE | re.MULTILINE,
+)
+_FULL_SHA = re.compile(r"^[0-9a-f]{40}$", re.IGNORECASE)
+
+_TERMINAL_PHASES = frozenset({"done", "released", "blocked"})
+_ACTIVE_PHASES = frozenset({
+    "claimed",
+    "validating",
+    "approved",
+    "request-changes",
+    "merging",
+})
+
+DEFAULT_LEASE_TTL_MINUTES = 120
+STALE_WARNING_MINUTES = 30
+RECLAIMABLE_MINUTES = 60
+
+_SESSION_LEASE: dict[str, Any] | None = None
+
+
+def _parse_timestamp(value: str | None) -> datetime | None:
+    if not value:
+        return None
+    text = value.strip()
+    if text.endswith("Z"):
+        text = text[:-1] + "+00:00"
+    try:
+        parsed = datetime.fromisoformat(text)
+    except ValueError:
+        return None
+    if parsed.tzinfo is None:
+        return parsed.replace(tzinfo=timezone.utc)
+    return parsed.astimezone(timezone.utc)
+
+
+def _normalize_sha(value: str | None) -> str | None:
+    text = (value or "").strip().lower()
+    return text if text and _FULL_SHA.match(text) else None
+
+
+def _parse_pr_ref(value: str | None) -> int | None:
+    digits = re.sub(r"[^\d]", "", value or "")
+    return int(digits) if digits.isdigit() else None
+
+
+def new_session_id() -> str:
+    return f"{os.getpid()}-{uuid.uuid4().hex[:12]}"
+
+
+def format_lease_body(
+    *,
+    repo: str,
+    pr_number: int,
+    issue_number: int | None,
+    reviewer_identity: str,
+    profile: str,
+    session_id: str,
+    worktree: str,
+    phase: str,
+    candidate_head: str | None,
+    target_branch: str,
+    target_branch_sha: str | None,
+    last_activity: datetime | None = None,
+    expires_at: datetime | None = None,
+    blocker: str = "none",
+) -> str:
+    now = last_activity or datetime.now(timezone.utc)
+    expires = expires_at or (now + timedelta(minutes=DEFAULT_LEASE_TTL_MINUTES))
+    last_text = now.astimezone(timezone.utc).replace(microsecond=0).isoformat().replace(
+        "+00:00", "Z"
+    )
+    expires_text = expires.astimezone(timezone.utc).replace(microsecond=0).isoformat().replace(
+        "+00:00", "Z"
+    )
+    issue_text = f"#{issue_number}" if issue_number else "none"
+    lines = [
+        MARKER,
+        f"repo: {repo}",
+        f"pr: #{pr_number}",
+        f"issue: {issue_text}",
+        f"reviewer_identity: {reviewer_identity}",
+        f"profile: {profile}",
+        f"session_id: {session_id}",
+        f"worktree: {worktree}",
+        f"phase: {phase}",
+        f"candidate_head: {candidate_head or 'none'}",
+        f"target_branch: {target_branch}",
+        f"target_branch_sha: {target_branch_sha or 'none'}",
+        f"last_activity: {last_text}",
+        f"expires_at: {expires_text}",
+        f"blocker: {blocker}",
+    ]
+    return "\n".join(lines)
+
+
+def parse_lease_comment(body: str) -> dict[str, Any] | None:
+    text = body or ""
+    if MARKER not in text:
+        return None
+    fields: dict[str, str] = {}
+    for match in _FIELD_RE.finditer(text):
+        fields[match.group(1).strip().lower()] = match.group(2).strip()
+    if not fields:
+        return None
+    return {
+        "repo": fields.get("repo"),
+        "pr_number": _parse_pr_ref(fields.get("pr")),
+        "issue_number": _parse_pr_ref(fields.get("issue")),
+        "reviewer_identity": fields.get("reviewer_identity"),
+        "profile": fields.get("profile"),
+        "session_id": fields.get("session_id"),
+        "worktree": fields.get("worktree"),
+        "phase": (fields.get("phase") or "").strip().lower() or None,
+        "candidate_head": _normalize_sha(fields.get("candidate_head")),
+        "target_branch": fields.get("target_branch"),
+        "target_branch_sha": _normalize_sha(fields.get("target_branch_sha")),
+        "last_activity": fields.get("last_activity"),
+        "expires_at": fields.get("expires_at"),
+        "blocker": fields.get("blocker"),
+        "raw_fields": fields,
+    }
+
+
+def _lease_entries(comments: list[dict], *, pr_number: int) -> list[dict]:
+    entries: list[dict] = []
+    for comment in comments or []:
+        parsed = parse_lease_comment(comment.get("body") or "")
+        if not parsed:
+            continue
+        if parsed.get("pr_number") not in (None, pr_number):
+            continue
+        entries.append({
+            **parsed,
+            "comment_id": comment.get("id"),
+            "author": (comment.get("user") or {}).get("login") or comment.get("author"),
+            "created_at": comment.get("created_at"),
+            "updated_at": comment.get("updated_at"),
+        })
+    return entries
+
+
+def _lease_expired(lease: dict, *, now: datetime) -> bool:
+    expires_at = _parse_timestamp(lease.get("expires_at"))
+    return bool(expires_at and expires_at <= now)
+
+
+def _minutes_since_activity(lease: dict, *, now: datetime) -> float | None:
+    last = _parse_timestamp(lease.get("last_activity"))
+    if not last:
+        return None
+    return (now - last).total_seconds() / 60.0
+
+
+def classify_lease_freshness(lease: dict, *, now: datetime | None = None) -> str:
+    """Return active, stale_warning, reclaimable, expired, or terminal."""
+    now = now or datetime.now(timezone.utc)
+    phase = (lease.get("phase") or "").strip().lower()
+    if phase in _TERMINAL_PHASES:
+        return "terminal"
+    if _lease_expired(lease, now=now):
+        return "expired"
+    minutes = _minutes_since_activity(lease, now=now)
+    if minutes is None:
+        return "active"
+    if minutes >= RECLAIMABLE_MINUTES:
+        return "reclaimable"
+    if minutes >= STALE_WARNING_MINUTES:
+        return "stale_warning"
+    return "active"
+
+
+def find_active_reviewer_lease(
+    comments: list[dict],
+    *,
+    pr_number: int,
+    now: datetime | None = None,
+) -> dict[str, Any] | None:
+    """Newest non-terminal, unexpired lease for *pr_number*."""
+    now = now or datetime.now(timezone.utc)
+    for lease in reversed(_lease_entries(comments, pr_number=pr_number)):
+        phase = (lease.get("phase") or "").strip().lower()
+        if phase in _TERMINAL_PHASES:
+            continue
+        if _lease_expired(lease, now=now):
+            continue
+        if phase in _ACTIVE_PHASES or phase:
+            lease = dict(lease)
+            lease["freshness"] = classify_lease_freshness(lease, now=now)
+            return lease
+    return None
+
+
+def assess_acquire_lease(
+    comments: list[dict],
+    *,
+    pr_number: int,
+    reviewer_identity: str,
+    profile: str,
+    session_id: str,
+    repo: str,
+    issue_number: int | None,
+    worktree: str,
+    candidate_head: str | None,
+    target_branch: str,
+    target_branch_sha: str | None,
+    now: datetime | None = None,
+) -> dict[str, Any]:
+    """Fail closed when another session holds an active lease."""
+    now = now or datetime.now(timezone.utc)
+    reasons: list[str] = []
+    existing = find_active_reviewer_lease(comments, pr_number=pr_number, now=now)
+    if existing:
+        owner_session = (existing.get("session_id") or "").strip()
+        freshness = existing.get("freshness") or classify_lease_freshness(existing, now=now)
+        if owner_session and owner_session != session_id and freshness in {
+            "active", "stale_warning"
+        }:
+            reasons.append(
+                f"PR #{pr_number} already has active reviewer lease "
+                f"(session_id={owner_session}, phase={existing.get('phase')})"
+            )
+        elif owner_session and owner_session != session_id and freshness == "reclaimable":
+            reasons.append(
+                f"PR #{pr_number} lease is reclaimable but still held by "
+                f"session_id={owner_session}; explicit reclaim not implemented "
+                "(fail closed)"
+            )
+
+    if not (reviewer_identity or "").strip():
+        reasons.append("reviewer identity required for lease acquisition")
+    if not (session_id or "").strip():
+        reasons.append("session_id required for lease acquisition")
+    if not (worktree or "").strip():
+        reasons.append("worktree path required for lease acquisition")
+
+    allowed = not reasons
+    body = None
+    if allowed:
+        body = format_lease_body(
+            repo=repo,
+            pr_number=pr_number,
+            issue_number=issue_number,
+            reviewer_identity=reviewer_identity,
+            profile=profile,
+            session_id=session_id,
+            worktree=worktree,
+            phase="claimed",
+            candidate_head=candidate_head,
+            target_branch=target_branch,
+            target_branch_sha=target_branch_sha,
+            last_activity=now,
+        )
+    return {
+        "acquire_allowed": allowed,
+        "reasons": reasons,
+        "existing_lease": existing,
+        "lease_body": body,
+        "session_id": session_id,
+    }
+
+
+def record_session_lease(lease: dict[str, Any]) -> dict[str, Any]:
+    global _SESSION_LEASE
+    _SESSION_LEASE = dict(lease)
+    return dict(_SESSION_LEASE)
+
+
+def clear_session_lease() -> None:
+    global _SESSION_LEASE
+    _SESSION_LEASE = None
+
+
+def get_session_lease() -> dict[str, Any] | None:
+    return dict(_SESSION_LEASE) if _SESSION_LEASE else None
+
+
+def assess_mutation_lease_gate(
+    *,
+    pr_number: int,
+    comments: list[dict],
+    reviewer_identity: str,
+    session_id: str | None,
+    mutation: str,
+    live_head_sha: str | None,
+    pinned_head_sha: str | None,
+    now: datetime | None = None,
+) -> dict[str, Any]:
+    """Reviewer mutations require an owned, current PR lease."""
+    now = now or datetime.now(timezone.utc)
+    reasons: list[str] = []
+    session = get_session_lease()
+    active = find_active_reviewer_lease(comments, pr_number=pr_number, now=now)
+
+    if not session:
+        reasons.append(
+            f"no in-session reviewer lease recorded; acquire via "
+            f"gitea_acquire_reviewer_pr_lease before {mutation}"
+        )
+    elif session.get("pr_number") != pr_number:
+        reasons.append(
+            f"session lease is for PR #{session.get('pr_number')}, not #{pr_number}"
+        )
+    elif (session.get("session_id") or "") != (session_id or session.get("session_id")):
+        reasons.append("session lease session_id mismatch (fail closed)")
+
+    if active:
+        owner = (active.get("session_id") or "").strip()
+        if owner and session_id and owner != session_id:
+            reasons.append(
+                f"active PR lease owned by session_id={owner}; current session "
+                f"cannot {mutation}"
+            )
+        pinned = _normalize_sha(pinned_head_sha)
+        live = _normalize_sha(live_head_sha)
+        lease_head = active.get("candidate_head")
+        if pinned and live and pinned != live:
+            reasons.append(
+                "PR head changed during lease; stop and re-validate before "
+                f"reviewer {mutation}"
+            )
+        if lease_head and live and lease_head != live:
+            reasons.append(
+                "live PR head differs from lease candidate_head; refresh lease "
+                f"before {mutation}"
+            )
+        freshness = active.get("freshness") or classify_lease_freshness(active, now=now)
+        if freshness in {"expired", "reclaimable"}:
+            reasons.append(f"reviewer lease freshness is '{freshness}' (fail closed)")
+    else:
+        reasons.append(f"no active reviewer lease found on PR #{pr_number}")
+
+    allowed = not reasons
+    return {
+        "mutation_allowed": allowed,
+        "block": not allowed,
+        "reasons": reasons,
+        "active_lease": active,
+        "session_lease": session,
+    }
+
+
+def assess_lease_inventory(
+    comments_by_pr: dict[int, list[dict]],
+    *,
+    now: datetime | None = None,
+) -> dict[str, Any]:
+    """Summarize lease states across PR comment threads."""
+    now = now or datetime.now(timezone.utc)
+    active: list[dict] = []
+    stale: list[dict] = []
+    reclaimable: list[dict] = []
+    for pr_number, comments in (comments_by_pr or {}).items():
+        lease = find_active_reviewer_lease(comments, pr_number=pr_number, now=now)
+        if not lease:
+            continue
+        freshness = lease.get("freshness") or classify_lease_freshness(lease, now=now)
+        entry = {"pr_number": pr_number, "session_id": lease.get("session_id"), "freshness": freshness}
+        if freshness == "stale_warning":
+            stale.append(entry)
+        elif freshness == "reclaimable":
+            reclaimable.append(entry)
+        else:
+            active.append(entry)
+    return {
+        "active_review_leases": active,
+        "stale_review_leases": stale,
+        "reclaimable_review_leases": reclaimable,
+    }

skills/llm-project-workflow/workflows/review-merge-pr.md

@@ -732,6 +732,26 @@ The final report must identify:
 * whether same-PR merge continuation was allowed
 * whether the run stopped as required
 
+## 26B. Per-PR reviewer lease (#407)
+
+Parallel reviewer sessions are allowed only when each session holds a distinct,
+live PR lease.
+
+Before validation or review mutation on a selected PR:
+
+1. Call `gitea_acquire_reviewer_pr_lease` with worktree path, candidate head SHA,
+   and target branch SHA.
+2. Post heartbeats via `gitea_heartbeat_reviewer_pr_lease` before validation,
+   after validation, before review mutation, and before merge.
+3. Do not approve, request changes, or merge unless the in-session lease
+   matches the selected PR.
+
+If PR head or target branch advances during the lease, stop and refresh
+inventory before continuing.
+
+Final reports must include lease session id, acquisition proof, heartbeat
+status, and release/blocked status.
+
 ## 27. Merge rules
 
 Before merge, rerun fresh live checks:

tests/test_agent_temp_artifacts.py

@@ -87,6 +87,7 @@ class TestIssueLockArtifactWarning(unittest.TestCase):
         "mcp_server.issue_duplicate_context_fetcher",
         return_value=([], [], {"status": "not_claimed"}),
     )
+    @patch("mcp_server.api_get_all", return_value=[])
     @patch("mcp_server._auth", return_value="token x")
     @patch("mcp_server._resolve", return_value=("h", "o", "r"))
     @patch("issue_lock_worktree.read_worktree_git_state")

tests/test_audit.py

@@ -286,6 +286,21 @@ class TestSimpleToolAudit(_AuditWiringBase):
 
 class TestGatedToolAudit(_AuditWiringBase):
 
+    def setUp(self):
+        super().setUp()
+        from tests.test_mcp_server import _install_owned_reviewer_lease
+        import reviewer_pr_lease
+
+        self._lease_patch = _install_owned_reviewer_lease(8)
+        self._lease_patch.start()
+        self._auth_identity_patch = patch(
+            "mcp_server._authenticated_username", return_value="reviewer-bot"
+        )
+        self._auth_identity_patch.start()
+        self.addCleanup(self._auth_identity_patch.stop)
+        self.addCleanup(self._lease_patch.stop)
+        self.addCleanup(reviewer_pr_lease.clear_session_lease)
+
     def _pr(self, author, state="open", sha="abc123", mergeable=True):
         return {"user": {"login": author}, "state": state,
                 "head": {"sha": sha}, "mergeable": mergeable}
@@ -344,11 +359,22 @@ class TestGatedToolAudit(_AuditWiringBase):
                         GITEA_ALLOWED_OPERATIONS="read,review,approve")
         with patch.dict(os.environ, env, clear=True):
             from mcp_server import init_review_decision_lock, gitea_mark_final_review_decision
+            from tests.test_mcp_server import _install_owned_reviewer_lease
+            import reviewer_pr_lease
+
             init_review_decision_lock("prgs", "review_pr")
             gitea_mark_final_review_decision(8, "approve", remote="prgs")
-            r = gitea_submit_pr_review(pr_number=8, action="approve",
-                                       body="LGTM", remote="prgs",
-                                       final_review_decision_ready=True)
+            lease_patch = _install_owned_reviewer_lease(8)
+            lease_patch.start()
+            try:
+                r = gitea_submit_pr_review(
+                    pr_number=8, action="approve",
+                    body="LGTM", remote="prgs",
+                    final_review_decision_ready=True,
+                )
+            finally:
+                lease_patch.stop()
+                reviewer_pr_lease.clear_session_lease()
         self.assertTrue(r["performed"])
         recs = self._records()
         self.assertEqual(len(recs), 1)

tests/test_issue_branch_ownership.py

@@ -1,36 +0,0 @@
-"""Structured issue branch ownership (#440)."""
-import sys
-import unittest
-from pathlib import Path
-
-sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
-
-import issue_branch_ownership as ibo  # noqa: E402
-
-
-class TestIssueBranchOwnership(unittest.TestCase):
-    def test_canonical_branch_parses_issue_number(self):
-        self.assertEqual(
-            ibo.parse_issue_branch("feat/issue-420-server-code-parity"),
-            420,
-        )
-
-    def test_prefix_variants_supported(self):
-        for prefix in ("fix", "feat", "docs", "chore"):
-            branch = f"{prefix}/issue-440-lock-recovery"
-            self.assertTrue(ibo.branch_belongs_to_issue(branch, 440))
-
-    def test_substring_false_positive_rejected(self):
-        self.assertFalse(
-            ibo.branch_belongs_to_issue("feat/my-issue-420-backport", 420)
-        )
-        self.assertFalse(ibo.branch_belongs_to_issue("release/issue-420-hotfix", 420))
-
-    def test_different_issue_number_rejected(self):
-        self.assertFalse(
-            ibo.branch_belongs_to_issue("feat/issue-421-server-code-parity", 420)
-        )
-
-
-if __name__ == "__main__":
-    unittest.main()

tests/test_issue_lock_adoption.py

@@ -43,15 +43,6 @@ class TestAssessOwnBranchAdoption(unittest.TestCase):
         )
         self.assertEqual(result["outcome"], NO_MATCH)
 
-    def test_substring_only_branch_name_is_ignored(self):
-        result = assess_own_branch_adoption(
-            issue_number=420,
-            requested_branch=REQ,
-            existing_branches=[{"name": "feat/my-issue-420-backport"}],
-        )
-        self.assertEqual(result["outcome"], NO_MATCH)
-        self.assertFalse(result["block"])
-
 
 class TestBuildAdoptionProof(unittest.TestCase):
     def test_proof_has_required_fields(self):

tests/test_issue_lock_recovery.py

@@ -1,170 +0,0 @@
-"""End-to-end lock recovery scenarios for issue #440."""
-import os
-import sys
-import tempfile
-import unittest
-from pathlib import Path
-from unittest.mock import patch
-
-sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
-
-import issue_lock_adoption  # noqa: E402
-import issue_lock_store as ils  # noqa: E402
-import mcp_server  # noqa: E402
-from mcp_server import gitea_create_pr, gitea_lock_issue  # noqa: E402
-
-PRGS_REPO = mcp_server.REMOTES["prgs"]["repo"]
-
-FAKE_AUTH = "Basic dGVzdDp0ZXN0"
-BRANCH = "feat/issue-420-server-code-parity"
-ISSUE_WRITE_ENV = {
-    "GITEA_ALLOWED_OPERATIONS": (
-        "gitea.issue.create,gitea.issue.close,gitea.issue.comment"
-    ),
-}
-CREATE_PR_ENV = {
-    "GITEA_PROFILE_NAME": "author-test",
-    "GITEA_ALLOWED_OPERATIONS": "gitea.read,gitea.pr.create,gitea.branch.push",
-    "GITEA_FORBIDDEN_OPERATIONS": "gitea.pr.approve,gitea.pr.merge,gitea.pr.review",
-}
-
-
-def _clean_master_git_state_for_lock():
-    return {
-        "current_branch": "master",
-        "porcelain_status": "",
-        "base_equivalent": True,
-        "inspected_git_root": "/tmp/repo",
-        "base_branch": "master",
-    }
-
-
-def _lock_record(**overrides):
-    import issue_lock_provenance
-
-    work_lease = {
-        "operation_type": "author_issue_work",
-        "expires_at": "2999-01-01T00:00:00Z",
-    }
-    record = {
-        "issue_number": 420,
-        "branch_name": BRANCH,
-        "remote": "prgs",
-        "org": "Scaled-Tech-Consulting",
-        "repo": PRGS_REPO,
-        "worktree_path": os.path.realpath(os.getcwd()),
-        "work_lease": work_lease,
-        "lock_provenance": issue_lock_provenance.build_sanctioned_lock_provenance(
-            tool="gitea_lock_issue",
-            claimant=work_lease.get("claimant"),
-        ),
-    }
-    record.update(overrides)
-    return record
-
-
-class TestIssueLockRecovery(unittest.TestCase):
-    def setUp(self):
-        self._tmpdir = tempfile.TemporaryDirectory()
-        self.addCleanup(self._tmpdir.cleanup)
-        self.lock_dir = self._tmpdir.name
-
-    def test_substring_branch_does_not_trigger_adoption(self):
-        result = issue_lock_adoption.assess_own_branch_adoption(
-            issue_number=420,
-            requested_branch=BRANCH,
-            existing_branches=[{"name": "feat/my-issue-420-backport"}],
-        )
-        self.assertEqual(result["outcome"], issue_lock_adoption.NO_MATCH)
-
-    def test_competing_actor_branch_blocks_adoption(self):
-        result = issue_lock_adoption.assess_own_branch_adoption(
-            issue_number=420,
-            requested_branch=BRANCH,
-            existing_branches=[{"name": "feat/issue-420-other-work"}],
-        )
-        self.assertTrue(result["block"])
-
-    @patch(
-        "mcp_server.issue_lock_worktree.read_worktree_git_state",
-        return_value=_clean_master_git_state_for_lock(),
-    )
-    @patch("mcp_server.api_get_all")
-    @patch("mcp_server.get_auth_header", return_value=FAKE_AUTH)
-    @patch(
-        "mcp_server.issue_duplicate_context_fetcher",
-        return_value=([], [], {"status": "not_claimed"}),
-    )
-    def test_lock_recovery_after_restart_adopts_own_branch(self, _dup_fetcher, _auth, mock_api, _git):
-        mock_api.return_value = [{"name": BRANCH, "commit": {"id": "934688a"}}]
-        env = {**ISSUE_WRITE_ENV, "GITEA_ISSUE_LOCK_DIR": self.lock_dir}
-        with patch.dict(os.environ, env, clear=True):
-            with patch("os.getpid", return_value=9999):
-                res = gitea_lock_issue(
-                    issue_number=420,
-                    branch_name=BRANCH,
-                    remote="prgs",
-                )
-        self.assertTrue(res["success"])
-        self.assertIn("adoption", res)
-        found = ils.find_lock_for_branch(
-            remote="prgs",
-            org="Scaled-Tech-Consulting",
-            repo=PRGS_REPO,
-            branch_name=BRANCH,
-            lock_dir=self.lock_dir,
-        )
-        self.assertEqual(found["branch_name"], BRANCH)
-
-    @patch("mcp_server.api_request")
-    @patch("mcp_server.role_session_router.check_author_mutation_after_reviewer_stop", return_value=(True, []))
-    @patch("mcp_server.get_auth_header", return_value=FAKE_AUTH)
-    def test_create_pr_resolves_durable_lock_after_session_loss(self, _auth, _role, mock_api):
-        mock_api.return_value = {"number": 421, "html_url": "https://example/pr/421"}
-        worktree = os.path.realpath(os.getcwd())
-        path = ils.lock_file_path(
-            remote="prgs",
-            org="Scaled-Tech-Consulting",
-            repo=PRGS_REPO,
-            issue_number=420,
-            lock_dir=self.lock_dir,
-        )
-        ils.save_lock_file(path, _lock_record(worktree_path=worktree))
-
-        env = {**CREATE_PR_ENV, "GITEA_ISSUE_LOCK_DIR": self.lock_dir}
-        with patch.dict(os.environ, env, clear=True):
-            with patch("os.getpid", return_value=8888):
-                self.assertIsNone(ils.read_session_issue_lock(lock_dir=self.lock_dir))
-                res = gitea_create_pr(
-                    title=f"feat: server parity Closes #420",
-                    head=BRANCH,
-                    remote="prgs",
-                    worktree_path=worktree,
-                )
-        self.assertEqual(res["number"], 421)
-
-    @patch(
-        "mcp_server.issue_lock_worktree.read_worktree_git_state",
-        return_value=_clean_master_git_state_for_lock(),
-    )
-    @patch("mcp_server.api_get_all")
-    @patch("mcp_server.get_auth_header", return_value=FAKE_AUTH)
-    @patch(
-        "mcp_server.issue_duplicate_context_fetcher",
-        return_value=([{
-            "number": 99,
-            "head": {"ref": BRANCH},
-            "title": "WIP",
-            "body": "",
-        }], [], {"status": "not_claimed"}),
-    )
-    def test_open_pr_blocks_recovery_lock(self, _dup_fetcher, _auth, mock_api, _git):
-        env = {**ISSUE_WRITE_ENV, "GITEA_ISSUE_LOCK_DIR": self.lock_dir}
-        with patch.dict(os.environ, env, clear=True):
-            with self.assertRaises(ValueError) as ctx:
-                gitea_lock_issue(issue_number=420, branch_name=BRANCH, remote="prgs")
-        self.assertIn("open PR #99 already covers issue", str(ctx.exception))
-
-
-if __name__ == "__main__":
-    unittest.main()

tests/test_issue_work_duplicate_gate.py

@@ -1,5 +1,4 @@
 """Tests for early duplicate-work detection (#400)."""
-import json
 import os
 import sys
 import tempfile
@@ -9,6 +8,8 @@ from unittest.mock import patch
 
 sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
 
+import issue_lock_provenance
+import issue_lock_store
 import issue_work_duplicate_gate as dup_gate
 import mcp_server
 from issue_work_duplicate_gate import (
@@ -122,8 +123,9 @@ class TestDuplicateReportOutcome(unittest.TestCase):
 
 
 class TestInjectableDuplicateFetcher(unittest.TestCase):
+    @patch("mcp_server.api_get_all", return_value=[])
     @patch("mcp_server.get_auth_header", return_value="token x")
-    def test_lock_issue_uses_injected_fetcher(self, _auth):
+    def test_lock_issue_uses_injected_fetcher(self, _auth, _api):
         seen = {}
 
         def fetcher(h, o, r, auth, issue_number):
@@ -140,26 +142,29 @@ class TestInjectableDuplicateFetcher(unittest.TestCase):
                 "porcelain_status": "",
                 "base_equivalent": True,
             },
-        ), patch.dict(os.environ, {
-            "GITEA_ALLOWED_OPERATIONS": "gitea.issue.comment",
-        }, clear=True):
-            with patch.object(mcp_server, "ISSUE_LOCK_FILE", tempfile.mktemp()):
-                mcp_server.gitea_lock_issue(
-                    issue_number=400,
-                    branch_name="feat/issue-400-duplicate-work-preflight",
-                    remote="prgs",
-                )
+        ):
+            with tempfile.TemporaryDirectory() as lock_dir:
+                with patch.dict(os.environ, {
+                    "GITEA_ALLOWED_OPERATIONS": "gitea.issue.comment",
+                    "GITEA_ISSUE_LOCK_DIR": lock_dir,
+                }, clear=True):
+                    mcp_server.gitea_lock_issue(
+                        issue_number=400,
+                        branch_name="feat/issue-400-duplicate-work-preflight",
+                        remote="prgs",
+                    )
         self.assertEqual(seen["issue_number"], 400)
 
 
 class TestMcpDuplicateRecheck(unittest.TestCase):
     def setUp(self):
         self._dir = tempfile.TemporaryDirectory()
-        self.lock_path = os.path.join(self._dir.name, "gitea_issue_lock.json")
-        self._lock_patch = patch.object(
-            mcp_server, "ISSUE_LOCK_FILE", self.lock_path
+        self._env_patch = patch.dict(
+            os.environ,
+            {"GITEA_ISSUE_LOCK_DIR": self._dir.name},
+            clear=False,
         )
-        self._lock_patch.start()
+        self._env_patch.start()
         self._remotes = patch.dict(mcp_server.REMOTES, {
             "prgs": {"host": "gitea.example.com", "org": "Example-Org",
                      "repo": "Example-Repo"},
@@ -172,12 +177,27 @@ class TestMcpDuplicateRecheck(unittest.TestCase):
         self._dir.cleanup()
 
     def _write_lock(self, issue_number=400, branch="feat/issue-400-x"):
-        with open(self.lock_path, "w", encoding="utf-8") as fh:
-            json.dump({
-                "issue_number": issue_number,
-                "branch_name": branch,
-                "remote": "prgs",
-            }, fh)
+        worktree_path = os.path.realpath(os.getcwd())
+        work_lease = {
+            "operation_type": "author_issue_work",
+            "issue_number": issue_number,
+            "branch": branch,
+            "claimant": {"username": "test-user", "profile": "test-author"},
+            "expires_at": "2999-01-01T00:00:00Z",
+        }
+        issue_lock_store.bind_session_lock({
+            "issue_number": issue_number,
+            "branch_name": branch,
+            "remote": "prgs",
+            "org": "Example-Org",
+            "repo": "Example-Repo",
+            "worktree_path": worktree_path,
+            "work_lease": work_lease,
+            "lock_provenance": issue_lock_provenance.build_sanctioned_lock_provenance(
+                tool="gitea_lock_issue",
+                claimant=work_lease.get("claimant"),
+            ),
+        })
 
     @patch("mcp_server._assess_issue_duplicate_gate")
     @patch("mcp_server.get_profile", return_value={
@@ -241,6 +261,7 @@ class TestMcpDuplicateRecheck(unittest.TestCase):
                 base="master",
                 body="Closes #400",
                 remote="prgs",
+                worktree_path=os.path.realpath(os.getcwd()),
             )
         self.assertFalse(result["success"])
         self.assertIsNone(result.get("number"))

tests/test_mcp_server.py

@@ -81,6 +81,64 @@ def _visible_approval_reviews(reviewer="reviewer-bot", sha="abc123"):
     return [_formal_review(reviewer, "APPROVED", sha=sha)]
 
 
+_DEFAULT_LEASE_SESSION = "mcp-test-reviewer-lease"
+
+
+def _reviewer_lease_comment(
+    pr_number,
+    *,
+    session_id=_DEFAULT_LEASE_SESSION,
+    head_sha="abc123",
+    reviewer="reviewer-bot",
+):
+    from datetime import datetime, timezone
+
+    import reviewer_pr_lease
+
+    body = reviewer_pr_lease.format_lease_body(
+        repo="Scaled-Tech-Consulting/Gitea-Tools",
+        pr_number=pr_number,
+        issue_number=407,
+        reviewer_identity=reviewer,
+        profile="gitea-reviewer",
+        session_id=session_id,
+        worktree="branches/review-test",
+        phase="claimed",
+        candidate_head=head_sha,
+        target_branch="master",
+        target_branch_sha="b" * 40,
+        last_activity=datetime.now(timezone.utc),
+    )
+    return {"id": 9001, "body": body, "user": {"login": reviewer}}
+
+
+def _install_owned_reviewer_lease(
+    pr_number,
+    *,
+    session_id=_DEFAULT_LEASE_SESSION,
+    head_sha="abc123",
+):
+    import reviewer_pr_lease
+
+    reviewer_pr_lease.clear_session_lease()
+    reviewer_pr_lease.record_session_lease({
+        "pr_number": pr_number,
+        "session_id": session_id,
+        "candidate_head": head_sha,
+        "target_branch": "master",
+    })
+    return patch(
+        "mcp_server._fetch_pr_comments",
+        return_value=[
+            _reviewer_lease_comment(
+                pr_number,
+                session_id=session_id,
+                head_sha=head_sha,
+            )
+        ],
+    )
+
+
 # Issue-write tools are profile-gated (#69).
 ISSUE_WRITE_ENV = {
     "GITEA_ALLOWED_OPERATIONS": (
@@ -568,6 +626,19 @@ class TestViewPR(unittest.TestCase):
 class TestMergePR(unittest.TestCase):
     """Gated merge workflow (#16). gitea_merge_pr is the only merge path."""
 
+    def setUp(self):
+        import reviewer_pr_lease
+
+        self._lease_patch = _install_owned_reviewer_lease(8)
+        self._lease_patch.start()
+        self._auth_identity_patch = patch(
+            "mcp_server._authenticated_username", return_value="reviewer-bot"
+        )
+        self._auth_identity_patch.start()
+        self.addCleanup(self._auth_identity_patch.stop)
+        self.addCleanup(self._lease_patch.stop)
+        self.addCleanup(reviewer_pr_lease.clear_session_lease)
+
     def _pr(self, author, state="open", sha="abc123", mergeable=True):
         return {
             "user": {"login": author},
@@ -828,9 +899,11 @@ class TestMergePR(unittest.TestCase):
                 pr_number=8, confirmation=self._confirm(8),
                 expected_head_sha="deadbeef", remote="prgs")
         self.assertFalse(r["performed"])
-        self.assertIn(
-            "expected head SHA does not match current PR head (fail closed)",
-            r["reasons"])
+        self.assertTrue(any(
+            "expected head SHA does not match current PR head (fail closed)" in reason
+            or "PR head changed during lease" in reason
+            for reason in r["reasons"]
+        ))
         self._assert_no_merge_call(mock_api)
 
     @patch("mcp_server.api_request")
@@ -1709,7 +1782,20 @@ class TestReviewDecisionValidationGate(unittest.TestCase):
         }
 
     def setUp(self):
+        import reviewer_pr_lease
+
         init_review_decision_lock("prgs", "review_pr")
+        self._lease_patch = _install_owned_reviewer_lease(
+            self.PR, head_sha=self.SHA,
+        )
+        self._lease_patch.start()
+        self._auth_identity_patch = patch(
+            "mcp_server._authenticated_username", return_value="reviewer-bot"
+        )
+        self._auth_identity_patch.start()
+        self.addCleanup(self._auth_identity_patch.stop)
+        self.addCleanup(self._lease_patch.stop)
+        self.addCleanup(reviewer_pr_lease.clear_session_lease)
 
     def _env(self):
         return patch.dict(os.environ, {
@@ -1804,8 +1890,19 @@ class TestSubmitPrReview(unittest.TestCase):
     """Gated review-mutation tool (#15)."""
 
     def setUp(self):
+        import reviewer_pr_lease
+
         init_review_decision_lock("prgs", "review_pr")
         gitea_mark_final_review_decision(8, "approve", remote="prgs")
+        self._lease_patch = _install_owned_reviewer_lease(8)
+        self._lease_patch.start()
+        self._auth_identity_patch = patch(
+            "mcp_server._authenticated_username", return_value="reviewer-bot"
+        )
+        self._auth_identity_patch.start()
+        self.addCleanup(self._auth_identity_patch.stop)
+        self.addCleanup(self._lease_patch.stop)
+        self.addCleanup(reviewer_pr_lease.clear_session_lease)
 
     def _pr(self, author, state="open", sha="abc123", mergeable=True):
         return {
@@ -2043,9 +2140,11 @@ class TestSubmitPrReview(unittest.TestCase):
                     final_review_decision_ready=True,
                 )
             self.assertFalse(r["performed"])
-            self.assertIn(
-                "expected head SHA does not match current PR head (fail closed)",
-                r["reasons"])
+            self.assertTrue(any(
+                "expected head SHA does not match current PR head (fail closed)" in reason
+                or "PR head changed during lease" in reason
+                for reason in r["reasons"]
+            ))
             self._assert_no_mutation(mock_api)
 
     def test_head_sha_match_allows(self):
@@ -2108,9 +2207,9 @@ class TestSubmitPrReview(unittest.TestCase):
         env = {"GITEA_PROFILE_NAME": "gitea-reviewer",
                "GITEA_ALLOWED_OPERATIONS": "read,review,approve"}
         with patch.dict(os.environ, env, clear=True):
-            gitea_mark_final_review_decision(5, "approve", remote="prgs")
+            gitea_mark_final_review_decision(8, "approve", remote="prgs")
             r = gitea_submit_pr_review(
-                pr_number=5, action="approve", remote="prgs",
+                pr_number=8, action="approve", remote="prgs",
                 final_review_decision_ready=True,
             )
         self.assertFalse(r["performed"])
@@ -2329,6 +2428,13 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
         self.assertEqual(res["cleanup_status"].get(1), "not present")
 
     def test_merge_pr_with_closes_removes_label(self):
+        import reviewer_pr_lease
+
+        lease_patch = _install_owned_reviewer_lease(1, head_sha="sha123")
+        lease_patch.start()
+        self.addCleanup(lease_patch.stop)
+        self.addCleanup(reviewer_pr_lease.clear_session_lease)
+
         def api_side_effect(method, url, auth, payload=None):
             if method == "GET" and "/user" in url:
                 return {"login": "merger"}
@@ -2363,6 +2469,13 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
         self.assertEqual(res["cleanup_status"].get(123), "released")
 
     def test_merge_pr_with_branch_name_removes_label(self):
+        import reviewer_pr_lease
+
+        lease_patch = _install_owned_reviewer_lease(1, head_sha="sha123")
+        lease_patch.start()
+        self.addCleanup(lease_patch.stop)
+        self.addCleanup(reviewer_pr_lease.clear_session_lease)
+
         def api_side_effect(method, url, auth, payload=None):
             if method == "GET" and "/user" in url:
                 return {"login": "merger"}
@@ -3044,10 +3157,12 @@ class TestVerifyMutationAuthority(unittest.TestCase):
         # profile; the active profile resolves as reviewer — side-channel
         # override rejected even with a matching in-process authority.
         self._authority()
-        with patch.dict(os.environ,
-                        {"GITEA_SESSION_PROFILE_LOCK": "prgs-author"}):
-            with self.assertRaises(RuntimeError) as ctx:
-                mcp_server.verify_mutation_authority("prgs")
+        with patch("mcp_server.gitea_config.is_runtime_switching_enabled",
+                   return_value=False):
+            with patch.dict(os.environ,
+                            {"GITEA_SESSION_PROFILE_LOCK": "prgs-author"}):
+                with self.assertRaises(RuntimeError) as ctx:
+                    mcp_server.verify_mutation_authority("prgs")
         self.assertIn("side-channel override rejected", str(ctx.exception))
 
     def test_foreign_pid_authority_is_not_trusted(self):
@@ -3146,7 +3261,7 @@ class TestIssueLocking(unittest.TestCase):
     def test_lock_issue_mismatch_branch_fails(self):
         with self.assertRaises(ValueError) as ctx:
             gitea_lock_issue(issue_number=196, branch_name="feat/issue-195-mutations", remote="prgs")
-        self.assertIn("must match", str(ctx.exception))
+        self.assertIn("must contain locked issue pattern", str(ctx.exception))
 
     @patch(
         "mcp_server.issue_lock_worktree.read_worktree_git_state",
@@ -3203,6 +3318,7 @@ class TestIssueLocking(unittest.TestCase):
     @patch("mcp_server.get_auth_header", return_value=FAKE_AUTH)
     def test_lock_issue_adopts_exact_own_branch(self, _auth, mock_api, _git_state):
         branch = "feat/issue-196-mutations"
+        self.mock_dup_fetcher.return_value = ([], [branch], {"status": "not_claimed"})
         mock_api.return_value = [{"name": branch, "commit": {"id": "abc123"}}]
         res = gitea_lock_issue(issue_number=196, branch_name=branch, remote="prgs")
         self.assertTrue(res["success"])
@@ -3430,16 +3546,17 @@ class TestIssueLocking(unittest.TestCase):
     @patch("mcp_server.get_auth_header", return_value=FAKE_AUTH)
     def test_create_pr_manual_lock_seed_blocked(self, _auth, _role):
         worktree = os.path.realpath(os.getcwd())
-        env = self._create_pr_env()
-        with patch.dict(os.environ, env, clear=True):
-            issue_lock_store.save_lock_file(
-                issue_lock_store.lock_file_path(
-                    remote="prgs",
-                    org="Scaled-Tech-Consulting",
-                    repo=mcp_server.REMOTES["prgs"]["repo"],
-                    issue_number=447,
-                    lock_dir=self._lock_dir.name,
-                ),
+        with tempfile.TemporaryDirectory() as lock_dir:
+            env = {**self._create_pr_env(), "GITEA_ISSUE_LOCK_DIR": lock_dir}
+            with patch.dict(os.environ, env, clear=True):
+                issue_lock_store.save_lock_file(
+                    issue_lock_store.lock_file_path(
+                        remote="prgs",
+                        org="Scaled-Tech-Consulting",
+                        repo=mcp_server.REMOTES["prgs"]["repo"],
+                        issue_number=447,
+                        lock_dir=lock_dir,
+                    ),
                 _sample_issue_lock(
                     issue_number=447,
                     branch_name="feat/issue-447-lock-provenance",
@@ -3449,14 +3566,14 @@ class TestIssueLocking(unittest.TestCase):
                     worktree_path=worktree,
                     lock_provenance=None,
                 ),
-            )
-            with self.assertRaises(RuntimeError) as ctx:
-                gitea_create_pr(
-                    title="feat: lock provenance Closes #447",
-                    head="feat/issue-447-lock-provenance",
-                    remote="prgs",
-                    worktree_path=worktree,
                 )
+                with self.assertRaises(RuntimeError) as ctx:
+                    gitea_create_pr(
+                        title="feat: lock provenance Closes #447",
+                        head="feat/issue-447-lock-provenance",
+                        remote="prgs",
+                        worktree_path=worktree,
+                    )
         self.assertIn("lock provenance", str(ctx.exception).lower())
 
     @patch("mcp_server.api_request")

tests/test_pr_queue_inventory.py

@@ -156,9 +156,22 @@ class TestPRQueueInventory(unittest.TestCase):
         ]
 
         from mcp_server import init_review_decision_lock, gitea_mark_final_review_decision
-        init_review_decision_lock("prgs", "review_pr")
-        gitea_mark_final_review_decision(1, "approve", remote="prgs")
-        result = gitea_review_pr(pr_number=1, event="APPROVE", remote="prgs", final_review_decision_ready=True)
+        from tests.test_mcp_server import _install_owned_reviewer_lease
+        import reviewer_pr_lease
+
+        with patch("mcp_server._authenticated_username", return_value="reviewer1"):
+            init_review_decision_lock("prgs", "review_pr")
+            gitea_mark_final_review_decision(1, "approve", remote="prgs")
+            lease_patch = _install_owned_reviewer_lease(
+                1, head_sha="abc1", session_id="inventory-review-lease",
+            )
+            lease_patch.start()
+            self.addCleanup(lease_patch.stop)
+            self.addCleanup(reviewer_pr_lease.clear_session_lease)
+            result = gitea_review_pr(
+                pr_number=1, event="APPROVE", remote="prgs",
+                final_review_decision_ready=True,
+            )
         self.assertTrue(result["success"])
         self.assertIn("=== PR Queue Inventory ===", result["message"])
         self.assertIn("Repository:", result["message"])

tests/test_reviewer_pr_lease.py

@@ -0,0 +1,193 @@
+"""Tests for per-PR reviewer leases (#407)."""
+
+import sys
+import unittest
+from datetime import datetime, timedelta, timezone
+from unittest.mock import patch
+
+sys.path.insert(0, str(__import__("pathlib").Path(__file__).resolve().parent.parent))
+
+import reviewer_pr_lease as leases
+
+
+def _lease_comment(
+    pr_number: int,
+    session_id: str,
+    *,
+    phase: str = "claimed",
+    minutes_ago: int = 0,
+    candidate_head: str = "a" * 40,
+) -> dict:
+    now = datetime.now(timezone.utc) - timedelta(minutes=minutes_ago)
+    body = leases.format_lease_body(
+        repo="Scaled-Tech-Consulting/Gitea-Tools",
+        pr_number=pr_number,
+        issue_number=295,
+        reviewer_identity="rev1",
+        profile="prgs-reviewer",
+        session_id=session_id,
+        worktree="branches/review-pr382",
+        phase=phase,
+        candidate_head=candidate_head,
+        target_branch="master",
+        target_branch_sha="b" * 40,
+        last_activity=now,
+    )
+    return {"id": 1, "body": body, "user": {"login": "rev1"}}
+
+
+class TestReviewerLeaseAcquire(unittest.TestCase):
+    def setUp(self):
+        leases.clear_session_lease()
+
+    def test_two_reviewers_cannot_lease_same_pr(self):
+        comments = [_lease_comment(382, "session-a")]
+        result = leases.assess_acquire_lease(
+            comments,
+            pr_number=382,
+            reviewer_identity="rev2",
+            profile="prgs-reviewer",
+            session_id="session-b",
+            repo="Scaled-Tech-Consulting/Gitea-Tools",
+            issue_number=295,
+            worktree="branches/review-pr382-b",
+            candidate_head="c" * 40,
+            target_branch="master",
+            target_branch_sha="d" * 40,
+        )
+        self.assertFalse(result["acquire_allowed"])
+        self.assertTrue(any("already has active" in r for r in result["reasons"]))
+
+    def test_two_reviewers_can_lease_different_prs(self):
+        comments = [_lease_comment(382, "session-a")]
+        result = leases.assess_acquire_lease(
+            comments,
+            pr_number=383,
+            reviewer_identity="rev2",
+            profile="prgs-reviewer",
+            session_id="session-b",
+            repo="Scaled-Tech-Consulting/Gitea-Tools",
+            issue_number=296,
+            worktree="branches/review-pr383",
+            candidate_head="c" * 40,
+            target_branch="master",
+            target_branch_sha="d" * 40,
+        )
+        self.assertTrue(result["acquire_allowed"])
+        self.assertIsNotNone(result["lease_body"])
+
+
+class TestReviewerLeaseFreshness(unittest.TestCase):
+    def test_stale_warning_after_30_minutes(self):
+        lease = leases.parse_lease_comment(
+            _lease_comment(382, "session-a", minutes_ago=35)["body"]
+        )
+        self.assertEqual(
+            leases.classify_lease_freshness(lease),
+            "stale_warning",
+        )
+
+    def test_reclaimable_after_60_minutes(self):
+        lease = leases.parse_lease_comment(
+            _lease_comment(382, "session-a", minutes_ago=65)["body"]
+        )
+        self.assertEqual(
+            leases.classify_lease_freshness(lease),
+            "reclaimable",
+        )
+
+
+class TestReviewerLeaseMutationGate(unittest.TestCase):
+    def setUp(self):
+        leases.clear_session_lease()
+
+    def test_reviewer_without_lease_cannot_mutate(self):
+        head = "f" * 40
+        comments = [_lease_comment(382, "other-session", candidate_head=head)]
+        result = leases.assess_mutation_lease_gate(
+            pr_number=382,
+            comments=comments,
+            reviewer_identity="rev1",
+            session_id="my-session",
+            mutation="approve",
+            live_head_sha=head,
+            pinned_head_sha=head,
+        )
+        self.assertTrue(result["block"])
+
+    def test_owned_lease_allows_mutation(self):
+        head = "f" * 40
+        comments = [_lease_comment(382, "my-session", candidate_head=head)]
+        leases.record_session_lease({
+            "pr_number": 382,
+            "session_id": "my-session",
+            "candidate_head": head,
+            "target_branch": "master",
+        })
+        result = leases.assess_mutation_lease_gate(
+            pr_number=382,
+            comments=comments,
+            reviewer_identity="rev1",
+            session_id="my-session",
+            mutation="approve",
+            live_head_sha=head,
+            pinned_head_sha=head,
+        )
+        self.assertFalse(result["block"])
+
+    def test_head_change_invalidates_lease(self):
+        reviewed = "f" * 40
+        live = "e" * 40
+        comments = [_lease_comment(382, "my-session", candidate_head=reviewed)]
+        leases.record_session_lease({
+            "pr_number": 382,
+            "session_id": "my-session",
+            "candidate_head": reviewed,
+        })
+        result = leases.assess_mutation_lease_gate(
+            pr_number=382,
+            comments=comments,
+            reviewer_identity="rev1",
+            session_id="my-session",
+            mutation="merge",
+            live_head_sha=live,
+            pinned_head_sha=reviewed,
+        )
+        self.assertTrue(result["block"])
+        self.assertTrue(any("head" in r.lower() for r in result["reasons"]))
+
+
+class TestReviewerLeaseMcpGate(unittest.TestCase):
+    def setUp(self):
+        leases.clear_session_lease()
+        patch("mcp_server.verify_preflight_purity").start()
+        patch("gitea_audit.audit_enabled", return_value=False).start()
+        mcp_server = __import__("mcp_server")
+        mcp_server._IDENTITY_CACHE.clear()
+        mcp_server.init_review_decision_lock("prgs", "review_pr")
+        mcp_server.record_preflight_check("whoami")
+        mcp_server.record_preflight_check("capability", "reviewer")
+
+    def tearDown(self):
+        patch.stopall()
+        leases.clear_session_lease()
+
+    def test_reviewer_pr_lease_gate_helper_blocks_without_session(self):
+        import mcp_server
+        head = "a" * 40
+        with patch("mcp_server._fetch_pr_comments", return_value=[]):
+            reasons = mcp_server._reviewer_pr_lease_gate(
+                pr_number=382,
+                remote="prgs",
+                host=None,
+                org=None,
+                repo=None,
+                mutation="approve",
+                live_head_sha=head,
+                pinned_head_sha=head,
+            )
+        self.assertTrue(any("lease" in r.lower() for r in reasons))
+
+
+if __name__ == "__main__":
+    unittest.main()