feat: add conflict-fix leases and stale-head protection (Closes #399)

Introduce structured PR work leases so author conflict-fix pushes cannot
race reviewer validation, approval, or merge on a moving head SHA.

- pr_work_lease.py: parse/acquire leases, push and reviewer mutation gates
- gitea_acquire_conflict_fix_lease, gitea_assess_conflict_fix_push MCP tools
- Enforce reviewed head SHA on mark_final_review_decision, submit_pr_review, merge_pr
- Final-report rules and workflow sections 20A / 26B
- tests/test_pr_work_lease.py (14 cases)

author_duplicate_work_gate.py

@@ -1,198 +0,0 @@
-"""Early duplicate-work detection for author work-issue flows (#400)."""
-
-from __future__ import annotations
-
-import re
-from typing import Any
-
-from issue_claim_heartbeat import (
-    _linked_open_pr,
-    _matching_branch_names,
-    classify_issue_claim,
-)
-
-STAGES = (
-    "claim",
-    "lock",
-    "worktree",
-    "edit",
-    "commit",
-    "push",
-    "create_pr",
-)
-
-ELIGIBILITY_OPEN_PR_EXISTS = "OPEN_PR_EXISTS"
-ELIGIBILITY_DUPLICATE_BRANCH_EXISTS = "DUPLICATE_BRANCH_EXISTS"
-ELIGIBILITY_ACTIVE_CLAIM = "ACTIVE_CLAIM_BY_OTHER"
-ELIGIBILITY_CLEAR = "CLEAR"
-
-
-def assess_author_duplicate_work(
-    issue_number: int,
-    *,
-    stage: str,
-    open_prs: list[dict] | None = None,
-    branch_names: list[str] | None = None,
-    claim_entry: dict | None = None,
-    matching_branches: list[str] | None = None,
-    allow_stale_takeover: bool = False,
-) -> dict[str, Any]:
-    """Fail closed when duplicate work is detected before author mutations (#400)."""
-    stage_norm = (stage or "").strip().lower()
-    if stage_norm not in STAGES:
-        return {
-            "allowed": False,
-            "block": True,
-            "eligibility_class": "INVALID_STAGE",
-            "stage": stage_norm or None,
-            "reasons": [f"unknown duplicate-work stage {stage!r}"],
-            "safe_next_action": f"use one of: {', '.join(STAGES)}",
-        }
-
-    prs = list(open_prs or [])
-    linked_pr = _linked_open_pr(int(issue_number), prs)
-    branches = list(
-        matching_branches
-        if matching_branches is not None
-        else _matching_branch_names(int(issue_number), list(branch_names or []))
-    )
-
-    reasons: list[str] = []
-    eligibility = ELIGIBILITY_CLEAR
-
-    if linked_pr:
-        eligibility = ELIGIBILITY_OPEN_PR_EXISTS
-        reasons.append(
-            f"open PR #{linked_pr.get('number')} already covers issue "
-            f"#{issue_number}"
-        )
-
-    if branches and stage_norm in {"claim", "lock", "worktree", "edit"}:
-        if eligibility == ELIGIBILITY_CLEAR:
-            eligibility = ELIGIBILITY_DUPLICATE_BRANCH_EXISTS
-        reasons.append(
-            f"remote branch(es) already exist for issue #{issue_number}: "
-            f"{', '.join(branches)}"
-        )
-
-    entry = claim_entry or {}
-    claim_status = (entry.get("status") or "").strip()
-    if claim_status in {"active", "awaiting_review"} and stage_norm == "claim":
-        if entry.get("reclaimable") and allow_stale_takeover:
-            pass
-        elif claim_status == "active" and not entry.get("reclaimable"):
-            if eligibility == ELIGIBILITY_CLEAR:
-                eligibility = ELIGIBILITY_ACTIVE_CLAIM
-            reasons.append(
-                f"issue #{issue_number} has active claim "
-                f"(status={claim_status})"
-            )
-    elif claim_status == "awaiting_review" and stage_norm == "claim":
-        if not linked_pr:
-            reasons.append(
-                f"issue #{issue_number} is awaiting_review but no linked open PR "
-                "was supplied for duplicate-work proof"
-            )
-
-    allowed = not reasons
-    outcome = "duplicate_work_prevented" if not allowed else "clear"
-    if stage_norm == "create_pr" and not allowed:
-        outcome = "duplicate_pr_prevented"
-    elif stage_norm in {"commit", "push"} and not allowed:
-        outcome = "duplicate_push_prevented" if stage_norm == "push" else "duplicate_commit_prevented"
-
-    return {
-        "allowed": allowed,
-        "block": not allowed,
-        "eligibility_class": eligibility if not allowed else ELIGIBILITY_CLEAR,
-        "stage": stage_norm,
-        "linked_open_pr": linked_pr.get("number") if linked_pr else None,
-        "matching_branches": branches,
-        "claim_status": claim_status or None,
-        "outcome": outcome,
-        "reasons": reasons,
-        "safe_next_action": (
-            "stop without edits/commit/push/PR; produce reconciliation handoff "
-            "preserving local work only"
-            if not allowed
-            else "proceed"
-        ),
-    }
-
-
-def build_claim_entry_from_classification(classification: dict) -> dict:
-    """Map ``classify_issue_claim`` output to gate claim metadata."""
-    return {
-        "status": classification.get("status"),
-        "reclaimable": classification.get("reclaimable"),
-        "linked_open_pr": classification.get("linked_open_pr"),
-    }
-
-
-_DUPLICATE_OUTCOME_RE = re.compile(
-    r"(duplicate\s+(?:pr|branch|commit|push)\s+prevented|"
-    r"duplicate\s+work\s+not\s+prevented|reconciliation\s+handoff)",
-    re.IGNORECASE,
-)
-
-
-def assess_work_issue_duplicate_prevention_report(report_text: str) -> dict:
-    """#400: work-issue reports must state duplicate-work prevention outcome."""
-    text = report_text or ""
-    if "duplicate work" not in text.lower() and "duplicate pr" not in text.lower():
-        return {
-            "proven": True,
-            "block": False,
-            "reasons": [],
-            "safe_next_action": "proceed",
-        }
-    if _DUPLICATE_OUTCOME_RE.search(text):
-        return {
-            "proven": True,
-            "block": False,
-            "reasons": [],
-            "safe_next_action": "proceed",
-        }
-    return {
-        "proven": False,
-        "block": True,
-        "reasons": [
-            "duplicate-work discussion must name a prevention outcome "
-            "(duplicate PR/branch/commit/push prevented, or duplicate work "
-            "not prevented, or reconciliation handoff)"
-        ],
-        "safe_next_action": "state exact duplicate-work prevention class in final report",
-    }
-
-
-def classify_and_assess(
-    issue: dict,
-    *,
-    stage: str,
-    comments: list[dict] | None = None,
-    open_prs: list[dict] | None = None,
-    branch_names: list[str] | None = None,
-    allow_stale_takeover: bool = False,
-) -> dict[str, Any]:
-    """Combine claim classification with duplicate-work gate assessment."""
-    issue_number = int(issue.get("number") or 0)
-    claim = classify_issue_claim(
-        issue=issue,
-        comments=comments or [],
-        open_prs=open_prs or [],
-        branch_names=branch_names or [],
-    )
-    assessment = assess_author_duplicate_work(
-        issue_number,
-        stage=stage,
-        open_prs=open_prs,
-        branch_names=branch_names,
-        claim_entry=build_claim_entry_from_classification(claim),
-        matching_branches=claim.get("matching_branches"),
-        allow_stale_takeover=allow_stale_takeover,
-    )
-    return {
-        "issue_number": issue_number,
-        "claim": claim,
-        "duplicate_work": assessment,
-    }

final_report_validator.py

@@ -490,6 +490,45 @@ def _rule_reviewer_validation_failure_history(
     ]
 
 
+def _rule_reviewer_stale_head_proof(report_text: str) -> list[dict[str, str]]:
+    from pr_work_lease import assess_reviewer_stale_head_final_report
+
+    result = assess_reviewer_stale_head_final_report(report_text)
+    if result.get("proven"):
+        return []
+    return _findings_from_reasons(
+        "reviewer.stale_head_proof",
+        result.get("reasons") or [],
+        field="Stale-head proof",
+        severity="block",
+        safe_next_action=(
+            "state reviewed head SHA, live head before approval/merge, and "
+            "whether any push occurred during validation"
+        ),
+    )
+
+
+def _rule_conflict_fix_push_proof(report_text: str) -> list[dict[str, str]]:
+    from pr_work_lease import assess_conflict_fix_final_report
+
+    text = report_text or ""
+    if "conflict-fix" not in text.lower() and "conflict fix" not in text.lower():
+        return []
+    result = assess_conflict_fix_final_report(text)
+    if result.get("proven"):
+        return []
+    return _findings_from_reasons(
+        "author.conflict_fix_push_proof",
+        result.get("reasons") or [],
+        field="Conflict-fix push proof",
+        severity="block",
+        safe_next_action=(
+            "state branch head before/after push, reviewer lease status, "
+            "fast-forward status, and whether any reviewer was active"
+        ),
+    )
+
+
 def _rule_reviewer_validation_command(report_text: str) -> list[dict[str, str]]:
     text = report_text or ""
     if not _BARE_PYTEST_RE.search(text):
@@ -909,6 +948,7 @@ _RULES_BY_TASK: dict[str, list[Callable[..., list[dict[str, str]]]]] = {
         _rule_reviewer_target_branch_freshness,
         _rule_reviewer_mutation_ledger,
         _rule_reviewer_review_mutation,
+        _rule_reviewer_stale_head_proof,
     ],
     "reconcile_already_landed": [
         _rule_reconcile_controller_handoff,
@@ -930,6 +970,7 @@ _RULES_BY_TASK: dict[str, list[Callable[..., list[dict[str, str]]]]] = {
         _rule_shared_controller_handoff,
         _rule_shared_email_disclosure,
         _rule_reviewer_vague_mutations_none,
+        _rule_conflict_fix_push_proof,
     ],
     "issue_filing": [
         _rule_shared_controller_handoff,

gitea_mcp_server.py

@@ -503,11 +503,11 @@ import issue_lock_worktree  # noqa: E402
 import already_landed_reconcile  # noqa: E402
 import author_mutation_worktree  # noqa: E402
 import issue_claim_heartbeat  # noqa: E402
-import author_duplicate_work_gate  # noqa: E402
 import merged_cleanup_reconcile  # noqa: E402
 import reconciler_profile  # noqa: E402
 import reconciliation_workflow  # noqa: E402
 import review_merge_state_machine  # noqa: E402
+import pr_work_lease  # noqa: E402
 import native_mcp_preference  # noqa: E402
 
 
@@ -1050,76 +1050,6 @@ def gitea_create_issue(
     return _with_optional_url({"number": data["number"]}, data.get("html_url"))
 
 
-def _list_repo_branch_names(h: str, o: str, r: str, auth: str, *, limit: int = 200) -> list[str]:
-    branches = api_get_all(f"{repo_api_url(h, o, r)}/branches", auth, limit=limit)
-    return [_branch_entry_name(branch) for branch in branches]
-
-
-def _gather_author_duplicate_work_context(
-    issue_number: int,
-    *,
-    h: str,
-    o: str,
-    r: str,
-    auth: str,
-    exclude_branch_name: str | None = None,
-) -> dict:
-    base = repo_api_url(h, o, r)
-    issue = api_request("GET", f"{base}/issues/{issue_number}", auth)
-    comments = api_request("GET", f"{base}/issues/{issue_number}/comments", auth) or []
-    open_prs = api_get_all(f"{base}/pulls?state=open", auth)
-    branch_names = _list_repo_branch_names(h, o, r, auth)
-    if exclude_branch_name:
-        branch_names = [
-            name for name in branch_names
-            if name != exclude_branch_name
-        ]
-    return {
-        "issue": issue,
-        "comments": comments,
-        "open_prs": open_prs,
-        "branch_names": branch_names,
-    }
-
-
-def _enforce_author_duplicate_work_gate(
-    issue_number: int,
-    stage: str,
-    *,
-    h: str,
-    o: str,
-    r: str,
-    auth: str,
-    allow_stale_takeover: bool = False,
-    exclude_branch_name: str | None = None,
-) -> dict:
-    """Fail closed when duplicate work is detected (#400)."""
-    ctx = _gather_author_duplicate_work_context(
-        issue_number,
-        h=h,
-        o=o,
-        r=r,
-        auth=auth,
-        exclude_branch_name=exclude_branch_name,
-    )
-    result = author_duplicate_work_gate.classify_and_assess(
-        ctx["issue"],
-        stage=stage,
-        comments=ctx["comments"],
-        open_prs=ctx["open_prs"],
-        branch_names=ctx["branch_names"],
-        allow_stale_takeover=allow_stale_takeover,
-    )
-    assessment = result.get("duplicate_work") or {}
-    if assessment.get("block"):
-        reasons = "; ".join(assessment.get("reasons") or ["duplicate work detected"])
-        raise RuntimeError(
-            f"Author duplicate-work gate (#400) blocked at stage '{stage}': "
-            f"{reasons} (fail closed)"
-        )
-    return result
-
-
 @mcp.tool()
 def gitea_lock_issue(
     issue_number: int,
@@ -1182,17 +1112,48 @@ def gitea_lock_issue(
             issue_lock_worktree.format_issue_lock_worktree_error(lock_assessment)
         )
 
+    # 2. Check if the issue already has an open PR (reuse protection)
     h, o, r = _resolve(remote, host, org, repo)
     auth = _auth(h)
-    _enforce_author_duplicate_work_gate(
+    url = f"{repo_api_url(h, o, r)}/pulls?state=open"
-        issue_number,
+
-        "lock",
+    try:
-        h=h,
+        prs = api_get_all(url, auth)
-        o=o,
+    except Exception as e:
-        r=r,
+        raise RuntimeError(f"Could not list open PRs to verify issue lock: {e}")
-        auth=auth,
+
-        exclude_branch_name=branch_name,
+    for pr in prs:
-    )
+        pr_head = pr.get("head", {}).get("ref", "")
+        pr_title = pr.get("title", "")
+        pr_body = pr.get("body", "")
+
+        if expected_pattern in pr_head:
+            raise ValueError(
+                f"Issue #{issue_number} is already tied to an open PR (PR #{pr.get('number')}, branch '{pr_head}') (fail closed)"
+            )
+
+        patterns = [
+            f"closes #{issue_number}",
+            f"fixes #{issue_number}",
+        ]
+        text_to_check = f"{pr_title} {pr_body}".lower()
+        if any(p in text_to_check for p in patterns):
+            raise ValueError(
+                f"Issue #{issue_number} is already tied to an open PR (PR #{pr.get('number')}) via Closes/Fixes reference (fail closed)"
+            )
+
+    branch_url = f"{repo_api_url(h, o, r)}/branches"
+    try:
+        branches = api_get_all(branch_url, auth)
+    except Exception as e:
+        raise RuntimeError(f"Could not list branches to verify issue lock: {e}")
+    for branch in branches:
+        name = _branch_entry_name(branch)
+        if expected_pattern in name:
+            raise ValueError(
+                f"Issue #{issue_number} already has matching branch '{name}' "
+                "(fail closed)"
+            )
 
     work_lease = _build_author_issue_work_lease(
         issue_number=issue_number,
@@ -1313,17 +1274,6 @@ def gitea_create_pr(
             f"PR head branch '{head}' does not match locked branch '{locked_branch}' (fail closed)"
         )
 
-    auth = _auth(h)
-    _enforce_author_duplicate_work_gate(
-        int(locked_issue),
-        "create_pr",
-        h=h,
-        o=o,
-        r=r,
-        auth=auth,
-        exclude_branch_name=locked_branch,
-    )
-
     # Check for forbidden terms anywhere in title/body
     forbidden_terms = ["equivalent", "related", "same as"]
     text_to_check = f"{title} {body}".lower()
@@ -1340,6 +1290,7 @@ def gitea_create_pr(
             f"PR title or body must contain 'Closes #{locked_issue}' or 'Fixes #{locked_issue}' exactly to ensure durable tracking (fail closed)"
         )
 
+    auth = _auth(h)
     url = f"{repo_api_url(h, o, r)}/pulls"
     payload = {"title": title, "body": body, "head": head, "base": base}
     meta = {"title": title, "head": head, "base": base}
@@ -2247,6 +2198,50 @@ def gitea_get_pr_review_feedback(
     }
 
 
+def _list_pr_lease_comments(
+    pr_number: int,
+    *,
+    remote: str,
+    host: str | None,
+    org: str | None,
+    repo: str | None,
+    limit: int = 100,
+) -> list[dict]:
+    """Fetch PR/issue thread comments used for reviewer/conflict-fix leases."""
+    h, o, r = _resolve(remote, host, org, repo)
+    auth = _auth(h)
+    api = f"{repo_api_url(h, o, r)}/issues/{pr_number}/comments"
+    comments = api_request("GET", api, auth) or []
+    return list(comments[:limit])
+
+
+def _pr_work_lease_reviewer_block(
+    *,
+    pr_number: int,
+    reviewed_head_sha: str | None,
+    live_head_sha: str | None,
+    mutation: str,
+    remote: str,
+    host: str | None,
+    org: str | None,
+    repo: str | None,
+) -> dict:
+    comments = _list_pr_lease_comments(
+        pr_number,
+        remote=remote,
+        host=host,
+        org=org,
+        repo=repo,
+    )
+    return pr_work_lease.assess_reviewer_mutation_blocked(
+        pr_number=pr_number,
+        comments=comments,
+        reviewed_head_sha=reviewed_head_sha,
+        live_head_sha=live_head_sha,
+        mutation=mutation,
+    )
+
+
 def _evaluate_pr_review_submission(
     pr_number: int,
     action: str,
@@ -2331,6 +2326,11 @@ def _evaluate_pr_review_submission(
     lock = _load_review_decision_lock() or {}
     if live and lock.get("ready_expected_head_sha"):
         pinned_sha = lock.get("ready_expected_head_sha")
+    if live and not pinned_sha:
+        reasons.append(
+            "reviewed head SHA required before live review mutation (fail closed, #399)"
+        )
+        return result
     if pinned_sha and actual_sha and pinned_sha != actual_sha:
         reasons.append(
             "expected head SHA does not match current PR head (fail closed)"
@@ -2340,6 +2340,21 @@ def _evaluate_pr_review_submission(
         reasons.append("PR head SHA unavailable (fail closed)")
         return result
 
+    lease_block = _pr_work_lease_reviewer_block(
+        pr_number=pr_number,
+        reviewed_head_sha=pinned_sha,
+        live_head_sha=actual_sha,
+        mutation=action,
+        remote=remote,
+        host=host,
+        org=org,
+        repo=repo,
+    )
+    if lease_block.get("block"):
+        reasons.extend(lease_block.get("reasons") or [])
+        result["pr_work_lease"] = lease_block
+        return result
+
     result["would_perform"] = True
     if not live:
         reasons.append(
@@ -2482,6 +2497,39 @@ def gitea_mark_final_review_decision(
                 f"{sorted(_REVIEW_ACTIONS)}"
             ],
         }
+    if not (expected_head_sha or "").strip():
+        return {
+            "marked_ready": False,
+            "reasons": [
+                "expected_head_sha required before marking final review "
+                "decision (fail closed, #399)"
+            ],
+        }
+    elig = gitea_check_pr_eligibility(
+        pr_number=pr_number,
+        action="review",
+        remote=remote,
+        host=None,
+        org=org,
+        repo=repo,
+    )
+    live_head = elig.get("head_sha")
+    lease_block = _pr_work_lease_reviewer_block(
+        pr_number=pr_number,
+        reviewed_head_sha=expected_head_sha,
+        live_head_sha=live_head,
+        mutation="mark_ready",
+        remote=remote,
+        host=None,
+        org=org,
+        repo=repo,
+    )
+    if lease_block.get("block"):
+        return {
+            "marked_ready": False,
+            "reasons": lease_block.get("reasons") or [],
+            "pr_work_lease": lease_block,
+        }
     if action == "request_changes":
         # Duplicate request-changes suppression (#332): an unresolved
         # REQUEST_CHANGES at the current head must not be duplicated.
@@ -3105,8 +3153,27 @@ def gitea_merge_pr(
             result["permission_report"] = elig["permission_report"]
         return result
 
-    # Gate 4 — head SHA must match if the caller pinned a reviewed SHA.
+    # Gate 4 — reviewed head SHA is mandatory and must match live PR head (#399).
     actual_sha = result["head_sha"]
+    if not (expected_head_sha or "").strip():
+        reasons.append(
+            "expected_head_sha required before merge (fail closed, #399)"
+        )
+        return result
+    lease_block = _pr_work_lease_reviewer_block(
+        pr_number=pr_number,
+        reviewed_head_sha=expected_head_sha,
+        live_head_sha=actual_sha,
+        mutation="merge",
+        remote=remote,
+        host=host,
+        org=org,
+        repo=repo,
+    )
+    if lease_block.get("block"):
+        reasons.extend(lease_block.get("reasons") or [])
+        result["pr_work_lease"] = lease_block
+        return result
     if expected_head_sha and actual_sha and expected_head_sha != actual_sha:
         reasons.append(
             "expected head SHA does not match current PR head (fail closed)"
@@ -6053,14 +6120,6 @@ def gitea_mark_issue(
         )
 
     if action == "start":
-        _enforce_author_duplicate_work_gate(
-            issue_number,
-            "claim",
-            h=h,
-            o=o,
-            r=r,
-            auth=auth,
-        )
         with _audited("label_issue", host=h, remote=remote, org=o, repo=r,
                       issue_number=issue_number,
                       request_metadata={"op": "add", "label": "status:in-progress"}):
@@ -6143,62 +6202,107 @@ def gitea_post_heartbeat(
 
 
 @mcp.tool()
-def gitea_assess_author_duplicate_work(
+def gitea_acquire_conflict_fix_lease(
-    issue_number: int,
+    pr_number: int,
-    stage: str,
+    branch: str,
+    worktree_path: str,
+    head_before: str,
     remote: str = "dadeschools",
     host: str | None = None,
     org: str | None = None,
     repo: str | None = None,
-    allow_stale_takeover: bool = False,
-    exclude_branch_name: str | None = None,
 ) -> dict:
-    """Read-only: assess duplicate-work risk before author mutations (#400).
+    """Acquire a conflict-fix lease on a PR branch before pushing (#399)."""
+    blocked = _profile_permission_block(
+        task_capability_map.required_permission("comment_issue"))
+    if blocked:
+        return blocked
+    verify_preflight_purity(remote, worktree_path=worktree_path)
+    comments = _list_pr_lease_comments(
+        pr_number,
+        remote=remote,
+        host=host,
+        org=org,
+        repo=repo,
+    )
+    reviewer_lease = pr_work_lease.find_active_reviewer_lease(
+        comments, pr_number=pr_number)
+    if reviewer_lease:
+        return {
+            "acquired": False,
+            "reasons": [
+                f"active reviewer lease on PR #{pr_number}; cannot acquire "
+                "conflict-fix lease (fail closed)"
+            ],
+            "active_reviewer_lease": reviewer_lease,
+        }
+    profile_name = get_profile().get("profile_name") or "unknown"
+    body = pr_work_lease.format_conflict_fix_lease_body(
+        pr_number=pr_number,
+        branch=branch,
+        worktree=worktree_path,
+        profile=profile_name,
+        head_before=head_before,
+        reviewer_active=bool(reviewer_lease),
+    )
+    posted = _post_structured_issue_comment(
+        issue_number=pr_number,
+        body=body,
+        remote=remote,
+        host=host,
+        org=org,
+        repo=repo,
+        audit_op="conflict_fix_lease_acquire",
+    )
+    return {
+        "acquired": posted.get("success", False),
+        "pr_number": pr_number,
+        "branch": branch,
+        "worktree_path": worktree_path,
+        "head_before": head_before,
+        "comment_id": posted.get("comment_id"),
+        "active_reviewer_lease": reviewer_lease,
+        "reasons": [] if posted.get("success") else ["lease comment post failed"],
+    }
 
-    Call at claim, lock, worktree, edit, commit, push, and create_pr stages.
+
-    """
+@mcp.tool()
+def gitea_assess_conflict_fix_push(
+    pr_number: int,
+    branch_head_before: str,
+    branch_head_after: str,
+    worktree_path: str,
+    push_cwd: str,
+    is_fast_forward: bool = True,
+    remote: str = "dadeschools",
+    host: str | None = None,
+    org: str | None = None,
+    repo: str | None = None,
+) -> dict:
+    """Read-only pre-push gate for author conflict-fix sessions (#399)."""
     read_block = _profile_operation_gate("gitea.read")
     if read_block:
         return {
-            "success": False,
+            "push_allowed": False,
             "reasons": read_block,
             "permission_report": _permission_block_report("gitea.read"),
         }
-    h, o, r = _resolve(remote, host, org, repo)
+    comments = _list_pr_lease_comments(
-    auth = _auth(h)
+        pr_number,
-    ctx = _gather_author_duplicate_work_context(
+        remote=remote,
-        issue_number,
+        host=host,
-        h=h,
+        org=org,
-        o=o,
+        repo=repo,
-        r=r,
-        auth=auth,
-        exclude_branch_name=exclude_branch_name,
     )
-    result = author_duplicate_work_gate.classify_and_assess(
+    return pr_work_lease.assess_conflict_fix_push(
-        ctx["issue"],
+        pr_number=pr_number,
-        stage=stage,
+        comments=comments,
-        comments=ctx["comments"],
+        branch_head_before=branch_head_before,
-        open_prs=ctx["open_prs"],
+        branch_head_after=branch_head_after,
-        branch_names=ctx["branch_names"],
+        worktree_path=worktree_path,
-        allow_stale_takeover=allow_stale_takeover,
+        push_cwd=push_cwd,
+        is_fast_forward=is_fast_forward,
     )
-    assessment = result.get("duplicate_work") or {}
-    return {
-        "success": True,
-        "performed": False,
-        "issue_number": issue_number,
-        "stage": stage,
-        "allowed": assessment.get("allowed"),
-        "block": assessment.get("block"),
-        "eligibility_class": assessment.get("eligibility_class"),
-        "outcome": assessment.get("outcome"),
-        "linked_open_pr": assessment.get("linked_open_pr"),
-        "matching_branches": assessment.get("matching_branches"),
-        "claim_status": assessment.get("claim_status"),
-        "reasons": assessment.get("reasons"),
-        "safe_next_action": assessment.get("safe_next_action"),
-        "claim": result.get("claim"),
-    }
 
 
 @mcp.tool()

pr_work_lease.py

@@ -0,0 +1,482 @@
+"""Conflict-fix and reviewer PR work leases (#399, #407 reader).
+
+Structured PR/issue comments prove exclusive phases so author conflict-fix
+pushes cannot race reviewer validation/approval/merge on the same head.
+"""
+
+from __future__ import annotations
+
+import re
+from datetime import datetime, timedelta, timezone
+from typing import Any
+
+REVIEWER_LEASE_MARKER = "<!-- mcp-review-lease:v1 -->"
+CONFLICT_FIX_LEASE_MARKER = "<!-- mcp-conflict-fix-lease:v1 -->"
+
+_FULL_SHA = re.compile(r"^[0-9a-f]{40}$", re.IGNORECASE)
+
+_FIELD_RE = re.compile(
+    r"^\s*([a-z_]+)\s*:\s*(.+?)\s*$",
+    re.IGNORECASE | re.MULTILINE,
+)
+
+_TERMINAL_REVIEWER_PHASES = frozenset({"done", "released", "blocked"})
+_ACTIVE_REVIEWER_PHASES = frozenset({
+    "claimed",
+    "validating",
+    "approved",
+    "request-changes",
+    "merging",
+})
+_TERMINAL_CONFLICT_FIX_PHASES = frozenset({"released", "blocked", "done"})
+_ACTIVE_CONFLICT_FIX_PHASES = frozenset({"claimed", "pushing", "pushed"})
+
+DEFAULT_CONFLICT_FIX_TTL_MINUTES = 120
+DEFAULT_REVIEWER_LEASE_TTL_MINUTES = 120
+
+
+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()
+    if not text:
+        return None
+    return text if _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 _parse_marker_comment(body: str, marker: str) -> dict[str, str] | 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()
+    return fields or None
+
+
+def parse_reviewer_lease_comment(body: str) -> dict[str, Any] | None:
+    fields = _parse_marker_comment(body, REVIEWER_LEASE_MARKER)
+    if not fields:
+        return None
+    return {
+        "lease_kind": "reviewer",
+        "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 parse_conflict_fix_lease_comment(body: str) -> dict[str, Any] | None:
+    fields = _parse_marker_comment(body, CONFLICT_FIX_LEASE_MARKER)
+    if not fields:
+        return None
+    ff = (fields.get("fast_forward") or "").strip().lower()
+    reviewer_active = (fields.get("reviewer_active") or "").strip().lower()
+    return {
+        "lease_kind": "conflict_fix",
+        "pr_number": _parse_pr_ref(fields.get("pr")),
+        "branch": fields.get("branch"),
+        "worktree": fields.get("worktree"),
+        "profile": fields.get("profile"),
+        "session_id": fields.get("session_id"),
+        "phase": (fields.get("phase") or "").strip().lower() or None,
+        "head_before": _normalize_sha(fields.get("head_before")),
+        "head_after": _normalize_sha(fields.get("head_after")),
+        "expires_at": fields.get("expires_at"),
+        "reviewer_active": reviewer_active in {"yes", "true", "1"},
+        "fast_forward": ff in {"yes", "true", "1"},
+        "raw_fields": fields,
+    }
+
+
+def _comment_entries(comments: list[dict], *, pr_number: int | None) -> list[dict]:
+    entries: list[dict] = []
+    for comment in comments or []:
+        body = comment.get("body") or ""
+        for parser in (parse_reviewer_lease_comment, parse_conflict_fix_lease_comment):
+            parsed = parser(body)
+            if not parsed:
+                continue
+            if pr_number is not None and 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"),
+            })
+            break
+    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 _lease_phase_active(lease: dict, *, active_phases: frozenset[str]) -> bool:
+    phase = (lease.get("phase") or "").strip().lower()
+    if phase in _TERMINAL_REVIEWER_PHASES or phase in _TERMINAL_CONFLICT_FIX_PHASES:
+        return False
+    return phase in active_phases or bool(phase and phase not in (
+        _TERMINAL_REVIEWER_PHASES | _TERMINAL_CONFLICT_FIX_PHASES
+    ))
+
+
+def find_active_reviewer_lease(
+    comments: list[dict],
+    *,
+    pr_number: int,
+    now: datetime | None = None,
+) -> dict[str, Any] | None:
+    """Return the newest unexpired reviewer lease for *pr_number*, if any."""
+    now = now or datetime.now(timezone.utc)
+    candidates = [
+        entry for entry in _comment_entries(comments, pr_number=pr_number)
+        if entry.get("lease_kind") == "reviewer"
+    ]
+    for lease in reversed(candidates):
+        if _lease_expired(lease, now=now):
+            continue
+        phase = (lease.get("phase") or "").strip().lower()
+        if phase in _TERMINAL_REVIEWER_PHASES:
+            continue
+        if phase in _ACTIVE_REVIEWER_PHASES or phase:
+            return lease
+    return None
+
+
+def find_active_conflict_fix_lease(
+    comments: list[dict],
+    *,
+    pr_number: int,
+    now: datetime | None = None,
+) -> dict[str, Any] | None:
+    """Return the newest unexpired conflict-fix lease for *pr_number*, if any."""
+    now = now or datetime.now(timezone.utc)
+    candidates = [
+        entry for entry in _comment_entries(comments, pr_number=pr_number)
+        if entry.get("lease_kind") == "conflict_fix"
+    ]
+    for lease in reversed(candidates):
+        if _lease_expired(lease, now=now):
+            continue
+        phase = (lease.get("phase") or "").strip().lower()
+        if phase in _TERMINAL_CONFLICT_FIX_PHASES:
+            continue
+        if phase in _ACTIVE_CONFLICT_FIX_PHASES or phase:
+            return lease
+    return None
+
+
+def format_conflict_fix_lease_body(
+    *,
+    pr_number: int,
+    branch: str,
+    worktree: str,
+    profile: str,
+    head_before: str,
+    phase: str = "claimed",
+    session_id: str = "unknown",
+    expires_at: datetime | None = None,
+    reviewer_active: bool = False,
+) -> str:
+    expires = expires_at or (
+        datetime.now(timezone.utc) + timedelta(minutes=DEFAULT_CONFLICT_FIX_TTL_MINUTES)
+    )
+    expires_text = expires.astimezone(timezone.utc).replace(microsecond=0).isoformat().replace(
+        "+00:00", "Z"
+    )
+    lines = [
+        CONFLICT_FIX_LEASE_MARKER,
+        f"pr: #{pr_number}",
+        f"branch: {branch}",
+        f"worktree: {worktree}",
+        f"profile: {profile}",
+        f"session_id: {session_id}",
+        f"phase: {phase}",
+        f"head_before: {head_before}",
+        f"expires_at: {expires_text}",
+        f"reviewer_active: {'yes' if reviewer_active else 'no'}",
+    ]
+    return "\n".join(lines)
+
+
+def assess_head_sha_equality(
+    reviewed_head_sha: str | None,
+    live_head_sha: str | None,
+) -> dict[str, Any]:
+    """Fail closed when reviewed and live PR heads differ."""
+    reviewed = _normalize_sha(reviewed_head_sha)
+    live = _normalize_sha(live_head_sha)
+    reasons: list[str] = []
+    if not reviewed or not live:
+        reasons.append(
+            "reviewed/live head SHA missing or not full 40-hex; fail closed"
+        )
+    elif reviewed != live:
+        reasons.append(
+            "PR head changed after validation; re-pin and re-validate before "
+            "approval or merge"
+        )
+    proven = not reasons
+    return {
+        "proven": proven,
+        "block": not proven,
+        "reasons": reasons,
+        "reviewed_head_sha": reviewed,
+        "live_head_sha": live,
+        "head_changed": bool(reviewed and live and reviewed != live),
+    }
+
+
+def assess_conflict_fix_push(
+    *,
+    pr_number: int,
+    comments: list[dict],
+    branch_head_before: str | None,
+    branch_head_after: str | None,
+    worktree_path: str | None,
+    push_cwd: str | None,
+    is_fast_forward: bool | None,
+    now: datetime | None = None,
+) -> dict[str, Any]:
+    """Author pre-push gate: block when a reviewer holds an active lease."""
+    now = now or datetime.now(timezone.utc)
+    reasons: list[str] = []
+    reviewer_lease = find_active_reviewer_lease(comments, pr_number=pr_number, now=now)
+    conflict_lease = find_active_conflict_fix_lease(comments, pr_number=pr_number, now=now)
+
+    if reviewer_lease:
+        reasons.append(
+            f"active reviewer lease on PR #{pr_number} "
+            f"(phase={reviewer_lease.get('phase')}); author push blocked"
+        )
+
+    head_before = _normalize_sha(branch_head_before)
+    head_after = _normalize_sha(branch_head_after)
+    if not head_before:
+        reasons.append("branch head before push missing or invalid SHA")
+    if head_after and head_before and head_before == head_after:
+        reasons.append("branch head unchanged; no push to perform")
+
+    worktree = (worktree_path or "").strip()
+    cwd = (push_cwd or "").strip()
+    if not worktree:
+        reasons.append("worktree path required for conflict-fix push proof")
+    elif cwd and worktree and not cwd.rstrip("/").endswith(worktree.rstrip("/").split("/")[-1]):
+        if worktree not in cwd:
+            reasons.append(
+                f"push cwd '{cwd}' does not match session worktree '{worktree}'"
+            )
+
+    if is_fast_forward is False:
+        reasons.append("non-fast-forward push rejected for conflict-fix (fail closed)")
+
+    if conflict_lease and conflict_lease.get("phase") == "pushing":
+        owner = conflict_lease.get("worktree")
+        if owner and worktree and owner != worktree:
+            reasons.append(
+                f"sibling conflict-fix lease active from worktree '{owner}'"
+            )
+
+    push_allowed = not reasons
+    return {
+        "push_allowed": push_allowed,
+        "block": not push_allowed,
+        "reasons": reasons,
+        "active_reviewer_lease": reviewer_lease,
+        "active_conflict_fix_lease": conflict_lease,
+        "branch_head_before": head_before,
+        "branch_head_after": head_after,
+        "reviewer_was_active": bool(reviewer_lease),
+        "fast_forward": is_fast_forward,
+    }
+
+
+def assess_reviewer_mutation_blocked(
+    *,
+    pr_number: int,
+    comments: list[dict],
+    reviewed_head_sha: str | None,
+    live_head_sha: str | None,
+    mutation: str,
+    now: datetime | None = None,
+) -> dict[str, Any]:
+    """Reviewer gate: block when conflict-fix lease active or head moved."""
+    now = now or datetime.now(timezone.utc)
+    reasons: list[str] = []
+    conflict_lease = find_active_conflict_fix_lease(comments, pr_number=pr_number, now=now)
+    if conflict_lease and (conflict_lease.get("phase") or "") in _ACTIVE_CONFLICT_FIX_PHASES:
+        reasons.append(
+            f"active conflict-fix lease on PR #{pr_number} "
+            f"(phase={conflict_lease.get('phase')}); reviewer {mutation} blocked"
+        )
+
+    head_check = assess_head_sha_equality(reviewed_head_sha, live_head_sha)
+    if head_check["block"]:
+        reasons.extend(head_check["reasons"])
+
+    if not _normalize_sha(reviewed_head_sha):
+        reasons.append(
+            f"reviewed head SHA required before reviewer {mutation} (fail closed)"
+        )
+
+    allowed = not reasons
+    return {
+        "mutation_allowed": allowed,
+        "block": not allowed,
+        "reasons": reasons,
+        "active_conflict_fix_lease": conflict_lease,
+        "head_check": head_check,
+        "reviewed_head_sha": head_check.get("reviewed_head_sha"),
+        "live_head_sha": head_check.get("live_head_sha"),
+        "push_during_validation": bool(
+            conflict_lease and conflict_lease.get("phase") in {"pushing", "pushed"}
+        ),
+    }
+
+
+_REVIEWED_HEAD_RE = re.compile(
+    r"reviewed head sha\s*:\s*([0-9a-f]{40})",
+    re.IGNORECASE,
+)
+_LIVE_HEAD_BEFORE_APPROVAL_RE = re.compile(
+    r"(?:live head sha before approval|final live head sha before approval)\s*:\s*([0-9a-f]{40})",
+    re.IGNORECASE,
+)
+_LIVE_HEAD_BEFORE_MERGE_RE = re.compile(
+    r"(?:live head sha before merge|final live head sha before merge)\s*:\s*([0-9a-f]{40})",
+    re.IGNORECASE,
+)
+_PUSH_DURING_VALIDATION_RE = re.compile(
+    r"push(?:es)? occurred during validation\s*:\s*(yes|no|true|false)",
+    re.IGNORECASE,
+)
+_CONFLICT_HEAD_BEFORE_RE = re.compile(
+    r"branch head before push\s*:\s*([0-9a-f]{40})",
+    re.IGNORECASE,
+)
+_CONFLICT_HEAD_AFTER_RE = re.compile(
+    r"branch head after push\s*:\s*([0-9a-f]{40})",
+    re.IGNORECASE,
+)
+_REVIEWER_LEASE_STATUS_RE = re.compile(
+    r"active reviewer lease status\s*:\s*(.+)$",
+    re.IGNORECASE | re.MULTILINE,
+)
+_FAST_FORWARD_RE = re.compile(
+    r"whether push was fast-forward\s*:\s*(yes|no|true|false)",
+    re.IGNORECASE,
+)
+_REVIEWER_ACTIVE_RE = re.compile(
+    r"whether any reviewer was active\s*:\s*(yes|no|true|false)",
+    re.IGNORECASE,
+)
+
+
+def assess_reviewer_stale_head_final_report(report_text: str) -> dict[str, Any]:
+    """Final-report proof for reviewed vs live head SHAs (#399 AC 6)."""
+    text = report_text or ""
+    reasons: list[str] = []
+    reviewed = _normalize_sha(_REVIEWED_HEAD_RE.search(text).group(1) if _REVIEWED_HEAD_RE.search(text) else None)
+    live_approval = _normalize_sha(
+        _LIVE_HEAD_BEFORE_APPROVAL_RE.search(text).group(1)
+        if _LIVE_HEAD_BEFORE_APPROVAL_RE.search(text)
+        else None
+    )
+    live_merge = _normalize_sha(
+        _LIVE_HEAD_BEFORE_MERGE_RE.search(text).group(1)
+        if _LIVE_HEAD_BEFORE_MERGE_RE.search(text)
+        else None
+    )
+    push_during = _PUSH_DURING_VALIDATION_RE.search(text)
+
+    if not reviewed:
+        reasons.append("reviewed head SHA not stated in final report")
+    if not live_approval:
+        reasons.append("final live head SHA before approval not stated")
+    if not live_merge:
+        reasons.append("final live head SHA before merge not stated")
+    if not push_during:
+        reasons.append("whether push occurred during validation not stated")
+    elif reviewed and live_approval and reviewed != live_approval:
+        reasons.append("live head before approval differs from reviewed head SHA")
+    elif reviewed and live_merge and reviewed != live_merge:
+        reasons.append("live head before merge differs from reviewed head SHA")
+
+    proven = not reasons
+    return {
+        "proven": proven,
+        "block": not proven,
+        "reasons": reasons,
+        "reviewed_head_sha": reviewed,
+        "live_head_sha_before_approval": live_approval,
+        "live_head_sha_before_merge": live_merge,
+        "push_during_validation": (push_during.group(1).lower() if push_during else None),
+    }
+
+
+def assess_conflict_fix_final_report(report_text: str) -> dict[str, Any]:
+    """Final-report proof for conflict-fix push sessions (#399 AC 7)."""
+    text = report_text or ""
+    reasons: list[str] = []
+    head_before = _normalize_sha(
+        _CONFLICT_HEAD_BEFORE_RE.search(text).group(1)
+        if _CONFLICT_HEAD_BEFORE_RE.search(text)
+        else None
+    )
+    head_after = _normalize_sha(
+        _CONFLICT_HEAD_AFTER_RE.search(text).group(1)
+        if _CONFLICT_HEAD_AFTER_RE.search(text)
+        else None
+    )
+    if not head_before:
+        reasons.append("branch head before push not stated")
+    if not head_after:
+        reasons.append("branch head after push not stated")
+    if not _REVIEWER_LEASE_STATUS_RE.search(text):
+        reasons.append("active reviewer lease status not stated")
+    if not _FAST_FORWARD_RE.search(text):
+        reasons.append("whether push was fast-forward not stated")
+    if not _REVIEWER_ACTIVE_RE.search(text):
+        reasons.append("whether any reviewer was active not stated")
+
+    proven = not reasons
+    return {
+        "proven": proven,
+        "block": not proven,
+        "reasons": reasons,
+        "branch_head_before": head_before,
+        "branch_head_after": head_after,
+    }

review_proofs.py

@@ -3622,33 +3622,18 @@ def assess_work_issue_mode_isolation(report_text: str) -> dict:
     }
 
 
-def assess_work_issue_duplicate_prevention_report(report_text, **kwargs):
-    """#400: work-issue reports must classify duplicate-work prevention."""
-    from author_duplicate_work_gate import (
-        assess_work_issue_duplicate_prevention_report as _assess,
-    )
-
-    return _assess(report_text, **kwargs)
-
-
 def assess_work_issue_final_report(report_text: str) -> dict:
     """#139: composite verifier for work-issue final reports."""
     checks = {
         "workflow_source": assess_work_issue_workflow_source(report_text),
         "mode_isolation": assess_work_issue_mode_isolation(report_text),
-        "duplicate_prevention": assess_work_issue_duplicate_prevention_report(
-            report_text
-        ),
     }
 
     reasons = []
     downgraded = False
     for name, result in checks.items():
         verdict = result.get("verdict")
-        if result.get("block"):
+        if verdict in ("missing", "incomplete"):
-            downgraded = True
-            reasons.extend(result.get("reasons") or [])
-        elif verdict in ("missing", "incomplete"):
             downgraded = True
             reasons.extend(result.get("reasons") or [])
         elif result.get("downgraded") or not result.get("complete", True):
@@ -3656,9 +3641,6 @@ def assess_work_issue_final_report(report_text: str) -> dict:
             reasons.extend(
                 f"{name}: {r}" for r in (result.get("reasons") or [])
             )
-        elif result.get("proven") is False:
-            downgraded = True
-            reasons.extend(result.get("reasons") or [])
 
     grade = "A" if not downgraded else "downgraded"
     return {

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

@@ -732,6 +732,24 @@ The final report must identify:
 * whether same-PR merge continuation was allowed
 * whether the run stopped as required
 
+## 26B. Conflict-fix lease and stale-head protection (#399)
+
+Before validating, approving, or merging a PR:
+
+1. Check for an active conflict-fix lease on the PR; stop if one is active.
+2. Pin `expected_head_sha` before validation and pass it to
+   `gitea_mark_final_review_decision`, `gitea_submit_pr_review`, and
+   `gitea_merge_pr`.
+3. Re-fetch live PR head immediately before approval and merge; refuse when
+   live head differs from the reviewed SHA.
+
+Final reports must state:
+
+* reviewed head SHA
+* final live head SHA before approval
+* final live head SHA before merge
+* whether any push occurred during validation
+
 ## 27. Merge rules
 
 Before merge, rerun fresh live checks:

skills/llm-project-workflow/workflows/work-issue.md

@@ -277,24 +277,6 @@ Do not select an issue based only on memory from a previous session.
 
 Before claiming or working on an issue, check whether there is already an open PR, branch, or active claim for that issue.
 
-Run `gitea_assess_author_duplicate_work` at these stages and stop when `block` is true:
-
-* `claim` — before `gitea_mark_issue`
-* `lock` — before `gitea_lock_issue`
-* `worktree` / `edit` — before creating a worktree or editing files
-* `commit` — immediately before `git commit`
-* `push` — immediately before `git push`
-* `create_pr` — immediately before `gitea_create_pr` (also enforced server-side)
-
-`gitea_mark_issue`, `gitea_lock_issue`, and `gitea_create_pr` enforce the same gate server-side and fail closed.
-
-If a concurrent open PR appears after work begins:
-
-* before commit or push — stop and preserve local work without pushing
-* after push but before PR creation — produce a reconciliation handoff instead of opening a PR
-
-Final reports must name the duplicate-work outcome (`duplicate PR prevented`, `duplicate branch prevented`, `duplicate commit prevented`, `duplicate push prevented`, `duplicate work not prevented`, or `reconciliation handoff`).
-
 If an open PR already exists for the issue, do not implement duplicate work.
 
 Classify the issue as:
@@ -595,6 +577,29 @@ After push, report:
 
 If push fails, stop and produce a recovery handoff.
 
+## 20A. Conflict-fix lease and push gate (#399)
+
+When pushing to an existing PR branch to resolve merge conflicts:
+
+1. Call `gitea_acquire_conflict_fix_lease` before any push.
+2. Call `gitea_assess_conflict_fix_push` immediately before `git push` with:
+   * branch head before push
+   * branch head after push (local)
+   * session worktree path
+   * push cwd
+   * whether the push is fast-forward
+3. Do not push when a reviewer holds an active lease on the same PR.
+4. Do not force-push.
+5. Do not push from the main checkout or wrong cwd.
+
+Conflict-fix final reports must state:
+
+* branch head before push
+* branch head after push
+* active reviewer lease status
+* whether push was fast-forward
+* whether any reviewer was active
+
 ## 21. PR creation rules
 
 Create a PR only if implementation and validation pass, unless project policy explicitly allows draft PRs with documented validation failures.

tests/test_author_duplicate_work_gate.py

@@ -1,102 +0,0 @@
-"""Tests for early author duplicate-work gate (#400)."""
-import sys
-import unittest
-from pathlib import Path
-
-sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
-
-from author_duplicate_work_gate import (  # noqa: E402
-    ELIGIBILITY_OPEN_PR_EXISTS,
-    assess_author_duplicate_work,
-    assess_work_issue_duplicate_prevention_report,
-)
-
-
-def _open_pr(number: int = 397, issue: int = 395) -> dict:
-    return {
-        "number": number,
-        "head": {"ref": f"feat/issue-{issue}-example"},
-        "title": f"feat: example (Closes #{issue})",
-        "body": f"Closes #{issue}",
-    }
-
-
-class TestAuthorDuplicateWorkGate(unittest.TestCase):
-    def test_clear_when_no_duplicates(self):
-        result = assess_author_duplicate_work(
-            400,
-            stage="claim",
-            open_prs=[],
-            branch_names=["master", "feat/issue-399-other"],
-        )
-        self.assertTrue(result["allowed"])
-        self.assertFalse(result["block"])
-
-    def test_open_pr_blocks_claim(self):
-        result = assess_author_duplicate_work(
-            395,
-            stage="claim",
-            open_prs=[_open_pr()],
-            branch_names=[],
-        )
-        self.assertFalse(result["allowed"])
-        self.assertEqual(result["eligibility_class"], ELIGIBILITY_OPEN_PR_EXISTS)
-
-    def test_matching_branch_blocks_lock_not_create_pr(self):
-        branches = ["feat/issue-400-early-duplicate-work-gate"]
-        lock = assess_author_duplicate_work(
-            400,
-            stage="lock",
-            open_prs=[],
-            branch_names=branches,
-        )
-        self.assertFalse(lock["allowed"])
-
-        create_pr = assess_author_duplicate_work(
-            400,
-            stage="create_pr",
-            open_prs=[],
-            branch_names=branches,
-            matching_branches=[],
-        )
-        self.assertTrue(create_pr["allowed"])
-
-    def test_open_pr_blocks_create_pr_stage(self):
-        result = assess_author_duplicate_work(
-            395,
-            stage="create_pr",
-            open_prs=[_open_pr()],
-            branch_names=["feat/issue-395-proof-backed-review-handoff"],
-        )
-        self.assertFalse(result["allowed"])
-        self.assertEqual(result["outcome"], "duplicate_pr_prevented")
-
-    def test_push_stage_blocks_on_concurrent_pr(self):
-        result = assess_author_duplicate_work(
-            395,
-            stage="push",
-            open_prs=[_open_pr()],
-            branch_names=[],
-        )
-        self.assertFalse(result["allowed"])
-        self.assertEqual(result["outcome"], "duplicate_push_prevented")
-
-    def test_duplicate_prevention_report_requires_outcome(self):
-        bad = assess_work_issue_duplicate_prevention_report(
-            "Duplicate work detected for issue #395."
-        )
-        self.assertFalse(bad["proven"])
-
-        good = assess_work_issue_duplicate_prevention_report(
-            "Duplicate PR prevented; reconciliation handoff produced."
-        )
-        self.assertTrue(good["proven"])
-
-    def test_exported_from_review_proofs(self):
-        from review_proofs import assess_work_issue_duplicate_prevention_report as exported
-
-        self.assertTrue(callable(exported))
-
-
-if __name__ == "__main__":
-    unittest.main()

tests/test_llm_workflow_split.py

@@ -95,12 +95,6 @@ def test_create_issue_workflow_contract():
     assert "## 9. Duplicate search before mutation" in text
 
 
-def test_author_duplicate_work_gate_exported():
-    from review_proofs import assess_work_issue_duplicate_prevention_report
-
-    assert callable(assess_work_issue_duplicate_prevention_report)
-
-
 def test_work_issue_workflow_contract():
     text = (SKILL_DIR / "workflows" / "work-issue.md").read_text(encoding="utf-8")
     assert "canonical: true" in text

tests/test_pr_work_lease.py

@@ -0,0 +1,207 @@
+#!/usr/bin/env python3
+"""Regression tests for conflict-fix and reviewer PR work leases (#399)."""
+
+from __future__ import annotations
+
+import os
+import sys
+import unittest
+from datetime import datetime, timedelta, timezone
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from pr_work_lease import (  # noqa: E402
+    CONFLICT_FIX_LEASE_MARKER,
+    REVIEWER_LEASE_MARKER,
+    assess_conflict_fix_final_report,
+    assess_conflict_fix_push,
+    assess_head_sha_equality,
+    assess_reviewer_mutation_blocked,
+    assess_reviewer_stale_head_final_report,
+    format_conflict_fix_lease_body,
+    parse_conflict_fix_lease_comment,
+    parse_reviewer_lease_comment,
+)
+
+HEAD_A = "a" * 40
+HEAD_B = "b" * 40
+NOW = datetime(2026, 7, 7, 15, 0, tzinfo=timezone.utc)
+
+
+def _reviewer_lease_body(*, phase: str = "validating", expires_minutes: int = 60) -> str:
+    expires = (NOW + timedelta(minutes=expires_minutes)).isoformat().replace("+00:00", "Z")
+    return "\n".join([
+        REVIEWER_LEASE_MARKER,
+        "pr: #376",
+        "phase: " + phase,
+        f"candidate_head: {HEAD_A}",
+        f"expires_at: {expires}",
+        "profile: prgs-reviewer",
+    ])
+
+
+def _conflict_fix_body(*, phase: str = "claimed", worktree: str = "branches/fix-376") -> str:
+    expires = (NOW + timedelta(minutes=60)).isoformat().replace("+00:00", "Z")
+    return "\n".join([
+        CONFLICT_FIX_LEASE_MARKER,
+        "pr: #376",
+        f"phase: {phase}",
+        f"worktree: {worktree}",
+        f"head_before: {HEAD_A}",
+        f"expires_at: {expires}",
+        "profile: prgs-author",
+    ])
+
+
+class TestLeaseParsing(unittest.TestCase):
+    def test_parse_reviewer_lease(self):
+        parsed = parse_reviewer_lease_comment(_reviewer_lease_body())
+        self.assertEqual(parsed["pr_number"], 376)
+        self.assertEqual(parsed["phase"], "validating")
+        self.assertEqual(parsed["candidate_head"], HEAD_A)
+
+    def test_parse_conflict_fix_lease(self):
+        parsed = parse_conflict_fix_lease_comment(_conflict_fix_body())
+        self.assertEqual(parsed["pr_number"], 376)
+        self.assertEqual(parsed["phase"], "claimed")
+
+
+class TestConflictFixPushGate(unittest.TestCase):
+    def test_blocks_push_during_active_reviewer_lease(self):
+        comments = [{"body": _reviewer_lease_body()}]
+        result = assess_conflict_fix_push(
+            pr_number=376,
+            comments=comments,
+            branch_head_before=HEAD_A,
+            branch_head_after=HEAD_B,
+            worktree_path="branches/fix-376",
+            push_cwd="/proj/branches/fix-376",
+            is_fast_forward=True,
+            now=NOW,
+        )
+        self.assertFalse(result["push_allowed"])
+        self.assertTrue(any("reviewer lease" in r for r in result["reasons"]))
+
+    def test_rejects_non_fast_forward(self):
+        result = assess_conflict_fix_push(
+            pr_number=376,
+            comments=[],
+            branch_head_before=HEAD_A,
+            branch_head_after=HEAD_B,
+            worktree_path="branches/fix-376",
+            push_cwd="/proj/branches/fix-376",
+            is_fast_forward=False,
+            now=NOW,
+        )
+        self.assertFalse(result["push_allowed"])
+        self.assertTrue(any("non-fast-forward" in r for r in result["reasons"]))
+
+    def test_wrong_cwd_push_attempt(self):
+        result = assess_conflict_fix_push(
+            pr_number=376,
+            comments=[],
+            branch_head_before=HEAD_A,
+            branch_head_after=HEAD_B,
+            worktree_path="branches/fix-376",
+            push_cwd="/proj/master",
+            is_fast_forward=True,
+            now=NOW,
+        )
+        self.assertFalse(result["push_allowed"])
+        self.assertTrue(any("cwd" in r.lower() for r in result["reasons"]))
+
+    def test_sibling_conflict_fix_collision(self):
+        comments = [{"body": _conflict_fix_body(phase="pushing", worktree="branches/other")}]
+        result = assess_conflict_fix_push(
+            pr_number=376,
+            comments=comments,
+            branch_head_before=HEAD_A,
+            branch_head_after=HEAD_B,
+            worktree_path="branches/fix-376",
+            push_cwd="/proj/branches/fix-376",
+            is_fast_forward=True,
+            now=NOW,
+        )
+        self.assertFalse(result["push_allowed"])
+        self.assertTrue(any("sibling conflict-fix" in r for r in result["reasons"]))
+
+
+class TestReviewerMutationGate(unittest.TestCase):
+    def test_blocks_review_during_conflict_fix(self):
+        comments = [{"body": _conflict_fix_body(phase="pushing")}]
+        result = assess_reviewer_mutation_blocked(
+            pr_number=376,
+            comments=comments,
+            reviewed_head_sha=HEAD_A,
+            live_head_sha=HEAD_A,
+            mutation="approve",
+            now=NOW,
+        )
+        self.assertFalse(result["mutation_allowed"])
+        self.assertTrue(any("conflict-fix lease" in r for r in result["reasons"]))
+
+    def test_stale_head_blocks_approval(self):
+        result = assess_reviewer_mutation_blocked(
+            pr_number=376,
+            comments=[],
+            reviewed_head_sha=HEAD_A,
+            live_head_sha=HEAD_B,
+            mutation="merge",
+            now=NOW,
+        )
+        self.assertFalse(result["mutation_allowed"])
+        self.assertTrue(result["head_check"]["head_changed"])
+
+    def test_head_equality_required_fields(self):
+        result = assess_head_sha_equality(HEAD_A, HEAD_B)
+        self.assertFalse(result["proven"])
+        self.assertTrue(result["head_changed"])
+
+
+class TestFinalReportProof(unittest.TestCase):
+    def test_reviewer_stale_head_report_requires_fields(self):
+        result = assess_reviewer_stale_head_final_report("no head proof here")
+        self.assertFalse(result["proven"])
+
+    def test_reviewer_stale_head_report_passes(self):
+        report = "\n".join([
+            f"Reviewed head SHA: {HEAD_A}",
+            f"Final live head SHA before approval: {HEAD_A}",
+            f"Final live head SHA before merge: {HEAD_A}",
+            "Push occurred during validation: no",
+        ])
+        result = assess_reviewer_stale_head_final_report(report)
+        self.assertTrue(result["proven"])
+
+    def test_conflict_fix_report_requires_fields(self):
+        result = assess_conflict_fix_final_report("incomplete")
+        self.assertFalse(result["proven"])
+
+    def test_conflict_fix_report_passes(self):
+        report = "\n".join([
+            f"Branch head before push: {HEAD_A}",
+            f"Branch head after push: {HEAD_B}",
+            "Active reviewer lease status: none",
+            "Whether push was fast-forward: yes",
+            "Whether any reviewer was active: no",
+        ])
+        result = assess_conflict_fix_final_report(report)
+        self.assertTrue(result["proven"])
+
+
+class TestFormatLease(unittest.TestCase):
+    def test_format_conflict_fix_lease_includes_marker(self):
+        body = format_conflict_fix_lease_body(
+            pr_number=376,
+            branch="feat/x",
+            worktree="branches/fix-376",
+            profile="prgs-author",
+            head_before=HEAD_A,
+        )
+        self.assertIn(CONFLICT_FIX_LEASE_MARKER, body)
+        parsed = parse_conflict_fix_lease_comment(body)
+        self.assertEqual(parsed["pr_number"], 376)
+
+
+if __name__ == "__main__":
+    unittest.main()