feat: surface explicit adoption proof in gitea_lock_issue response (Closes #477)

When gitea_lock_issue adopts an existing own branch, the live tool
response now carries explicit, citable adoption-proof fields so #473-style
recovery sessions can quote the lock output directly instead of inferring
adoption from separate offline checks.

- issue_lock_adoption.py: add DECISION_LABELS + decision_label()/
  safe_next_action() helpers; extend build_adoption_proof() with
  adoption_decision, adopted, adopted_branch, adopted_branch_head,
  matcher_summary (boundary-safe reason), competing_branch_check, and
  safe_next_action for all outcomes; add build_non_adoption_lock_proof()
  for adoption-free NO_MATCH metadata.
- gitea_mcp_server.py: attach adoption-free adoption_check block to normal
  (non-adopt) lock responses so they cannot be misread as claiming adoption.
- docs/llm-workflow-runbooks.md: document the adoption/adoption_check
  response blocks and instruct recovery reports to cite them directly.
- tests: explicit-field proof for ADOPT/BLOCK_COMPETING/NO_MATCH,
  substring-collision boundary safety (issue-42 vs issue-420), non-adoption
  proof, and MCP-level live-response assertions.

BLOCK_COMPETING lock attempts still fail closed (raise); no raw API
fallback, branch deletion, force-push, or manual lock seeding introduced.

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

issue_lock_adoption.py

@@ -20,6 +20,43 @@ ADOPT = "adopt_existing_branch"
 BLOCK_COMPETING = "block_competing_branch"
 NO_MATCH = "no_matching_branch"
 
+# Citable decision labels aligned with the ``assess_own_branch_adoption``
+# outcomes, surfaced verbatim in the live ``gitea_lock_issue`` response so
+# recovery reports (#473-style) can quote the lock tool output directly
+# instead of inferring adoption from separate offline checks (#477).
+DECISION_LABELS = {
+    ADOPT: "ADOPT",
+    BLOCK_COMPETING: "BLOCK_COMPETING",
+    NO_MATCH: "NO_MATCH",
+}
+
+_SAFE_NEXT_ACTIONS = {
+    ADOPT: (
+        "Own existing branch adopted for lock recovery; proceed to "
+        "gitea_create_pr for this issue and cite this adoption proof."
+    ),
+    BLOCK_COMPETING: (
+        "Competing same-issue branch(es) exist; resolve branch ownership "
+        "before locking. No adoption performed (fail closed)."
+    ),
+    NO_MATCH: (
+        "No existing branch carries this issue marker; normal lock path "
+        "applied. No adoption performed."
+    ),
+}
+
+
+def decision_label(outcome: str) -> str:
+    """Map an ``assess_own_branch_adoption`` outcome to its citable label."""
+    return DECISION_LABELS.get(outcome, "UNKNOWN")
+
+
+def safe_next_action(outcome: str) -> str:
+    """Return the safe next action string for an adoption *outcome*."""
+    return _SAFE_NEXT_ACTIONS.get(
+        outcome, "Unknown adoption outcome; treat as fail closed."
+    )
+
 
 def _branch_name(entry) -> str:
     if isinstance(entry, dict):
@@ -128,6 +165,42 @@ def assess_own_branch_adoption(
     }
 
 
+def _matcher_summary(issue_number: int, assessment: dict) -> str:
+    """Explain, citably, why the assessed branch did or did not qualify.
+
+    Names the numeric word-boundary rule so reports can show that
+    ``issue-42`` was not matched inside ``issue-420`` (#440 / #477 AC3).
+    """
+    outcome = assessment.get("outcome")
+    matched = assessment.get("matched_branch")
+    competing = assessment.get("competing_branches") or []
+    if outcome == ADOPT and matched:
+        return (
+            f"branch '{matched}' exactly matches the issue-{int(issue_number)} "
+            f"marker (numeric word-boundary; 'issue-{int(issue_number)}' is not "
+            f"matched inside 'issue-{int(issue_number)}0')"
+        )
+    if outcome == BLOCK_COMPETING:
+        return (
+            f"competing same-issue branch(es) {competing} carry the "
+            f"issue-{int(issue_number)} marker but are not the requested "
+            f"branch; ownership is ambiguous (fail closed)"
+        )
+    return (
+        f"no existing branch carries the issue-{int(issue_number)} marker "
+        f"under the numeric word-boundary rule"
+    )
+
+
+def _competing_branch_check(assessment: dict) -> dict:
+    """Structured competing-branch verdict for the proof block."""
+    competing = list(assessment.get("competing_branches") or [])
+    return {
+        "result": "blocked" if competing else "clear",
+        "competing_branches": competing,
+    }
+
+
 def build_adoption_proof(
     *,
     issue_number: int,
@@ -143,7 +216,18 @@ def build_adoption_proof(
     Requirement #4: adoption results must carry issue number, branch name,
     branch head commit, adoption reason, no-existing-PR proof, no-competing-
     live-lock proof, and lock file path/status.
+
+    #477: additionally surface explicit, citable adoption-proof fields tied to
+    the ``assess_own_branch_adoption`` outcome (``adoption_decision``,
+    ``adopted``, ``adopted_branch``, ``adopted_branch_head``,
+    ``matcher_summary``, ``competing_branch_check``, ``safe_next_action``) so a
+    recovery session can quote the live lock response directly. The explicit
+    fields are populated for any outcome; ``adopted_branch`` /
+    ``adopted_branch_head`` are set only when the outcome is ADOPT so a
+    non-adoption proof can never be misread as claiming adoption.
     """
+    outcome = assessment.get("outcome")
+    adopted = outcome == ADOPT
     return {
         "issue_number": issue_number,
         "branch_name": branch_name,
@@ -153,4 +237,36 @@ def build_adoption_proof(
         "no_competing_live_lock_proof": bool(competing_lock_checked),
         "lock_file_path": lock_file_path,
         "lock_file_status": lock_file_status,
+        # Explicit citable fields (#477).
+        "adoption_decision": decision_label(outcome),
+        "adopted": adopted,
+        "adopted_branch": branch_name if adopted else None,
+        "adopted_branch_head": assessment.get("matched_head_sha") if adopted else None,
+        "matcher_summary": _matcher_summary(issue_number, assessment),
+        "competing_branch_check": _competing_branch_check(assessment),
+        "safe_next_action": safe_next_action(outcome),
+    }
+
+
+def build_non_adoption_lock_proof(*, issue_number: int, branch_name: str) -> dict:
+    """Safe, adoption-free proof metadata for a normal (NO_MATCH) lock.
+
+    Requirement #477 AC2: non-adoption lock responses must stay clear and must
+    not imply adoption. This returns explicit ``adopted: False`` metadata with
+    the ``NO_MATCH`` decision so a normal lock response can carry citable proof
+    without ever asserting a branch was adopted.
+    """
+    return {
+        "issue_number": issue_number,
+        "branch_name": branch_name,
+        "adoption_decision": DECISION_LABELS[NO_MATCH],
+        "adopted": False,
+        "adopted_branch": None,
+        "adopted_branch_head": None,
+        "matcher_summary": (
+            f"no existing branch carries the issue-{int(issue_number)} marker; "
+            f"normal lock path (no adoption)"
+        ),
+        "competing_branch_check": {"result": "clear", "competing_branches": []},
+        "safe_next_action": safe_next_action(NO_MATCH),
     }