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]>

tests/test_mcp_server.py

@@ -3325,6 +3325,45 @@ class TestIssueLocking(unittest.TestCase):
         self.assertIn("adoption", res)
         self.assertEqual(res["adoption"]["branch_head_commit"], "abc123")
 
+    @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)
+    def test_lock_issue_adoption_response_has_explicit_proof(self, _auth, mock_api, _git_state):
+        # #477 AC1: the live lock response must carry citable adoption proof.
+        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")
+        proof = res["adoption"]
+        self.assertEqual(proof["adoption_decision"], "ADOPT")
+        self.assertTrue(proof["adopted"])
+        self.assertEqual(proof["adopted_branch"], branch)
+        self.assertEqual(proof["adopted_branch_head"], "abc123")
+        self.assertEqual(proof["competing_branch_check"]["result"], "clear")
+        self.assertIn("gitea_create_pr", proof["safe_next_action"])
+        self.assertIn("196", proof["matcher_summary"])
+
+    @patch(
+        "mcp_server.issue_lock_worktree.read_worktree_git_state",
+        return_value=_clean_master_git_state_for_lock(),
+    )
+    @patch("mcp_server.api_get_all", return_value=[])
+    @patch("mcp_server.get_auth_header", return_value=FAKE_AUTH)
+    def test_lock_issue_no_match_response_does_not_claim_adoption(self, _auth, _api, _git_state):
+        # #477 AC2/AC3: a normal (NO_MATCH) lock must carry adoption-free proof
+        # and must NOT expose an ``adoption`` block.
+        res = gitea_lock_issue(issue_number=196, branch_name="feat/issue-196-mutations", remote="prgs")
+        self.assertTrue(res["success"])
+        self.assertNotIn("adoption", res)
+        check = res["adoption_check"]
+        self.assertEqual(check["adoption_decision"], "NO_MATCH")
+        self.assertFalse(check["adopted"])
+        self.assertIsNone(check["adopted_branch"])
+        self.assertEqual(check["competing_branch_check"]["result"], "clear")
+
     @patch(
         "mcp_server.issue_lock_worktree.read_worktree_git_state",
         return_value=_clean_master_git_state_for_lock(),