feat(mcp): bind issue lock to author scratch worktree (#249)

gitea_lock_issue and gitea_create_pr accept worktree_path so lock
preconditions validate the caller's scratch clone instead of the shared
MCP server CWD. Lock records store the validated path; PR creation fails
closed when the declared path does not match.

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

gitea_mcp_server.py

@@ -260,6 +260,7 @@ import role_session_router  # noqa: E402
 import role_namespace_gate  # noqa: E402
 import task_capability_map  # noqa: E402
 import review_proofs  # noqa: E402
+import issue_lock_worktree  # noqa: E402
 
 
 # Fail-closed exact-issue-lock file (#204): written by gitea_lock_issue,
@@ -625,6 +626,7 @@ def gitea_lock_issue(
     host: str | None = None,
     org: str | None = None,
     repo: str | None = None,
+    worktree_path: str | None = None,
 ) -> dict:
     """Lock exactly one Gitea issue and its branch name to ensure durable tracking.
 
@@ -635,6 +637,8 @@ def gitea_lock_issue(
         host: Override Gitea host.
         org: Override Org.
         repo: Override Repo.
+        worktree_path: Author scratch-clone path to validate (defaults to
+            GITEA_AUTHOR_WORKTREE or the MCP server project root).
     """
     # 1. Enforce branch name includes issue number
     expected_pattern = f"issue-{issue_number}"
@@ -643,6 +647,20 @@ def gitea_lock_issue(
             f"Branch name '{branch_name}' must contain locked issue pattern '{expected_pattern}' (fail closed)"
         )
 
+    resolved_worktree = issue_lock_worktree.resolve_author_worktree_path(
+        worktree_path, PROJECT_ROOT
+    )
+    git_state = issue_lock_worktree.read_worktree_git_state(resolved_worktree)
+    lock_assessment = issue_lock_worktree.assess_issue_lock_worktree(
+        worktree_path=resolved_worktree,
+        current_branch=git_state.get("current_branch"),
+        porcelain_status=git_state.get("porcelain_status") or "",
+    )
+    if lock_assessment["block"]:
+        raise RuntimeError(
+            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)
@@ -679,6 +697,7 @@ def gitea_lock_issue(
         "remote": remote,
         "org": o,
         "repo": r,
+        "worktree_path": resolved_worktree,
     }
 
     try:
@@ -689,9 +708,13 @@ def gitea_lock_issue(
 
     return {
         "success": True,
-        "message": f"Successfully locked issue #{issue_number} to branch '{branch_name}' (fail-closed check complete).",
+        "message": (
+            f"Successfully locked issue #{issue_number} to branch '{branch_name}' "
+            f"from worktree '{resolved_worktree}' (fail-closed check complete)."
+        ),
         "issue_number": issue_number,
         "branch_name": branch_name,
+        "worktree_path": resolved_worktree,
     }
 
 
@@ -705,6 +728,7 @@ def gitea_create_pr(
     host: str | None = None,
     org: str | None = None,
     repo: str | None = None,
+    worktree_path: str | None = None,
 ) -> dict:
     """Create a pull request on a Gitea repository.
 
@@ -717,6 +741,7 @@ def gitea_create_pr(
         host: Override the Gitea host.
         org: Override the owner/organization.
         repo: Override the repository name.
+        worktree_path: Author worktree path; must match the path stored at lock time.
 
     Returns:
         dict with 'number' of the created PR ('url' only with the reveal opt-in).
@@ -755,6 +780,13 @@ def gitea_create_pr(
 
     locked_issue = lock_data.get("issue_number")
     locked_branch = lock_data.get("branch_name")
+    locked_worktree = lock_data.get("worktree_path")
+
+    worktree_check = issue_lock_worktree.verify_pr_worktree_matches_lock(
+        locked_worktree, worktree_path, PROJECT_ROOT
+    )
+    if worktree_check["block"]:
+        raise ValueError(worktree_check["reasons"][0])
 
     if head != locked_branch:
         raise ValueError(