fix(mcp): line-anchor conflict scan and worktree scan paths (#272)

Match git conflict markers on whole lines only so decorative equals
borders in mcp_discoverability.py no longer false-positive. Scan
session worktrees under branches/ without skipping the entire tree
when the worktree path contains "branches".

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

role_session_router.py

@@ -14,6 +14,45 @@ ROUTE_TO_REVIEWER = "route_to_reviewer_session"
 ROUTE_AMBIGUOUS = "ambiguous_task_stop"
 ROUTE_INFRA_STOP = "infra_stop"
 
+_CONFLICT_HEAD = b"<" * 7 + b" "
+_CONFLICT_TAIL = b">" * 7 + b" "
+_CONFLICT_SEPARATOR = b"=" * 7
+
+
+def python_bytes_have_conflict_markers(content: bytes) -> bool:
+    """Return True when *content* contains git merge-conflict marker lines."""
+    for line in content.splitlines():
+        stripped = line.rstrip(b"\r\n")
+        if stripped.startswith(_CONFLICT_HEAD):
+            return True
+        if stripped.startswith(_CONFLICT_TAIL):
+            return True
+        if stripped == _CONFLICT_SEPARATOR:
+            return True
+    return False
+
+
+def skip_python_scan_walk_root(project_root: str, walk_root: str) -> bool:
+    """Skip venv/git/cache and sibling worktrees under orchestration checkout.
+
+    When *project_root* is itself a worktree inside ``branches/``, still scan
+    that tree — do not treat the ``branches`` path segment as a skip signal.
+    """
+    rel = os.path.relpath(walk_root, project_root)
+    if rel == ".":
+        return False
+    head = rel.split(os.sep, 1)[0]
+    if head in ("venv", ".git", ".pytest_cache"):
+        return True
+    if head == "branches":
+        nested = os.path.join(project_root, "branches")
+        if os.path.isdir(nested) and (
+            walk_root == nested or walk_root.startswith(nested + os.sep)
+        ):
+            return True
+    return False
+
+
 REVIEWER_TASKS = frozenset({
     "review_pr",
     "merge_pr",
@@ -259,6 +298,25 @@ def check_author_mutation_after_reviewer_stop(mutation_task: str) -> tuple[bool,
     return True, []
 
 
+def first_conflict_marker_path(project_root: str | None = None) -> str | None:
+    """Return the first .py path containing a git conflict marker, or None."""
+    root_dir = project_root or os.path.dirname(os.path.abspath(__file__))
+    for root, dirs, files in os.walk(root_dir):
+        if skip_python_scan_walk_root(root_dir, root):
+            continue
+        for file in files:
+            if not file.endswith(".py"):
+                continue
+            file_path = os.path.join(root, file)
+            try:
+                with open(file_path, "rb") as f:
+                    if python_bytes_have_conflict_markers(f.read()):
+                        return file_path
+            except OSError:
+                pass
+    return None
+
+
 def check_mid_merge() -> bool:
     """Return True if the repository is mid-merge, mid-rebase, or has conflict markers."""
     project_root = os.path.dirname(os.path.abspath(__file__))
@@ -269,24 +327,4 @@ def check_mid_merge() -> bool:
                 or os.path.exists(os.path.join(git_dir, "rebase-apply"))):
             return True
 
-    # Scan python files for conflict markers
-    conflict_patterns = [
-        b"<" * 7 + b" ",
-        b"=" * 7 + b"\n",
-        b"=" * 7 + b"\r\n",
-        b">" * 7 + b" "
-    ]
-    for root, dirs, files in os.walk(project_root):
-        if any(p in root for p in ("venv", ".git", ".pytest_cache", "branches")):
-            continue
-        for file in files:
-            if file.endswith(".py"):
-                file_path = os.path.join(root, file)
-                try:
-                    with open(file_path, "rb") as f:
-                        content = f.read()
-                        if any(pattern in content for pattern in conflict_patterns):
-                            return True
-                except Exception:
-                    pass
-    return False
+    return first_conflict_marker_path(project_root) is not None