diff --git a/skills/bmad-story-automator/src/story_automator/commands/basic.py b/skills/bmad-story-automator/src/story_automator/commands/basic.py
index 3869f8ea..2f8cb16a 100644
--- a/skills/bmad-story-automator/src/story_automator/commands/basic.py
+++ b/skills/bmad-story-automator/src/story_automator/commands/basic.py
@@ -141,7 +141,7 @@ def cmd_ensure_stop_hook(args: list[str]) -> int:
 
 
 def cmd_stop_hook(_: list[str]) -> int:
-    sys.stdin.read()
+    raw = sys.stdin.read()
     if os.environ.get("STORY_AUTOMATOR_CHILD", "").lower() == "true":
         return 0
     marker = active_marker_path()
@@ -151,6 +151,16 @@ def cmd_stop_hook(_: list[str]) -> int:
         payload = json.loads(marker.read_text())
     except json.JSONDecodeError:
         return 0
+    owner = (payload.get("ownerSession") or "").strip()
+    if owner:
+        sid = ""
+        try:
+            if raw.strip():
+                sid = (json.loads(raw) or {}).get("session_id", "") or ""
+        except json.JSONDecodeError:
+            sid = ""
+        if sid and sid != owner:
+            return 0
     remaining = payload.get("storiesRemaining", 0)
     if isinstance(remaining, str) and remaining.isdigit():
         remaining = int(remaining)
diff --git a/skills/bmad-story-automator/src/story_automator/commands/orchestrator.py b/skills/bmad-story-automator/src/story_automator/commands/orchestrator.py
index 87d048c1..41938cf4 100644
--- a/skills/bmad-story-automator/src/story_automator/commands/orchestrator.py
+++ b/skills/bmad-story-automator/src/story_automator/commands/orchestrator.py
@@ -191,6 +191,7 @@ def _marker(args: list[str]) -> int:
             "heartbeat": options["heartbeat"] or iso_now(),
             "pid": int(options["pid"] or "0"),
             "projectSlug": options["project-slug"],
+            "ownerSession": os.environ.get("CLAUDE_CODE_SESSION_ID", ""),
         }
         atomic_write(marker_file, json.dumps(payload, indent=2) + "\n")
         print(f"Marker created: {marker_file}")
diff --git a/tests/test_stop_hooks.py b/tests/test_stop_hooks.py
index a27513b9..56a179b8 100644
--- a/tests/test_stop_hooks.py
+++ b/tests/test_stop_hooks.py
@@ -13,6 +13,7 @@
 from unittest.mock import patch
 
 from story_automator.commands.basic import cmd_ensure_stop_hook, cmd_stop_hook
+from story_automator.commands.orchestrator import cmd_orchestrator_helper
 
 
 REPO_ROOT = Path(__file__).resolve().parents[1]
@@ -416,6 +417,56 @@ def test_stop_hook_uses_project_root_env_when_invoked_from_nested_directory(self
         payload = json.loads(stdout.getvalue())
         self.assertEqual(payload["decision"], "block")
 
+    def test_stop_hook_blocks_the_owning_session(self) -> None:
+        self._install_bundle(".agents")
+        marker = self.project_root / ".agents" / ".story-automator-active"
+        marker.parent.mkdir(parents=True, exist_ok=True)
+        marker.write_text(json.dumps({"storiesRemaining": 2, "ownerSession": "owner-123"}), encoding="utf-8")
+        stdout = io.StringIO()
+        with (
+            patch.dict(os.environ, {"PROJECT_ROOT": str(self.project_root)}, clear=False),
+            patch("story_automator.commands.basic.sys.stdin", io.StringIO(json.dumps({"session_id": "owner-123"}))),
+            patch("os.getcwd", return_value=str(self.project_root)),
+            redirect_stdout(stdout),
+        ):
+            code = cmd_stop_hook([])
+        self.assertEqual(code, 0)
+        self.assertEqual(json.loads(stdout.getvalue())["decision"], "block")
+
+    def test_stop_hook_allows_a_different_session_while_run_active(self) -> None:
+        self._install_bundle(".agents")
+        marker = self.project_root / ".agents" / ".story-automator-active"
+        marker.parent.mkdir(parents=True, exist_ok=True)
+        marker.write_text(json.dumps({"storiesRemaining": 2, "ownerSession": "owner-123"}), encoding="utf-8")
+        stdout = io.StringIO()
+        with (
+            patch.dict(os.environ, {"PROJECT_ROOT": str(self.project_root)}, clear=False),
+            patch("story_automator.commands.basic.sys.stdin", io.StringIO(json.dumps({"session_id": "other-session"}))),
+            patch("os.getcwd", return_value=str(self.project_root)),
+            redirect_stdout(stdout),
+        ):
+            code = cmd_stop_hook([])
+        self.assertEqual(code, 0)
+        self.assertEqual(stdout.getvalue(), "")
+
+    def test_marker_create_records_owner_session_from_env(self) -> None:
+        self._install_bundle(".agents")
+        stdout = io.StringIO()
+        with (
+            patch.dict(
+                os.environ,
+                {"PROJECT_ROOT": str(self.project_root), "CLAUDE_CODE_SESSION_ID": "owner-xyz"},
+                clear=False,
+            ),
+            patch("os.getcwd", return_value=str(self.project_root)),
+            redirect_stdout(stdout),
+        ):
+            code = cmd_orchestrator_helper(["marker", "create", "--epic", "e1", "--story", "e1-1", "--remaining", "2"])
+        self.assertEqual(code, 0)
+        marker = self.project_root / ".agents" / ".story-automator-active"
+        payload = json.loads(marker.read_text(encoding="utf-8"))
+        self.assertEqual(payload["ownerSession"], "owner-xyz")
+
     def test_ensure_stop_hook_codex_updates_dotted_features_toml(self) -> None:
         self._install_bundle(".agents")
         codex_dir = self.project_root / ".codex"