diff --git a/src/outerloop/syscall.py b/src/outerloop/syscall.py
index 4bca7b8c..70d3e121 100644
--- a/src/outerloop/syscall.py
+++ b/src/outerloop/syscall.py
@@ -47,6 +47,7 @@
 
 from outerloop.compute import GONE
 from outerloop.contract import Benchmark, Budgets
+from outerloop.syscall_cli import _rel_path_ok
 
 log = logging.getLogger(__name__)
 
@@ -254,15 +255,6 @@ def launch_task_ids(launches: Iterable[Launch], job_ids: list[str]) -> list[str]
     return []
 
 
-def _rel_path_ok(path: str) -> bool:
-    """A declared artifact must stay inside the job's tree: repo-relative,
-    no traversal, no absolute paths. (Same stance as scope normalization.)"""
-    if not path or len(path) > 500 or path.startswith(("/", "~")) or "\\" in path:
-        return False
-    parts = path.split("/")
-    return all(p not in ("", ".", "..") for p in parts)
-
-
 def read_request(workspace: Path) -> SyscallRequest | None:
     """Read and CONSUME the author's request. None = no request (the session
     finished; today's path). Malformed or over per-request bounds ->
diff --git a/src/outerloop/syscall_cli.py b/src/outerloop/syscall_cli.py
index 2ddfafe8..08c3014a 100644
--- a/src/outerloop/syscall_cli.py
+++ b/src/outerloop/syscall_cli.py
@@ -76,11 +76,10 @@ class ToolError(Exception):
 
 
 def _rel_path_ok(path: str) -> bool:
-    """MUST match syscall._rel_path_ok exactly — the CLI's fast check has to
-    accept precisely what the kernel accepts, or the author burns a sleep on a
-    post-session validation error (the very thing the tool exists to prevent).
-    Rejects absolute/`~`, backslashes, over-long, and any empty/`.`/`..`
-    component (so ``, `.`, `out/./x`, `out//x` all fail here as they do there)."""
+    """The kernel's artifact-path rule; the CLI uses the same function for
+    early feedback. It rejects absolute and home paths, backslashes, paths
+    over 500 characters, and empty, `.` or `..` path parts. This module uses
+    only the standard library because it is copied into workspaces."""
     if not path or len(path) > 500 or path.startswith(("/", "~")) or "\\" in path:
         return False
     return all(p not in ("", ".", "..") for p in path.split("/"))