diff --git a/tests/tools/test_terminal_tool_requirements.py b/tests/tools/test_terminal_tool_requirements.py
index b87bca9da4..bdf85c9d04 100644
--- a/tests/tools/test_terminal_tool_requirements.py
+++ b/tests/tools/test_terminal_tool_requirements.py
@@ -360,3 +360,34 @@ class TestCheckFnTransientFailureSuppression:
 
         assert "terminal" not in names
         assert "execute_code" not in names
+
+
+class TestUnscopedSecretReadLogging:
+    """#100697: with multiplexing on, boot-time check_fns run before any
+    profile secret scope exists, so get_secret fails closed with
+    UnscopedSecretError. That expected signal must not be logged like a
+    crashed check_fn (WARNING + traceback); an unscoped read reported while
+    the scope was *resolved* is a genuinely lost scope and stays loud."""
+
+    def test_expected_fail_closed_probe_is_quiet_but_lost_scope_stays_loud(self, caplog):
+        import logging
+
+        import tools.registry as reg
+        from agent.secret_scope import get_secret, set_multiplex_active
+
+        def probe():
+            return bool(get_secret("REGISTRY_LOG_PROBE_TOKEN", ""))
+
+        set_multiplex_active(True)
+        try:
+            with caplog.at_level(logging.DEBUG, logger="tools.registry"):
+                assert reg._run_check_fn_uncached(probe, unresolved_scope=True) is False
+                boot = [r for r in caplog.records if r.name == "tools.registry"]
+                caplog.clear()
+                assert reg._run_check_fn_uncached(probe, unresolved_scope=False) is False
+                lost = [r for r in caplog.records if r.name == "tools.registry"]
+        finally:
+            set_multiplex_active(False)
+
+        assert boot and all(r.levelno == logging.DEBUG and r.exc_info is None for r in boot)
+        assert any(r.levelno >= logging.WARNING and r.exc_info for r in lost)
diff --git a/tools/registry.py b/tools/registry.py
index bf6d52f2ee..7107b3ad31 100644
--- a/tools/registry.py
+++ b/tools/registry.py
@@ -348,8 +348,33 @@ def check_fn_cache_scope() -> Optional[str]:
 
 def _run_check_fn_uncached(fn: Callable, *, unresolved_scope: bool = False) -> bool:
     """Run an availability check without cache/grace handling."""
+    from agent.secret_scope import UnscopedSecretError
+
     try:
         return bool(fn())
+    except UnscopedSecretError:
+        if unresolved_scope:
+            # Expected fail-closed probe: with multiplexing on, boot-time
+            # check_fns run before any profile secret scope exists, so
+            # get_secret raises by design. The tool re-probes on the first
+            # scoped turn — log without a traceback so this cannot be
+            # mistaken for a crashed check_fn (#100697).
+            logger.debug(
+                "check_fn %s hit the multiplex fail-closed path with no "
+                "profile secret scope active; dependent tools re-probe on "
+                "the first scoped turn",
+                getattr(fn, "__qualname__", fn),
+            )
+            return False
+        # The scope resolved but the read still failed closed: a genuinely
+        # lost scope. Keep the loud crash-style report.
+        logger.warning(
+            "check_fn %s raised UnscopedSecretError while the profile cache "
+            "scope was resolved; dependent tools will be unavailable this turn",
+            getattr(fn, "__qualname__", fn),
+            exc_info=True,
+        )
+        return False
     except Exception:
         detail = " while profile cache scope was unresolved" if unresolved_scope else ""
         logger.warning(