perf(cron): skip config load on idle scheduler ticks (idea from #33612)

Re-derivation of #33612 by @LeonSGP43 onto the rewritten scheduler (the
original is 10,692 commits behind; its tick() no longer exists in that
shape, so this is a fresh minimal fix crediting the PR's idea).

The gateway's built-in ticker calls tick(verbose=False) every 60s. The
idle early-return was gated on 'verbose and not due_jobs', so idle
GATEWAY ticks fell through to load_config() + worker-pool resolution
every minute. Return early on ANY idle tick; keep the post-tick MCP
orphan sweep (main intentionally reaps orphaned stdio children on idle
ticks).

3 new tests; mutation-checked (restoring the verbose-gated guard fails
the config-skip test). 66 scheduler tests green.

cron/scheduler.py

@@ -4158,8 +4158,20 @@ def tick(
 
         due_jobs = get_due_jobs()
 
-        if verbose and not due_jobs:
-            logger.info("%s - No jobs due", _hermes_now().strftime('%H:%M:%S'))
+        if not due_jobs:
+            # Idle tick: skip config load + pool partitioning entirely
+            # (#33612 — the gateway ticker calls tick(verbose=False) every
+            # 60s, so idle ticks previously fell through to load_config()).
+            # Still run the post-tick MCP orphan sweep: main intentionally
+            # sweeps on idle ticks so orphaned stdio children from crashed
+            # jobs are reaped even when nothing is due.
+            if verbose:
+                logger.info("%s - No jobs due", _hermes_now().strftime('%H:%M:%S'))
+            try:
+                from tools.mcp_tool import _kill_orphaned_mcp_children
+                _kill_orphaned_mcp_children()
+            except Exception as _e:
+                logger.debug("Post-tick MCP orphan cleanup failed: %s", _e)
             return 0
 
         if verbose:

tests/cron/test_idle_tick_config_skip.py

@@ -0,0 +1,58 @@
+"""Idle cron ticks must not load config (#33612 salvage).
+
+The gateway's built-in ticker calls tick(verbose=False) every 60s. Before
+the fix, idle ticks (no due jobs) fell through the verbose-only early
+return and paid a full load_config() + worker-pool resolution per tick.
+The fix returns early on ANY idle tick while preserving the post-tick MCP
+orphan sweep that main intentionally runs even when nothing is due.
+"""
+
+from __future__ import annotations
+
+from unittest.mock import patch
+
+import cron.scheduler as scheduler_mod
+
+
+def _run_idle_tick(**kwargs):
+    """Run tick() with no due jobs; return (load_config_called, sweep_called)."""
+    calls = {"load_config": 0, "sweep": 0}
+
+    def _fake_load_config(*a, **k):
+        calls["load_config"] += 1
+        return {}
+
+    def _fake_sweep():
+        calls["sweep"] += 1
+
+    with (
+        patch.object(scheduler_mod, "get_due_jobs", return_value=[]),
+        patch.object(scheduler_mod, "load_config", side_effect=_fake_load_config),
+        patch(
+            "tools.mcp_tool._kill_orphaned_mcp_children",
+            side_effect=_fake_sweep,
+        ),
+    ):
+        rc = scheduler_mod.tick(verbose=kwargs.get("verbose", False))
+    return rc, calls
+
+
+class TestIdleTickSkipsConfigLoad:
+    def test_idle_nonverbose_tick_skips_load_config(self):
+        """Gateway-style tick(verbose=False) with no due jobs: no config load."""
+        rc, calls = _run_idle_tick(verbose=False)
+        assert rc == 0
+        assert calls["load_config"] == 0, (
+            "idle tick must not load config (was loading every 60s in the gateway ticker)"
+        )
+
+    def test_idle_verbose_tick_skips_load_config(self):
+        rc, calls = _run_idle_tick(verbose=True)
+        assert rc == 0
+        assert calls["load_config"] == 0
+
+    def test_idle_tick_still_sweeps_mcp_orphans(self):
+        """The idle-tick orphan sweep is intentional on main — must survive."""
+        rc, calls = _run_idle_tick(verbose=False)
+        assert rc == 0
+        assert calls["sweep"] == 1, "idle tick must still reap orphaned MCP children"