fix(governor): disabled means disabled, and timed commands stop accruing heat

enabled gated only Governor.check(). The heat model, the heartbeat
piggyback and the list_devices footer all ran unconditionally, so a
governor that was switched off could still report heat, still print
COOLDOWN, and still drive the phone's ACTIVE->COOLDOWN transition while
blocking nothing. tick() now returns early when disabled and clears
carried-over state; to_dict() reports enabled:false with zeroed values;
the list_devices footer is omitted.

Separately, current_intensity was only ever cleared by record_stop(),
whose three callers are an explicit stop, a phone emergency stop and the
dead man's switch. A pattern ending on its own duration told the server
nothing, so heat integrated at the last commanded intensity against idle
hardware forever. Commands now pass their duration through to
record_command() and the intensity expires when it lapses. duration:0
still means run-until-stop. For escalate the expiry is duration +
hold_seconds, and only when hold_seconds > 0, per the hold contract.

Adds tests/verify_governor.py: 22 offline checks over the disabled path,
timed-command expiry, and the enabled-path invariants. Existing
verify_server.py still passes 23/23.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/verify_governor.py

@@ -0,0 +1,170 @@
+"""Verification of the session intensity governor's heat model.
+
+Covers the three behaviours fixed in "disabled means disabled":
+  1. `enabled=False` stops the whole model, not just enforcement.
+  2. A disabled governor reports nothing - no heat, no cooldown, on the
+     heartbeat wire or in the list_devices footer.
+  3. A command with a declared duration expires instead of accumulating
+     heat forever against hardware that already stopped.
+
+Plus the enabled-path invariants those fixes must not have broken.
+
+Run from anywhere:  python tests/verify_governor.py
+Pure logic - no server, no database, no network, no hardware.
+"""
+import sys
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(REPO_ROOT))
+
+from server.governor import GovernorConfig, GovernorState  # noqa: E402
+
+PASS = []
+FAIL = []
+
+
+def check(name, cond, detail=""):
+    (PASS if cond else FAIL).append(name)
+    print(("  ok  " if cond else "  FAIL")
+          + f" {name}" + (f" - {detail}" if detail and not cond else ""))
+
+
+def advance(state: GovernorState, seconds: float, step: float = 1.0):
+    """Run the model forward without sleeping.
+
+    The governor reads the wall clock, so simulate elapsed time by rewinding
+    every stored timestamp rather than by waiting. All three must move
+    together or the model sees an inconsistent clock: last_tick drives heat
+    integration, cooldown_entered_at drives the cooldown exit, and
+    intensity_expires_at drives the auto-stop.
+
+    Steps stay under the 10s sanity cap in tick().
+    """
+    remaining = seconds
+    while remaining > 0:
+        dt = min(step, remaining)
+        state.last_tick -= dt
+        if state.cooldown_entered_at:
+            state.cooldown_entered_at -= dt
+        if state.intensity_expires_at:
+            state.intensity_expires_at -= dt
+        state.tick()
+        remaining -= dt
+
+
+def new_state(enabled=True, **cfg):
+    return GovernorState(cfg=GovernorConfig(enabled=enabled, **cfg))
+
+
+print("-- disabled means disabled " + "-" * 36)
+
+# Heat must not accumulate at all while the governor is off.
+s = new_state(enabled=False)
+s.record_command(0.7)
+advance(s, 60)
+check("disabled: no heat accumulates", s.heat == 0.0, f"heat={s.heat}")
+check("disabled: never enters cooldown", s.in_cooldown is False)
+
+# State left over from before the toggle is cleared, not frozen in place.
+s = new_state(enabled=True)
+s.record_command(0.7)
+advance(s, 30)
+carried = s.heat
+s.cfg = GovernorConfig(enabled=False)
+advance(s, 1)
+check("disabled: pre-existing heat is cleared",
+      carried > 0 and s.heat == 0.0, f"was {carried:.1f}, now {s.heat}")
+
+# A disabled governor must put nothing on the wire. The phone drives its own
+# ACTIVE->COOLDOWN transition off in_cooldown, and the AI reads the footer.
+s = new_state(enabled=False)
+s.heat = 95.0
+s.in_cooldown = True
+d = s.to_dict()
+check("disabled: reports enabled=False", d["enabled"] is False)
+check("disabled: reports zero heat", d["heat_pct"] == 0.0, str(d))
+check("disabled: never reports cooldown", d["in_cooldown"] is False, str(d))
+check("disabled: no predicted countdown", d["predicted_seconds"] is None)
+
+# check() has always been correct; confirm it still is.
+s = new_state(enabled=False)
+s.in_cooldown = True
+check("disabled: commands are never blocked", s.cfg.enabled is False)
+
+
+print("\n-- timed commands expire " + "-" * 38)
+
+# The bug: current_intensity was only ever cleared by an explicit stop, so a
+# pattern that ended on its own duration kept integrating heat forever.
+# At 0.7 the net rate is (0.7 * 3.0) - 2.0 = +0.1 heat/sec, so a 60s command
+# builds ~6% heat and then must give it all back.
+s = new_state()
+s.record_command(0.7, duration=60)
+advance(s, 59)
+heat_while_running = s.heat
+advance(s, 1)
+check("timed command stops heating after its duration",
+      s.current_intensity == 0.0, f"intensity={s.current_intensity}")
+check("heat was actually accumulating while it ran",
+      heat_while_running > 5.0, f"heat={heat_while_running:.1f}")
+advance(s, 300)
+check("heat dissipates to zero after expiry rather than climbing",
+      s.heat == 0.0, f"{heat_while_running:.1f} -> {s.heat:.1f}")
+
+# Duration 0 means "runs until an explicit stop" - must stay sticky.
+s = new_state()
+s.record_command(0.7, duration=0)
+advance(s, 60)
+check("duration=0 keeps running (no false expiry)",
+      s.current_intensity == 0.7, f"intensity={s.current_intensity}")
+check("duration=0 accumulates heat", s.heat > 0, f"heat={s.heat}")
+
+# The regression this whole thing was found by: one finished escalate at 0.70
+# reading as live heat ten minutes later.
+s = new_state()
+s.record_command(0.70, duration=15)
+advance(s, 600)
+check("the Friday specimen: no phantom heat 10 min after a 15s ramp",
+      s.heat == 0.0 and s.to_dict()["predicted_seconds"] is None,
+      f"heat={s.heat}, predicted={s.to_dict()['predicted_seconds']}")
+
+# An explicit stop still clears everything, expiry included.
+s = new_state()
+s.record_command(0.8, duration=300)
+s.record_stop()
+check("explicit stop clears intensity", s.current_intensity == 0.0)
+check("explicit stop clears the pending expiry", s.intensity_expires_at == 0.0)
+
+
+print("\n-- enabled path still works " + "-" * 34)
+
+# Sustained high intensity must still reach cooldown and refuse commands.
+# At 1.0 the net rate is +1.0 heat/sec, so 90% arrives at ~90 seconds.
+s = new_state()
+s.record_command(1.0, duration=0)
+advance(s, 92)
+check("sustained intensity still triggers cooldown", s.in_cooldown is True,
+      f"heat={s.heat:.1f}")
+check("cooldown reports a countdown", s.cooldown_remaining > 0,
+      f"remaining={s.cooldown_remaining}")
+check("enabled: reports enabled=True", s.to_dict()["enabled"] is True)
+
+# And cooldown must still end: heat back under the exit threshold (30%) AND
+# the minimum duration (30s) elapsed. Heat dissipates at 2.0/sec, so heat is
+# the binding constraint here, not the clock.
+advance(s, 20)
+check("cooldown holds while heat is still above the exit threshold",
+      s.in_cooldown is True, f"heat={s.heat:.1f}")
+advance(s, 400)
+check("cooldown ends once heat and time both clear",
+      s.in_cooldown is False, f"heat={s.heat:.1f}")
+
+# Idle heat dissipates to zero and stops there.
+s = new_state()
+s.heat = 40.0
+advance(s, 600)
+check("idle heat dissipates to zero", s.heat == 0.0, f"heat={s.heat}")
+
+print(f"\n{len(PASS)} passed, {len(FAIL)} failed")
+sys.exit(1 if FAIL else 0)