runbook(fv-outage): the circuit case — split power survives a trip on battery, but only if the colo handoff does

Operator: 'unless of course the thing trips the circuit anyway.' Correct, and it splits
into two halves with different answers.

A breaker trip is the event the split-power proposal survives: firewall + BMC is 25-40 W
on a 1500 VA unit, which is hours of battery, and on a trip the UPS stops being a
load-bearing supply and goes back to being what it is for. What it does NOT cover is the
colo's own handoff -- their switch, ONT or demarc. If that sits on the circuit we just
tripped, the outcome is a firewall running on battery with nothing upstream to talk to
and the drive happens anyway. Added as a question for the facility, because it decides
whether split power delivers remote diagnosis or merely feels like it does.

Records the case where none of it matters: removing an undersized UPS does not remove
the constraint, it promotes the next one -- UPS ~900-1200 W to circuit ~1800 W at 15 A
or ~2400 W at 20 A. Which side the four-card figure lands on decides everything, which
is what makes that single ammeter reading the load-bearing measurement of the visit.

Surfaces the lever that may avoid an electrician entirely: nvidia-smi -pl caps per-card
TGP, so the box can be made to fit its feed at a throughput cost rather than a rewiring
cost. Read nvidia-smi -q -d POWER for the enforced range before assuming how much room
the dial has, and persist any cap -- one that evaporates on reboot will hold right up
until the next power event and then silently stop holding.

persistent-memory.md

@@ -132,6 +132,17 @@ cross-check on the GPU share. Measure idle / 1-card / **2-card** / **4-card**, a
 overload; an average-only meter's figure is a FLOOR, not the draw). ⭐ The 4-card number
 goes into `servers/fv-ml1/README.md` permanently — it closes the cutover's open
 "circuit specced against half the real draw" question with a measurement.
+⚠⚠ **Removing an undersized UPS does not remove the constraint, it promotes the next
+one** (UPS ~900-1200 W → circuit ~1800 W @15 A / ~2400 W @20 A). If 4 cards + host
+exceeds the circuit, NO UPS arrangement helps. ⭐ **The lever is `nvidia-smi -pl`** —
+cap per-card TGP so the box fits its feed at a throughput cost instead of a rewiring
+cost; read `nvidia-smi -q -d POWER` for the enforced range first, and **persist the cap**
+(a limit that evaporates on reboot holds until the next power event and then does not).
+⭐ Split power (firewall+BMC on UPS, chassis on PDU) survives a *breaker* trip on
+battery — 25-40 W on a 1500 VA unit is hours — **but only delivers remote access if the
+COLO'S HANDOFF survives too**; ask the facility whether the handoff is on our circuit or
+theirs. Three questions for the visit: breaker rating, is the circuit dedicated, whose
+gear is the handoff on.
 **It will not self-recover; do not poll FV addresses.** 19 of 30 gateway aliases are
 down with no local fallback (every free local model was on fv-ml1; irv-ml1 runs no
 chat seat). On recovery: recover `power.log` first, mask Docker before the network,