What a reversed, unfed or misplaced supply reaches – 3 codes.
Each engine decides one kind of relation; a finding's code is ENGINE.relation. Severities are the catalog's defaults – a project's domains may set others; a grade is a sub-case with its own severity, a topic the part of a code a domain switches on.
PATH.reverse reverse polarity blocked
errorpolarized: warning
What a reversed source (a battery holder, a source marked reversible) reaches through fuses, switches and push buttons is only capacitors without polarity, holders, connectors – their contacts are separate, a connector hands nothing on from one pin to another –, a bidirectional TVS, the anode of a blocking diode – on a negative rail (the protected net declared at or below 0 V) its cathode – or the drain of a PMOS whose source and gate are outside; an N-MOSFET in the ground return – drain on the source's return, source on ground, gate from the plus side – cuts the board's ground off, and then only the parts between the source's own nets count; a polarized capacitor it reaches is reverse biased (grade polarized).
reverse polarity from the topology: what a reversed source (battery holders, "source": "reversible" on the component) reaches through fuses, switches and push buttons may only be a capacitor, a holder, a connector – it passes nothing on from one contact to another –, a bidirectional TVS (values.tvs"bidirectional"), the anode of a diode whose cathode is outside, or the drain of a PMOS whose source and gate are outside; behind an N-MOSFET in the ground return ([reverse] cuts) only the parts across the source's own nets – finds e.g.: the protection diode bypassed, an IC directly on the battery
Why
A battery inserted the wrong way drives the supply negative; every IC on that rail conducts through its substrate diodes and dies within milliseconds.
What to do
A Schottky diode in series, a PMOS in the supply path with its gate to ground (block reverse-pmos), or an NMOS in the ground return with its gate to the plus side.
Sources
TI SLVA139, Reverse Current/Battery Protection Circuits (2003) – https://www.ti.com/lit/an/slva139/slva139.pdf
Open design atoomnetmarc-adlsc (2026-11-03, handbook 19.5): the bidirectional SMBJ5.0CA (D4) across the terminal, which the parts schema could not call bidirectional
Open design atoomnetmarc-adlsc (2026-11-03, handbook 19.5): the reverse-polarity N-MOSFET in the ground return (Q1, AOD442) – the README's own test: reversed, the board draws about 10 mA –, 18 false findings while PATH.reverse did not know it
Open design adafruit-microlipo-usb-c (2026-11-03, handbook 19.5): a connector passing every pin to every pin carried the reversed cell from JP4's VBAT pad to 5V and through the USB-C receptacle to CC1 and CC2
Replaces G-10
PATH.unfed every supply pin reached by a supply
error
Every supply pin (power_in) is on a net a supply reaches – a power output, a battery holder, a connector with a vbus pin – or a line or neutral pin, a mains terminal – or marked as a source, a simulation source – directly or through fuses, switches, push buttons, connectors, inductors, MOSFETs, resistors up to 100 Ω and diodes in forward direction – on a negative rail from cathode to anode.
ground and supply pins: every ground pin on the ground net (or one joined to it by a 0 Ω bridge or an inductor, or in grounds); every power_in pin on a net that a supply reaches – a power_output pin, a battery holder, a connector with a vbus, line or neutral pin or in "source": "reversible" on the component, a simulation source – directly or through fuses, switches, push buttons, connectors, inductors, MOSFETs, resistors up to 100 Ω and diodes in forward direction – finds e.g.: a rail split by a typo in its name, a ground pin on a net of its own, VDD swapped with a signal
Why
A rail split by a typo in a net name kills every board and passes every other check.
What to do
Put the pin on its rail; usually a typo in a net name or two pins swapped.
Sources
Lesson of pytree (MVP risk review, item 10, 2026-10-23): pin-to-net checked by hand for every IC, about 20 minutes, and nothing repeats it after the next change
Every ground pin is on the ground net (or one joined to it by an inductor, or in the graph's grounds), and no supply pin is on ground.
Why
A ground pin on a net of its own leaves the part unpowered; a supply pin on ground shorts the rail.
What to do
Put the pin on ground; a ground separate on purpose goes into the graph's grounds.
Sources
Lesson of pytree (MVP risk review, item 10, 2026-10-23): pin-to-net checked by hand for every IC, about 20 minutes, and nothing repeats it after the next change
