jitx-skills

Base skill for JITX Python hardware design projects, PCB design, circuit creation, board builds, and JITX CLI workflows. Use when the user asks to build a JITX design, set up the environment, create circuits, design a PCB from requirements, or create a full project. Route component modeling to jitx-component-modeler, substrate or stackup work to jitx-substrate-modeler, physical layout code to jitx-physical-layout, and mechanical CAD import/export work to jitx-mechanical.

This skill should be used when the user asks to "wire up", "connect", "build a circuit", create an "application circuit", work with passives (resistors, capacitors), set up power connections, "add pours", or "place components". Covers the Circuit class, net operators, passive queries, voltage dividers, and copper geometry. For provide/require pin assignment patterns, use jitx-pin-assignment instead.

Same-model self-critique pass for JITX Python code just written in this workspace. Use when the user asks to "review my JITX code", "self-critique", "check JITX conventions", "find string-hacking", "check framework-boundary issues", "audit before merge", or any equivalent. Mandatory for complete-board tier at task acceptance (folds into Think Twice); user-invoked for single-task work. Catches the architectural failure modes that grep gates and static linters miss — parallel string-keyed models, reflection-as-iteration (regardless of whether on self), owner-shaped data misplaced in design code, build-spec-then-iterate, module-import-time parallel models, and framework-boundary-bypass (the "framework does it, therefore so can I" trap). Applies an ownership test to every banned-pattern hit or proposed exception. Produces severity-tagged findings (CRITICAL / WARNING / NOTE) that fold into the task acceptance block.

Use when the user asks about topology using the double-greater-than operator, timing constraints, skew matching, insertion loss limits, differential pairs, DiffPair bundles, protocol constraints for PCIe, USB, DisplayPort, RGMII, Ethernet, DDR, pin models, reference planes, length matching, impedance-controlled routing, or SignalConstraint definitions. Covers TopologyNet, Constrain, ConstrainDiffPair, ConstrainReferenceDifference, DiffPairConstraint, ReferencePlanes, and protocol-specific constraint patterns.

Mechanical CAD interface for JITX designs. Use when the user asks to import DXF, EMN, IDF, IDX, or BDF mechanical data; set a board outline from mechanical CAD; export a JITX board to DXF; attach STEP models; or work with mechanical CAD data. Also covers how to export a full board STEP (UI-only in py-jitx 4.2.x — there is no CLI).

Use when the user asks to author PCB physical layout from code: draw copper, antennas, filters, net ties, custom shapes, board outlines, custom pads, soldermask or paste openings, thermal pads with vias, code-placed vias, fanout or escape tags, direct-connect or thermal-relief tags, control points, code-based routes, escape routing, or deskew. Covers shapely geometry, Copper, OverlappableCopper, Pour, pad features, PortAttachment, explicit placement, layout-intent tags, and Route control-point APIs. Use jitx-substrate-modeler for stackups, vias, routing structures, fence-via rules, and fenced pours; use jitx-circuit-builder for net wiring, passives, and basic pours.

Use when the user asks about provide/require patterns, provide.one_of or provide.subset_of decorators, programmatic Provide, pin muxing, MCU peripherals on shared pins, DiffPair polarity swapping, PCIe lane swapping or width variants, DDR byte or bit swapping, LPDDR5 channel swapping, hierarchical provider composition, topology on pin-assigned ports, constraints with provide/require, or flexible pin mapping for FPGAs and MCUs. Covers provide, Provide, require, all_of, one_of, subset_of, and protocol-specific pin flexibility with SI constraints.

Use when the user asks to create a substrate, define a stackup, add via definitions, set up routing structures, configure impedance control, define differential pairs, set fabrication rules, ring a shape with fence vias, fence a pour outline, fence an antipad, model a PCB layer structure, model a substrate from a fabrication house's stackup report (CSV, PDF, or quote), or verify a substrate against its source report. Ask which fabrication house is targeted. If JLCPCB is confirmed, use available jitxlib.jlcpcb predefined substrates; otherwise create a custom substrate. Covers Stackup, Symmetric, materials, vias, routing structures, differential routing structures, NeckDown, via fencing, fenced pours, geometry, reference planes, and FabricationConstraints.