[Gherkin]

Closes #14. Part of #73.

Adds skills/pcb-viewer/SKILL.md, a Claude Code skill that tells an agent how to use the viewer MCP tools, and a README section on how to install it.

The skill says to:

• take net and pin names from the netlist MCP and use them as written (+3.3V on netdaq); match pads to REFDES:PIN with pin where the board has it;
• use nearest first; read testpoint, type, own, covered_by, side and distance as the tools define them; prefer a test point or through-hole pad when it is about as close;
• use nearest_vias only when no usable pad is near, and say a via is a last resort and likely under soldermask;
• give only links made by link, with a marker on a single pad or via; ask for the board list address when link warns that none is set;
• check a link with snapshot when it matters.

Format checked against https://code.claude.com/docs/en/skills: folder with SKILL.md, YAML frontmatter with name and description, description says when to use it, body well under 500 lines.

End-to-end test: static site built from tests/fixtures/netdaq-small.json, server in stdio mode, an MCP client script, and the netlist MCP. Question: "Is there a point where I can patch +3.3V close to U24?" Netlist: U24:4 (V+) is on +3.3V. nearest gave U24 pad 4 (own, SMD, TSSOP lead, F) at 0; the next pads on the trimmed board are 43 mm away. nearest_vias has a through via 0.85 mm away. link with a marker on U24:4 and focus on U24; snapshot showed the marker on pin 4. Testing showed that zoom: "selected" with +3.3V selected zooms out to most of the board, so the skill now says to focus the part instead.

Tests: mcp npm test passes (HTTP and stdio). Playwright: 105 passed, 1 failed (interaction.spec.js "an inner layer checkbox changes both sides", the known flake); that file alone then passed 46/46.

🤖 Generated with Claude Code

https://claude.ai/code/session_01FzHC7LspikUyimHw5ptN8x

[github-actions]

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2026-10-11 17:20 UTC

[Gherkin]

Review round 1 (/code-review and a line-by-line check of the skill against mcp/src/tools/*.js).

Findings:

1. skills/pcb-viewer/SKILL.md:100: the snapshot fallback covers only "not set up" and "busy". snapshot also fails with no browser, no sandbox, timeouts and "cannot open the viewer" (mcp/src/browser.js:150-173). Fix: on any snapshot error, give the link and say it was not checked.
2. skills/pcb-viewer/SKILL.md:83: "focus the part (comp:U24)" reads as the near part. selectFootprint zooms to that footprint only (web/app.js:915-921), so a marker on another part's pad can end up out of view. Fix: focus the pad's own part (its ref).
3. skills/pcb-viewer/SKILL.md:79-81,92: the skill says to select the net with a via marker, but link fails on a net with no pads (mcp/src/tools/link.js:155). Fix: on that error, leave out nets and keep the marker.
4. skills/pcb-viewer/SKILL.md:54-55: "Through-hole pads can be reached from both sides" is too broad. When one side is covered, reach() gives only the free side (mcp/src/near.js:82-88). Fix: trust side.
5. README.md:270-272: running ln -s after the cp step makes a nested pcb-viewer/pcb-viewer link, and the old copy still loads. Fix: present the link as an alternative to the copy.
6. skills/pcb-viewer/SKILL.md:33-34: a generic skill names one board ("On netdaq ..."). Fix: give it as an example.
7. skills/pcb-viewer/SKILL.md:14: "no pcb-viewer tools" assumes the server name. The user picks that name in claude mcp add. Fix: check for the tool names.
8. skills/pcb-viewer/SKILL.md:68-72: a Markdown glitch. "Vias under the near part..." joins the last bullet. "likely covered" is also stronger than the tool's "often covered" (nearest_vias.js:10-13). Fix: add a blank line and say "often".

Not fixing:

• skills/pcb-viewer/SKILL.md:57-58: "Own pads under a BGA or QFN body ... do not offer those". code-review says QFN edge pads often have a toe you can solder to. The line is about pads under the body, and it matches the tool's own warning. Whether QFN edge pads count is a hardware call, so I leave it.

Checked, no issue: frontmatter (name, a 366-char description, well under the 1,536-char listing cap); the cp and ln install commands, run into a mktemp HOME; every tool, input and output field named in the skill exists with that meaning.