Skill frontmatter parser silently drops triggers (block sequences → empty, inline → quote-polluted) #1970

Summary

parseFrontmatter (packages/squad-sdk/src/skills/skill-loader.ts:48) is a naive line-based parser that only understands inline arrays. Two consequences, both of which silently disable skill discovery — no error, no warning, skill just never matches.

Found while strengthening a test in #1946 (the weak assertion there had been masking it).

Defect 1 — YAML block sequences produce no triggers

triggers:
  - "set up Squad agentic workflows"

The triggers: line has an empty post-colon value, so the parser stores the empty string. parseSkillFile then does Array.isArray(meta.triggers) ? meta.triggers : [] (skill-loader.ts:131) → []. The - "…" lines contain no colon and are skipped entirely.

Defect 2 — inline arrays retain quote characters

The inline branch splits on , and trims, but never strips quotes, so triggers come back as "\"squad commands\"" — with literal " characters that will never match user text.

Measured

block         -> ""                     (undiscoverable)
inline+quoted -> ["\"a phrase\"", ...]  (quotes retained — never matches)
inline bare   -> ["a phrase", ...]      (correct)

Affected skills

27 skills exist; only 3 declare triggers at all:

So every skill that declares triggers is currently mis-parsed, and #1946 worked around it locally rather than fixing the parser.

This is the array the runtime matcher iterates (packages/squad-sdk/src/skills/index.ts:75), so the impact is real skill-matching failure, not cosmetic.

Reproduce

const { parseFrontmatter } = require('packages/squad-sdk/dist/skills/skill-loader.js');
const t = (l, fm) => console.log(l, '->', JSON.stringify(parseFrontmatter('---\n'+fm+'\n---\nbody').meta.triggers));
t('block      ', 'triggers:\n  - "a phrase"');
t('inline+quot', 'triggers: ["a phrase"]');
t('inline bare', 'triggers: [a phrase]');

Blast radius

parseFrontmatter is shared — skill-source.ts calls it in 6 places (lines 68, 87, 107, 160, 177, 195). There is no real YAML parser anywhere in this path, so fixing it changes behavior for all skill loading. Notably, fixing quote-stripping will change squad-commands' runtime triggers from quoted to unquoted, which is the intended correction but is still a behavior change worth calling out in review.

Suggested fix

1. Support block sequences: after a key with an empty value, consume following - item lines into an array.
2. Strip surrounding matched quotes from scalar and array values.
3. Convert cross-squad and squad-commands to whatever form is then canonical, and pick one documented form for skill authors.
4. Add a guard asserting that every skill declaring triggers: parses to a non-empty array — that single assertion would have caught all of this.

Acceptance criteria

• Block-sequence triggers: parses to a non-empty string array
• Quotes stripped from both scalar and array frontmatter values
• cross-squad and squad-commands verified discoverable at runtime
• Guard test fails if any skill's declared triggers parse to []
• Existing 27 skills still load; no regression in skill-source.ts consumers