Summary

Fixes #1711 — list_skills / get_skill returned the literal YAML block-scalar indicator (| or >) as a skill's description for any SKILL.md authored with description: | (or >).

Root cause

src/core/skill-catalog.ts → parseDescriptionField:

const m = raw.match(/^description:\s*["']?(.+?)["']?\s*$/m);
...
return v.length > 0 ? v : undefined;   // returns "|" for `description: |`

The single-line regex captured the block indicator | (length 1 > 0), so oneLineDescription's ?? firstProseLine(body) fallback never fired.

Fix

parseDescriptionField now detects a block-scalar header (|/> with optional chomping +/- and indent digit, optional trailing comment), folds the following indented lines into a single line, and returns undefined for an empty block so the body fallback still works. Inline (and quoted) descriptions are unchanged.

Tests

Added 4 cases to the existing oneLineDescription suite in test/skill-catalog.test.ts:

• folds a literal block scalar (|)
• folds a folded block scalar (>)
• handles chomping indicators (|-)
• never leaks a bare indicator; empty block falls back to body (regression)

bun test test/skill-catalog.test.ts   → 19 pass / 0 fail
bun run verify                         → 29 checks, all green

Scope: catalog-display only; no data path or get_skill body change.