Phase 4: add expandSkill — skill meta to injectable user text.

Compose readBody, formatBlock, and appendSuffix for reinject and /skill-reinject now (SPEC §5.3).

Co-authored-by: Cursor <cursoragent@cursor.com>

src/expand.ts

@@ -27,3 +27,10 @@ export function appendSuffix(block: string, suffix: string | undefined): string
 	}
 	return `${block}\n\n${trimmed}`;
 }
+
+/** Read SKILL.md and format full user message text for re-inject (SPEC §5.3). */
+export function expandSkill(meta: SkillBlockMeta, suffix?: string): string {
+	const body = readSkillBody(meta.filePath);
+	const block = formatBlock(meta, body);
+	return appendSuffix(block, suffix);
+}