Skill Builder

/skill-builder — Scaffold or absorb a new SKILL.md

Materializes a new skill against the unified template at references/skill-template.md (extracted from anthropics/financial-services). Runs skill-auditor on the new skill as a self-check before declaring success.

⚠️ Critical Constraints

• Template is canonical. All four modes produce SKILL.md files conforming to references/skill-template.md. Do not invent ad-hoc structures. Why: skill-auditor validates against this template; drift creates auditor false-fails.
• Self-audit is mandatory. After every successful build, the build script invokes /skill-auditor against the new skill directory. A FAIL verdict aborts the build. Why: PR-002 (external validation gate) — the builder must not declare its own work complete.
• Codex parity is day-1, not later. from-scratch, from-template, and absorb-external modes must produce both skills/<name>/SKILL.md AND skills-codex/<name>/SKILL.md + skills-codex/<name>/prompt.md. Why: finding 2026-05-03-codex-skill-shape-is-dual-file — codex SKILL.md uses slim frontmatter (no skill_api_version); prompt.md is mandatory; audit-codex-parity.sh is a content scanner that won't catch frontmatter drift.
• 250-line ceiling on new SKILL.md. Use references/ for overflow. Why: finding f-2026-05-01-025 — every Skill() invocation reloads 5-15KB; multi-lifecycle sessions compound to 150-200KB+ pure scaffolding.

Modes

Workflow

Phase 1: Mode dispatch

scripts/build.sh reads $1 and routes:

build.sh from-scratch <new-skill-name>          # → init.sh --interactive
build.sh from-template <new-skill-name> --like council
build.sh absorb-external <new-skill-name> --from /path/to/SKILL.md
build.sh from-pattern                            # → ao flywheel close-loop

Checkpoint: Confirm with user the new skill's metadata.tier and metadata.dependencies before generation.

Phase 2: Materialize from template

scripts/init.sh reads references/skill-template.md (the canonical template section) and renders a SKILL.md skeleton with frontmatter pre-filled. For from-template, structure is copied from the source skill; section bodies are blanked and replaced with template stubs.

For absorb-external, the external SKILL.md's content (Constraints / Workflow / Output / Quality sections) is preserved verbatim where possible; AgentOps' structured frontmatter is added on top; the external description is reformatted to satisfy description-has-triggers.

Checkpoint: /heal-skill --check skills/<new-name> returns clean.

Phase 3: Codex parity

scripts/init.sh invokes /converter skills/<new-name> codex to produce skills-codex/<new-name>/{SKILL.md,prompt.md}. Then trims skill_api_version from the codex SKILL.md (converter may preserve it). Asserts prompt.md exists.

Checkpoint: bash scripts/audit-codex-parity.sh returns clean AND grep -q "^skill_api_version:" skills-codex/<name>/SKILL.md returns nothing.

Phase 4: Self-audit

The build script tail invokes /skill-auditor on skills/<new-name>. WARN is acceptable for v1 skills (e.g., experimental stability). FAIL aborts.

Checkpoint: audit_pass=true in build report.

Output Specification

Format: JSON conforming to schemas/build-report.json written to stdout; markdown audit report written to .agents/audits/<skill>-build.md.

Files created (from-scratch mode):

skills/<name>/
├── SKILL.md                         (≤250 lines, full template spine)
├── scripts/
│   └── validate.sh                  (self-validation per AgentOps convention)
└── references/                      (only if expected to exceed 400 lines)
skills-codex/<name>/
├── SKILL.md                         (slim frontmatter — no skill_api_version)
└── prompt.md                        (~10-20 line Execution Profile)

Quality Rubric

• All four modes produce skills that pass skill-auditor PASS or WARN (not FAIL)
• Codex parity files exist and pass slim-frontmatter check
• No SKILL.md exceeds 250 lines (overflow goes to references/)
• Build report JSON validates against schemas/build-report.json
• from-pattern mode prominently marked alpha/passthrough in user output

Examples

Create a new skill from scratch:

/skill-builder from-scratch hello-world
# → interactive prompt: tier? deps? primary deliverable?
# → writes skills/hello-world/SKILL.md + skills-codex/hello-world/{SKILL.md,prompt.md}
# → runs /skill-auditor on the new skill

Clone structure from an existing skill:

/skill-builder from-template my-new-skill --like council
# → mirrors council's section spine; substitutes new metadata

Absorb a skill from anthropics/financial-services:

/skill-builder absorb-external dcf-helper \
  --from ~/dev/financial-services/plugins/vertical-plugins/financial-analysis/skills/dcf-model/SKILL.md
# → preserves Constraints/Workflow/Output content, wraps in AgentOps frontmatter

Troubleshooting

See Also

• skill-auditor — companion audit gate, invoked by build self-check
• heal-skill — structural hygiene (Pass 1 of skill-auditor wraps heal.sh)
• converter — produces codex parity artifacts
• scaffold — scaffolds projects/components/CI (NOT skills)
• forge — mines transcripts into learnings (different layer)

References

• references/skill-template.md — canonical SKILL.md template + auditor checklist + PRODUCT.md alignment