version: "1.0.0" name: express description: Use to build an XS (express-lane) feature in one pass — intake→implement→verify in a single context, no handoff chain, code-first. Triggers — "/engineer.express", "express build", building a feature whose gate_profile.lane is express.

express

The express lane for size: XS features (${CLAUDE_PLUGIN_ROOT}/references/express-lane.md). One born-die agent runs intake → implement → verify in a single context — no CP2→CP8 handoff chain, no sub-agents, no acs.md/spec.md/plan.md. The acceptance test is the spec; docs stay capped below code. Same tracker row and deterministic gates as any feature — just without the per-checkpoint re-prime that dominates a normal feature's cost.

Runs after feature-init has created the size: XS feature (or a converged prototype landed at prototype_disposition: in-place).

When to use

• feature-init handed off a feature with gate_profile.lane: express.
• A converged XS prototype (in-place) — the prototype code is the starting

implementation.

Not for: anything charter-flagged (payments/auth/migration/blast-radius), autonomy_level: low, or bigger than ~1 PR — those take the full pipeline. If you find yourself here on one of them, escalate (Step 5).

Workflow

Do the whole thing in one context. No sub-agents, no inter-phase handoffs.

1. Resolve + branch — root + manifest via ${CLAUDE_PLUGIN_ROOT}/scripts/dae_resolve.py;

load feature.md + CHARTER.md (+ prototype/ if in-place). Enforce branch hygiene via ${CLAUDE_PLUGIN_ROOT}/scripts/dae_branch.py. Re-check the guardrails — charter-flagged or autonomy_level: low → stop, hand to the full pipeline (discover-acs); express is not for those.

1. Pin behavior (test = spec) — write one Given/When/Then acceptance test

that defines done. If a prototype is the seed, reverse-engineer the test from what it demonstrates. This replaces acs.md + spec.md; do not write them.

1. Implement to green — build the minimum that passes the test. Code-first;

the only prose allowed is a ≤5-line approach note in feature.md, and only if the diff is not self-evident. Prototype in-place: the prototype code is the start — clean it, don't rewrite.

1. Verify (light) — run the deterministic gates: the acceptance test + CRAP +

${CLAUDE_PLUGIN_ROOT}/scripts/dae_ontology.py + dae_arch + dae_prose.py --changed <feature-dir> (no judgment prose pass). LLM attention only on red. No mutation, no gauntlet, no review-panel.

1. Code-over-doc check — non-code doc chars must not exceed code chars for

this feature; if they do, surface a one-line note (inform, don't block).

1. Escalation ratchet (one-way up) — if at any point the change is more than

~1 PR (decomposition trips, hidden coupling, the acceptance test won't close), promote to full S/M: write the missing acs.md/spec.md/plan.md, hand to discover-acs/plan, keep the tracker row and branch. Never downgrade silently.

1. Land — open the PR; update the tracker row via the driver

(references/tracker.md). Back gate is verify: light — present it as a choice point (${CLAUDE_PLUGIN_ROOT}/references/choice-points.md): recommend merge on green gates, autonomy_level-dialed. Honor the external-write gate (PR merge is human unless verify: auto + dae_mergeready green).

Handoff

Emit per ${CLAUDE_PLUGIN_ROOT}/references/handoff-summary.md. One handoff for the whole lane (not one per phase) — `checkpoint: null`: express is off the numbered pipeline (like discuss/prototype), so it carries no CP2→CP8 stop and its deterministic gates — not an independent LLM reviewer — are the verifier (the disjoint-verifier principle is satisfied by the scripts, and the numbered- pipeline completeness checks do not apply to an XS feature). recommended_next: "review the PR" (or auto-merge note if verify: auto). On escalation, the feature joins the numbered pipeline — emit status: escalated naming what tripped and pointing at discover-acs (CP2 onward).

References

• ${CLAUDE_PLUGIN_ROOT}/references/plain-prose.md: write every artifact this skill produces to these rules
• ${CLAUDE_PLUGIN_ROOT}/references/express-lane.md — the XS contract, guardrails, ratchet
• ${CLAUDE_PLUGIN_ROOT}/references/gate-profile.md — the size dial (XS = this lane)
• ${CLAUDE_PLUGIN_ROOT}/references/choice-points.md — the projection that sized it XS + the back-gate choice point
• Sister skills: feature-init (creates the XS feature), discover-acs (the escalation target), prototype (the in-place seed).