demo-agent skill

What this is, honestly

This SKILL.md is not a running agent. It is the declaration carrier and
display identity the integrate-band guard needs to exist as a first-class citizen
of the platform (a composition.guards entry, a studio/catalog.yaml display
row, a real roster member forge studio lint can validate) — nothing more. It
is the same shape `skills/contract-check/SKILL.md`
already has for the onboard-preflight band.

The develop flow's integrate node carries agent: "demo-agent" (ADR-039 declared
dispatch); at runtime execAgent
(`packages/factory/phases/executor-table.ts`)
resolves the declared integrate-band guard and routes the node to execIntegrate, which
runs the band directly, orchestrator-side. No agent is spawned, no prompt is
assembled, and no budget is drawn.

What the band does instead

The band is spec §5 item 4's integrate step. In order:

1. boundary commit — commit stragglers so the gate and the bundle see the
   real branch tip;
2. sync invariant — push/sync the integrated branch;
3. empty-branch guard — a dev loop that produced nothing opens no PR;
4. merge-boundary gate — the full suite on the integrated tip, failing LOUD
   on a project-config error (no agent can fix a config it cannot see);
5. derive (`derive-demo-model.ts`,
   `derive-pr-body.ts`) — the
   demo.json, the DEMO.md and .forge/pr-description.md are built from the
   work items' acceptance criteria, the gate evidence those gates just produced,
   and the diff;
6. capture where the class says so — the class → gate-profile table's
   capture column selects checkpoint capture, plan output, or neither.

Why the author was deleted

The demo used to be authored by a model here, validated afterwards, and retried
with the errors pasted back into the prompt. Everything it wrote was already
known to the orchestrator, so the authoring bought nothing and cost a spawn, two
retries, a token-overlap coverage heuristic and a fix-proposal loop. Deriving the
same artifacts is reproducible and cannot fail validation, so all of that went
with it.

One thing is deliberately NOT derived: the per-criterion verdict. An
orchestrator that scored the criteria it also built the evidence for would be
grading its own work. That verdict belongs to the read-only review agent.

The name

The band's spec word is integrate, and as of forge-8vfn.6.10.18 (operator
item 85) the STATION identity matches it: the flow node id, the band guard,
resume_from, the requeue API field and the --resume-from CLI flag are all
integrate now. Two things deliberately did NOT move: this skill's own slug
(demo-agent — a name, not the station) and the demo ARTIFACT concept
(demo.json, DEMO.md, demo capture) the band still produces — those are
about the demo, not the station that runs it.