git:20261026.b67f9d5 to git:20261031.51fa223

---

name: orbyn-ai-application

description: "Design, implement or evaluate model-powered application behavior: grounded answers, retrieval, structured generation, tool workflows and quality/cost operation. Not model training, generic AI-assisted coding or host/provider setup."

---

# Engineer a model-powered application

Start from the user's task and the consuming project's current source, authority,

provider capabilities and data policy. AI is an implementation choice, not the

outcome. Compare the existing/manual or deterministic baseline before adding a

model, retrieval pipeline or autonomous loop. Use the smallest design that can

meet the task's quality, latency, cost and failure requirements.

For problem evidence and whether to build, use [product discovery](../orbyn-plan/references/product-discovery.md).

For an ordinary API, UI, bug fix or agent-host setup with no model-powered product

contract, use its existing owner. This skill does not train models, install an

SDK/provider, enable capture, purchase access or authorize live calls.

## Select the changed boundary

Read only the relevant method:

- [Application contract](references/application-contract.md): use-case baseline,

model versus workflow/agent, prompt/context versions and structured outputs.

- [Grounded retrieval](references/retrieval.md): ingestion/query lineage,

permission filtering, source quality and answer support.

- [Tool effects](references/tool-effects.md): proposals versus authorized effects,

semantic validation, approval, unknown outcomes and bounded loops.

- [Task evaluations](references/evaluations.md): representative slices, independent

outcomes, repeated comparisons, calibrated grading and privacy.

- [Operation and change](references/operations.md): version bundles, budgets,

fallback, qualification, rollout and retention.

## Connect the owners and evidence

Use [backend design](../orbyn-backend-design/SKILL.md) for actual authorization,

state, concurrency and effect mechanics; [UI design](../orbyn-ui-design/SKILL.md)

for usable suggestions, progress, correction, manual alternatives and recovery.

Use [TDD](../tdd/SKILL.md) for deterministic contract regressions and the

[CI owner's designated gates](../orbyn-ci-design/references/change-scope.md#designate-gates-for-the-feature-worktree)

for affected checks. Ordinary unit tests and task-quality evaluations answer

different questions. Security controls belong at actual data/effect boundaries;

a prompt instruction or schema is neither authorization nor an injection barrier.

A security scan still needs its own explicit request.

Deliver the selected baseline/design, inputs and trust boundaries, permission and

output/effect contracts, versioned evaluation plan/results, resource bounds and

unverified surfaces. Distinguish a proposed experiment, offline fixture, live

provider observation and released behavior. Missing credentials/data/authority

are limits, not reasons to install, fabricate results or run paid calls.

The [document-assistant example](examples/document-assistant.md) connects retrieval,

revocation, a tool timeout and evaluation without requiring a provider. Methods

are original local guidance; linked primary sources are research/update pointers,

not mandatory downloads or imported workflows.