orbyn-ai-application git:20261031.51fa223A

Immutable. This exact content never changes and is served at /api/v1/blob/de1bbba70122622a.

---
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.
- [Streaming interactions](references/streaming-interactions.md): typed progress,
  state convergence, terminal witnesses, passive history and supported pending resume.
- [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.