# Internal Sources And Validation

## Purpose

This document describes Promptkit's implemented internal source, artifact,
rendering, and output-validation behavior. The
[architecture policy](../policy/architecture.md) owns the library boundary and
dependency rules. None of these internal packages is a supported consumer API,
and the root package does not yet assemble them into a usable engine.

## Prompt Definitions

`internal/promptdef` loads prompt definitions from an operating-system
filesystem or an `fs.FS`. It discovers YAML deterministically, decodes fields
strictly, validates definitions, selects an ID and optional version, and
resolves file-backed message content within the selected source.

Its package tests own prompt selection, strict decoding, definition validation,
duplicate detection, and source containment:
[prompt-definition repository tests](../../internal/promptdef/repository_test.go).

## Profiles And Built-Ins

`internal/profile` loads strictly decoded execution profiles from an
operating-system filesystem or an `fs.FS`. It validates required profile data,
rejects raw API keys, and supports a primary repository with fallback only
when the primary reports that a profile is absent.

`internal/profile/builtin` embeds the maintained built-in profile catalog and
can place a caller-selected repository ahead of that catalog. Profile behavior
is owned by the
[profile repository tests](../../internal/profile/repository_test.go), while
catalog completeness, duplicate IDs, and overlay behavior are owned by the
[built-in repository tests](../../internal/profile/builtin/repository_test.go).

## Ordinary Artifacts

`internal/artifact` resolves inline references and unrestricted,
caller-selected file paths. It copies content into an artifact, records
metadata and a content hash, applies a content-type fallback, and honors
context cancellation.

This ordinary reader does not implement an inbound HTTP security boundary. In
particular, it does not constrain files to an application root or impose an
HTTP request-size policy. Scriptorium's restricted HTTP reader remains an
application concern outside Promptkit. The
[artifact reader tests](../../internal/artifact/reader_test.go) own the
implemented reader behavior and failures.

## Rendering

`internal/prompt` renders definition messages as Go templates using named
artifacts and variables. It carries message roles, session IDs, and cache
control into the rendered prompt. The
[renderer tests](../../internal/prompt/renderer_test.go) own rendering behavior.

## Schemas And Output Validation

`internal/validate` provides validators backed by an operating-system
filesystem or an `fs.FS`. Validation can be skipped, require non-empty output,
require JSON, or apply a JSON Schema loaded with the source's path semantics.
Invalid generated content is returned as a validation result; inability to
load, register, or compile a schema is an operational error.

The [validator tests](../../internal/validate/standard_validator_test.go) own
basic, JSON, JSON Schema, source resolution, schema loading, compilation, and
content-failure behavior.