8.6 KiB
Internal Sources And Validation
Purpose
This document describes Promptkit's implemented internal source, artifact, rendering, and output-validation behavior. The architecture policy owns the library boundary and dependency rules. None of these internal packages is a supported consumer API, and the root engine assembles them behind its public source options and values. The framework format reference owns the exact file fields, validation modes, built-in catalog, and source precedence.
Prompt Definitions
internal/promptdef uses one source-neutral flow for prompt selection and
normalization. That flow scans normalized YAML ID and version metadata,
requires one strictly decoded document per file, classifies errors for the
selected definition, detects duplicates, and normalizes the exact match.
Small operating-system and fs.FS adapters own discovery, byte reads, display
paths, content opening, and root containment. Each lookup remains a
point-in-time scan: definitions and catalogs are not cached, and file-backed
message content is opened only for the exact selected candidate.
Operating-system sources enforce containment against canonical roots and
targets so symlinks cannot escape. Injected fs.FS sources enforce containment
in their clean relative path namespace. A single-file source uses the selected
prompt file's containing directory as its root. Every content path must be
relative and is opened from its exact parsed text after a separate blank check;
contained parent components and whitespace-bearing names remain valid.
Exact prompt inspection performs one point-in-time lookup through that same repository and validates referenced message content before returning declared metadata. It does not parse templates or read profile, input, or schema sources, and it does not retain the definition for a later execution.
Its package tests own prompt selection, strict decoding, definition validation, duplicate detection, and source containment: prompt-definition repository tests.
Profiles And Built-Ins
internal/profile loads and validates execution profiles from an
operating-system filesystem or an fs.FS. A file contains exactly one YAML
document and its trimmed YAML id is its only selection identity; filenames do
not confer authority. Each point lookup reads discovered files once for their
metadata and reuses the selected file's bytes for strict decoding; unrelated
profiles are not fully decoded. Strict selected decoding recognizes the
optional backend field, trims its value, and requires a model plus at least
one non-blank backend or endpoint. File-backed extra_params values are
validated and defensively copied through the shared bounded JSON-value owner
before a profile is published. OpenAI-compatible reserved-field policy remains
with the model-client and backend-registry owners.
The overlay repository consults the next repository only when the higher-precedence repository reports that a profile is absent. A reliably selected malformed profile stops fallback, while an unrelated malformed file does not become authoritative through its filename. Loading does not check backend registry membership because the available registry belongs to the assembled engine; the runner checks membership during preparation and exact profile inspection.
The root engine assembles profile repositories in precedence order: in-memory
profiles, one ordinary configured source, an application fallback source, then
the embedded built-in catalog. An explicit file or fs.FS profile source
replaces Config.ProfileDir within the ordinary configured-source category.
Exact profile inspection performs one point-in-time lookup through those profile sources and checks the resolved target without reading prompt, input, or schema sources. It does not retain that lookup for a later execution.
internal/profile/builtin embeds the maintained built-in profile catalog.
Every embedded profile selects openrouter and inherits its endpoint and
credential environment-variable name from the built-in backend registry rather
than repeating those values. Profile loading and overlay behavior are owned by
the profile repository tests,
while catalog completeness, the backend-selection invariant, and duplicate IDs
are owned by the
built-in repository tests.
Ordinary Artifacts
internal/artifact accepts explicitly typed inline references even when their
body is empty. It also resolves unrestricted, caller-selected paths only when
they identify regular operating-system files, checking that condition before
and after opening the file. It copies content into an artifact, records
metadata and an opaque content-equality value, and applies a content-type
fallback.
Regular files are read synchronously in bounded chunks. Cancellation is checked before opening, before and after every read, and before publishing the artifact, so a canceled read never publishes partial content. The ordinary reader does not detach file reads into background goroutines.
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 own the implemented reader behavior and failures.
Rendering
internal/prompt renders definition messages as Go templates using named
artifacts and variables. Within one render, each referenced artifact body is
converted to text lazily and cached by input name for reuse across the session
and every message; the cache is not shared across renders. Conversion uses
bounded chunks and preserves the artifact bytes exactly.
Session and message parsing and execution remain synchronous. The renderer checks cancellation before and after each parse and execution boundary, between artifact conversion chunks, around each message, and before publishing the complete prompt. It cannot interrupt template work already in progress and never publishes a partial prompt after observing cancellation. It carries message roles, session IDs, and cache control into the rendered prompt. The renderer tests own rendering behavior.
Schemas And Output Validation
internal/validate provides validators backed by an operating-system
filesystem or an fs.FS. Invalid generated content is returned as a validation
result; inability to load, register, or compile a schema is an operational
error.
Every preparation operation creates one operation-local validation plan. None, basic, and JSON modes retain the effective output contract without source access. JSON Schema mode loads the root document once, resolves and compiles each transitive reference, and retains the compiled validator. Schema compiler resources use canonical escaped file or private-scheme URLs; loaders decode their paths once and enforce the configured source boundary. The provider-facing structured-output metadata uses the root document captured by the same plan.
Schema preparation and execution remain synchronous. Promptkit checks
cancellation before and after source resolution, JSON decoding, compilation,
and validation, and between bounded schema-read chunks. Once cancellation is
observed it returns the context error without publishing a partial plan or
validation result, even when a compiler or validator has just returned a
different error or a successful result. An fs.FS method or JSON Schema
dependency call already in progress cannot be preempted; Promptkit waits for
that call to return and then gives cancellation precedence. Validation does
not detach dependency work into background goroutines.
Prepare discards its validation plan after returning metadata. Run retains
its plan for initial and repaired-output validation, then discards it with the
operation. PrepareExecution retains the plan in its private frozen payload;
RunPrepared uses that plan without reopening prompt, profile, input, or
schema sources or rerendering the request. A later ordinary Run always
performs fresh source resolution and preparation.
The validator tests own basic, JSON, JSON Schema, source resolution, schema loading, compilation, frozen-reference behavior, content-failure behavior, and the synchronous cancellation boundary. Prepared execution orchestration is owned by the use-case tests.