# Report Template Internals

`internal/reporttemplate` embeds and renders the repository's native Markdown
templates. The current template IDs are `daily`, `today`, `tomorrow`, and
`hourly`. The template files, partials, and complete render-context field
reference are maintained in
[report templates](../templates.md).

## Assets and lookup

The package embeds top-level templates and shared partials. `Template` returns
the requested embedded template and fails with the requested ID when it is
unknown or unreadable.

Generated-text schemas and Promptkit definitions are owned by
`internal/promptassets`; report-template owns Markdown source only. Report
definitions select IDs, while [generated-text internals](generatedtext.md)
verifies the supported schema/template pairing.

## Rendering

`Render` loads the top-level template, creates a `text/template` with helper
functions and `missingkey=error`, parses the template, parses every shared
partial, and executes the result against the typed render context. This makes
missing context fields, bad template syntax, unreadable partials, and execution
failures actionable with template or partial context.

Top-level templates decide which shared partials they invoke. The current
partials cover daypart forecast variants, alert digest, and precipitation
timing. Template code receives curated typed contexts rather than raw data
packages or complete fact bundles, and it must not reimplement weather
selection or generated-text validation. Context construction rejects
report-identity disagreements before template execution.

## Boundaries and verification

This package does not collect weather data, build modules, validate generated
text, construct contexts, resolve report definitions, write state, execute
Promptkit, or upload reports. It produces Markdown bytes for application
orchestration to persist.

Focused tests cover template lookup, rendering, partial behavior, daypart
fallbacks, missing keys, and malformed context:

```sh
go test ./internal/reporttemplate
```

Embedded templates stay as separate files and shared fragments stay under the
partial directory. Generated-text schemas are embedded separately by
`internal/promptassets` and describe prose slots rather than deterministic
weather facts.