# Generated Text Internals

This document describes structured generated-text handling in
`internal/generatedtext`.

## Purpose

`internal/generatedtext` validates structured text returned for
generated-text-template reports and builds curated render contexts for
templates. It also owns the generated-text catalog that connects report
definitions to validators, render-context builders, schema assets, and template
assets. The implemented contracts are Tomorrow Report and Hourly Report.

## Inputs And Outputs

Inputs:

- raw GeneratedText JSON for Tomorrow Report or Hourly Report
- report metadata from `internal/briefing`
- a module snapshot from `internal/module`
- validated generated text

Outputs:

- typed `Tomorrow` generated text
- typed `Hourly` generated text
- normalized stable JSON for validated generated text
- typed `TomorrowRenderContext` values for `internal/reporttemplate`
- typed `HourlyRenderContext` values for `internal/reporttemplate`
- generated-text catalog handlers for report definitions that use
  `generated_text_template`

The hourly generated text JSON accepts:

```json
{
  "summary": "string",
  "forecast_discussion": "string",
  "precipitation_timing": "string",
  "confidence": "string"
}
```

`summary` and `forecast_discussion` are required after trimming whitespace.
`precipitation_timing` and `confidence` are optional and omitted from normalized
JSON when blank.

The Tomorrow generated text JSON accepts:

```json
{
  "summary": "string",
  "forecast_discussion": ["string"],
  "precipitation_timing": "string",
  "confidence": "string"
}
```

`summary` is required after trimming whitespace. `forecast_discussion` must
contain at least one nonblank paragraph after trimming blank items.
`precipitation_timing` and `confidence` are optional and omitted from normalized
JSON when blank.

## Boundaries

- This package owns typed generated-text validation and render-context shaping.
- It owns generated-text catalog lookup for schema/template combinations.
- It uses typed module snapshot decoding through `module.StanzaValue`.
- It does not invoke Scriptorium, write state artifacts, choose report
  definitions, compare snapshots, or own embedded template/schema files.
- It renders through `internal/reporttemplate`; embedded asset lookup remains
  in `internal/reporttemplate`.
- It does not use a Go JSON Schema dependency; schema enforcement in Go is
  limited to typed JSON decoding, unknown-field rejection, and required-field
  checks.

## Failure Behavior

- Malformed generated-text JSON fails with decode context.
- Unknown generated-text JSON fields fail during decoding.
- Empty required fields fail after trimming whitespace.
- Tomorrow forecast discussion fails when no nonblank paragraphs remain.
- Missing optional render-context stanzas become nil module pointers.
- Invalid render metadata, including missing timezone, missing generated time,
  or invalid valid period, fails before template rendering.
- Unsupported generated-text schema IDs, template IDs, or schema/template
  combinations fail during catalog lookup with report ID context.

## Tests

Inspect:

- `internal/generatedtext/hourly_test.go`
- `internal/generatedtext/tomorrow_test.go`
- `internal/generatedtext/catalog_test.go`
- `internal/generatedtext/render_context_test.go`

## Invariants

- Render contexts are curated structs, not raw prompt-input packages.
- Required generated text is normalized before downstream artifact storage.
- Generated-text-template reports must have one catalog entry matching their
  report definition schema and template IDs.
- Missing optional weather narrative stanzas produce empty or fallback render
  context fields rather than forcing raw module data into templates.