# Prompt Input Internals

This document describes prompt input data package construction.

## Purpose

`internal/promptinput` converts report metadata, module snapshots, and optional
Recent Changes into the YAML `data_package` passed to Scriptorium prompts.

## Inputs And Outputs

Inputs:

- report metadata
- `module.Snapshot`
- optional `[]changes.Change`

Outputs:

- `promptinput.Package` containing schema version, RunID, report metadata,
  named module stanzas under `briefing`, Recent Changes, and source warnings.
- report metadata includes `currentLocalDate`, the generation date formatted as
  `YYYY-MM-DD` in the effective report timezone.
- optional YAML file written by `promptinput.Save`

## Boundaries

- This package owns the prompt input schema and validation.
- It does not fetch weather data, derive forecast summaries, find prior
  snapshots, compare changes, or invoke Scriptorium.

## Config Fields Used

None directly. Config-derived values, including timezone and prompt location
context, are already present in report metadata and module stanzas before this
package runs.

## External Adapters Used

None.

## State Or Manifest Behavior

`promptinput.Save` writes YAML atomically. Managed workspace paths are owned by
`internal/state`.

## Skip And Resume Behavior

None. Recent Changes is always present as an `items` list and may be empty.

## Failure Behavior

Validation fails before render preflight when required top-level fields are
missing or inconsistent, or when no named module stanzas are present. Save
failures include filesystem operation and path context.

## Tests

Inspect:

- `internal/promptinput/package_test.go`
- `internal/app/app_test.go`

## Invariants

- Scriptorium receives structured `data_package` YAML.
- Module stanza order is deterministic for generated snapshots.
- Recent Changes are not inferred from rendered report text.