# Briefing Internals

This document describes the implemented briefing package boundary.

## Purpose

`internal/briefing` builds structured report-specific briefing packages from
forecast summaries and report metadata. The package currently implements the
Daily briefing only.

## Inputs and Outputs

Inputs:

- resolved report definition and valid period
- forecast bundle
- derived daily forecast summary
- configured units and timezone

Output:

- `briefing.Package` JSON containing common metadata and Daily briefing content

## Boundaries

- Briefings are structured weather facts and context for later prompt input.
- This package does not fetch weather data, compare prior snapshots, build
  `scriptorium` data packages, or render final report prose.

## Behavior

- Common metadata includes schema version, RunID, report ID, variant, prompt ID,
  generation time, units, timezone, valid period, source location, source
  provenance, hashes, and source warnings.
- Daily content includes bottom-line inputs, daypart summaries, relevant alerts,
  outdoor window inputs, narrative periods, discussion context, and weather
  story context when available.
- Briefing JSON is written atomically by `briefing.Save`.

## Failure Behavior

- Daily briefing construction requires a Daily report definition and a derived
  daily forecast summary.
- Save failures include path and operation context.

## Tests

Inspect:

- `internal/briefing/daily_test.go`
- `internal/app/app_test.go`
- `internal/cli/root_test.go`

## Invariants

- Weather facts come from normalized and derived source data.
- Briefing output remains JSON-inspectable.
- LLM prompt input packaging and `scriptorium` execution remain outside this
  boundary.