Files
weatherreporter/docs/internal/changes.md

76 lines
2.0 KiB
Markdown

# Changes Internals
This document describes structured Recent Changes comparison.
## Purpose
`internal/changes` compares current and prior module snapshots and emits
compact change records for prompt input data packages.
## Inputs And Outputs
Inputs:
- prior module snapshot
- current module snapshot
- comparison thresholds from configuration
Outputs:
- ordered `changes.Change` items with type, message, previous value, and current
value where useful
## Boundaries
- This package compares structured module snapshot data only.
- It does not read filesystem state, find prior snapshots, render Markdown,
invoke Scriptorium, or compare generated report text.
## Config Fields Used
The app maps these fields into comparison thresholds:
- `recent_change.temperature_degrees`
- `recent_change.precip_probability_points`
- `recent_change.wind_gust_miles_per_hour`
- `recent_change.precip_timing_shift_minutes`
## External Adapters Used
None.
## State Or Manifest Behavior
None directly. The app loads prior module snapshots through `internal/state`
before calling comparison functions.
## Skip And Resume Behavior
No resume behavior. When the app has no prior comparable snapshot, it sends an
empty Recent Changes list without calling a comparison function.
## Failure Behavior
- Daily comparison requires `derived_daily_summary` and
`derived_daypart_summaries` stanzas. It also uses `alert_digest` and
`precip_timing` when present.
- 3-Day comparison requires `derived_daypart_summaries`.
- Weekend comparison requires `derived_daypart_summaries`.
- Storm Report comparison returns no changes.
## Tests
Inspect:
- `internal/changes/daily_test.go`
- `internal/changes/three_day_test.go`
- `internal/changes/weekend_test.go`
- `internal/app/app_test.go`
## Invariants
- Recent Changes are based on structured snapshots, not Markdown report text.
- Report compatibility is determined outside this package by report definitions
and state lookup.
- Output stays compact enough for prompt input.