Document template partials

docs/internal/reporttemplate.md

@@ -12,6 +12,7 @@ Tomorrow, and Hourly.
 The package embeds assets from:
 
 - `internal/reporttemplate/templates/*.md.tmpl`
+- `internal/reporttemplate/templates/partials/*.md.tmpl`
 - `internal/reporttemplate/schemas/*.schema.json`
 
 Generated-text prompt source files live under
@@ -73,6 +74,12 @@ template and renders from `generatedtext.DailyRenderContext`.
 Templates use `text/template` with `missingkey=error`, so missing context fields
 fail rendering instead of producing incomplete Markdown.
 
+Daily and Tomorrow call the shared `daypart_forecast` partial. Today calls
+`today_daypart_forecast` so it can omit elapsed or missing dayparts. Daily,
+Today, and Tomorrow call the shared `precipitation_timing` partial. Partial
+files are parsed with each top-level template at render time and receive the
+same typed render context as the caller.
+
 ## Schema Contract
 
 The GeneratedText schemas describe the structured prose Scriptorium is expected
@@ -92,6 +99,7 @@ slots consumed by the template.
 - Unknown template IDs return actionable lookup errors.
 - Unknown schema IDs return actionable lookup errors.
 - Template parse errors include the template ID.
+- Partial read or parse errors include the partial path.
 - Template execution errors include the template ID and usually identify the
   missing context field.
 
@@ -107,6 +115,7 @@ Inspect:
 ## Invariants
 
 - Embedded templates and schemas live as separate files, not inline Go strings.
+- Shared Markdown partials live under `templates/partials/`.
 - Report definitions select templates by ID.
 - Templates render from curated render contexts, not raw data packages.
 - GeneratedText schemas describe LLM prose slots, not deterministic weather

docs/templates.md

@@ -13,6 +13,12 @@ Templates are Go `text/template` files. The current implemented templates are:
 - `internal/reporttemplate/templates/tomorrow.md.tmpl`
 - `internal/reporttemplate/templates/hourly.md.tmpl`
 
+Shared named partials live under `internal/reporttemplate/templates/partials/`:
+
+- `daypart_forecast.md.tmpl`, used by Daily and Tomorrow
+- `today_daypart_forecast.md.tmpl`, used by Today
+- `precipitation_timing.md.tmpl`, used by Daily, Today, and Tomorrow
+
 Templates are rendered from structured contexts such as `DailyRenderContext`,
 `TodayRenderContext`, `TomorrowRenderContext`, and `HourlyRenderContext`.
 Weather data collection, derivation, module execution, generated text
@@ -27,6 +33,9 @@ validation, and artifact paths are handled before template rendering.
   templates.
 - Missing template keys are errors. A misspelled variable will fail rendering.
 - No custom template functions are currently registered.
+- Named partials are invoked with `{{ template "name" . }}`. Pass the current
+  render context (`.`) unless the partial is intentionally designed for a
+  narrower value.
 - Optional module stanzas are pointers and should be guarded with
   `{{ with .Modules.WeatherStory }}...{{ end }}`.
 - Slices can be rendered with `{{ range .Items }}...{{ else }}...{{ end }}`.
@@ -131,6 +140,8 @@ Daily generated text uses `.GeneratedText.Summary`,
 `.GeneratedText.Confidence`. Forecast discussion is a slice of paragraphs and
 should be rendered with `range`.
 
+Daily uses the shared `daypart_forecast` and `precipitation_timing` partials.
+
 Daily uses template ID `daily`, generated-text schema ID `daily`, and prompt
 source `internal/reporttemplate/prompts/daily.generated_text.md`.
 
@@ -162,6 +173,10 @@ Today generated text uses `.GeneratedText.Summary`,
 `.GeneratedText.Confidence`. Forecast discussion is a slice of paragraphs and
 should be rendered with `range`.
 
+Today uses the `today_daypart_forecast` partial so elapsed or missing dayparts
+can be omitted while Daily and Tomorrow keep their fallback row. It also uses
+the shared `precipitation_timing` partial.
+
 Today uses template ID `today`, generated-text schema ID `today`, and prompt
 source `internal/reporttemplate/prompts/today.generated_text.md`.
 
@@ -282,6 +297,10 @@ Daily, Today, and Tomorrow templates should use `.Modules.Dayparts` for
 ordered daypart rendering. Each item has `Key` and `Summary`; `Summary` is a
 rich `briefing.DerivedDaypartSummaryModule`.
 
+The shared daypart partials render from these same `.Modules.Dayparts` values.
+Edit `daypart_forecast.md.tmpl` for common Daily/Tomorrow wording, and edit
+`today_daypart_forecast.md.tmpl` for Today-specific omission behavior.
+
 Common rich daypart fields:
 
 | Variable | Type | Description |