Centralize report path policy

docs/internal/report-registry.md

@@ -6,8 +6,9 @@ membership, and comparison declarations in `internal/report`.
 ## Purpose
 
 `internal/report` centralizes report definitions so report IDs, prompt IDs,
-default output names, comparison strategies, and valid periods are declared in
-one package.
+artifact groups, batch output names, generated-report eligibility, comparison
+compatibility, comparison strategies, and valid periods are declared in one
+package.
 
 ## Inputs And Outputs
 
@@ -32,8 +33,8 @@ Outputs:
 
 ## Config Fields Used
 
-The app supplies `weather_api.timezone` as a loaded `time.Location`. Report
-output path copying uses default output names from report definitions.
+The app supplies `weather_api.timezone` as a loaded `time.Location`. Batch
+output path copying uses batch output names from report definitions.
 
 ## External Adapters Used
 
@@ -43,7 +44,8 @@ None.
 
 None directly. Resolved metadata contributes RunID, report ID, prompt ID,
 generation time, timezone, and valid period to later briefing and state
-metadata.
+metadata. Artifact groups declared by report definitions are used by state path
+construction.
 
 ## Skip And Resume Behavior
 
@@ -68,4 +70,6 @@ Inspect:
 - Report selection goes through the registry.
 - Daily Today and Daily Tomorrow both use `weather.daily_report`.
 - Valid periods are half-open intervals independent of rendered report text.
-- Comparison strategy is declared by report definition.
+- Artifact grouping, batch output filenames, generated-report eligibility,
+  comparison compatibility, and comparison strategy are declared by report
+  definition.