Document current outlook schema behavior

docs/internal/postgres-sink.md

@@ -19,11 +19,16 @@ Inputs are canonical feed events. The mapper currently handles these schemas:
 - `weather.forecast_discussion.v1`
 - `weather.weather_story.v1`
 - `weather.alert.v1`
-- `weather.outlook.v1`
+- `weather.outlook.v2`
 
 Outputs are feedkit `PostgresWrite` values for weatherfeeder-owned tables.
 Unsupported schemas produce no writes and no error.
 
+Outlook runs are written to `outlook_runs`, retained local polygons are written
+to `outlooks`, and run-level day discussions are written to
+`outlook_discussions`. The parent run row stores `outlook_count` and
+`discussion_count`.
+
 ## Boundaries
 
 - Weatherfeeder owns table definitions in `schema.go`.
@@ -82,6 +87,7 @@ Child rows use positional indexes to preserve canonical array order:
 - `alert_index`
 - `reference_index`
 - `outlook_index`
+- `discussion_index`
 
 Required canonical fields are validated before writes are returned:
 
@@ -94,7 +100,10 @@ Required canonical fields are validated before writes are returned:
 - alert runs require `asOf`, and each alert requires `id`;
 - outlook runs require `asOf`, and each outlook requires `id`, `provider`,
   `product`, `day`, `outlookType`, `label`, `validFrom`, `validTo`, `issuedAt`,
-  `expiresAt`, and `geometry`.
+  `expiresAt`, `containsLocation: true`, and `geometry`;
+- outlook discussions require day `1`, `2`, or `3`; at least one of
+  `headline`, `summary`, or `discussion`; and no duplicate discussion day in the
+  same run.
 
 Nullable canonical values are converted to SQL nulls by mapper helpers.
 Observation present-weather raw values and outlook geometry values are stored as