finish local dev setup

supabase/README.md

@@ -44,12 +44,41 @@ Write plain SQL. Conventions:
 
 ## Local dev
 
-`nix run .#dev` starts a plain Postgres via process-compose; apply migrations
-to it the same way:
+`nix run .#dev` applies everything automatically: its `db-migrate` process
+bootstraps the Supabase roles/schemas, runs `supabase db push`, and loads
+`seed.sql` on every start (all idempotent — see
+`nix/dev/process-compose.nix`). To re-apply by hand against the running dev
+Postgres, do it as the local superuser (your OS user — `gebos_ingest` is only
+*created* by the migration and has no DDL rights). The CLI ignores `sslmode`
+in the URL, so TLS must be disabled via the environment:
 
 ```sh
-supabase db push --db-url "postgres://gebos_ingest:dev@127.0.0.1:5432/gebos"
+PGSSLMODE=disable supabase db push --db-url "postgres://$USER@127.0.0.1:5432/gebos"
 ```
 
-(Note: the dev database has no TimescaleDB unless the process-compose postgres
-gains the extension — `create_hypertable` calls will fail there until then.)
+(The dev postgres ships TimescaleDB — the Apache edition, which covers
+hypertables; TSL-only features like compression are absent locally.)
+
+## Seed / fixture data (dev and tests only)
+
+`seed.sql` fills the local database with a self-consistent fixture world:
+2 buildings (gas / district heating), 8 apartments, tenants incl. a
+Mieterwechsel and a vacancy, gateways, sensors (incl. one unassigned), ~13
+months of daily cumulative measurements with realistic seasonality, and
+approximate reference data (thresholds, CO2 factors, prices, HDD). The header
+comment in the file documents every scenario and the fixed-UUID namespaces.
+
+Apply it after the migrations, with a superuser (the seed writes tables the
+`gebos_ingest` role may not):
+
+```sh
+psql -h 127.0.0.1 -p 5432 -d gebos -f supabase/seed.sql
+```
+
+It is idempotent (fixed UUIDs + `ON CONFLICT DO NOTHING`, deterministic
+measurement generation) — re-running on a later day only appends the new
+days of measurements.
+
+**Never apply it to prod**: the tenants and devices are fake, and the
+regulatory numbers are development approximations, not verified values from
+the legal sources. Verified reference data belongs in its own migration.