test: isolate tests on void_test DB (stop resetDb wiping prod void)

resetDb() DROPs schema; dev DATABASE_URL pointed at the shared prod void DB on
.215. setup.js now forces a dedicated void_test DB (TEST_DATABASE_URL or derived)
and throws if it would target prod. Created void_test + pg_hba rule on CT 310.
Verified: full suite green, prod void space count unchanged (2→2).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/testing.md

@@ -0,0 +1,51 @@
+# Testing — database isolation
+
+## TL;DR
+
+Tests run `resetDb()` → **`DROP SCHEMA public CASCADE`**. They MUST run against a
+dedicated **`void_test`** database, never the prod `void` DB. This is enforced
+in code (`tests/helpers/setup.js` throws if the resolved URL still targets
+`/void`).
+
+## Why
+
+The void2 Postgres cluster on `192.168.1.215` (CT 310) is shared: the prod app
+(CT 311) and dev runs both use it. The dev `DATABASE_URL` points at the prod
+`void` database. Before isolation, `npm test` wiped production data on every run
+(spaces/tasks/etc. gone; migrations + the seeded `companion` agent re-created by
+`migrateUp`, which masked the damage).
+
+## Setup (already done — 2026-06-01)
+
+1. **`void_test` database** created on the `.215` cluster, owned by `void`:
+   ```sql
+   -- run while connected to the `void` db (the `postgres` maintenance db is
+   -- not reachable from the dev box per pg_hba.conf):
+   CREATE DATABASE void_test OWNER void;
+   ```
+2. **`pg_hba.conf`** on CT 310 (`/etc/postgresql/16/main/pg_hba.conf`) — added a
+   rule mirroring the `void` one, then `systemctl reload postgresql@16-main`:
+   ```
+   host    void_test    void    192.168.1.0/24    scram-sha-256
+   ```
+3. **`tests/helpers/setup.js`** (vitest `setupFiles`) forces the test DB and
+   guards against prod:
+   - uses `TEST_DATABASE_URL` if set, else derives it by swapping `/void` →
+     `/void_test` in `DATABASE_URL`;
+   - **throws** if the resolved URL still points at `/void`.
+4. Dev **`.env`** has `TEST_DATABASE_URL=postgres://void:…@192.168.1.215:5432/void_test`.
+
+## Running tests
+
+```bash
+npm test          # vitest; binds the pool to void_test via setup.js
+```
+
+`resetDb()` + `migrateUp()` rebuild `void_test`'s schema each run. Prod `void`
+is never touched. The guard makes a misconfiguration fail loudly instead of
+silently wiping prod.
+
+## Note
+
+`.env` (incl. `TEST_DATABASE_URL`) is git-ignored and not deployed — this is a
+dev-box concern only. Prod (CT 311) never runs the test suite.