# 4.1.0 → 5.0.0, entry by entry

Two breaking entries over six surfaces, one of which needs an edit. There is no codemod, and there
does not need to be: **the whole migration is deleting one line, and only if you wrote it.**

### Start here — the one edit

```diff
  jobs: {
-   driver: 'postgres',
    queues: ['app-default'],
    concurrency: 8,
  },
```

`jobs.driver` accepted `'postgres' | 'redis' | 'nats'` and had **no reader anywhere**. Boot always
built `createPgDriver`, so setting it to `redis` did not throw, did not warn and did not boot Redis
— it changed nothing and you silently got Postgres. If you were relying on it doing something, it
was not: you were on Postgres the whole time.

Which driver runs is `setJobDriver(driver)`, and only that:

```ts
setJobDriver(createPgDriver({ executor }))   // production
setJobDriver(createMemoryDriver())           // a test
```

`JobsDriver` (the type) goes with it. `JobsConfig.driver` was its only use.

**Leaving the line in also works.** A spread carries a key no type names, so a stale
`app.config.ts` still boots and the field still does nothing — `packages/core/src/config.test.ts`
pins exactly that. TypeScript will flag it; the runtime will not.

### The other four need no edit unless you wrote a test driver

They are `@ultimat3/testing`'s `subscribe` fixture, which was **declared and had no driver** — so
nothing could have been implementing these types. They changed because they described an API that
could not work: `LiveTarget` was `{ name, queryHash }`, and a node keys a subscription by
`(name, input)`; a hash is the input already thrown away.

| Was | Is |
|---|---|
| `Subscribe = (target) => Promise<LiveFeed>` | `(target, input, actor?) => Promise<LiveFeed>` |
| `LiveTarget = { name, queryHash }` | `{ name }` — the query itself |
| `LiveFeed` had no `reconnect()` | it has one |
| `DRIVER_FIXTURE_NAMES` held `subscribe` | `FRAMEWORK_FIXTURE_NAMES` does; the framework builds it |

A test that destructured `subscribe` and called it now reads:

```diff
-const feed = await subscribe(liveFeed.as(actorFor(ada), { orgId: acme.id }));
+const feed = await subscribe(liveFeed, { orgId: acme.id }, actorFor(ada));
```

The actor is the third argument rather than baked into the target because that is where the
framework puts it: the shared window is built with **no subject**, and every decision about an
actor is per subscriber.

### Behaviour that changed without breaking a type

**Error fields are escaped where they are built.** `UltimateError` and `SchemaError` run
`singleLine` over `code`, `title`, `cause`, `fix` and `docs` in their constructors, so `.message`,
`.cause`, `format()`, `toJSON()` and any renderer you write are one line by construction. Measured
over every shipped `cause:`/`fix:` literal: none contains a newline, so no framework message
changed. If you build error text from a value a CALLER controls, you no longer have to remember —
and if you were already escaping, `singleLine` is idempotent, so nothing doubles.

**One `fix:` line changed text.** `X_REPLICATION_FAILED` on SQLSTATE `42704` said
`x db replication init`, which is not a command — `x db` takes `gen`, `migrate`, `reset`, `seed`,
`studio`, `branch`, `backfill`. It now names the `CREATE PUBLICATION` an operator can paste.

### One thing to know before you subscribe to a projected live query

Not a change in this release — a defect it made visible. If a `query({ live: true })` declares an
`orderBy` on a column its rows do **not** carry (a projection that omits it), every change to a row
reads as a move, and the re-delivered row is the raw entity row rather than the projection. Columns
you left out of the projection reach the subscriber. [#230](https://github.com/developerz-ai/ultimate/issues/230),
and [Known gaps](/known-gaps) carries it. Until it is fixed, order a live query by a column its rows
carry.