Use `InstanceState` (from `src/effect/instance-state.ts`) for services that need per-directory state, per-instance cleanup, or project-bound background work. InstanceState uses a `ScopedCache` keyed by directory, so each open project gets its own copy of the state that is automatically cleaned up on disposal.
Use `makeRuntime` (from `src/effect/run-service.ts`) to create a per-service `ManagedRuntime` that lazily initializes and shares layers via a global `memoMap`. Returns `{ runPromise, runFork, runCallback }`.
When a service uses Effect Schema internally but needs Zod schemas for the HTTP layer, derive Zod from Schema using the `zod()` helper from `@/util/effect-zod`:
The `InstanceState.make` init callback receives a `Scope`, so you can use `Effect.acquireRelease`, `Effect.addFinalizer`, and `Effect.forkScoped` inside it. Resources acquired this way are automatically cleaned up when the instance is disposed or invalidated by `ScopedCache`. This makes it the right place for:
- **Subscriptions**: Yield `Bus.Service` at the layer level, then use `Stream` + `forkScoped` inside the init closure. The fiber is automatically interrupted when the instance scope closes:
- **Resource cleanup**: Use `Effect.acquireRelease` or `Effect.addFinalizer` for resources that need teardown (native watchers, process handles, etc.):
- **Background fibers**: Use `Effect.forkScoped` — the fiber is interrupted on disposal.
- **Side effects at init**: Config notification, event wiring, etc. all belong in the init closure. Callers just do `InstanceState.get(cache)` to trigger everything, and `ScopedCache` deduplicates automatically.
The key insight: don't split init into a separate method with a `started` flag. Put everything in the `InstanceState.make` closure and let `ScopedCache` handle the run-once semantics.
Use `Effect.cached` when multiple concurrent callers should share a single in-flight computation. It memoizes the result and deduplicates concurrent fibers — second caller joins the first caller's fiber instead of starting a new one.
```ts
// Inside the layer — yield* to initialize the memo
- Storing a `Fiber.Fiber | undefined` with manual check-and-fork (e.g. `file/index.ts``ensure`)
- Storing a `Promise<void>` task for deduplication (e.g. `skill/index.ts``ensure`)
-`let cached: X | undefined` with check-and-load (races when two callers see `undefined` before either resolves)
`Effect.cached` handles the run-once + concurrent-join semantics automatically. For invalidatable caches, reassign with `yield* Effect.cached(...)` — the old memo is discarded.
This checklist is only about the service shape migration. Many of these services still keep `makeRuntime(...)` plus async facade exports; that facade-removal phase is tracked separately in `facades.md`.
Some already-effectified areas still use raw `Filesystem.*` or `Process.spawn` in their implementation or helper modules. These are low-hanging fruit — the layers already exist, they just need the dependency swap.
`util/filesystem.ts` is still used widely across `src/`, and raw `fs` / `fs/promises` imports still exist in multiple tooling and infrastructure files. As services and tools are effectified, they should switch from `Filesystem.*` to yielding `AppFileSystem.Service` where possible — this should happen naturally during each migration, not as a separate sweep.
This phase is still broadly open. As of 2026-04-13 there are still 15 `makeRuntime(...)` call sites under `src/`, with 13 still in scope for facade removal. The live checklist now lives in `facades.md`.
These facades exist because cyclic imports used to force each service to build its own independent runtime. Now that the layer DAG is acyclic and `AppRuntime` (`src/effect/app-runtime.ts`) composes everything into one `ManagedRuntime`, we're removing them.
1.**Find callers.**`grep -n "Namespace\.(methodA|methodB|...)"` across `src/` and `test/`. Skip the service file itself.
2.**Migrate production callers.** For each effectful caller that does `Effect.tryPromise(() => Namespace.method(...))`:
- Add the service to the caller's layer R type (`Layer.Layer<Self,never,...|Namespace.Service>`)
- Yield it at the top of the layer: `const ns = yield* Namespace.Service`
- Replace `Effect.tryPromise(() => Namespace.method(...))` with `yield* ns.method(...)` (or `ns.method(...).pipe(Effect.orElseSucceed(...))` for the common fallback case)
- Add `Layer.provide(Namespace.defaultLayer)` to the caller's own `defaultLayer` chain
3.**Fix tests that used the caller's raw `.layer`.** Any test that composes `Caller.layer` (not `defaultLayer`) needs to also provide the newly-required service tag. The fastest fix is usually switching to `Caller.defaultLayer` since it now pulls in the new dependency.
4.**Migrate test callers of the facade.** Tests calling `Namespace.method(...)` directly get converted to full effectful style using `testEffect(Namespace.defaultLayer)` + `it.live` / `it.effect` + `yield* svc.method(...)`. Don't wrap the test body in `Effect.promise(async () => {...})` — do the whole thing in `Effect.gen` and use `AppFileSystem.Service` / `tmpdirScoped` / `Effect.addFinalizer` for what used to be raw `fs` / `Bun.write` / `try/finally`.
5.**Delete the facades.** Once `grep` shows zero callers, remove the `export async function` block AND the `makeRuntime(...)` line from the service namespace. Also remove the now-unused `import { makeRuntime }`.
### Pitfalls
- **Layer caching inside tests.** `testEffect(layer)` constructs the Storage (or whatever) service once and memoizes it. If a test then tries `inner.pipe(Effect.provide(customStorage))` to swap in a differently-configured Storage, the outer cached one wins and the inner provision is a no-op. Fix: wrap the overriding layer in `Layer.fresh(...)`, which forces a new instance to be built instead of hitting the memoMap cache. This lets a single `testEffect(...)` serve both simple and per-test-customized cases.
- **`Effect.tryPromise` → `yield*` drops the Promise layer.** The old code was `Effect.tryPromise(() => Storage.read(...))` — a `tryPromise` wrapper because the facade returned a Promise. The new code is `yield* storage.read(...)` directly — the service method already returns an Effect, so no wrapper is needed. Don't reach for `Effect.promise` or `Effect.tryPromise` during migration; if you're using them on a service method call, you're doing it wrong.
- **Raw `.layer` test callers break silently in the type checker.** When you add a new R requirement to a service's `.layer`, any test that composes it raw (not `defaultLayer`) becomes under-specified. `tsgo` will flag this — the error looks like `Type 'Storage.Service' is not assignable to type '... | Service | TestConsole'`. Usually the fix is to switch that composition to `defaultLayer`, or add `Layer.provide(NewDep.defaultLayer)` to the custom composition.
- **Tests that do async setup with `fs`, `Bun.write`, `tmpdir`.** Convert these to `AppFileSystem.Service` calls inside `Effect.gen`, and use `tmpdirScoped()` instead of `tmpdir()` so cleanup happens via the scope finalizer. For file operations on the actual filesystem (not via a service), a small helper like `const writeJson = Effect.fnUntraced(function* (file, value) { const fs = yield* AppFileSystem.Service; yield* fs.makeDirectory(path.dirname(file), { recursive: true }); yield* fs.writeFileString(file, JSON.stringify(value, null, 2)) })` keeps the migration tests clean.
-`SessionStatus` — migrated 2026-04-11. Replaced the last route and retry-policy callers with `AppRuntime.runPromise(SessionStatus.Service.use(...))` and removed the `makeRuntime(...)` facade.
-`ShareNext` — migrated 2026-04-11. Swapped remaining async callers to `AppRuntime.runPromise(ShareNext.Service.use(...))`, removed the `makeRuntime(...)` facade, and kept instance bootstrap on the shared app runtime.
-`SessionTodo` — migrated 2026-04-10. Already matched the target service shape in `session/todo.ts`: single namespace, traced Effect methods, and no `makeRuntime(...)` facade remained; checklist updated to reflect the completed migration.
-`Storage` — migrated 2026-04-10. One production caller (`Session.diff`) and all storage.test.ts tests converted to effectful style. Facades and `makeRuntime` removed.
