Iii Engine ConfigSAFE

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---
name: iii-engine-config
description: >-
  Configure a managed iii engine through worker-compose.yaml or a directly supervised engine
  through config.yaml. Use for engine ports, RBAC via the rbac-proxy worker, observer limits,
  streams, sandboxes, and configuration storage.
---

# Engine Config

iii has two engine configuration modes. Do not mix them.

## Managed Compose engine

The presence of `engine:` means that Compose owns the engine process. Engine worker values are
direct mappings; there is no nested `config:` field.

```yaml
namespace: orders
engine:
  url: ws://127.0.0.1:49134
  registration_namespace_grace_ms: 5000
  workers:
    configuration:
      adapter:
        name: fs
        config:
          directory: ./config
    iii-worker-manager:
      host: 127.0.0.1
      port: 49134
    iii-http-functions: {}
    iii-stream:
      host: 127.0.0.1
      port: 3112
    iii-sandbox:
      auto_install: true
containers: {}
```

Start it with:

```bash
iii compose --namespace orders-daemon --up --file worker-compose.yaml
```

`engine.url` defaults to `ws://127.0.0.1:49134` and uses Compose's `${VAR:-default}` expansion.
`engine.workers` stays opaque until the engine reads the generated YAML, so its values use
`${VAR:default}` and retain numeric types. Compose materializes an owner-only config under
`<project-dir>/.iii/compose/<daemon-namespace>/` and removes it after clean shutdown. With
`III_COMPOSE_STATE_DIR`, it uses `<state-root>/<project-slug>/<daemon-namespace>/`. Changing `engine:`
requires restarting Compose. Do not combine a managed file with explicit `--engine`.

Allowed engine worker base names are:

- `configuration`
- `iii-worker-manager`
- `iii-http-functions`
- `iii-stream`
- `iii-sandbox`

Use `#instance` for another instance of an allowed worker. `iii-engine-functions`,
`iii-telemetry`, and `iii-observability` are injected automatically and must not be declared.

HTTP, cron, queue, state, pubsub, bridge, application, and custom workers belong under
`containers:`. Add registry packages with:

```bash
iii trigger -n orders-daemon compose::add worker=state
```

## Observers

Since 0.25 the engine reads an optional top-level `observers:` section (`iii-observe` explains the
model). Every key is optional; these are the defaults:

```yaml
observers:
  local_dispatch: true            # let SDKs run a worker's own functions in-process
  max_per_connection: 1024        # observers one connection may own (LIMIT_EXCEEDED)
  max_per_function: 4096          # observers one function may have (LIMIT_EXCEEDED)
  max_observe_depth: 8            # deeper activations are dropped (LOOP_GUARD)
  observer_grace_ms: 30000        # suspended observers of a disconnected worker wait this long
  disposed_retention_ms: 3600000  # a worker back after the grace period is told they were disposed
  owner_ack_timeout_ms: 30000     # an unacknowledged add fails with OWNER_TIMEOUT
  activation_timeout_ms: 30000    # an unanswered activation frees its slot and counts as TIMEOUT
  default_max_in_flight: 64       # max_in_flight of an observer that sets none
  max_queue_per_observer: 1024    # queued activations beyond max_in_flight (then OVERFLOW)
```

- In `config.yaml` it sits next to `workers:`. In a managed Compose file it goes under
  `engine.observers` and is passed through as written.
- Unknown keys and zero counts or depth are rejected at load; zero timeouts only warn. Changes need
  an engine restart.
- `observers.local_dispatch: false` turns off in-process calls for every worker.
- Inspect live observers with `engine::observers::list({ function_id?, namespace?, worker? })` and
  `engine::observers::get({ id })` (results are filtered to functions the caller may invoke).
  `engine::observers::dispose({ id })` is allowed for the observing worker and unrestricted callers.
- Metrics: `iii.observer.activations.total{function_id,delivery}`,
  `iii.observer.dropped.total{function_id,reason}`, `iii.observers{state}`,
  `iii.observer.reports.total{function_id}`,
  `iii.observer.activation.failures.total{function_id,reason}`; locally dispatched calls are counted
  in `iii.invocations.total` with `dispatch="local"`.

## RBAC with `rbac-proxy`

Keep the engine port internal and put the `rbac-proxy` worker in front of it when
untrusted workers, browsers, or agents need to connect:

```bash
iii trigger -n orders-daemon compose::add worker=rbac-proxy
```

`rbac-proxy` opens its own WebSocket port, speaks the worker protocol verbatim, and at the boundary
authenticates each connection (`rbac.auth_function_id`), gates every invocation and trigger binding
(`rbac.expose_functions`, plus `allowed_functions` / `forbidden_functions` from the auth result),
namespaces a session's registrations (`function_registration_prefix`), runs
`middleware_function_id` and the registration hooks, and filters `engine::*` discovery results to
what the caller may invoke. Its settings live in the `configuration` worker under id `rbac-proxy`:

```yaml
host: 0.0.0.0
port: 49200                        # the public RBAC port
engine_url: ws://127.0.0.1:49134   # the trusted internal engine listener
rbac:
  auth_function_id: my-project::auth-function
  expose_functions:
    - match("api::*")
```

RBAC is mandatory on untrusted networks: only the proxy's port may face one, never the engine port,
and a public proxy must always set `auth_function_id`. Full schema: https://workers.iii.dev/workers/rbac-proxy.

Observers under RBAC (0.25 engine): creating one requires that the session may invoke both the
observed function and the target, or it fails with `FORBIDDEN`. The engine's `rbac:` settings
accept `on_observer_registration_function_id`, a hook with the same contract as
`on_trigger_registration_function_id`: an object answer may rewrite `function_id`,
`target_function_id`, `args`, `filters`, and `metadata`; any other answer denies with `FORBIDDEN`.
Sessions with a `middleware_function_id` get no local dispatch, so the middleware always 

SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (1)

sdk/packages/node/iii/local.yml

Gates applied: no_behavioural_pass.

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