Migration

Upgrade notes for Arqen releases.

Alpha → beta startup behavior

arqen start is now the strict production path. It validates configuration before binding and rejects memory storage, incomplete native or HTTP storage, unsupported cloud storage, disabled authentication, pretty logs, missing credentials, and unsafe worker settings. Use arqen dev for local memory-mode development and tests. Applications that call the library directly should also call AppConfig::validate_production() before starting a production listener.

The new ScopedThingdBackend should wrap an application backend whenever data is tenant- or user-owned. Its tenant, instance, and subject values must come from verified authentication or trusted server configuration, never from a request body.

0.3 → 0.4

Single published crate

Arqen moved from a multi-crate workspace to a single published crate. The CLI binary is feature-gated behind cli and is not a separate package.

Action required:

Update your dependency:

[dependencies]
arqen = { version = "0.4", features = ["logging", "http-server"] }

Remove any workspace-level references to internal crates that no longer exist.

Config section rename

The [thingd] section in arqen.toml was renamed to [storage].

Before (0.3):

[thingd]
mode = "memory"

After (0.4):

[storage]
mode = "memory"

The environment variable ARQEN_THINGD_URL still sets the HTTP URL for thingd connectivity, but the config file key is now storage.http_url.

Module trait changes

The Module trait now requires Send + Sync on implementors and provides:

• register(&self, ctx: &mut ModuleContext<'_>) for explicit tool and health check registration.
• dependencies() for declaring inter-module dependencies.
• health_check() returning ModuleHealth for module-level health.

If you have custom modules, update them to implement the current trait shape. The EmptyModule test helper is available for simple cases.

Breaking changes

See CHANGELOG.md for the full list. Key breaking changes:

• ModuleBuilder::validate() now returns Result<(), ModuleGraphError>.
• HealthReport::probe_type field added.
• HealthRegistry::register() now takes Arc<dyn HealthCheck> instead of boxed trait objects.

General upgrade steps

1. Update the version in Cargo.toml.
2. Run cargo update -p arqen.
3. Fix any compilation errors from API changes.
4. Run cargo test -p arqen --all-features to verify.
5. Update any arqen.toml config files to match new section names.