host: tighten venue-registry install seam and mutex discipline

crates/videre-host/Cargo.toml

@@ -26,7 +26,18 @@ tokio.workspace = true
 toml.workspace = true
 tracing.workspace = true
 
+[features]
+# Test-only helpers: the direct `VenueRegistry::install_for_test` seam, so an
+# out-of-crate test installs a mock adapter without the provider boot path.
+# Off by default; the self dev-dependency below turns it on for this crate's
+# own tests.
+test-utils = []
+
 [dev-dependencies]
+# Self dev-dependency enabling `test-utils` for this crate's own test targets,
+# so `cargo test -p videre-host` sees `install_for_test` without every
+# invocation passing `--features test-utils`.
+videre-host = { path = ".", features = ["test-utils"] }
 nexum-runtime = { path = "../nexum-runtime", features = ["test-utils"] }
 nexum-tasks = { path = "../nexum-tasks" }
 tempfile.workspace = true

crates/videre-host/src/registry.rs

@@ -347,12 +347,17 @@ impl VenueRegistry {
     /// adapters answering the same venue would silently shadow one another,
     /// which is a config error worth failing boot over. A dead incumbent is
     /// replaced: that is the sweep restarting a trapped adapter.
-    pub fn install(
+    ///
+    /// Crate-internal: adapters install at provider boot, never post-boot
+    /// through a shared handle clone.
+    pub(crate) fn install(
         &self,
         venue: VenueId,
         liveness: Liveness,
         invoker: impl VenueInvoker + 'static,
     ) -> Result<(), DuplicateVenue> {
+        // Takes the adapter-map mutex only for the synchronous insert; never
+        // held across an await.
         let mut adapters = self.inner.adapters.lock().expect("adapter map poisoned");
         if adapters.get(&venue).is_some_and(|v| v.liveness.is_alive()) {
             return Err(DuplicateVenue { venue });
@@ -367,6 +372,17 @@ impl VenueRegistry {
         Ok(())
     }
 
+    /// Test-only direct install, bypassing the provider boot path.
+    #[cfg(feature = "test-utils")]
+    pub fn install_for_test(
+        &self,
+        venue: VenueId,
+        liveness: Liveness,
+        invoker: impl VenueInvoker + 'static,
+    ) -> Result<(), DuplicateVenue> {
+        self.install(venue, liveness, invoker)
+    }
+
     /// Resolve a venue id to its installed adapter slot. An uninstalled
     /// venue is `unknown-venue`; an installed but dead one is `unavailable`
     /// pending the supervisor's restart sweep, without touching its

crates/videre-host/tests/platform.rs

@@ -281,7 +281,7 @@ impl VenueInvoker for ScriptedAdapter {
 fn scripted_registry(adapter: ScriptedAdapter) -> VenueRegistry {
     let registry = VenueRegistryBuilder::new(Default::default()).build();
     registry
-        .install(
+        .install_for_test(
             VenueId::from("cow"),
             nexum_runtime::host::actor::Liveness::default(),
             adapter,