feat: add Tess runtime provider registry (#722)

packages/agent/src/runtime-provider-registry.ts

@@ -0,0 +1,40 @@
+import type { AgentRuntimeProvider } from '@mosaicstack/types';
+
+/**
+ * Registry for runtime providers. Registration is explicit and replacement is
+ * forbidden so a provider identity cannot be silently hijacked at runtime.
+ */
+export class AgentRuntimeProviderRegistry {
+  private readonly providers = new Map<string, AgentRuntimeProvider>();
+
+  register(provider: AgentRuntimeProvider): void {
+    const providerId = provider.id.trim();
+    if (providerId.length === 0) {
+      throw new Error('Runtime provider ID is required');
+    }
+    if (this.providers.has(providerId)) {
+      throw new Error(`Runtime provider is already registered: ${providerId}`);
+    }
+    this.providers.set(providerId, provider);
+  }
+
+  get(providerId: string): AgentRuntimeProvider | undefined {
+    return this.providers.get(providerId);
+  }
+
+  require(providerId: string): AgentRuntimeProvider {
+    const normalizedProviderId = providerId.trim();
+    if (normalizedProviderId.length === 0) {
+      throw new Error('Runtime provider ID is required');
+    }
+    const provider = this.providers.get(normalizedProviderId);
+    if (!provider) {
+      throw new Error(`Runtime provider is not registered: ${normalizedProviderId}`);
+    }
+    return provider;
+  }
+
+  list(): AgentRuntimeProvider[] {
+    return Array.from(this.providers.values());
+  }
+}