feat(M3-001): refactor ProviderService into IProviderAdapter pattern (#306)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/gateway/src/agent/provider.service.ts

@@ -1,19 +1,43 @@
 import { Injectable, Logger, type OnModuleInit } from '@nestjs/common';
 import { ModelRegistry, AuthStorage } from '@mariozechner/pi-coding-agent';
 import { getModel, type Model, type Api } from '@mariozechner/pi-ai';
-import type { ModelInfo, ProviderInfo, CustomProviderConfig } from '@mosaic/types';
+import type {
+  CustomProviderConfig,
+  IProviderAdapter,
+  ModelInfo,
+  ProviderHealth,
+  ProviderInfo,
+} from '@mosaic/types';
+import { OllamaAdapter } from './adapters/index.js';
 import type { TestConnectionResultDto } from './provider.dto.js';
 
+/** DI injection token for the provider adapter array. */
+export const PROVIDER_ADAPTERS = Symbol('PROVIDER_ADAPTERS');
+
 @Injectable()
 export class ProviderService implements OnModuleInit {
   private readonly logger = new Logger(ProviderService.name);
   private registry!: ModelRegistry;
 
-  onModuleInit(): void {
+  /**
+   * Adapters registered with this service.
+   * Built-in adapters (Ollama) are always present; additional adapters can be
+   * supplied via the PROVIDER_ADAPTERS injection token in the future.
+   */
+  private adapters: IProviderAdapter[] = [];
+
+  async onModuleInit(): Promise<void> {
     const authStorage = AuthStorage.inMemory();
     this.registry = new ModelRegistry(authStorage);
 
-    this.registerOllamaProvider();
+    // Build the default set of adapters that rely on the registry
+    this.adapters = [new OllamaAdapter(this.registry)];
+
+    // Run all adapter registrations first (Ollama, and any future adapters)
+    await this.registerAll();
+
+    // Register API-key providers directly (Anthropic, OpenAI, Z.ai, custom)
+    // These do not yet have dedicated adapter classes (M3-002 through M3-005).
     this.registerAnthropicProvider();
     this.registerOpenAIProvider();
     this.registerZaiProvider();
@@ -23,6 +47,59 @@ export class ProviderService implements OnModuleInit {
     this.logger.log(`Providers initialized: ${available.length} models available`);
   }
 
+  // ---------------------------------------------------------------------------
+  // Adapter-pattern API
+  // ---------------------------------------------------------------------------
+
+  /**
+   * Call register() on each adapter in order.
+   * Errors from individual adapters are logged and do not abort the others.
+   */
+  async registerAll(): Promise<void> {
+    for (const adapter of this.adapters) {
+      try {
+        await adapter.register();
+      } catch (err) {
+        this.logger.error(
+          `Adapter "${adapter.name}" registration failed`,
+          err instanceof Error ? err.stack : String(err),
+        );
+      }
+    }
+  }
+
+  /**
+   * Return the adapter registered under the given provider name, or undefined.
+   */
+  getAdapter(providerName: string): IProviderAdapter | undefined {
+    return this.adapters.find((a) => a.name === providerName);
+  }
+
+  /**
+   * Run healthCheck() on all adapters and return results keyed by provider name.
+   */
+  async healthCheckAll(): Promise<Record<string, ProviderHealth>> {
+    const results: Record<string, ProviderHealth> = {};
+    await Promise.all(
+      this.adapters.map(async (adapter) => {
+        try {
+          results[adapter.name] = await adapter.healthCheck();
+        } catch (err) {
+          results[adapter.name] = {
+            status: 'down',
+            lastChecked: new Date().toISOString(),
+            error: err instanceof Error ? err.message : String(err),
+          };
+        }
+      }),
+    );
+    return results;
+  }
+
+  // ---------------------------------------------------------------------------
+  // Legacy / Pi-SDK-facing API (preserved for AgentService and RoutingService)
+  // ---------------------------------------------------------------------------
+
   getRegistry(): ModelRegistry {
     return this.registry;
   }
@@ -69,6 +146,18 @@ export class ProviderService implements OnModuleInit {
   }
 
   async testConnection(providerId: string, baseUrl?: string): Promise<TestConnectionResultDto> {
+    // Delegate to the adapter when one exists and no URL override is given
+    const adapter = this.getAdapter(providerId);
+    if (adapter && !baseUrl) {
+      const health = await adapter.healthCheck();
+      return {
+        providerId,
+        reachable: health.status !== 'down',
+        latencyMs: health.latencyMs,
+        error: health.error,
+      };
+    }
+
     // Resolve baseUrl: explicit override > registered provider > ollama env
     let resolvedUrl = baseUrl;
 
@@ -143,6 +232,11 @@ export class ProviderService implements OnModuleInit {
     this.logger.log(`Registered custom provider: ${config.id} (${config.models.length} models)`);
   }
 
+  // ---------------------------------------------------------------------------
+  // Private helpers — direct registry registration for providers without adapters yet
+  // (Anthropic, OpenAI, Z.ai will move to adapters in M3-002 through M3-005)
+  // ---------------------------------------------------------------------------
+
   private registerAnthropicProvider(): void {
     const apiKey = process.env['ANTHROPIC_API_KEY'];
     if (!apiKey) {
@@ -203,36 +297,6 @@ export class ProviderService implements OnModuleInit {
     this.logger.log('Z.ai provider registered with 3 models');
   }
 
-  private registerOllamaProvider(): void {
-    const ollamaUrl = process.env['OLLAMA_BASE_URL'] ?? process.env['OLLAMA_HOST'];
-    if (!ollamaUrl) return;
-
-    const modelsEnv = process.env['OLLAMA_MODELS'] ?? 'llama3.2,codellama,mistral';
-    const modelIds = modelsEnv
-      .split(',')
-      .map((modelId: string) => modelId.trim())
-      .filter(Boolean);
-
-    this.registry.registerProvider('ollama', {
-      baseUrl: `${ollamaUrl}/v1`,
-      apiKey: 'ollama',
-      api: 'openai-completions' as never,
-      models: modelIds.map((id) => ({
-        id,
-        name: id,
-        reasoning: false,
-        input: ['text'] as ('text' | 'image')[],
-        cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
-        contextWindow: 8192,
-        maxTokens: 4096,
-      })),
-    });
-
-    this.logger.log(
-      `Ollama provider registered at ${ollamaUrl} with models: ${modelIds.join(', ')}`,
-    );
-  }
-
   private registerCustomProviders(): void {
     const customJson = process.env['MOSAIC_CUSTOM_PROVIDERS'];
     if (!customJson) return;