feat: multi-provider support — Anthropic + Ollama (P2-002) (#74)

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

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

@@ -0,0 +1,139 @@
+import { Injectable, Logger, type OnModuleInit } from '@nestjs/common';
+import { ModelRegistry, AuthStorage } from '@mariozechner/pi-coding-agent';
+import type { Model, Api } from '@mariozechner/pi-ai';
+import type { ModelInfo, ProviderInfo, CustomProviderConfig } from '@mosaic/types';
+
+@Injectable()
+export class ProviderService implements OnModuleInit {
+  private readonly logger = new Logger(ProviderService.name);
+  private registry!: ModelRegistry;
+
+  async onModuleInit(): Promise<void> {
+    const authStorage = AuthStorage.create();
+    this.registry = new ModelRegistry(authStorage);
+
+    this.registerOllamaProvider();
+    this.registerCustomProviders();
+
+    const available = this.registry.getAvailable();
+    this.logger.log(`Providers initialized: ${available.length} models available`);
+  }
+
+  getRegistry(): ModelRegistry {
+    return this.registry;
+  }
+
+  findModel(provider: string, modelId: string): Model<Api> | undefined {
+    return this.registry.find(provider, modelId);
+  }
+
+  getDefaultModel(): Model<Api> | undefined {
+    const available = this.registry.getAvailable();
+    return available[0];
+  }
+
+  listProviders(): ProviderInfo[] {
+    const allModels = this.registry.getAll();
+    const availableModels = this.registry.getAvailable();
+    const availableIds = new Set(availableModels.map((m) => `${m.provider}:${m.id}`));
+
+    const providerMap = new Map<string, ProviderInfo>();
+
+    for (const model of allModels) {
+      let info = providerMap.get(model.provider);
+      if (!info) {
+        info = {
+          id: model.provider,
+          name: model.provider,
+          available: false,
+          models: [],
+        };
+        providerMap.set(model.provider, info);
+      }
+
+      const isAvailable = availableIds.has(`${model.provider}:${model.id}`);
+      if (isAvailable) info.available = true;
+
+      info.models.push(this.toModelInfo(model));
+    }
+
+    return Array.from(providerMap.values());
+  }
+
+  listAvailableModels(): ModelInfo[] {
+    return this.registry.getAvailable().map((m) => this.toModelInfo(m));
+  }
+
+  registerCustomProvider(config: CustomProviderConfig): void {
+    this.registry.registerProvider(config.id, {
+      baseUrl: config.baseUrl,
+      apiKey: config.apiKey,
+      models: config.models.map((m) => ({
+        id: m.id,
+        name: m.name,
+        reasoning: m.reasoning ?? false,
+        input: ['text'] as ('text' | 'image')[],
+        cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+        contextWindow: m.contextWindow ?? 4096,
+        maxTokens: m.maxTokens ?? 4096,
+      })),
+    });
+
+    this.logger.log(`Registered custom provider: ${config.id} (${config.models.length} 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((m) => m.trim())
+      .filter(Boolean);
+
+    this.registerCustomProvider({
+      id: 'ollama',
+      name: 'Ollama',
+      baseUrl: `${ollamaUrl}/v1`,
+      models: modelIds.map((id) => ({
+        id,
+        name: id,
+        reasoning: false,
+        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;
+
+    try {
+      const configs = JSON.parse(customJson) as CustomProviderConfig[];
+      for (const config of configs) {
+        this.registerCustomProvider(config);
+      }
+    } catch (err) {
+      this.logger.error('Failed to parse MOSAIC_CUSTOM_PROVIDERS', String(err));
+    }
+  }
+
+  private toModelInfo(model: Model<Api>): ModelInfo {
+    return {
+      id: model.id,
+      provider: model.provider,
+      name: model.name,
+      reasoning: model.reasoning,
+      contextWindow: model.contextWindow,
+      maxTokens: model.maxTokens,
+      inputTypes: model.input,
+      cost: model.cost,
+    };
+  }
+}