feat(M3-005): implement ZaiAdapter for Z.ai GLM-5 provider

Z.ai exposes an OpenAI-compatible API at https://open.bigmodel.cn/api/paas/v4.
The adapter uses the openai SDK with a custom baseURL and ZAI_API_KEY env var.

- Add ZaiAdapter implementing IProviderAdapter with register(), listModels(),
  healthCheck(), and createCompletion() (streaming via OpenAI-compat API)
- Register GLM-5 (128K context, standard tier, tools support) from model-capabilities
- Support ZAI_BASE_URL override for custom deployments
- Graceful degradation when ZAI_API_KEY is absent
- Remove legacy registerZaiProvider() direct-registry method from ProviderService
- Export ZaiAdapter from adapters/index.ts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/gateway/src/agent/adapters/index.ts

@@ -2,3 +2,4 @@ export { OllamaAdapter } from './ollama.adapter.js';
 export { AnthropicAdapter } from './anthropic.adapter.js';
 export { OpenAIAdapter } from './openai.adapter.js';
 export { OpenRouterAdapter } from './openrouter.adapter.js';
+export { ZaiAdapter } from './zai.adapter.js';

apps/gateway/src/agent/adapters/zai.adapter.ts

@@ -0,0 +1,187 @@
+import { Logger } from '@nestjs/common';
+import OpenAI from 'openai';
+import type {
+  CompletionEvent,
+  CompletionParams,
+  IProviderAdapter,
+  ModelInfo,
+  ProviderHealth,
+} from '@mosaic/types';
+import { getModelCapability } from '../model-capabilities.js';
+
+/**
+ * Default Z.ai API base URL.
+ * Z.ai (BigModel / Zhipu AI) exposes an OpenAI-compatible API at this endpoint.
+ * Can be overridden via the ZAI_BASE_URL environment variable.
+ */
+const DEFAULT_ZAI_BASE_URL = 'https://open.bigmodel.cn/api/paas/v4';
+
+/**
+ * GLM-5 model identifier on the Z.ai platform.
+ */
+const GLM5_MODEL_ID = 'glm-5';
+
+/**
+ * Z.ai (Zhipu AI / BigModel) provider adapter.
+ *
+ * Z.ai exposes an OpenAI-compatible REST API. This adapter uses the `openai`
+ * SDK with a custom base URL and the ZAI_API_KEY environment variable.
+ *
+ * Configuration:
+ *   ZAI_API_KEY   — required; Z.ai API key
+ *   ZAI_BASE_URL  — optional; override the default API base URL
+ */
+export class ZaiAdapter implements IProviderAdapter {
+  readonly name = 'zai';
+
+  private readonly logger = new Logger(ZaiAdapter.name);
+  private client: OpenAI | null = null;
+  private registeredModels: ModelInfo[] = [];
+
+  async register(): Promise<void> {
+    const apiKey = process.env['ZAI_API_KEY'];
+    if (!apiKey) {
+      this.logger.debug('Skipping Z.ai provider registration: ZAI_API_KEY not set');
+      return;
+    }
+
+    const baseURL = process.env['ZAI_BASE_URL'] ?? DEFAULT_ZAI_BASE_URL;
+
+    this.client = new OpenAI({ apiKey, baseURL });
+
+    this.registeredModels = this.buildModelList();
+    this.logger.log(`Z.ai provider registered with ${this.registeredModels.length} model(s)`);
+  }
+
+  listModels(): ModelInfo[] {
+    return this.registeredModels;
+  }
+
+  async healthCheck(): Promise<ProviderHealth> {
+    const apiKey = process.env['ZAI_API_KEY'];
+    if (!apiKey) {
+      return {
+        status: 'down',
+        lastChecked: new Date().toISOString(),
+        error: 'ZAI_API_KEY not configured',
+      };
+    }
+
+    const baseURL = process.env['ZAI_BASE_URL'] ?? DEFAULT_ZAI_BASE_URL;
+    const start = Date.now();
+
+    try {
+      const res = await fetch(`${baseURL}/models`, {
+        method: 'GET',
+        headers: {
+          Authorization: `Bearer ${apiKey}`,
+          Accept: 'application/json',
+        },
+        signal: AbortSignal.timeout(5000),
+      });
+      const latencyMs = Date.now() - start;
+
+      if (!res.ok) {
+        return {
+          status: 'degraded',
+          latencyMs,
+          lastChecked: new Date().toISOString(),
+          error: `HTTP ${res.status}`,
+        };
+      }
+
+      return { status: 'healthy', latencyMs, lastChecked: new Date().toISOString() };
+    } catch (err) {
+      const latencyMs = Date.now() - start;
+      const error = err instanceof Error ? err.message : String(err);
+      return { status: 'down', latencyMs, lastChecked: new Date().toISOString(), error };
+    }
+  }
+
+  /**
+   * Stream a completion through Z.ai's OpenAI-compatible API.
+   */
+  async *createCompletion(params: CompletionParams): AsyncIterable<CompletionEvent> {
+    if (!this.client) {
+      throw new Error('ZaiAdapter is not initialized. Ensure ZAI_API_KEY is set.');
+    }
+
+    const stream = await this.client.chat.completions.create({
+      model: params.model,
+      messages: params.messages.map((m) => ({ role: m.role, content: m.content })),
+      temperature: params.temperature,
+      max_tokens: params.maxTokens,
+      stream: true,
+    });
+
+    let inputTokens = 0;
+    let outputTokens = 0;
+
+    for await (const chunk of stream) {
+      const choice = chunk.choices[0];
+      if (!choice) continue;
+
+      const delta = choice.delta;
+
+      if (delta.content) {
+        yield { type: 'text_delta', content: delta.content };
+      }
+
+      if (choice.finish_reason === 'stop') {
+        const usage = (chunk as { usage?: { prompt_tokens?: number; completion_tokens?: number } })
+          .usage;
+        if (usage) {
+          inputTokens = usage.prompt_tokens ?? 0;
+          outputTokens = usage.completion_tokens ?? 0;
+        }
+      }
+    }
+
+    yield {
+      type: 'done',
+      usage: { inputTokens, outputTokens },
+    };
+  }
+
+  // ---------------------------------------------------------------------------
+  // Private helpers
+  // ---------------------------------------------------------------------------
+
+  private buildModelList(): ModelInfo[] {
+    const capability = getModelCapability(GLM5_MODEL_ID);
+
+    if (!capability) {
+      this.logger.warn(`Model capability entry not found for '${GLM5_MODEL_ID}'; using defaults`);
+      return [
+        {
+          id: GLM5_MODEL_ID,
+          provider: 'zai',
+          name: 'GLM-5',
+          reasoning: false,
+          contextWindow: 128000,
+          maxTokens: 8192,
+          inputTypes: ['text'],
+          cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+        },
+      ];
+    }
+
+    return [
+      {
+        id: capability.id,
+        provider: 'zai',
+        name: capability.displayName,
+        reasoning: capability.capabilities.reasoning,
+        contextWindow: capability.contextWindow,
+        maxTokens: capability.maxOutputTokens,
+        inputTypes: capability.capabilities.vision ? ['text', 'image'] : ['text'],
+        cost: {
+          input: capability.costPer1kInput ?? 0,
+          output: capability.costPer1kOutput ?? 0,
+          cacheRead: 0,
+          cacheWrite: 0,
+        },
+      },
+    ];
+  }
+}

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

@@ -13,6 +13,7 @@ import {
   OllamaAdapter,
   OpenAIAdapter,
   OpenRouterAdapter,
+  ZaiAdapter,
 } from './adapters/index.js';
 import type { TestConnectionResultDto } from './provider.dto.js';
 
@@ -52,14 +53,13 @@ export class ProviderService implements OnModuleInit, OnModuleDestroy {
       new AnthropicAdapter(this.registry),
       new OpenAIAdapter(this.registry),
       new OpenRouterAdapter(),
+      new ZaiAdapter(),
     ];
 
-    // Run all adapter registrations first (Ollama, Anthropic, and any future adapters)
+    // Run all adapter registrations first (Ollama, Anthropic, OpenAI, OpenRouter, Z.ai)
     await this.registerAll();
 
-    // Register API-key providers directly (Z.ai, custom)
-    // OpenAI now has a dedicated adapter (M3-003).
-    this.registerZaiProvider();
+    // Register API-key providers directly (custom)
     this.registerCustomProviders();
 
     const available = this.registry.getAvailable();
@@ -340,30 +340,9 @@ export class ProviderService implements OnModuleInit, OnModuleDestroy {
   }
 
   // ---------------------------------------------------------------------------
-  // Private helpers — direct registry registration for providers without adapters yet
-  // (Z.ai will move to an adapter in M3-005)
+  // Private helpers
   // ---------------------------------------------------------------------------
 
-  private registerZaiProvider(): void {
-    const apiKey = process.env['ZAI_API_KEY'];
-    if (!apiKey) {
-      this.logger.debug('Skipping Z.ai provider registration: ZAI_API_KEY not set');
-      return;
-    }
-
-    const models = ['glm-4.5', 'glm-4.5-air', 'glm-4.5-flash'].map((id) =>
-      this.cloneBuiltInModel('zai', id),
-    );
-
-    this.registry.registerProvider('zai', {
-      apiKey,
-      baseUrl: 'https://open.bigmodel.cn/api/paas/v4',
-      models,
-    });
-
-    this.logger.log('Z.ai provider registered with 3 models');
-  }
-
   private registerCustomProviders(): void {
     const customJson = process.env['MOSAIC_CUSTOM_PROVIDERS'];
     if (!customJson) return;