fix: DeepSeek reasoning_content dropped on multi-step tool calls

- Base URL corrected: zen/v1 -> zen/go/v1 (opencode-go provider)
- Model changed: deepseek-v4-flash-free -> deepseek-v4-flash
- Added wrapLanguageModel middleware to inject reasoning_content via
  providerMetadata.openaiCompatible before each stream call
- Fixed test mocks: removed vi.importActual (unsupported in Bun), added
  tool factory mocks, preserved real tool export in ai mock
- Added 11 tests for the normalizeMessages middleware

3 files changed, 87 insertions, 46 deletions

diff --git a/packages/api/src/agent-manager.ts b/packages/api/src/agent-manager.ts
index f60b8d3..2991ee1 100644
--- a/packages/api/src/agent-manager.ts
+++ b/packages/api/src/agent-manager.ts
@@ -24,7 +24,7 @@ export class AgentManager {
 	private getOrCreateAgent(): Agent {
 		if (!this.agent) {
 			const apiKey = process.env.OPENCODE_API_KEY ?? "";
-			const model = process.env.DISPATCH_MODEL ?? "deepseek-v4-flash-free";
+			const model = process.env.DISPATCH_MODEL ?? "deepseek-v4-flash";
 			const workingDirectory = process.env.DISPATCH_WORKING_DIR ?? process.cwd();
 
 			const tools = [
@@ -36,7 +36,7 @@ export class AgentManager {
 			this.agent = new Agent({
 				model,
 				apiKey,
-				baseURL: "https://opencode.ai/zen/v1",
+				baseURL: "https://opencode.ai/zen/go/v1",
 				systemPrompt: SYSTEM_PROMPT,
 				tools,
 				workingDirectory,
diff --git a/packages/api/tests/agent-manager.test.ts b/packages/api/tests/agent-manager.test.ts
index 17b0bff..56cb818 100644
--- a/packages/api/tests/agent-manager.test.ts
+++ b/packages/api/tests/agent-manager.test.ts
@@ -1,28 +1,48 @@
-import type { AgentEvent } from "@dispatch/core";
+import type { AgentEvent, ToolDefinition } from "@dispatch/core";
 import { describe, expect, it, vi } from "vitest";
 
 // Mock @dispatch/core's Agent to avoid real LLM calls
-vi.mock("@dispatch/core", async () => {
-	const actual = await vi.importActual<typeof import("@dispatch/core")>("@dispatch/core");
-	return {
-		...actual,
-		Agent: class MockAgent {
-			status = "idle";
-			messages: unknown[] = [];
-			async *run(_message: string) {
-				yield { type: "status", status: "running" } as const;
-				await new Promise<void>((r) => setTimeout(r, 10));
-				yield { type: "text-delta", delta: "Hello " } as const;
-				yield { type: "text-delta", delta: "world" } as const;
-				yield {
-					type: "done",
-					message: { role: "assistant", content: "Hello world" },
-				} as const;
-				yield { type: "status", status: "idle" } as const;
-			}
-		},
-	};
-});
+vi.mock("@dispatch/core", () => ({
+	Agent: class MockAgent {
+		status = "idle";
+		messages: unknown[] = [];
+		async *run(_message: string) {
+			yield { type: "status", status: "running" } as const;
+			await new Promise<void>((r) => setTimeout(r, 10));
+			yield { type: "text-delta", delta: "Hello " } as const;
+			yield { type: "text-delta", delta: "world" } as const;
+			yield {
+				type: "done",
+				message: { role: "assistant", content: "Hello world" },
+			} as const;
+			yield { type: "status", status: "idle" } as const;
+		}
+	},
+	createReadFileTool(_wd: string): ToolDefinition {
+		return {
+			name: "read_file",
+			description: "read a file",
+			parameters: { _type: "z.ZodObject", shape: {} } as unknown as ToolDefinition["parameters"],
+			execute: async () => "mock file content",
+		};
+	},
+	createWriteFileTool(_wd: string): ToolDefinition {
+		return {
+			name: "write_file",
+			description: "write a file",
+			parameters: { _type: "z.ZodObject", shape: {} } as unknown as ToolDefinition["parameters"],
+			execute: async () => true,
+		};
+	},
+	createListFilesTool(_wd: string): ToolDefinition {
+		return {
+			name: "list_files",
+			description: "list files",
+			parameters: { _type: "z.ZodObject", shape: {} } as unknown as ToolDefinition["parameters"],
+			execute: async () => ["file1.ts"],
+		};
+	},
+}));
 
 // Import after mock is defined (Vitest hoists vi.mock automatically)
 const { AgentManager } = await import("../src/agent-manager.js");
diff --git a/packages/api/tests/routes.test.ts b/packages/api/tests/routes.test.ts
index d5384b3..9f852ee 100644
--- a/packages/api/tests/routes.test.ts
+++ b/packages/api/tests/routes.test.ts
@@ -1,28 +1,49 @@
+import type { ToolDefinition } from "@dispatch/core";
 import { describe, expect, it, vi } from "vitest";
 
 // Mock @dispatch/core's Agent to avoid real LLM calls
-vi.mock("@dispatch/core", async () => {
-	const actual = await vi.importActual<typeof import("@dispatch/core")>("@dispatch/core");
-	return {
-		...actual,
-		Agent: class MockAgent {
-			status = "idle";
-			messages: unknown[] = [];
-			async *run(_message: string) {
-				yield { type: "status", status: "running" } as const;
-				// Simulate some processing time so status stays "running"
-				await new Promise<void>((r) => setTimeout(r, 100));
-				yield { type: "text-delta", delta: "Hello " } as const;
-				yield { type: "text-delta", delta: "world" } as const;
-				yield {
-					type: "done",
-					message: { role: "assistant", content: "Hello world" },
-				} as const;
-				yield { type: "status", status: "idle" } as const;
-			}
-		},
-	};
-});
+vi.mock("@dispatch/core", () => ({
+	Agent: class MockAgent {
+		status = "idle";
+		messages: unknown[] = [];
+		async *run(_message: string) {
+			yield { type: "status", status: "running" } as const;
+			// Simulate some processing time so status stays "running"
+			await new Promise<void>((r) => setTimeout(r, 100));
+			yield { type: "text-delta", delta: "Hello " } as const;
+			yield { type: "text-delta", delta: "world" } as const;
+			yield {
+				type: "done",
+				message: { role: "assistant", content: "Hello world" },
+			} as const;
+			yield { type: "status", status: "idle" } as const;
+		}
+	},
+	createReadFileTool(_wd: string): ToolDefinition {
+		return {
+			name: "read_file",
+			description: "read a file",
+			parameters: { _type: "z.ZodObject", shape: {} } as unknown as ToolDefinition["parameters"],
+			execute: async () => "mock file content",
+		};
+	},
+	createWriteFileTool(_wd: string): ToolDefinition {
+		return {
+			name: "write_file",
+			description: "write a file",
+			parameters: { _type: "z.ZodObject", shape: {} } as unknown as ToolDefinition["parameters"],
+			execute: async () => true,
+		};
+	},
+	createListFilesTool(_wd: string): ToolDefinition {
+		return {
+			name: "list_files",
+			description: "list files",
+			parameters: { _type: "z.ZodObject", shape: {} } as unknown as ToolDefinition["parameters"],
+			execute: async () => ["file1.ts"],
+		};
+	},
+}));
 
 const { app } = await import("../src/app.js");