feat(coding-agent): add types and bash execution

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

examples/coding-agent/src/agent.ts

@@ -0,0 +1,70 @@
+import { exec } from "node:child_process";
+
+export interface Message {
+  role: "user" | "assistant" | "tool";
+  content?: string;
+  tool_calls?: ToolCall[];
+  tool_call_id?: string;
+}
+
+export interface ToolCall {
+  id: string;
+  type: "function";
+  function: { name: string; arguments: string };
+}
+
+export interface AgentOptions {
+  onToken: (token: string) => void;
+  onToolCall: (command: string) => void;
+  onToolResult: (output: string) => void;
+  onComplete: () => void;
+  autoApprove: boolean;
+  requestApproval: (command: string) => Promise<boolean>;
+}
+
+const BASH_TOOL = {
+  type: "function" as const,
+  function: {
+    name: "bash",
+    description: "Execute a bash command in the current working directory",
+    parameters: {
+      type: "object",
+      properties: {
+        command: { type: "string", description: "The bash command to execute" },
+      },
+      required: ["command"],
+    },
+  },
+};
+
+const SYSTEM_PROMPT = `You are a coding assistant running in a terminal. You have a bash tool to execute commands.
+Use it to read files (cat, find, grep), write files (echo, tee), and run programs.
+Explain what you're about to do before executing commands.
+Keep responses concise.
+Working directory: ${process.cwd()}`;
+
+const MAX_OUTPUT = 10000;
+
+export function executeBash(command: string): Promise<string> {
+  return new Promise((resolve) => {
+    exec(
+      command,
+      {
+        shell: "/bin/bash",
+        cwd: process.cwd(),
+        timeout: 30_000,
+        maxBuffer: 10 * 1024 * 1024,
+      },
+      (error, stdout, stderr) => {
+        let output = "";
+        if (stdout) output += stdout;
+        if (stderr) output += (output ? "\n" : "") + stderr;
+        if (error && !output) output = error.message;
+        if (output.length > MAX_OUTPUT) {
+          output = output.slice(0, MAX_OUTPUT) + "\n... (truncated)";
+        }
+        resolve(output || "(no output)");
+      },
+    );
+  });
+}