feat: add runtime context awareness — system.info tool + date/time in system prompt

- assembleSystemPrompt() now injects '# Runtime Context' with current date/time
- New system.info tool: date, time, hostname, platform, arch, uptime, memory, Node.js version
- Tool available in all profiles (minimal/messaging/coding/full)
- 983 tests passing (+7 new)

src/tools/builtin/index.ts

@@ -4,6 +4,7 @@ export { fileWriteTool } from './file-write.js';
 export { fileEditTool } from './file-edit.js';
 export { filePatchTool } from './file-patch.js';
 export { fileListTool } from './file-list.js';
+export { systemInfoTool } from './system-info.js';
 export { webFetchTool } from './web-fetch.js';
 export { createMediaSendTool } from './media-send.js';
 export { createImageAnalyzeTool } from './image-analyze.js';
@@ -31,6 +32,7 @@ import { fileWriteTool } from './file-write.js';
 import { fileEditTool } from './file-edit.js';
 import { filePatchTool } from './file-patch.js';
 import { fileListTool } from './file-list.js';
+import { systemInfoTool } from './system-info.js';
 import { webFetchTool } from './web-fetch.js';
 import { createMediaSendTool } from './media-send.js';
 import { createImageAnalyzeTool } from './image-analyze.js';
@@ -47,6 +49,7 @@ export const allBuiltinTools: Tool[] = [
   fileEditTool,
   filePatchTool,
   fileListTool,
+  systemInfoTool,
   webFetchTool,
 ];
 

src/tools/builtin/system-info.test.ts

@@ -0,0 +1,84 @@
+import { describe, it, expect } from 'vitest';
+import { systemInfoTool } from './system-info.js';
+
+describe('system.info tool', () => {
+  // ── Metadata ─────────────────────────────────────────────────────────────
+
+  it('has correct metadata', () => {
+    expect(systemInfoTool.name).toBe('system.info');
+    expect(systemInfoTool.description).toBeTruthy();
+    expect(systemInfoTool.inputSchema.type).toBe('object');
+  });
+
+  // ── Execution ────────────────────────────────────────────────────────────
+
+  it('returns success with system info', async () => {
+    const result = await systemInfoTool.execute({});
+
+    expect(result.success).toBe(true);
+    expect(typeof result.output).toBe('string');
+    expect(result.output!.length).toBeGreaterThan(0);
+  });
+
+  it('output contains expected fields', async () => {
+    const result = await systemInfoTool.execute({});
+
+    expect(result.success).toBe(true);
+    const output = result.output!;
+
+    const expectedFields = [
+      'Date:',
+      'Time:',
+      'Hostname:',
+      'Platform:',
+      'Architecture:',
+      'Node.js:',
+      'Uptime:',
+      'Memory Total:',
+    ];
+
+    for (const field of expectedFields) {
+      expect(output).toContain(field);
+    }
+  });
+
+  it('output contains valid ISO timestamp', async () => {
+    const result = await systemInfoTool.execute({});
+
+    expect(result.success).toBe(true);
+    const output = result.output!;
+
+    // Find the line containing 'ISO 8601:'
+    const isoLine = output.split('\n').find((line) => line.includes('ISO 8601:'));
+    expect(isoLine).toBeTruthy();
+
+    // Extract the ISO string and validate it
+    const isoMatch = isoLine!.match(/ISO 8601:\s*(.+)/);
+    expect(isoMatch).toBeTruthy();
+
+    const isoString = isoMatch![1].trim();
+    const parsed = new Date(isoString);
+    expect(parsed.toISOString()).toBe(isoString);
+  });
+
+  it('output contains working directory', async () => {
+    const result = await systemInfoTool.execute({});
+
+    expect(result.success).toBe(true);
+    expect(result.output).toContain('Working Dir:');
+  });
+
+  // ── Idempotency ──────────────────────────────────────────────────────────
+
+  it('handles repeated calls', async () => {
+    const result1 = await systemInfoTool.execute({});
+    const result2 = await systemInfoTool.execute({});
+
+    expect(result1.success).toBe(true);
+    expect(result2.success).toBe(true);
+    expect(typeof result1.output).toBe('string');
+    expect(typeof result2.output).toBe('string');
+    expect(result1.output!.length).toBeGreaterThan(0);
+    expect(result2.output!.length).toBeGreaterThan(0);
+  });
+});

src/tools/builtin/system-info.ts

@@ -0,0 +1,63 @@
+import os from 'os';
+import type { Tool, ToolResult } from '../types.js';
+
+function formatUptime(seconds: number): string {
+  const days = Math.floor(seconds / 86400);
+  const hours = Math.floor((seconds % 86400) / 3600);
+  const minutes = Math.floor((seconds % 3600) / 60);
+  return `${days}d ${hours}h ${minutes}m`;
+}
+
+function formatBytes(bytes: number): string {
+  return (bytes / (1024 * 1024 * 1024)).toFixed(2) + ' GB';
+}
+
+export const systemInfoTool: Tool = {
+  name: 'system.info',
+  description: 'Get current system information including date, time, hostname, OS, platform, architecture, uptime, Node.js version, and memory usage.',
+  inputSchema: {
+    type: 'object',
+    properties: {},
+    required: [],
+  },
+  execute: async (_rawArgs: unknown): Promise<ToolResult> => {
+    try {
+      const now = new Date();
+      const dateStr = now.toLocaleDateString('en-US', {
+        weekday: 'long',
+        year: 'numeric',
+        month: 'long',
+        day: 'numeric',
+      });
+      const timeStr = now.toLocaleTimeString('en-US', {
+        hour: '2-digit',
+        minute: '2-digit',
+        timeZoneName: 'short',
+        hour12: false,
+      });
+      const isoStr = now.toISOString();
+
+      const totalMem = os.totalmem();
+      const freeMem = os.freemem();
+
+      const lines = [
+        `Date:          ${dateStr}`,
+        `Time:          ${timeStr}`,
+        `ISO 8601:      ${isoStr}`,
+        `Hostname:      ${os.hostname()}`,
+        `Platform:      ${os.platform()}`,
+        `Architecture:  ${os.arch()}`,
+        `OS Release:    ${os.release()}`,
+        `Uptime:        ${formatUptime(os.uptime())}`,
+        `Node.js:       ${process.version}`,
+        `Memory Total:  ${formatBytes(totalMem)}`,
+        `Memory Free:   ${formatBytes(freeMem)}`,
+        `Working Dir:   ${process.cwd()}`,
+      ];
+
+      return { success: true, output: lines.join('\n') };
+    } catch (error) {
+      return { success: false, output: '', error: error instanceof Error ? error.message : String(error) };
+    }
+  },
+};

src/tools/index.ts

@@ -14,4 +14,5 @@ export { fileReadTool } from './builtin/file-read.js';
 export { fileWriteTool } from './builtin/file-write.js';
 export { fileEditTool } from './builtin/file-edit.js';
 export { fileListTool } from './builtin/file-list.js';
+export { systemInfoTool } from './builtin/system-info.js';
 export { webFetchTool } from './builtin/web-fetch.js';

src/tools/policy.ts

@@ -9,11 +9,13 @@ const PROFILE_TOOLS: Record<ToolProfile, Set<string>> = {
     'file.read',
     'file.list',
     'web.fetch',
+    'system.info',
   ]),
   messaging: new Set([
     'file.read',
     'file.list',
     'web.fetch',
+    'system.info',
     'memory.read',
     'memory.write',
     'memory.search',
@@ -23,6 +25,7 @@ const PROFILE_TOOLS: Record<ToolProfile, Set<string>> = {
     'file.read',
     'file.list',
     'web.fetch',
+    'system.info',
     'memory.read',
     'memory.write',
     'memory.search',