diff --git a/cli/src/commands/__tests__/doctor.test.ts b/cli/src/commands/__tests__/doctor.test.ts
new file mode 100644
index 0000000000..1630809d63
--- /dev/null
+++ b/cli/src/commands/__tests__/doctor.test.ts
@@ -0,0 +1,58 @@
+import { describe, expect, test, mock, afterEach } from 'bun:test'
+
+import { collectDoctorReport, formatDoctorReport } from '../doctor'
+
+describe('/doctor command', () => {
+  test('collectDoctorReport returns a valid report', async () => {
+    const report = await collectDoctorReport()
+    
+    expect(report).toBeDefined()
+    expect(report.product).toBeDefined()
+    expect(report.results).toBeInstanceOf(Array)
+    expect(report.results.length).toBeGreaterThan(0)
+    expect(report.summary).toBeDefined()
+    expect(report.summary.ok).toBeDefined()
+    expect(report.summary.warnings).toBeDefined()
+    expect(report.summary.errors).toBeDefined()
+  })
+
+  test('collectDoctorReport includes platform check', async () => {
+    const report = await collectDoctorReport()
+    
+    const platformCheck = report.results.find((r) => r.name === 'platform')
+    expect(platformCheck).toBeDefined()
+    expect(platformCheck!.status).toBe('ok')
+  })
+
+  test('collectDoctorReport includes runtime check', async () => {
+    const report = await collectDoctorReport()
+    
+    const runtimeCheck = report.results.find((r) => r.name === 'runtime')
+    expect(runtimeCheck).toBeDefined()
+    expect(runtimeCheck!.status).toBe('ok')
+  })
+
+  test('formatDoctorReport returns a string', async () => {
+    const report = await collectDoctorReport()
+    const formatted = formatDoctorReport(report)
+    
+    expect(typeof formatted).toBe('string')
+    expect(formatted.length).toBeGreaterThan(0)
+  })
+
+  test('formatDoctorReport includes product name', async () => {
+    const report = await collectDoctorReport()
+    const formatted = formatDoctorReport(report)
+    
+    expect(formatted).toContain(report.product)
+    expect(formatted).toContain('doctor')
+  })
+
+  test('formatDoctorReport includes summary icon', async () => {
+    const report = await collectDoctorReport()
+    const formatted = formatDoctorReport(report)
+    
+    // Should contain either ✅, ⚠️, or ❌
+    expect(formatted).toMatch(/[✅⚠️❌]/)
+  })
+})
diff --git a/cli/src/commands/command-registry.ts b/cli/src/commands/command-registry.ts
index 18d0eea0d3..541fb16e14 100644
--- a/cli/src/commands/command-registry.ts
+++ b/cli/src/commands/command-registry.ts
@@ -9,6 +9,10 @@ import {
   collectProcessDiagnostics,
   formatProcessDiagnostics,
 } from './process-diagnostics'
+import {
+  collectDoctorReport,
+  formatDoctorReport,
+} from './doctor'
 import { buildInterviewPrompt, buildPlanPrompt, buildReviewPromptFromArgs } from './prompt-builders'
 import { handleReasoningCommand } from './reasoning'
 import { runBashCommand } from './router'
@@ -230,6 +234,17 @@ const ALL_COMMANDS: CommandDefinition[] = [
       clearInput(params)
     },
   }),
+  defineCommand({
+    name: 'doctor',
+    aliases: ['check', 'health'],
+    handler: async (params) => {
+      const report = await collectDoctorReport()
+      const formatted = formatDoctorReport(report)
+      params.setMessages((prev) => [...prev, getSystemMessage(formatted)])
+      params.saveToHistory(params.inputValue.trim())
+      clearInput(params)
+    },
+  }),
   defineCommand({
     name: 'copy',
     aliases: ['copy-chat', 'export'],
diff --git a/cli/src/commands/doctor.ts b/cli/src/commands/doctor.ts
new file mode 100644
index 0000000000..9f87ab61a2
--- /dev/null
+++ b/cli/src/commands/doctor.ts
@@ -0,0 +1,282 @@
+import { execSync } from 'child_process'
+import { existsSync } from 'fs'
+import { join } from 'path'
+
+import { IS_FREEBUFF } from '../utils/constants'
+import { getWebsiteUrl } from '@codebuff/sdk'
+
+export type DiagnosticResult = {
+  name: string
+  status: 'ok' | 'warning' | 'error'
+  message: string
+  details?: string
+}
+
+export type DoctorReport = {
+  product: string
+  results: DiagnosticResult[]
+  summary: {
+    ok: number
+    warnings: number
+    errors: number
+  }
+}
+
+/**
+ * Check if a command is available in PATH
+ */
+function isCommandAvailable(command: string): boolean {
+  try {
+    const which = process.platform === 'win32' ? 'where' : 'which'
+    execSync(`${which} ${command}`, { stdio: 'ignore', timeout: 5000 })
+    return true
+  } catch {
+    return false
+  }
+}
+
+/**
+ * Check if ripgrep (rg) is available and executable
+ */
+function checkRipgrep(): DiagnosticResult {
+  const rgAvailable = isCommandAvailable('rg')
+  
+  if (!rgAvailable) {
+    return {
+      name: 'ripgrep (rg)',
+      status: 'error',
+      message: 'ripgrep not found in PATH',
+      details: 'Code search requires ripgrep. Install it:\n  - macOS: brew install ripgrep\n  - Ubuntu/Debian: sudo apt install ripgrep\n  - Windows: scoop install ripgrep',
+    }
+  }
+
+  return {
+    name: 'ripgrep (rg)',
+    status: 'ok',
+    message: 'Available',
+  }
+}
+
+/**
+ * Check git availability and repository status
+ */
+function checkGit(): DiagnosticResult[] {
+  const results: DiagnosticResult[] = []
+
+  // Check git availability
+  const gitAvailable = isCommandAvailable('git')
+  if (!gitAvailable) {
+    results.push({
+      name: 'git',
+      status: 'error',
+      message: 'git not found in PATH',
+      details: 'Git is required for version control features. Install it:\n  - macOS: xcode-select --install\n  - Ubuntu/Debian: sudo apt install git\n  - Windows: https://git-scm.com/download/win',
+    })
+    return results
+  }
+
+  results.push({
+    name: 'git',
+    status: 'ok',
+    message: 'Available',
+  })
+
+  // Check if we're in a git repository
+  try {
+    execSync('git rev-parse --is-inside-work-tree', { 
+      stdio: 'ignore', 
+      timeout: 5000,
+      cwd: process.cwd() 
+    })
+    results.push({
+      name: 'git repository',
+      status: 'ok',
+      message: 'Current directory is a git repository',
+    })
+  } catch {
+    results.push({
+      name: 'git repository',
+      status: 'warning',
+      message: 'Current directory is not a git repository',
+      details: 'Some features may not work correctly outside a git repository.',
+    })
+  }
+
+  return results
+}
+
+/**
+ * Check API connectivity
+ */
+async function checkConnectivity(): Promise<DiagnosticResult> {
+  const websiteUrl = getWebsiteUrl()
+  
+  try {
+    const controller = new AbortController()
+    const timeoutId = setTimeout(() => controller.abort(), 5000)
+    
+    const response = await fetch(`${websiteUrl}/api/healthz`, {
+      method: 'GET',
+      signal: controller.signal,
+    })
+    
+    clearTimeout(timeoutId)
+    
+    if (response.ok) {
+      return {
+        name: 'API connectivity',
+        status: 'ok',
+        message: `Connected to ${websiteUrl}`,
+      }
+    } else {
+      return {
+        name: 'API connectivity',
+        status: 'warning',
+        message: `API responded with status ${response.status}`,
+        details: 'The API is reachable but returned an error. This may indicate a temporary issue.',
+      }
+    }
+  } catch (error) {
+    const isTimeout = error instanceof Error && error.name === 'AbortError'
+    return {
+      name: 'API connectivity',
+      status: 'error',
+      message: isTimeout ? 'Connection timed out' : 'Failed to connect',
+      details: `Could not reach ${websiteUrl}. Check your internet connection and firewall settings.`,
+    }
+  }
+}
+
+/**
+ * Check if tmux is available
+ */
+function checkTmux(): DiagnosticResult {
+  const tmuxAvailable = isCommandAvailable('tmux')
+  
+  if (!tmuxAvailable) {
+    return {
+      name: 'tmux',
+      status: 'warning',
+      message: 'tmux not found',
+      details: 'tmux is optional but recommended for multiplexing and detached sessions. Install it:\n  - macOS: brew install tmux\n  - Ubuntu/Debian: sudo apt install tmux\n  - Windows: Available through WSL',
+    }
+  }
+
+  return {
+    name: 'tmux',
+    status: 'ok',
+    message: 'Available',
+  }
+}
+
+/**
+ * Check Node.js/Bun runtime
+ */
+function checkRuntime(): DiagnosticResult {
+  if (typeof Bun !== 'undefined') {
+    return {
+      name: 'runtime',
+      status: 'ok',
+      message: `Bun ${Bun.version}`,
+    }
+  }
+  
+  return {
+    name: 'runtime',
+    status: 'ok',
+    message: `Node.js ${process.version}`,
+  }
+}
+
+/**
+ * Check platform and architecture
+ */
+function checkPlatform(): DiagnosticResult {
+  return {
+    name: 'platform',
+    status: 'ok',
+    message: `${process.platform} ${process.arch}`,
+  }
+}
+
+/**
+ * Collect all diagnostic information
+ */
+export async function collectDoctorReport(): Promise<DoctorReport> {
+  const results: DiagnosticResult[] = []
+
+  // Add basic info
+  results.push(checkPlatform())
+  results.push(checkRuntime())
+  
+  // Check dependencies
+  results.push(checkRipgrep())
+  results.push(...checkGit())
+  results.push(checkTmux())
+  
+  // Check connectivity (async)
+  const connectivity = await checkConnectivity()
+  results.push(connectivity)
+
+  // Calculate summary
+  const summary = {
+    ok: results.filter((r) => r.status === 'ok').length,
+    warnings: results.filter((r) => r.status === 'warning').length,
+    errors: results.filter((r) => r.status === 'error').length,
+  }
+
+  return {
+    product: IS_FREEBUFF ? 'Freebuff' : 'Codebuff',
+    results,
+    summary,
+  }
+}
+
+/**
+ * Format the doctor report for display
+ */
+export function formatDoctorReport(report: DoctorReport): string {
+  const lines: string[] = []
+
+  lines.push(`### ${report.product} doctor`)
+  lines.push('')
+
+  // Summary
+  const { ok, warnings, errors } = report.summary
+  if (errors === 0 && warnings === 0) {
+    lines.push('✅ All checks passed!')
+  } else if (errors === 0) {
+    lines.push(`⚠️ ${warnings} warning(s) found`)
+  } else {
+    lines.push(`❌ ${errors} error(s), ${warnings} warning(s) found`)
+  }
+  lines.push('')
+
+  // Detailed results
+  for (const result of report.results) {
+    const icon = result.status === 'ok' ? '✅' : result.status === 'warning' ? '⚠️' : '❌'
+    lines.push(`${icon} **${result.name}**: ${result.message}`)
+    if (result.details) {
+      // Indent details
+      const detailLines = result.details.split('\n')
+      for (const line of detailLines) {
+        lines.push(`   ${line}`)
+      }
+    }
+  }
+
+  lines.push('')
+  
+  // Recommendations
+  if (errors > 0) {
+    lines.push('### Recommendations')
+    lines.push('')
+    lines.push('Fix the errors above to ensure full functionality.')
+  } else if (warnings > 0) {
+    lines.push('### Notes')
+    lines.push('')
+    lines.push('The warnings above are optional but may improve your experience.')
+  }
+
+  return lines.join('\n')
+}
diff --git a/cli/src/data/slash-commands.ts b/cli/src/data/slash-commands.ts
index c6e187a0c4..c719993649 100644
--- a/cli/src/data/slash-commands.ts
+++ b/cli/src/data/slash-commands.ts
@@ -62,6 +62,12 @@ const ALL_SLASH_COMMANDS: SlashCommand[] = [
     description: 'Show local CLI resource usage and terminal tool process IDs',
     aliases: ['diag', 'processes'],
   },
+  {
+    id: 'doctor',
+    label: 'doctor',
+    description: 'Diagnose local environment and dependencies',
+    aliases: ['check', 'health'],
+  },
   {
     id: 'ads:enable',
     label: 'ads:enable',