feat: add Elixir framework support

src/frameworks/elixir/elixir-wizard-agent.ts

@@ -0,0 +1,105 @@
+/* Elixir wizard using posthog-agent with PostHog MCP */
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+import type { WizardRunOptions } from '@utils/types';
+import type { FrameworkConfig } from '@lib/framework-config';
+import { mixPackageManager } from '@lib/detection/package-manager';
+import { Integration } from '@lib/constants';
+
+type ElixirContext = {
+  phoenix?: boolean;
+};
+
+function readMixExs(installDir: string): string | undefined {
+  const mixExsPath = path.join(installDir, 'mix.exs');
+  if (!fs.existsSync(mixExsPath)) {
+    return undefined;
+  }
+  return fs.readFileSync(mixExsPath, 'utf-8');
+}
+
+/** Phoenix apps get the Plug integration; plain Elixir apps don't. */
+function isPhoenixProject(installDir: string): boolean {
+  const mixExs = readMixExs(installDir);
+  return !!mixExs && /\{\s*:phoenix\s*,/.test(mixExs);
+}
+
+export const ELIXIR_AGENT_CONFIG: FrameworkConfig<ElixirContext> = {
+  metadata: {
+    name: 'Elixir',
+    integration: Integration.elixir,
+    docsUrl: 'https://posthog.com/docs/libraries/elixir',
+    gatherContext: (options: WizardRunOptions) => {
+      const phoenix = isPhoenixProject(options.installDir);
+      return Promise.resolve({ phoenix });
+    },
+  },
+
+  detection: {
+    packageName: 'posthog',
+    packageDisplayName: 'Elixir',
+    usesPackageJson: false,
+    getVersion: () => undefined,
+    // A mix.exs defining a project marks a Mix project root; the def project
+    // check keeps stray files named mix.exs from claiming the directory.
+    detect: (options) => {
+      const mixExs = readMixExs(options.installDir);
+      return Promise.resolve(!!mixExs && /def\s+project\b/.test(mixExs));
+    },
+    detectPackageManager: mixPackageManager,
+  },
+
+  environment: {
+    uploadToHosting: false,
+    getEnvVars: (apiKey: string, host: string) => ({
+      POSTHOG_API_KEY: apiKey,
+      POSTHOG_HOST: host,
+    }),
+  },
+
+  analytics: {
+    getTags: (context) => ({
+      projectType: context.phoenix ? 'phoenix' : 'elixir',
+    }),
+  },
+
+  prompts: {
+    projectTypeDetection:
+      'This is an Elixir project. Look for mix.exs, mix.lock, config/, lib/, and application.ex to confirm; Phoenix apps also have endpoint and router modules.',
+    packageInstallation:
+      'Mix has no single add command. Add `{:posthog, "~> 2.0"}` to the deps list in mix.exs, then run `mix deps.get` to fetch it.',
+    getAdditionalContextLines: (context) => {
+      const lines = [
+        `Framework docs ID: elixir (use posthog://docs/frameworks/elixir for documentation)`,
+        'Configure PostHog in application config (api_key, api_host, in_app_otp_apps) reading from environment variables; set test_mode: true in the test environment.',
+      ];
+      if (context.phoenix) {
+        lines.push(
+          'This is a Phoenix app — add PostHog.Integrations.Plug before the router so request context is attached to captured events.',
+        );
+      }
+      return lines;
+    },
+  },
+
+  ui: {
+    successMessage: 'PostHog integration complete',
+    estimatedDurationMinutes: 5,
+    getOutroChanges: (context) => [
+      `Analyzed your ${
+        context.phoenix ? 'Phoenix' : 'Elixir'
+      } project structure`,
+      'Added the posthog Hex package to mix.exs and fetched it with mix deps.get',
+      'Configured PostHog in application config from environment variables',
+      'Instrumented meaningful events with PostHog.capture',
+    ],
+    getOutroNextSteps: (context) => [
+      context.phoenix
+        ? 'Start your Phoenix server with `mix phx.server` and trigger the instrumented code paths'
+        : 'Run your Elixir application and trigger the instrumented code paths',
+      'Visit your PostHog dashboard to see incoming events',
+      'Use PostHog.capture/2 to track custom events',
+      'Use PostHog.set_context/1 to set a distinct_id once per request or job process',
+    ],
+  },
+};

src/lib/__tests__/wizard-can-use-tool.test.ts

@@ -139,6 +139,21 @@ describe('bash fence — allows real toolchain commands (from skills + field log
     expect(allow('carthage bootstrap')).toBe('allow');
   });
 
+  it('elixir ecosystem', () => {
+    expect(allow('mix deps.get')).toBe('allow');
+    expect(allow('mix deps.update posthog')).toBe('allow');
+    expect(allow('mix deps.tree')).toBe('allow');
+    expect(allow('mix compile')).toBe('allow');
+    expect(allow('mix format')).toBe('allow');
+    expect(allow('mix hex.info posthog')).toBe('allow');
+    // mix runs arbitrary project-defined tasks — everything else stays denied.
+    expect(allow('mix run priv/repo/seeds.exs')).toBe('deny');
+    expect(allow('mix test')).toBe('deny');
+    expect(allow('mix phx.server')).toBe('deny');
+    expect(allow('mix ecto.migrate')).toBe('deny');
+    expect(allow('mix do deps.get, run evil.exs')).toBe('deny');
+  });
+
   it('android/jvm ecosystem', () => {
     expect(allow('./gradlew assembleDebug')).toBe('allow');
     expect(allow('./gradlew :app:assembleDebug')).toBe('allow');

src/lib/agent/bash-fence.ts

@@ -84,6 +84,16 @@ const SIMPLE_MANAGERS: Record<string, readonly string[]> = {
   swift: ['package', 'build'],
   pod: ['install', 'update', 'search'],
   carthage: ['bootstrap', 'update'],
+  // mix runs arbitrary project-defined tasks, so only the dependency +
+  // verify tasks are listed — run/test/phx.server execute project code.
+  mix: [
+    'deps.get',
+    'deps.update',
+    'deps.tree',
+    'compile',
+    'format',
+    'hex.info',
+  ],
 };
 
 // Gradle tasks are verb-anchored camelCase: assembleDebug yes, publishToMavenCentral no.
@@ -102,7 +112,8 @@ const ALLOWED_TOOLS_SUMMARY =
   'composer (install|require|update|remove|show), bundle (install|add|remove|update|show|exec <lint tool>), ' +
   'gem (install|uninstall|list|search), swift (package|build), pod (install|update|search), carthage (bootstrap|update), ' +
   'xcodebuild (build/clean/archive actions), gradle/gradlew (build|clean|dependencies|assemble*/compile*/bundle*/lint* tasks), ' +
-  'mvn (install|compile|package|verify|dependency:tree).';
+  'mvn (install|compile|package|verify|dependency:tree), ' +
+  'mix (deps.get|deps.update|deps.tree|compile|format|hex.info).';
 
 function deny(analyticsReason: string, message: string): BashFenceDecision {
   return { allowed: false, message, analyticsReason };

src/lib/agent/runner/sequence/orchestrator/__tests__/variant-resolution.test.ts

@@ -48,7 +48,7 @@ const INTEGRATION_ENTRIES = [
   { id: 'integration-javascript_node', framework: 'javascript_node' },
   { id: 'integration-javascript_web', framework: 'javascript_web' },
   { id: 'integration-ruby', framework: 'ruby' },
-  { id: 'integration-elixir' },
+  { id: 'integration-elixir', framework: 'elixir' },
   { id: 'integration-go' },
   { id: 'integration-swift', framework: 'swift' },
   { id: 'integration-kmp', framework: 'kmp' },

src/lib/constants.ts

@@ -100,6 +100,7 @@ export enum Integration {
   swift = 'swift',
   android = 'android',
   rails = 'rails',
+  elixir = 'elixir',
 
   // Language fallbacks. Keep javascriptNode last: it matches any package.json.
   python = 'python',

src/lib/detection/__tests__/framework.test.ts

@@ -5,6 +5,7 @@ import { detectFramework } from '@lib/detection/framework';
 import { Integration } from '@lib/constants';
 import { ANDROID_AGENT_CONFIG } from '../../../frameworks/android/android-wizard-agent';
 import { KMP_AGENT_CONFIG } from '../../../frameworks/kmp/kmp-wizard-agent';
+import { ELIXIR_AGENT_CONFIG } from '../../../frameworks/elixir/elixir-wizard-agent';
 
 /** A throwaway project dir seeded with the given files. */
 function makeProject(files: Record<string, string>): string {
@@ -137,6 +138,17 @@ describe('detectFramework (end-to-end over real project dirs)', () => {
     );
   });
 
+  test('a Phoenix project resolves to elixir', async () => {
+    const opts = project({
+      'mix.exs':
+        'defmodule MyApp.MixProject do\n  use Mix.Project\n\n  def project do\n    [app: :my_app, deps: deps()]\n  end\n\n  defp deps do\n    [{:phoenix, "~> 1.7"}]\n  end\nend\n',
+      'config/config.exs': 'import Config',
+    });
+    await expect(detectFramework(opts.installDir)).resolves.toBe(
+      Integration.elixir,
+    );
+  });
+
   test('a Flutter project is not claimed by anything', async () => {
     const opts = project({
       'pubspec.yaml': 'name: my_flutter_app\nenvironment:\n  sdk: ^3.0.0\n',
@@ -169,6 +181,28 @@ describe('android detect', () => {
   });
 });
 
+describe('elixir detect', () => {
+  const detect = ELIXIR_AGENT_CONFIG.detection.detect;
+
+  const mixExs =
+    'defmodule MyApp.MixProject do\n  use Mix.Project\n\n  def project do\n    [app: :my_app]\n  end\nend\n';
+
+  test('claims a Mix project', async () => {
+    const opts = project({ 'mix.exs': mixExs });
+    await expect(detect(opts)).resolves.toBe(true);
+  });
+
+  test('does not claim a mix.exs without a project definition', async () => {
+    const opts = project({ 'mix.exs': '# placeholder\n' });
+    await expect(detect(opts)).resolves.toBe(false);
+  });
+
+  test('does not claim a project without a mix.exs', async () => {
+    const opts = project({ 'lib/my_app.ex': 'defmodule MyApp do\nend\n' });
+    await expect(detect(opts)).resolves.toBe(false);
+  });
+});
+
 describe('kmp detect', () => {
   const detect = KMP_AGENT_CONFIG.detection.detect;
 

src/lib/detection/__tests__/package-manager.test.ts

@@ -7,6 +7,7 @@ import {
   composerPackageManager,
   swiftPackageManager,
   gradlePackageManager,
+  mixPackageManager,
 } from '@lib/detection/package-manager';
 
 vi.mock('../../../utils/debug');
@@ -188,6 +189,7 @@ describe('static package manager helpers', () => {
     { fn: composerPackageManager, name: 'composer' },
     { fn: swiftPackageManager, name: 'spm' },
     { fn: gradlePackageManager, name: 'gradle' },
+    { fn: mixPackageManager, name: 'mix' },
   ])('$name returns valid PackageManagerInfo', async ({ fn }) => {
     const result = await fn();
     expect(result.detected).toHaveLength(1);

src/lib/detection/agentic.ts

@@ -74,11 +74,12 @@ export const PROJECT_MANIFESTS: readonly string[] = [
   // Ruby / PHP
   'Gemfile',
   'composer.json',
-  // Rust / Go / Elixir / JVM / .NET: no framework targets yet, but found so
+  // Elixir
+  'mix.exs',
+  // Rust / Go / JVM / .NET: no framework targets yet, but found so
   // an existing PostHog SDK is reported (feeds self-driving's "continue" path).
   'Cargo.toml',
   'go.mod',
-  'mix.exs',
   'pom.xml',
   '*.csproj',
   // Mobile / native

src/lib/detection/package-manager.ts

@@ -215,6 +215,25 @@ export function bundlerPackageManager(): Promise<PackageManagerInfo> {
   });
 }
 
+// ---------------------------------------------------------------------------
+// Elixir (Mix) helper
+// ---------------------------------------------------------------------------
+
+const MIX: DetectedPackageManager = {
+  name: 'mix',
+  label: 'Mix',
+  installCommand: 'mix deps.get',
+};
+
+export function mixPackageManager(): Promise<PackageManagerInfo> {
+  return Promise.resolve({
+    detected: [MIX],
+    primary: MIX,
+    recommendation:
+      'Use Mix. Add the dependency to the deps list in mix.exs, then run mix deps.get.',
+  });
+}
+
 // ---------------------------------------------------------------------------
 // Android (Gradle) helper
 // ---------------------------------------------------------------------------

src/lib/registry.ts

@@ -18,6 +18,7 @@ import { SWIFT_AGENT_CONFIG } from '@frameworks/swift/swift-wizard-agent';
 import { KMP_AGENT_CONFIG } from '@frameworks/kmp/kmp-wizard-agent';
 import { ANDROID_AGENT_CONFIG } from '@frameworks/android/android-wizard-agent';
 import { RAILS_AGENT_CONFIG } from '@frameworks/rails/rails-wizard-agent';
+import { ELIXIR_AGENT_CONFIG } from '@frameworks/elixir/elixir-wizard-agent';
 import { PYTHON_AGENT_CONFIG } from '@frameworks/python/python-wizard-agent';
 import { RUBY_AGENT_CONFIG } from '@frameworks/ruby/ruby-wizard-agent';
 import { JAVASCRIPT_NODE_AGENT_CONFIG } from '@frameworks/javascript-node/javascript-node-wizard-agent';
@@ -42,6 +43,7 @@ export const FRAMEWORK_REGISTRY: Record<Integration, FrameworkConfig> = {
   [Integration.swift]: SWIFT_AGENT_CONFIG,
   [Integration.android]: ANDROID_AGENT_CONFIG,
   [Integration.rails]: RAILS_AGENT_CONFIG,
+  [Integration.elixir]: ELIXIR_AGENT_CONFIG,
   [Integration.python]: PYTHON_AGENT_CONFIG,
   [Integration.ruby]: RUBY_AGENT_CONFIG,
   [Integration.javascriptNode]: JAVASCRIPT_NODE_AGENT_CONFIG,