From 1fae608bf74583301e56f900f300654c4aaa9438 Mon Sep 17 00:00:00 2001
From: Ghina Ajour <ghina@glownet.com>
Date: Wed, 22 Apr 2026 11:30:13 +0300
Subject: [PATCH] Detect Rails in tool-detector #25

---
 .../core/src/analyzer/tool-detector.test.ts   | 42 +++++++++++++++++++
 packages/core/src/analyzer/tool-detector.ts   | 24 +++++++++--
 2 files changed, 63 insertions(+), 3 deletions(-)
 create mode 100644 packages/core/src/analyzer/tool-detector.test.ts

diff --git a/packages/core/src/analyzer/tool-detector.test.ts b/packages/core/src/analyzer/tool-detector.test.ts
new file mode 100644
index 0000000..f610078
--- /dev/null
+++ b/packages/core/src/analyzer/tool-detector.test.ts
@@ -0,0 +1,42 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { mkdirSync, writeFileSync, rmSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
+import { detectTools } from './tool-detector.js';
+
+let root: string;
+
+beforeEach(() => {
+  root = join(tmpdir(), `tool-detector-test-${Date.now()}`);
+  mkdirSync(root, { recursive: true });
+});
+
+afterEach(() => rmSync(root, { recursive: true, force: true }));
+
+describe('Rails detection', () => {
+  it('detects via Gemfile containing rails', () => {
+    writeFileSync(join(root, 'Gemfile'), `gem "rails", "~> 7.1"`);
+    const tools = detectTools(root);
+    expect(tools.find(t => t.id === 'rails')).toBeDefined();
+  });
+
+  it('does not detect rails from a non-rails Gemfile', () => {
+    writeFileSync(join(root, 'Gemfile'), `gem "sinatra"`);
+    const tools = detectTools(root);
+    expect(tools.find(t => t.id === 'rails')).toBeUndefined();
+  });
+
+  it('detects via config/application.rb with Rails::Application', () => {
+    mkdirSync(join(root, 'config'), { recursive: true });
+    writeFileSync(join(root, 'config/application.rb'), `class Application < Rails::Application\nend`);
+    const tools = detectTools(root);
+    expect(tools.find(t => t.id === 'rails')).toBeDefined();
+  });
+
+  it('detects via bin/rails existence alone', () => {
+    mkdirSync(join(root, 'bin'), { recursive: true });
+    writeFileSync(join(root, 'bin/rails'), '#!/usr/bin/env ruby');
+    const tools = detectTools(root);
+    expect(tools.find(t => t.id === 'rails')).toBeDefined();
+  });
+});
diff --git a/packages/core/src/analyzer/tool-detector.ts b/packages/core/src/analyzer/tool-detector.ts
index 4919675..ad4afc0 100644
--- a/packages/core/src/analyzer/tool-detector.ts
+++ b/packages/core/src/analyzer/tool-detector.ts
@@ -36,6 +36,8 @@ interface ToolSignature {
   versionFrom?: 'package.json' | 'config';
   /** Package name in package.json (for version extraction) */
   packageName?: string;
+  /** If a signal file matches an entry here, its contents must match the pattern */
+  fileContains?: Array<{ file: string; pattern: RegExp }>;
   /** Context hint template */
   contextHint: string;
 }
@@ -63,6 +65,16 @@ const TOOL_SIGNATURES: ToolSignature[] = [
     contextHint: 'Supabase: PostgreSQL + Auth + Storage + Realtime, config in supabase/',
   },
   // Frameworks
+  {
+    id: 'rails', name: 'Ruby on Rails', category: 'framework',
+    signals: ['Gemfile', 'config/application.rb', 'bin/rails'],
+    fileContains: [
+      { file: 'Gemfile', pattern: /gem\s+['"]rails['"]/i },
+      { file: 'config/application.rb', pattern: /Rails::Application/ },
+    ],
+    filePatterns: ['app/controllers/**', 'app/models/**', 'app/views/**', 'config/**', 'db/**', 'Gemfile'],
+    contextHint: 'Ruby on Rails: MVC framework, app/ has models/views/controllers, db/ has migrations, config/routes.rb defines routes',
+  },
   {
     id: 'nextjs', name: 'Next.js', category: 'framework',
     signals: ['next.config.js', 'next.config.mjs', 'next.config.ts'],
@@ -209,10 +221,16 @@ export function detectTools(repoRoot: string, scanResult?: ScanEntry): DetectedT
     // Check file signals
     for (const signal of sig.signals) {
       const fullPath = join(repoRoot, signal);
-      if (existsSync(fullPath)) {
-        configPath = signal;
-        break;
+      if (!existsSync(fullPath)) continue;
+      const contentCheck = sig.fileContains?.find(c => c.file === signal);
+      if (contentCheck) {
+        try {
+          const contents = readFileSync(fullPath, 'utf-8');
+          if (!contentCheck.pattern.test(contents)) continue;
+        } catch { continue; }
       }
+      configPath = signal;
+      break;
     }
 
     // Check package.json deps (for tools without config files, like Express)