feat: add detect-tools utility and Gemini sync with tests

src/utils/detect-tools.ts

@@ -0,0 +1,46 @@
+import os from "os"
+import path from "path"
+import { pathExists } from "./files"
+
+export type DetectedTool = {
+  name: string
+  detected: boolean
+  reason: string
+}
+
+export async function detectInstalledTools(
+  home: string = os.homedir(),
+  cwd: string = process.cwd(),
+): Promise<DetectedTool[]> {
+  const checks: Array<{ name: string; paths: string[] }> = [
+    { name: "opencode", paths: [path.join(home, ".config", "opencode"), path.join(cwd, ".opencode")] },
+    { name: "codex", paths: [path.join(home, ".codex")] },
+    { name: "droid", paths: [path.join(home, ".factory")] },
+    { name: "cursor", paths: [path.join(cwd, ".cursor"), path.join(home, ".cursor")] },
+    { name: "pi", paths: [path.join(home, ".pi")] },
+    { name: "gemini", paths: [path.join(cwd, ".gemini"), path.join(home, ".gemini")] },
+  ]
+
+  const results: DetectedTool[] = []
+  for (const check of checks) {
+    let detected = false
+    let reason = "not found"
+    for (const p of check.paths) {
+      if (await pathExists(p)) {
+        detected = true
+        reason = `found ${p}`
+        break
+      }
+    }
+    results.push({ name: check.name, detected, reason })
+  }
+  return results
+}
+
+export async function getDetectedTargetNames(
+  home: string = os.homedir(),
+  cwd: string = process.cwd(),
+): Promise<string[]> {
+  const tools = await detectInstalledTools(home, cwd)
+  return tools.filter((t) => t.detected).map((t) => t.name)
+}