Discover installed Chromium executable

web/backend/src/ChromiumFallback.ts

@@ -1,4 +1,5 @@
 import { ChildProcess, spawn } from "child_process";
+import { accessSync, constants } from "fs";
 import { mkdtemp, rm } from "fs/promises";
 import os from "os";
 import path from "path";
@@ -15,9 +16,26 @@ export class ChromiumFallback {
 
     constructor(
         private readonly onExit: (url: string) => void = () => undefined,
-        private readonly executable = process.env.QUEUECUBE_CHROME_BIN || "chromium",
+        private readonly executable = process.env.QUEUECUBE_CHROME_BIN || ChromiumFallback.findExecutable(),
     ) {}
 
+    private static findExecutable(): string {
+        const directories = (process.env.PATH || "").split(path.delimiter);
+        for (const name of ["chromium", "chromium-browser", "google-chrome"]) {
+            for (const directory of directories) {
+                if (!directory) continue;
+                const candidate = path.join(directory, name);
+                try {
+                    accessSync(candidate, constants.X_OK);
+                    return candidate;
+                } catch {
+                    // Keep checking the remaining supported executable names.
+                }
+            }
+        }
+        return "chromium";
+    }
+
     public get isRunning(): boolean {
         return this.active !== null;
     }

web/backend/test/ChromiumFallback.test.cjs

@@ -41,6 +41,32 @@ test("uses isolated profile and safe argv; stop kills only its process and clean
   }
 });
 
+test("discovers chromium-browser when that is the installed executable", async () => {
+  const fixture = await fs.mkdtemp(path.join(os.tmpdir(), "queuecube-browser-path-test-"));
+  const argsFile = path.join(fixture, "argv.json");
+  const executable = path.join(fixture, "chromium-browser");
+  const previousPath = process.env.PATH;
+  const previousOverride = process.env.QUEUECUBE_CHROME_BIN;
+  await fs.writeFile(executable, `#!/usr/bin/env node\nconst fs=require('fs'); fs.writeFileSync(${JSON.stringify(argsFile)}, JSON.stringify(process.argv.slice(2))); setInterval(()=>{},1000);\n`);
+  await fs.chmod(executable, 0o700);
+  await fs.symlink(process.execPath, path.join(fixture, "node"));
+
+  try {
+    process.env.PATH = fixture;
+    delete process.env.QUEUECUBE_CHROME_BIN;
+    const browser = new ChromiumFallback();
+    assert.equal(await browser.start("https://example.test/browser-discovery", () => true), true);
+    await waitFor(async () => { try { await fs.access(argsFile); return true; } catch { return false; } });
+    assert.equal(JSON.parse(await fs.readFile(argsFile, "utf8")).at(-1), "https://example.test/browser-discovery");
+    await browser.stop();
+  } finally {
+    process.env.PATH = previousPath;
+    if (previousOverride === undefined) delete process.env.QUEUECUBE_CHROME_BIN;
+    else process.env.QUEUECUBE_CHROME_BIN = previousOverride;
+    await fs.rm(fixture, { recursive: true, force: true });
+  }
+});
+
 test("canceled startup cleans its profile without spawning", async () => {
   const browser = new ChromiumFallback(() => undefined, "/bin/false");
   assert.equal(await browser.start("https://example.test/", () => false), false);