test(terminal): support local browser bench runs

README.md

@@ -21,16 +21,22 @@ Change `app_config/src/lib.rs` to test another base path.
 The terminal benchmark script connects to an already-running dev server; it does
 not start or stop services.
 
-Install the Node dependency and Chromium browser once before running it:
+Install the Node dependency once before running it:
 
 ```bash
 npm install
-npx playwright install chromium
 ```
 
 ```bash
 npm run terminal:bench -- --url http://127.0.0.1:3100/rustui/terminal
 ```
 
+If Playwright's browser download is slow, use an installed Chrome/Chromium
+instead:
+
+```bash
+npm run terminal:bench -- --url http://127.0.0.1:3100/rustui/terminal --browser-executable /usr/bin/google-chrome
+```
+
 It writes `target/terminal-bench/terminal-bench.json` plus screenshots when
 Playwright is available in the workspace.

scripts/terminal-bench.mjs

@@ -22,6 +22,8 @@ export function parseArgs(argv) {
     viewports: [...DEFAULT_VIEWPORTS],
     timeoutMs: 120000,
     screenshot: true,
+    browserChannel: process.env.PLAYWRIGHT_BROWSER_CHANNEL || "",
+    browserExecutable: process.env.PLAYWRIGHT_BROWSER_EXECUTABLE || "",
   };
 
   for (let index = 0; index < argv.length; index += 1) {
@@ -44,6 +46,10 @@ export function parseArgs(argv) {
       options.timeoutMs = positiveInt(next(), "--timeout-ms");
     } else if (arg === "--viewport") {
       options.viewports = [parseViewport(next())];
+    } else if (arg === "--browser-channel") {
+      options.browserChannel = next();
+    } else if (arg === "--browser-executable") {
+      options.browserExecutable = next();
     } else if (arg === "--no-screenshot") {
       options.screenshot = false;
     } else if (arg === "--help" || arg === "-h") {
@@ -52,6 +58,9 @@ export function parseArgs(argv) {
       throw new Error(`Unknown argument: ${arg}`);
     }
   }
+  if (options.browserChannel && options.browserExecutable) {
+    throw new Error("Use only one of --browser-channel or --browser-executable");
+  }
 
   return options;
 }
@@ -133,7 +142,7 @@ async function main() {
   const { chromium } = await importPlaywright();
   fs.mkdirSync(options.outputDir, { recursive: true });
 
-  const browser = await chromium.launch();
+  const browser = await chromium.launch(browserLaunchOptions(options));
   const results = [];
   try {
     for (const viewport of options.viewports) {
@@ -253,6 +262,16 @@ async function runScenario(browser, options, viewport) {
   }
 }
 
+function browserLaunchOptions(options) {
+  if (options.browserChannel) {
+    return { channel: options.browserChannel };
+  }
+  if (options.browserExecutable) {
+    return { executablePath: options.browserExecutable };
+  }
+  return {};
+}
+
 export function pngSmokeFromBuffer(buffer) {
   const signature = buffer.subarray(0, 8).toString("hex");
   const isPng = signature === "89504e470d0a1a0a";
@@ -342,6 +361,8 @@ Options:
   --lines <n>                 Default: ${DEFAULT_LINES}
   --viewport <cols>x<rows>    Run one scenario with inferred browser size
   --viewport <c>x<r>:<w>x<h>  Run one scenario with explicit browser size
+  --browser-channel <name>    Use an installed browser channel, e.g. chrome
+  --browser-executable <path> Use a local Chromium/Chrome executable path
   --timeout-ms <n>            Default: 120000
   --no-screenshot            Skip screenshot capture
   --help                     Show this help