build: Decouple browser opening from watch mode in extension dev (#726)

- Add `--start-maximized` Chrome arg to extensionDev plugin
- Replace `--watch` trigger with `OPEN_BROWSER` env var for browser
opening
- Add `build:browser` script that sets `OPEN_BROWSER=true`
- Update `start.sh` scripts to use `yarn build:browser`

Browser now opens maximized so dev mode toggle is visible.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Decouples automatic browser launch from watch mode and adds a
dedicated opt‑in.
> 
> - Adds `build:browser` in `packages/extension` and
`packages/omnium-gatherum`; updates `scripts/start.sh` to use it
> - Vite configs now gate `extensionDev` on `OPEN_BROWSER`
(`shouldOpenBrowser`) instead of `--watch`
> - `extension-dev` plugin launches Chrome with `--start-maximized` and
removes explicit viewport sizing
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
2fef526. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Co-authored-by: Claude Opus 4.5 <[email protected]>

Author: rekmarks

packages/extension/package.json

@@ -18,6 +18,7 @@
     "build": "yarn build:vite && yarn test:build",
     "build:dev": "yarn build:vite --mode development",
     "build:watch": "yarn build:dev --watch",
+    "build:browser": "OPEN_BROWSER=true yarn build:dev --watch",
     "build:vite": "vite build --configLoader runner --config vite.config.ts",
     "changelog:validate": "../../scripts/validate-changelog.sh @ocap/extension",
     "clean": "rimraf --glob './*.tsbuildinfo' ./.eslintcache ./coverage ./dist ./.turbo",

packages/extension/scripts/start.sh

@@ -23,4 +23,4 @@ function cleanup() {
 # Ensure we always close the ocap cli
 trap cleanup EXIT
 
-yarn build:watch
+yarn build:browser

packages/extension/vite.config.ts

@@ -44,6 +44,7 @@ const staticCopyTargets: readonly (string | Target)[] = [
 export default defineConfig(({ mode }) => {
   const isDev = mode === 'development';
   const isWatching = process.argv.includes('--watch');
+  const shouldOpenBrowser = process.env.OPEN_BROWSER === 'true';
   if (isWatching && !isDev) {
     throw new Error('Cannot watch in non-development mode');
   }
@@ -111,8 +112,8 @@ export default defineConfig(({ mode }) => {
       }),
       moveHtmlFilesToRoot(),
       watchInternalPackages({ rootDir, packages: ['kernel-ui'] }),
-      // Open the extension in the browser when watching
-      isWatching && extensionDev({ extensionPath: outDir }),
+      // Open the extension in the browser when --browser flag is passed
+      shouldOpenBrowser && extensionDev({ extensionPath: outDir }),
     ],
   };
 });

packages/omnium-gatherum/package.json

@@ -19,6 +19,7 @@
     "build": "yarn build:vite && yarn test:build",
     "build:dev": "yarn build:vite --mode development",
     "build:watch": "yarn build:dev --watch",
+    "build:browser": "OPEN_BROWSER=true yarn build:dev --watch",
     "build:vite": "vite build --configLoader runner --config vite.config.ts",
     "changelog:validate": "../../scripts/validate-changelog.sh @ocap/omnium-gatherum",
     "clean": "rimraf --glob './*.tsbuildinfo' ./.eslintcache ./coverage ./dist ./.turbo",

packages/omnium-gatherum/scripts/start.sh

@@ -23,4 +23,4 @@ function cleanup() {
 # Ensure we always close the ocap cli
 trap cleanup EXIT
 
-yarn build:watch
+yarn build:browser

packages/omnium-gatherum/vite.config.ts

@@ -52,6 +52,7 @@ const trustedPreludes: PreludeRecord = {
 export default defineConfig(({ mode }) => {
   const isDev = mode === 'development';
   const isWatching = process.argv.includes('--watch');
+  const shouldOpenBrowser = process.env.OPEN_BROWSER === 'true';
   if (isWatching && !isDev) {
     throw new Error('Cannot watch in non-development mode');
   }
@@ -121,8 +122,8 @@ export default defineConfig(({ mode }) => {
       }),
       moveHtmlFilesToRoot(),
       watchInternalPackages({ rootDir, packages: ['kernel-ui'] }),
-      // Open the extension in the browser when watching
-      isWatching && extensionDev({ extensionPath: outDir }),
+      // Open the extension in the browser when --browser flag is passed
+      shouldOpenBrowser && extensionDev({ extensionPath: outDir }),
     ],
   };
 });

packages/repo-tools/src/vite-plugins/extension-dev.ts

@@ -62,6 +62,7 @@ export function extensionDev({
       args: [
         `--disable-extensions-except=${extensionPath}`,
         `--load-extension=${extensionPath}`,
+        '--start-maximized',
       ],
     });
 
@@ -89,7 +90,6 @@ export function extensionDev({
 
     // Open the extensions page for our extension
     const extensionsPage = await browserContext.newPage();
-    await extensionsPage.setViewportSize({ width: 1300, height: 700 });
     await extensionsPage.goto(`chrome://extensions/?id=${extensionId}`);
 
     // Update state after all checks