feat(predictive-echo): second vendor bundle wiring

postinstall + build.mjs build vendor/xterm-predictive-echo.js as a SEPARATE
IIFE (window.PredictiveEchoAddon + self-activating PredictiveEchoOverlay);
the zerolag bundle command is untouched and its output verified
sha256-identical. index.html loads it after the zerolag tag (cacheBustAssets
covers it), sw.js precaches it, build.mjs HASHABLE content-hashes it.
A missing or broken bundle degrades codex to plain PTY echo.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/build.mjs

@@ -65,6 +65,22 @@ appendFileSync(
   '}\n'
 );
 
+// Predictive echo (codex): separate bundle so the zerolag bundle stays byte-identical
+run('xterm-predictive-echo', 'npx esbuild packages/xterm-zerolag-input/src/predictive-echo-addon.ts --bundle --minify --format=iife --global-name=XtermPredictiveEcho --outfile=dist/web/public/vendor/xterm-predictive-echo.js');
+appendFileSync(
+  join(ROOT, 'dist/web/public/vendor/xterm-predictive-echo.js'),
+  '\n// Global aliases for browser usage\n' +
+  'if(typeof window!=="undefined"){' +
+    'window.PredictiveEchoAddon=XtermPredictiveEcho.PredictiveEchoAddon;' +
+    'window.PredictiveEchoOverlay=class extends XtermPredictiveEcho.PredictiveEchoAddon{' +
+      'constructor(terminal){' +
+        'super({});' +
+        'this.activate(terminal);' +
+      '}' +
+    '};' +
+  '}\n'
+);
+
 // 4. Minify frontend assets
 run('minify input-cjk.js', 'npx esbuild dist/web/public/input-cjk.js --minify --outfile=dist/web/public/input-cjk.js --allow-overwrite');
 run('minify i18n.js', 'npx esbuild dist/web/public/i18n.js --minify --outfile=dist/web/public/i18n.js --allow-overwrite');
@@ -106,6 +122,7 @@ console.log('\n[build] content-hash cache busting');
     'subagent-windows.js',
     'image-input.js',
     'vendor/xterm-zerolag-input.js',
+    'vendor/xterm-predictive-echo.js',
   ];
   const manifest = {};
   for (const file of HASHABLE) {

scripts/postinstall.js

@@ -304,6 +304,35 @@ if (isGlobalInstall) {
         } catch {
             console.log(colors.yellow('⚠ Failed to bundle xterm-zerolag-input — overlay may not work in dev mode'));
         }
+
+        // Predictive echo (codex): SEPARATE bundle so the zerolag bundle above stays
+        // byte-identical. If this file is missing or broken, codex simply falls back
+        // to plain PTY echo (pre-predictive behavior); nothing else is affected.
+        try {
+            const predSrc = join(import.meta.dirname, '..', 'packages', 'xterm-zerolag-input', 'src', 'predictive-echo-addon.ts');
+            const predOut = join(vendorDir, 'xterm-predictive-echo.js');
+            execSync(
+                `npx esbuild "${predSrc}" --bundle --format=iife --global-name=XtermPredictiveEcho --outfile="${predOut}"`,
+                { stdio: 'pipe' }
+            );
+            const { appendFileSync } = await import('fs');
+            appendFileSync(
+                predOut,
+                '\n// Global aliases for browser usage\n' +
+                'if(typeof window!=="undefined"){' +
+                    'window.PredictiveEchoAddon=XtermPredictiveEcho.PredictiveEchoAddon;' +
+                    'window.PredictiveEchoOverlay=class extends XtermPredictiveEcho.PredictiveEchoAddon{' +
+                        'constructor(terminal){' +
+                            'super({});' +
+                            'this.activate(terminal);' +
+                        '}' +
+                    '};' +
+                '}\n'
+            );
+            console.log(colors.green('✓ xterm-predictive-echo bundled to vendor/'));
+        } catch (e) {
+            console.log(colors.yellow('⚠ predictive-echo bundle failed (codex uses plain echo): ' + e.message));
+        }
     } catch (err) {
         hasWarnings = true;
         console.log(colors.yellow('⚠ Failed to copy xterm vendor files'));

src/web/public/index.html

@@ -38,6 +38,7 @@
   <!-- WebGL addon lazy-loaded by app.js on desktop only (skipped on mobile, saving 244KB) -->
   <script defer src="vendor/xterm-addon-unicode11.min.js"></script>
   <script defer src="vendor/xterm-zerolag-input.js"></script>
+  <script defer src="vendor/xterm-predictive-echo.js"></script>
   <script defer src="vendor/marked.min.js"></script>
   <!-- DOMPurify (allowlist HTML sanitizer for rendered markdown).
        Must load before sanitize-html.js (which wires it) and app.js (which calls it). -->

src/web/public/sw.js

@@ -40,6 +40,7 @@ const APP_SHELL = [
   '/vendor/xterm-addon-fit.min.js',
   '/vendor/xterm-addon-unicode11.min.js',
   '/vendor/xterm-zerolag-input.js',
+  '/vendor/xterm-predictive-echo.js',
   '/vendor/xterm.css',
   '/icon-192.png',
   '/icon-512.png',