From c1a74c195bd8f7bbfa20d957fd0931c4953db8d7 Mon Sep 17 00:00:00 2001
From: Bohdan Triapitsyn <artmore@protonmail.com>
Date: Sat, 1 Aug 2026 21:31:51 +0300
Subject: [PATCH] fix(electron): preserve HMR connection limits

---
 packages/electron/README.md                   |  2 +-
 packages/electron/main.mjs                    | 19 +++++++++++--------
 packages/electron/startup-url-selection.mjs   |  4 ++++
 .../electron/startup-url-selection.test.mjs   |  8 +++++++-
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/packages/electron/README.md b/packages/electron/README.md
index 1cb2f2dd..2e052833 100644
--- a/packages/electron/README.md
+++ b/packages/electron/README.md
@@ -19,7 +19,7 @@ The preload bridge exposes desktop-only APIs to the web UI through `window.__OPE
 | File | Purpose |
 |------|---------|
 | `main.mjs` | Electron main process, app lifecycle, windows, menus, deep links, native IPC handlers, updates, local server startup |
-| `startup-url-selection.mjs` | Pure bundled/HMR startup probe policy used by main-process URL resolution |
+| `startup-url-selection.mjs` | Pure bundled/HMR startup probe and loopback connection-limit policy |
 | `preload.mjs` | Safe bridge from the rendered UI to Electron IPC |
 | `ssh-manager.mjs` | SSH host import, connection lifecycle, tunnel/port forwarding helpers |
 | `scripts/electron-dev.mjs` | Desktop dev launcher with Vite HMR support |
diff --git a/packages/electron/main.mjs b/packages/electron/main.mjs
index 0b94d190..d82fbb3b 100644
--- a/packages/electron/main.mjs
+++ b/packages/electron/main.mjs
@@ -13,7 +13,7 @@ import updaterPkg from 'electron-updater';
 import { ElectronSshManager } from './ssh-manager.mjs';
 import { createTrayController } from './tray.mjs';
 import { resolveManagedOpenCodeCwd } from './opencode-cwd.mjs';
-import { resolveStartupUrlProbePlan } from './startup-url-selection.mjs';
+import { resolveStartupUrlProbePlan, shouldIgnoreLoopbackConnectionLimit } from './startup-url-selection.mjs';
 import { sanitizeRuntimeRequestHeaders } from './runtime-request-headers.mjs';
 import { assertUpdaterCapability } from './updater-capability.mjs';
 import { checkForDesktopUpdate } from './updater-check.mjs';
@@ -89,13 +89,16 @@ if (isDev) {
 }
 app.setAppUserModelId(APP_USER_MODEL_ID);
 app.commandLine.appendSwitch('proxy-bypass-list', '<-loopback>');
-// Lift Chromium's ~6-connections-per-host cap for the loopback backend. The
-// packaged renderer is cross-origin (openchamber-ui:// → http://127.0.0.1), so
-// every API call also needs a CORS preflight; during startup a few slow
-// OpenCode-proxied requests otherwise hold the whole pool and every other
-// request — including opening the first session — queues for seconds behind
-// them. Loopback has no per-host connection cost that the cap protects.
-app.commandLine.appendSwitch('ignore-connections-limit', '127.0.0.1,localhost');
+// Lift Chromium's per-host cap only for bundled UI. Applying this to Vite HMR
+// lets the renderer request most of the module graph at once, overwhelming the
+// dev server's transform pipeline and leaving the HTML splash visible for up
+// to a minute before React mounts.
+if (shouldIgnoreLoopbackConnectionLimit({
+  development: isDev,
+  packagedUi: process.env.OPENCHAMBER_ELECTRON_USE_BUNDLED_UI === '1',
+})) {
+  app.commandLine.appendSwitch('ignore-connections-limit', '127.0.0.1,localhost');
+}
 
 protocol.registerSchemesAsPrivileged([
   {
diff --git a/packages/electron/startup-url-selection.mjs b/packages/electron/startup-url-selection.mjs
index c7827606..c34d0f04 100644
--- a/packages/electron/startup-url-selection.mjs
+++ b/packages/electron/startup-url-selection.mjs
@@ -2,3 +2,7 @@ export const resolveStartupUrlProbePlan = ({ development, packagedUi, skipLocalS
   probeHmrApi: development === true && packagedUi !== true && skipLocalServer !== true,
   probeHmrUi: development === true && packagedUi !== true,
 });
+
+export const shouldIgnoreLoopbackConnectionLimit = ({ development, packagedUi }) => (
+  development !== true || packagedUi === true
+);
diff --git a/packages/electron/startup-url-selection.test.mjs b/packages/electron/startup-url-selection.test.mjs
index 48d3dba8..6497265d 100644
--- a/packages/electron/startup-url-selection.test.mjs
+++ b/packages/electron/startup-url-selection.test.mjs
@@ -1,7 +1,7 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 
-import { resolveStartupUrlProbePlan } from './startup-url-selection.mjs';
+import { resolveStartupUrlProbePlan, shouldIgnoreLoopbackConnectionLimit } from './startup-url-selection.mjs';
 
 test('bundled development never probes HMR endpoints', () => {
   assert.deepEqual(resolveStartupUrlProbePlan({
@@ -46,3 +46,9 @@ test('production does not probe HMR endpoints', () => {
     probeHmrUi: false,
   });
 });
+
+test('keeps Chromium connection limits for the Vite HMR module graph', () => {
+  assert.equal(shouldIgnoreLoopbackConnectionLimit({ development: true, packagedUi: false }), false);
+  assert.equal(shouldIgnoreLoopbackConnectionLimit({ development: true, packagedUi: true }), true);
+  assert.equal(shouldIgnoreLoopbackConnectionLimit({ development: false, packagedUi: false }), true);
+});