fix(dev): Wait for old Electron to exit on mprocs restart (#3291)

Author: charlesvien

mprocs.yaml

@@ -1,6 +1,6 @@
 procs:
   1-code:
-    shell: 'node scripts/pnpm-run.mjs --filter code run start'
+    shell: 'node scripts/wait-for-electron-exit.mjs && node scripts/pnpm-run.mjs --filter code run start'
     env:
       DEBUG: "false"
     depends_on:

scripts/wait-for-electron-exit.mjs

@@ -0,0 +1,55 @@
+import { execFileSync } from "node:child_process";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const WAIT_TIMEOUT_MS = 15_000;
+const POLL_INTERVAL_MS = 200;
+
+const repoRoot = path.resolve(
+  path.dirname(fileURLToPath(import.meta.url)),
+  "..",
+);
+const electronDist = path.join(repoRoot, "node_modules", "electron", "dist");
+const pattern = electronDist.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+
+function runningElectronPids() {
+  try {
+    const out = execFileSync("pgrep", ["-f", pattern], { encoding: "utf8" });
+    return out.split("\n").filter(Boolean);
+  } catch (error) {
+    if (error.status === 1) return [];
+    throw error;
+  }
+}
+
+const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
+
+if (process.platform !== "win32") {
+  try {
+    const initialPids = runningElectronPids();
+    if (initialPids.length > 0) {
+      console.log(
+        `Waiting for previous Electron instance to exit (pids: ${initialPids.join(", ")})`,
+      );
+      const startedAt = Date.now();
+      while (Date.now() - startedAt < WAIT_TIMEOUT_MS) {
+        await sleep(POLL_INTERVAL_MS);
+        if (runningElectronPids().length === 0) break;
+      }
+      const remaining = runningElectronPids();
+      if (remaining.length > 0) {
+        console.warn(
+          `Previous Electron instance still running after ${WAIT_TIMEOUT_MS}ms (pids: ${remaining.join(", ")}), starting anyway`,
+        );
+      } else {
+        console.log(
+          `Previous Electron instance exited after ${((Date.now() - startedAt) / 1000).toFixed(1)}s`,
+        );
+      }
+    }
+  } catch (error) {
+    console.warn(
+      `Skipping wait for previous Electron instance, pgrep failed: ${error.code ?? error.status ?? error.message}`,
+    );
+  }
+}