fix(analytics): Resolve feature flags before first render

apps/code/src/main/posthog-session-arg.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it } from "vitest";
+import { parseSessionIdArg } from "./posthog-session-arg";
+
+describe("parseSessionIdArg", () => {
+  it("returns the value when the flag is present", () => {
+    expect(parseSessionIdArg(["--posthog-session-id=abc-123"])).toBe("abc-123");
+  });
+
+  it("finds the flag among other arguments", () => {
+    expect(
+      parseSessionIdArg(["--foo", "--posthog-session-id=xyz", "--bar"]),
+    ).toBe("xyz");
+  });
+
+  it("returns null when the flag is absent", () => {
+    expect(parseSessionIdArg(["--type=renderer", "--no-sandbox"])).toBeNull();
+  });
+
+  it("ignores arguments that only share the prefix", () => {
+    expect(parseSessionIdArg(["--posthog-session-id-extra=foo"])).toBeNull();
+  });
+
+  it("returns an empty string when the flag has no value", () => {
+    expect(parseSessionIdArg(["--posthog-session-id="])).toBe("");
+  });
+});

apps/code/src/main/posthog-session-arg.ts

@@ -0,0 +1,9 @@
+export const POSTHOG_SESSION_ID_ARG = "--posthog-session-id=";
+
+export function parseSessionIdArg(argv: string[]): string | null {
+  return (
+    argv
+      .find((arg) => arg.startsWith(POSTHOG_SESSION_ID_ARG))
+      ?.slice(POSTHOG_SESSION_ID_ARG.length) ?? null
+  );
+}

apps/code/src/main/preload.ts

@@ -1,11 +1,16 @@
 import { exposeElectronTRPC } from "@posthog/electron-trpc/main";
 import { contextBridge, webUtils } from "electron";
 import "electron-log/preload";
+import { parseSessionIdArg } from "./posthog-session-arg";
 
 contextBridge.exposeInMainWorld("electronUtils", {
   getPathForFile: (file: File) => webUtils.getPathForFile(file),
 });
 
+contextBridge.exposeInMainWorld("__posthogBootstrap", {
+  sessionId: parseSessionIdArg(process.argv),
+});
+
 if (process.argv.includes("--posthog-code-dev")) {
   contextBridge.exposeInMainWorld("__posthogCodeTest", {
     crash: () => {

apps/code/src/main/window.ts

@@ -13,6 +13,8 @@ import {
 import { container } from "./di/container";
 import { buildApplicationMenu } from "./menu";
 import type { ElectronMainWindow } from "./platform-adapters/electron-main-window";
+import { posthogNodeAnalytics } from "./platform-adapters/posthog-analytics";
+import { POSTHOG_SESSION_ID_ARG } from "./posthog-session-arg";
 import { trpcRouter } from "./trpc/router";
 import { collectMemorySnapshot } from "./utils/crash-diagnostics";
 import { isDevBuild } from "./utils/env";
@@ -203,7 +205,10 @@ export function createWindow(): void {
       preload: path.join(__dirname, "preload.js"),
       enableBlinkFeatures: "GetDisplayMedia",
       partition: "persist:main",
-      additionalArguments: isDev ? ["--posthog-code-dev"] : [],
+      additionalArguments: [
+        ...(isDev ? ["--posthog-code-dev"] : []),
+        `${POSTHOG_SESSION_ID_ARG}${posthogNodeAnalytics.getOrCreateSessionId()}`,
+      ],
       ...(isDev && { webSecurity: false }),
     },
   });

apps/code/src/renderer/contributions/app-boot.contributions.ts

@@ -13,13 +13,15 @@ const log = logger.scope("app-boot");
 export class AnalyticsBootContribution implements Contribution {
   start(): void {
     void (async () => {
-      let sessionId: string | undefined;
-      try {
-        ({ sessionId } = await trpcClient.analytics.getSessionId.query());
-      } catch (error) {
-        log.warn("Failed to fetch session id from main", { error });
+      if (!window.__posthogBootstrap?.sessionId) {
+        let sessionId: string | undefined;
+        try {
+          ({ sessionId } = await trpcClient.analytics.getSessionId.query());
+        } catch (error) {
+          log.warn("Failed to fetch session id from main", { error });
+        }
+        initializePostHog(sessionId);
       }
-      initializePostHog(sessionId);
       trpcClient.os.getAppVersion
         .query()
         .then(registerAppVersion)

apps/code/src/renderer/main.tsx

@@ -16,6 +16,7 @@ import { preloadHighlighter } from "@pierre/diffs";
 import { boot } from "@posthog/di/contribution";
 import { ServiceProvider } from "@posthog/di/react";
 import App from "@posthog/ui/shell/App";
+import { initializePostHog } from "@posthog/ui/shell/posthogAnalyticsImpl";
 import { registerDesktopContributions } from "@renderer/desktop-contributions";
 import { container } from "@renderer/di/container";
 import "@renderer/desktop-services";
@@ -74,6 +75,11 @@ document.title = import.meta.env.DEV
   ? "PostHog Code (Development)"
   : "PostHog Code";
 
+const bootstrapSessionId = window.__posthogBootstrap?.sessionId;
+if (bootstrapSessionId) {
+  initializePostHog(bootstrapSessionId);
+}
+
 registerDesktopContributions();
 void boot(container);
 

apps/code/src/renderer/types/electron.d.ts

@@ -5,5 +5,8 @@ declare global {
     electronUtils?: {
       getPathForFile: (file: File) => string;
     };
+    __posthogBootstrap?: {
+      sessionId: string | null;
+    };
   }
 }