fix(analytics): Resolve feature flags before first render

[charlesvien]

Problem

The "Cloud" option in the workspace-mode picker intermittently vanished on launch and only returned after a hard refresh or restart. It is gated by the twig-cloud-mode-toggle feature flag, but the renderer deferred PostHog initialization behind an async getSessionId IPC round-trip. React mounted first, so useFeatureFlag read the flag as false (flags not loaded yet) and hid the option until init finished and flags arrived. Every useFeatureFlag consumer was exposed to the same race; the || import.meta.env.DEV fallback masked it during local development.

Closes #2598

Changes

1. Pass the main-owned session id to the renderer synchronously via additionalArguments
2. Expose it on window.__posthogBootstrap from the preload
3. Initialize PostHog before React mounts so flags resolve on the first render
4. Keep AnalyticsBootContribution as an idempotent async fallback when the bridge value is absent
5. Session stitching is preserved — the renderer still uses the main process session id

How did you test this?

• pnpm --filter code typecheck (main + renderer tsconfigs) — pass
• biome check on the changed files — clean (also enforced by the pre-commit hook)
• pnpm --filter code exec vitest run src/main/platform-adapters/posthog-analytics.test.ts — 7/7 pass
• pnpm --filter @posthog/ui exec vitest run src/shell/posthogAnalyticsImpl.test.ts — 11/11 pass

Not yet run: an end-to-end check on a production build with twig-cloud-mode-toggle enabled — the flag path is dev-forced on, so the race only manifests in production builds. A genuinely cold flag cache still has a one-time load window until the network flags response arrives, which is expected first-load behavior.

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

[charlesvien]

• fix(analytics): Resolve feature flags before first render #2656 👈 (View in Graphite)
• fix(auth): Auto-recover project-less session after re-auth #2655
• fix(agent): Surface real session-init errors and kill leaked CLIs #2654
• main

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[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit b704380.}

[github-actions]

Low-risk analytics timing fix fully contained within the Electron host layer. Uses correct Electron patterns (contextBridge, additionalArguments), the session ID is not a secret, and the fallback async path remains intact if the sync bridge is absent.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "initialize posthog before first render" | Re-trigger Greptile}

New commits pushed (delta classified non_linear_history) — stamphog approval dismissed; re-review running automatically.

[github-actions]

Low-risk analytics timing fix fully contained within the Electron host layer. The synchronous bootstrap path via contextBridge and additionalArguments is correct, the async fallback remains intact when the bootstrap value is absent, and the session ID is not sensitive data.

New commits pushed (delta classified non_linear_history) — stamphog approval dismissed; re-review running automatically.

[github-actions]

Low-risk analytics timing fix fully contained within the Electron host layer. Uses correct Electron patterns (contextBridge, additionalArguments), the async fallback remains intact, and no sensitive data is exposed.

New commits pushed (delta classified non_linear_history) — stamphog approval dismissed; re-review running automatically.

[github-actions]

Low-risk analytics timing fix fully contained in the Electron host layer. The idempotency guard in initializePostHog prevents double initialization, the async fallback is preserved when the sync bridge is absent, and the session ID is a non-sensitive analytics UUID.

New commits pushed (delta classified non_linear_history) — stamphog approval dismissed; re-review running automatically.

[github-actions]

No showstoppers. Low-risk analytics timing fix fully contained within the Electron host layer — correct use of contextBridge and additionalArguments, the async fallback is preserved when the sync bridge is absent, and the session ID is a non-sensitive analytics UUID. Logic paths in main.tsx and app-boot.contributions.ts are consistent (sync path initializes PostHog, async path skips it, no double-init risk).