Add Mixpanel + PostHog analytics to docs

[abhishekmishragithub]

Summary

• Adds PostHog native integration via docs.yml analytics config (project: docs.smallest.ai)
• Adds analytics.js custom script that loads Mixpanel SDK and sets up custom event tracking
• Both platforms receive identical events via dual-send pattern

Events Tracked

Event	Trigger
docs_page_viewed	Every page load/SPA navigation
docs_code_copied	Code block copy button click
docs_search_performed	Search input (debounced, 3+ chars)
docs_search_result_clicked	Click on search result
docs_nav_clicked	Sidebar/nav link click
docs_product_toggled	Waves ↔ Atoms toggle
docs_signup_clicked	CTA / signup / console links
docs_console_link_clicked	Any link to console.smallest.ai
docs_sdk_install_copied	pip/npm/yarn install command copy
docs_feedback_submitted	Thumbs up/down feedback widget
docs_scroll_depth	25%, 50%, 75%, 100% scroll milestones
docs_api_playground_used	API playground "Try it" button

Files Changed

• fern/docs.yml — Added analytics: (PostHog) + js: (analytics.js) sections
• fern/docs/assets/scripts/analytics.js — New: Mixpanel loader + all event trackers

How to Test

1. Merge → fern generate --docs
2. Visit docs.smallest.ai → open browser devtools → Network tab
3. Verify requests going to cdn.mxpnl.com (Mixpanel) and us.i.posthog.com (PostHog)
4. Check Mixpanel Live View + PostHog Live Events for event stream

PostHog Dashboards (already created)

• Docs — TOFU Overview (8 insights)
• Docs — BOFU & Activation (10 insights)
• Docs — Funnels & User Journeys (3 funnels)
• Docs — UX Deep Dive (9 insights for friction/stuck analysis)

[github-actions]

🌿 Preview your docs: https://smallest-ai-preview-dca07174-9c8d-44fd-ad71-e736da6df42a.docs.buildwithfern.com

[entelligence-ai-pr-reviews]

EntelligenceAI PR Summary

Adds dual-platform analytics instrumentation (Mixpanel + PostHog) to the Fern documentation site.

• fern/docs.yml: Registers PostHog analytics with API key/endpoint and includes analytics.js as a custom script
• fern/docs/assets/scripts/analytics.js: Dynamically loads Mixpanel SDK and sets up 10 event trackers
• Tracks page views, code copy, search, navigation clicks, product toggling, CTA/signup/console links, SDK install copy, feedback buttons, and scroll depth milestones (25/50/75/100%)
• Enriches all events with product, page path, and UTM parameter metadata
• Implements History API monkey-patching for SPA-aware route change detection

---

Confidence Score: 2/5 - Changes Needed

Not safe to merge — analytics.js contains a runtime-breaking bug where call2_args and call2 are implicitly assigned without var/let/const inside a "use strict" context, causing a ReferenceError whenever get_group is invoked and silently disabling Mixpanel group tracking. The PR itself is well-scoped and achieves a clean dual-platform analytics integration (Mixpanel + PostHog) with meaningful event coverage including scroll depth milestones, SDK copy tracking, and CTA clicks, but this strict-mode variable declaration bug must be fixed before the script can run reliably in production.

Key Findings:

• In analytics.js, the variables call2_args and call2 are assigned without any var/let/const declaration inside a "use strict" file — this is a hard ReferenceError in strict mode that will throw at runtime whenever get_group is called, not a silent failure or degraded experience.
• The analytics instrumentation is otherwise comprehensive, covering 10 distinct event types (page views, code copy, search, scroll depth at 25/50/75/100%, CTA links, feedback buttons) which represents solid coverage for a docs analytics initiative.
• Only 1 of 2 changed files was reviewed, meaning fern/docs.yml — which registers the PostHog API key and endpoint — was not assessed; hardcoded API keys in config files warrant verification that these are public/client-side safe keys and not secret tokens.

Files requiring special attention

• fern/docs/assets/scripts/analytics.js
• fern/docs.yml

[entelligence-ai-pr-reviews]

Correctness: call2_args and call2 are assigned without var/let/const declarations inside a file that opens with "use strict" — this throws a ReferenceError at runtime whenever get_group is invoked, silently breaking any Mixpanel group tracking call.

🤖 AI Agent Prompt for Cursor/Windsurf

📋 Copy this prompt to your AI coding assistant (Cursor, Windsurf, etc.) to get help fixing this issue

In fern/docs/assets/scripts/analytics.js, lines 57-58, inside the `b()` function within `a.get_group`, the variables `call2_args` and `call2` are assigned without any `var`/`let`/`const` declaration. Because the outer IIFE file uses `"use strict"`, assigning to undeclared variables throws a ReferenceError at runtime. Fix by prepending `var` to both assignments: `var call2_args = arguments;` and `var call2 = [c].concat(...)`.  The same variables are referenced on lines 58-59 (the push call) so no further changes are needed there once they are properly declared.