fix(sessions): drop redundant generic "PostHog" resource chip

[adboio]

Problem

In a session's "PostHog resources used" bar, one chip just said PostHog. As Matt flagged in the thread: inside a bar literally titled "PostHog resources used", a chip that says "PostHog" is redundant.

It was the generic fallback (posthog product id) the MCP sub-tool classifier returned whenever a call's domain wasn't recognized. Digging into what was actually hitting that fallback surfaced two further problems:

• No visibility — an unrecognized call fell to the fallback silently, with nothing logged, so we had no way to know which sub-tools were landing there.
• Real coverage gaps — several DOMAIN_PRODUCT keys were written more specifically than the actual MCP domain token (e.g. notebooks vs notebook, cdp-functions vs cdp-function, llma-personal-spend vs the llma-* family). Legitimate product calls were being mis-bucketed into the fallback instead of showing their real product chip.

Changes

• Removed the generic posthog product id. Unrecognized domains now classify as null and surface nothing — matching how known admin/meta domains already behave. The exhaustive Record<PostHogProductId, …> types compile-enforced dropping its icon/docs-URL entries in SessionResourcesBar.
• Added isUnclassifiedPostHogSubTool + a debug log in the agent, so genuinely-unknown PostHog sub-tools become visible and DOMAIN_PRODUCT can be expanded deliberately. Deliberately-suppressed admin domains (project, docs-search, …) don't log.
• Closed domain-map gaps so real product calls resolve to the right chip: consolidated the whole llma-* family → AI observability, fixed notebook / cdp-function / external-data / web-analytics, and added event-definition (Product analytics) and vision (Replay Vision → Session replay).

No frontend screenshot — the only UI effect is removing a chip that should never have rendered.

How did you test this?

• pnpm --filter @posthog/agent test posthog-products — 82 passing (incl. new coverage for the fixed domains and the new predicate)
• pnpm --filter @posthog/agent --filter @posthog/ui typecheck — clean
• biome lint on the changed files — clean
• (Note: the rest of @posthog/agent's suite has pre-existing failures on main unrelated to this change — stale @posthog/shared / @posthog/git dist artifacts.)

Automatic notifications

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

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Created with PostHog Code from a Slack thread

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit cfb510e.}

[greptile-apps]

_{Reviews (1): Last reviewed commit: "fix(sessions): drop redundant generic "P..." | Re-trigger Greptile}