feat(bluebird): mirror Code view's top nav in the Website space

[raquelmsmith]

Problem

The Code view of PostHog Code has a set of top items in the left nav that were missing from the Website (Bluebird / Channels) view, and the ones that did exist bounced the user back to the /code space. This brings the Website nav to parity and keeps every destination inside /website.

Why: the Website space should stand on its own — navigating to Inbox, Agents, etc. shouldn't kick you out of Channels and into the Code view.

Changes

The Website left nav now mirrors the Code view's top items, all staying in the /website space. New order: Home · Search · Inbox · Canvas · Agents · Customize.

• Search — adds the shared SearchItem (opens the command menu, shows the ⌘K hint), identical to the Code view.
• Inbox (/website/inbox) — the inbox subtree is forked under /website/inbox/* sharing the same view components. Navigation is made space-aware: a new inboxSpaceFromPath + per-space route maps in @posthog/core, a useInboxSpace()/useInboxRoutes() hook, and every tab, card, back-link and redirect resolves to the space you're in. Uses the real InboxItem (PR-review badge + Beta tag). Cmd+I and the "open associated report" action are space-aware too.
• Agents (/website/agents) — the agents subtree is forked (scouts + the agent-applications platform). A space-keyed AGENTS_ROUTE map + a useAgentsRoutes() hook drive every link/navigate across the shared components (including the AI agent-builder's client tools).
• Customize (/website/customize) — a new page with its own secondary left sidebar (Skills · MCP servers), each rendering the shared view. Replaces the old standalone /website/skills and /website/mcp-servers routes.

The route tree was regenerated and the useAppView active-state mapping updated so highlighting works across both spaces.

How did you test this?

• @posthog/core typecheck: clean
• @posthog/ui typecheck: clean
• Biome check on changed files: clean
• @posthog/core tests: 1797 passed
• @posthog/ui tests: 1096 passed

Automatic notifications

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

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Created with PostHog Code

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit e1a0b5f.}

[greptile-apps]

_{Reviews (1): Last reviewed commit: "feat(bluebird): mirror Code view's top n..." | Re-trigger Greptile}

[greptile-apps]

Comments Outside Diff (1)

1. packages/ui/src/features/sidebar/components/SidebarNavSection.tsx, line 43-49 (link)

   The block comment was written before this PR added /website mirrors for Inbox and Agents, but now directly contradicts the goInbox / goAgents logic on the very next lines. A future reader following the comment might conclude those items still jump to /code and "fix" them, reverting the space-awareness added here.

   Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

_{Reviews (2): Last reviewed commit: "feat(bluebird): mirror Code view's top n..." | Re-trigger Greptile}

[greptile-apps]

_{Reviews (3): Last reviewed commit: "fix(bluebird): address review findings o..." | Re-trigger Greptile}

[raquelmsmith]

🤖 Agent (PostHog Code) posting on @raquelmsmith's behalf at her request.

Rebased onto main and resolved the conflict in useAgentBuilderClientTools.ts — the useCallback dependency array now includes both setPendingMcpConnect (from main) and routes (from this branch).

All Greptile review findings are addressed on the branch:

• P1 — MCP servers vs Skills now route to distinct /website/customize/* targets (replied inline).
• P2 — inboxTabFromPath regex hoisted to module scope (replied inline).
• P2 — CustomizeLayout isSkills is now an explicit prefix check (replied inline).
• P2 (comment outside diff) — the SidebarNavSection block comment was updated to describe the space-aware goInbox/goAgents mirroring, so it no longer contradicts the code.

Verified after rebase: @posthog/core + @posthog/ui typecheck clean, Biome clean on changed files, core tests 1847 passed, ui tests 1120 passed, and the route tree regenerates with no diff.