fix(app): every left-nav section changes the main area (0388)

[crs48]

Implements exploration 0388.

The report

"When I click on People or Views or a lot of the sections, nothing happens. The main screen should pretty much change for every section, I think."

Accurate, and not a rendering bug. Five of eleven sections were kind: 'lens', and the lens branch of useActivateSection called setActiveLens(...) and returned — no navigate(). activeLensId was read only inside the sidebar; nothing in the main region ever subscribed to it.

Two of those five were regressions from the 0353 nav rewrite: People used to be a route to /crm, and Views' natural home /data lost its entry. Both routes still rendered fine — they were simply unreachable from the nav.

Two further findings while auditing:

• The whole kind: 'panel' surface class lost its entry point in 0353. AI was the casualty with no successor.
• The floating Assistant's send handler called setActiveSurface('ai') and cleared the input. Under unified nav nothing reads activeSurface, so every question typed into the dock since 0353 was silently destroyed.

The rule

Every primary nav row changes the main area. No exceptions.

A lens is now a destination as well as a filter — SidebarLens carries a route, so the mapping lives with the lens instead of in a switch.

Section	Goes to
All / Docs / Chats	/, which renders that projection
People	/crm — restored
Views	/data — restored
AI	/ai — restored
Inbox / Tasks / Meetings / Discover / Finance	unchanged
Companion / Experiments / Import	no longer URL-only
Analytics	absent unless VITE_TELEMETRY_DASHBOARD is set

Active state now derives from the route, so exactly one row is ever lit — the old predicate could light none (a non-pinned lens) or leave the sidebar claiming "Views" while the main area showed Meetings. A route owned by one lens restores that lens on load, so reloading /crm comes back with People selected.

Two supporting fixes: the 0166 startup-surface redirect now fires once per session (otherwise clicking Docs would bounce straight back out of /), and SavedView gets a Tier-1 seeder — it had only Tier-2 coverage, which the demo profile skips, so Views read "Nothing here yet." on first contact.

Verification

• apps/web/src/workbench/sidebar/sections.test.ts — 12 tests; fails if a section is added without a destination, or if any location lights more than one row
• tests/e2e/src/left-nav.spec.ts — 5 tests clicking every section in the real shell, wired into the required editor-ux lane as a chromium-only step (the mobile shell renders no sections)
• 1101 unit tests pass; pnpm lint 0 errors
• Manually verified in the app: all 14 sections change the main area, Views shows seeded rows in a fresh ?demo=1 workspace, Analytics absent, reload on /crm restores the People lens, /finance → Docs returns home without stranding

Known-adjacent, deliberately out of scope

/tasks still renders its own VIEWS / PROJECTS nav inside the main area — the second-nav pattern 0353 set out to remove. Tracked as a follow-up rather than smuggled into this change. MobileShell renders no sections at all, so none of this reaches mobile; noted as an open question in the exploration.

🤖 Generated with Claude Code

[github-actions]

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[github-actions]

Preview removed for PR #617.