New REST capability

Read

• docs/src/content/docs/contributing/boundaries.md
• docs/src/content/docs/extend/server-api.md
• docs/src/content/docs/reference/api.md
• Existing similar method in server/hub.js + route in server/http.js + helper in web/src/lib/api.ts

Edit (all four if UI needs it)

1. hub.js — method on the hub, session-scoped, no new global locks unless required
2. http.js — route → hub; JSON in/out
3. api.ts — typed-ish helper
4. Component or palette — call site

Don’t touch

• SSE seq / ring / chat-stream.ts unless the feature is streaming-related (then stop and re-scope)
• Session open/close path locks “for convenience”

Done when

• curl or UI proves the route
• npm test still passes
• No new HTTP framework