docs(fleet): north-star socket refs → mosaic-fleet (brand-consistent)

Reconciles the doctrine with the socket rename (#630): the production-isolation
socket is mosaic-fleet (matches the product brand). mosaic-factory now appears
only where it legitimately describes the LEGACY dogfood canary (pending
migration). Adjusts the PoC-socket-hygiene note + the unified-identity note.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EsgTQzV5YUGk1JtCLP4B83

docs/fleet/north-star.md

@@ -67,9 +67,10 @@ One **definition** is the source of truth; the **session** is how it runs.
 | **Budget / spend governance**    | **per-tenant budget policy** ingested by the orchestrator + routing layer                   | none today (spend is unmetered)                        | usage-vs-limit feedback ingested; spend auto-paced to the limit window; per-provider/per-account/concurrency/API-$ budgets enforced |
 
 > **PoC socket hygiene:** the PoC fleet runs on the **default tmux socket** (no `-L`).
-> `mosaic-factory` is just a named socket for production isolation — not a product or
-> component — and an absent roster `socket_name` means the default socket everywhere
-> (spawn, `fleet ps`, onboarding cheat-sheet).
+> The named production-isolation socket is **`mosaic-fleet`** (matches the product brand);
+> an absent roster `socket_name` means the default socket everywhere (spawn, `fleet ps`,
+> onboarding cheat-sheet). The legacy dogfood canary still runs on the old `mosaic-factory`
+> socket pending migration.
 
 ## Operating model (inherited, not reinvented)
 
@@ -330,9 +331,10 @@ re-evaluate if isolation or write-volume demands it.
   user-facing identity and CLI surface. **forge** is the Fleet's **internal** delivery/orchestration
   engine (not a separate product); the control-plane **Postgres register is the Fleet's register**;
   workers/runtime are the **Fleet substrate**. **"factory" is RETIRED as a product term** — it was
-  only ever the software-factory concept (which forge implements) and the `mosaic-factory` tmux socket
-  name; `mosaic-factory` remains **just a socket name** (production isolation), not a product/component,
-  and may be renamed later. **Code stays layered** (forge + fleet + control-plane as internal layers);
+  only ever the software-factory concept (which forge implements) and the old `mosaic-factory` tmux
+  socket name. The production-isolation socket is now **`mosaic-fleet`** (matches the product brand);
+  the legacy dogfood canary remains on the old `mosaic-factory` socket pending migration. **Code stays
+  layered** (forge + fleet + control-plane as internal layers);
   only the **identity + CLI surface unify under Fleet.**
 - **Role-based session naming (Jason, 2026-06-22):** agent tmux sessions are named by **role**
   (`orchestrator`, `enhancer`, `research`, `coder0-0`, …), not by persona. **Persona lives in