Add Broker client and writer quick dialogs

docs/agent/design-decisions.md

@@ -66,6 +66,8 @@ Phase 8D.2 adds a third identity: non-reused 64-bit originating web-session IDs
 
 **Wrap contract:** Three-slot-bit/29-generation-bit broker IDs now retire exhausted slots instead of wrapping. A32-bit lease generation saturates at UINT32_MAX, survives counter clear, and advances for each grant/release/revoke emission before advisory queue delivery. Forced transfer can advance twice; it is an opaque version, not a count. Saturation rejects typed assignment but never prevents normal release/disconnect/request or recovery force. Future writer transitions must preserve the central event-emission invariant. Reboot resets broker state but invalidates web sessions, so authorized old browser work cannot span boots.
 
+**8D.18 browser selection contract:** Live refresh preserves explicit target identity and its original lease token, not just the select value. Lease/identity mismatch, absence or failed read latches invalidation; later matching snapshots cannot resurrect validity or silently reselect a missing target. Only explicit reselection captures a new token, and transfer still requires separate confirmation. One shared quick/full controller fences reads/operations; contextual activation never destroys full-page drafts. Focused controls remain focusable with aria-disabled while independent action guards reject unavailable work. See `docs/phase8d18_implementation.md` for bounds and test limits.
+
 **Consequence:** Never implement snapshot-check-unlock-force, compare only current writer ID, or renew a confirmation implicitly during Refresh. UI must require explicit target selection and confirmation, retain uncertain-outcome handling and never retry mutations automatically. Bounded login-isolated result slots and the existing dispatcher remain the typed HTTP boundary. Details/tests: `docs/phase8d16_implementation.md`, `src/session_broker.{c,h}`, `src/web_broker_settings.{c,h}`.
 
 ## UART0 is the physical recovery authority