Make model and permission choices provider-specific

PLAN.md

@@ -221,6 +221,13 @@ phone and auto-resume need no Codex branch. This is the CLI's local protocol
 and is treated defensively for the same reason as Claude's undocumented usage
 endpoint: missing fields or a refusal degrade to an unavailable snapshot.
 
+The model picker asks the selected setup's Codex app-server for `model/list`
+when it is opened. The catalog is account- and CLI-version-specific, so it is
+never copied into the app or inferred from another setup; a lookup failure is
+shown as unavailable while the free-text escape remains. Permission choices
+are likewise reported per provider: Codex offers its read-only,
+workspace-write and full-access modes, while Claude keeps its own modes.
+
 ### The llama driver
 
 One `llama-server` per session, started through the same `Transport` as any