## Why
With the local model layer and app-server routing in place from PR1,
this PR moves the active TUI runtime onto app-server notifications. The
affected pieces share the same event flow, so the command surface,
session state, bottom-pane prompts, chat rendering, history/status
views, and tests move together to keep the stacked branch buildable.
This PR also removes the obsolete compatibility surface that is no
longer used after the migration. The proposed protocol-boundary verifier
layer was dropped from the stack; enforcing that final boundary will be
simpler once `codex-tui` no longer needs any `codex_protocol`
references.
This PR is part 2 of a 2-PR stack:
1. Add TUI-owned replacement models and extract app-server event
routing.
2. Move the active TUI flow to app-server notifications and delete
obsolete adapter code.
## What changed
- Rewired app command and session handling to use app-server request and
notification shapes.
- Moved approval overlays, request-user-input flows, MCP elicitation,
realtime events, and review commands onto the app-server-facing model
surface.
- Updated chat rendering, history cells, status views, multi-agent UI,
replay state, and TUI tests to use app-server notifications plus the
local models introduced in PR1.
- Deleted `codex-rs/tui/src/app/app_server_adapter.rs` and the
superseded `chatwidget/tests/background_events.rs` fixture path.
## Verification
- `cargo check -p codex-tui --tests`
- Top of stack: `cargo test -p codex-tui`
## Why
This is part 1 of a 7-PR stack to remove direct
`codex_protocol::protocol` usage from `codex-tui` while keeping each
layer reviewable and shippable.
This first layer reduces the size of the later `chatwidget` diff by
mechanically moving MCP startup bookkeeping out of the central widget
file without changing the event shapes or behavior.
## What changed
- Extracted MCP startup status handling into
`tui/src/chatwidget/mcp_startup.rs`.
- Kept the existing core event types in place for this purely mechanical
move.
- Updated the MCP startup tests to import the moved test-only event
types directly.
## Verification
- `cargo test -p codex-tui chatwidget::tests::mcp_startup`
Eric TrautandGitHub