docs(runtime): document /runtime command path and status semantics

README.md

@@ -363,12 +363,16 @@ backends:
 
 `pi_embedded` is intended for canary migration cohorts. In spike mode (`no_tools_mode: true`), Flynn keeps tool-oriented turns on native and only routes plain-text turns to Pi.
 
+When `pi_embedded` is selected, Flynn forwards the assembled runtime system prompt (for example `SOUL.md`/`IDENTITY.md`/`USER.md`/`TOOLS.md`, plus runtime/security sections) to Pi when `system_prompt_mode` is `flynn` or `hybrid`.
+
 Runtime backend mode can be controlled live (persisted in `~/.local/share/flynn/preferences.json`):
 
-- `/backend status` shows runtime mode and effective backend selection
-- `/backend activate pi` forces `pi_embedded` globally
-- `/backend deactivate pi` forces native for Pi-routed turns
-- `/backend use config` resets to `backends.default`
+- `/runtime status` shows runtime mode and effective backend selection
+- `/runtime activate pi` forces `pi_embedded` globally
+- `/runtime deactivate pi` forces native for Pi-routed turns
+- `/runtime use config` resets to `backends.default`
+
+`/backend ...` remains a supported alias for compatibility.
 
 This manual runtime mode control is the intended Pi activation/deactivation switch.
 
@@ -611,7 +615,7 @@ Notes:
 | `/approve [id]` | Approve latest (or specific) pending gate |
 | `/deny [id] [reason]` | Deny latest (or specific) pending gate |
 | `/skill <list|search|install>` | In-chat skill discovery/install (`list`, `search <term>`, `install <registry-id>`) |
-| `/backend <status\|activate pi\|deactivate pi\|use config>` | Show or control global runtime backend mode |
+| `/runtime <status\|activate pi\|deactivate pi\|use config>` | Show or control global runtime backend mode (`/backend ...` alias also supported) |
 
 ## Web UI Dashboard
 
@@ -669,6 +673,8 @@ pnpm tui:fs
 
 TUI keyboard controls: `Esc` cancels active prompt/running response. `Ctrl+C` clears the current input; press `Ctrl+C` twice quickly to exit.
 
+Note: runtime backend mode control is a daemon/channel command (`/runtime ...`, `/backend ...` alias), not the TUI-local `/backend [provider]` switch.
+
 #### Runtime Model Switching
 
 Switch providers and models on the fly without editing config or restarting: