M FORK.md → FORK.md

@@ -50,11 +50,32 @@ (`DEFAULT_REMOTE_CDP` in `src/cdp/endpoint.ts`).
 
 ## Choosing a browser
 
+From inside a pi session:
+
+```
+/browser-target                 show the current target
+/browser-target local           this machine's own browser
+/browser-target default         back to castle
+/browser-target host:port       somewhere else
+```
+
+The choice persists in `~/.pi/agent/browser-target.json` and applies to every
+session on the machine, because the browser daemon is machine-wide. Switching
+replaces that daemon process — it resolves its target once at startup and holds
+the WebSocket to the old browser, so nothing short of a restart actually moves
+you.
+
+Or set it per-process:
+
 | `BU_CDP_HTTP` | behaviour |
 |---|---|
-| unset | castle, falling back to this machine's browser if unreachable |
+| unset | the stored choice, else castle, falling back to this machine's browser if unreachable |
 | `host:port` | that endpoint; **unreachable is a hard error** |
 | `local` (also `localhost`, `off`, `none`, `0`, `no`) | upstream behaviour — this machine's own browser |
+
+Precedence is `BU_CDP_HTTP` > `/browser-target` > built-in default, so a one-off
+`BU_CDP_HTTP=… pi` is never silently overridden by a choice made days ago. When
+the variable is set, `/browser-target` says so instead of pretending to obey.
 
 The asymmetry is deliberate. An explicit endpoint is an instruction, so failing
 to reach it must not quietly automate a different browser — that would drive