Offer Claude sign-in from failed sessions

PLAN.md

@@ -759,15 +759,17 @@ it. A concurrent read serves the last answer when there is one; a first read
 waits for the single producer. Different machines and providers proceed
 independently.
 
-When Claude cannot renew an expired login, the phone offers sign-in from both
-the Machines tab and the usage dialog. The backend starts the configured
-Claude CLI's headless `auth login` on that machine, returns only its Anthropic
-authorization URL, and accepts the one code copied back from the browser. The
-CLI remains the OAuth client and the only credential writer: the backend keeps
-the URL and code only for the live attempt and never sees or persists an access
-token or refresh token. An explicit login holds
-the same machine/provider gate as usage refresh, is cancelable, expires after
-ten minutes, and is killed when the backend stops.
+When Claude cannot renew an expired login, the driver records that as an
+actionable authentication event rather than leaving the phone to recognise
+the CLI's error sentence. The phone opens sign-in directly over the affected
+session, and also offers it from the Machines tab and the usage dialog. The
+backend starts the configured Claude CLI's headless `auth login` on that
+machine, returns only its Anthropic authorization URL, and accepts the one code
+copied back from the browser. The CLI remains the OAuth client and the only
+credential writer: the backend keeps the URL and code only for the live attempt
+and never sees or persists an access token or refresh token. An explicit login
+holds the same machine/provider gate as usage refresh, is cancelable, expires
+after ten minutes, and is killed when the backend stops.
 
 **The five-hour window has no reset time between blocks, and that is not a
 missing value.** Measured 2026-08-31: the API anchors the window to the block