feat: auto-name sessions from first prompt

src/web/routes/session-routes.ts

@@ -1103,6 +1103,7 @@ export function registerSessionRoutes(
       workingDir,
       mode,
       name: body.name || '',
+      nameSource: body.name ? undefined : 'auto',
       mux: ctx.mux,
       useMux: true,
       niceConfig: globalNice,
@@ -3333,6 +3334,7 @@ export function registerSessionRoutes(
     const session = new Session({
       workingDir: resolvedCasePath,
       name: sessionName ? sessionName.slice(0, MAX_SESSION_NAME_LENGTH) : '',
+      nameSource: sessionName ? undefined : 'auto',
       mux: ctx.mux,
       useMux: true,
       mode: mode,