Studio: auto-detect server GH_TOKEN and widen Easy-mode detection

The GitHub seed form now fetches /api/data-recipe/seed/github/env-token
on mount and, when the server exposes a GH_TOKEN / GITHUB_TOKEN env var
and the token field is blank, shows a small 'Using server env var' badge
and swaps the placeholder text. The token value itself is never returned
to the UI.

Widens Easy-mode detection in recipe-studio-page.tsx so that recipes
saved before ui.seed_source_type was persisted also get the Easy tab:
falls back to recipe.seed_config.source.seed_type, which is always
present for github_repo seeds.

studio/backend/routes/data_recipe/seed.py

@@ -8,6 +8,7 @@ from __future__ import annotations
 import base64
 import binascii
 import json
+import os
 import re
 from itertools import islice
 from pathlib import Path
@@ -627,3 +628,16 @@ def inspect_seed_upload(payload: SeedInspectUploadRequest) -> SeedInspectRespons
         split = None,
         subset = None,
     )
+
+
+@router.get("/seed/github/env-token")
+def get_github_env_token_status() -> dict:
+    """Report whether the server has a GH_TOKEN / GITHUB_TOKEN env var.
+
+    The value is never returned; the UI uses this to tell the user they
+    can leave the token field blank.
+    """
+    has_token = bool(
+        os.environ.get("GH_TOKEN") or os.environ.get("GITHUB_TOKEN")
+    )
+    return {"has_token": has_token}

studio/frontend/src/features/recipe-studio/api/index.ts

@@ -315,6 +315,13 @@ export async function inspectSeedUpload(
   return postJson<SeedInspectResponse>("/seed/inspect-upload", payload);
 }
 
+// biome-ignore lint/style/useNamingConvention: api schema
+export type GithubEnvTokenStatus = { has_token: boolean };
+
+export async function getGithubEnvTokenStatus(): Promise<GithubEnvTokenStatus> {
+  return getJson<GithubEnvTokenStatus>("/seed/github/env-token");
+}
+
 export async function listMcpTools(
   payload: McpToolsListRequest,
 ): Promise<McpToolsListResponse> {

studio/frontend/src/features/recipe-studio/dialogs/seed/seed-dialog.tsx

@@ -40,7 +40,7 @@ import {
 import { type ReactElement, useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { cn } from "@/lib/utils";
 import { UnstructuredDropZone, type FileEntry } from "./unstructured-drop-zone";
-import { inspectSeedDataset, inspectSeedUpload } from "../../api";
+import { getGithubEnvTokenStatus, inspectSeedDataset, inspectSeedUpload } from "../../api";
 import { resolveImagePreview } from "../../utils/image-preview";
 import type {
   SeedConfig,
@@ -83,8 +83,26 @@ export function GithubRepoSeedForm({
   onUpdate: (patch: Partial<SeedConfig>) => void;
 }): ReactElement {
   const [advancedOpen, setAdvancedOpen] = useState(false);
+  const [serverHasEnvToken, setServerHasEnvToken] = useState<boolean | null>(
+    null,
+  );
   const limitStr = (config.github_limit ?? "100").trim();
   const allMode = limitStr === "" || limitStr === "0";
+  useEffect(() => {
+    let cancelled = false;
+    void getGithubEnvTokenStatus()
+      .then((status) => {
+        if (!cancelled) setServerHasEnvToken(status.has_token);
+      })
+      .catch(() => {
+        if (!cancelled) setServerHasEnvToken(false);
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+  const userTokenEmpty = !(config.github_token ?? "").trim();
+  const usingEnvToken = userTokenEmpty && serverHasEnvToken === true;
   return (
     <div className="space-y-3 rounded-xl corner-squircle border border-border/60 p-3">
       <div className="grid gap-1.5">
@@ -100,16 +118,27 @@ export function GithubRepoSeedForm({
         />
       </div>
       <div className="grid gap-1.5">
-        <FieldLabel
-          label="GitHub token"
-          hint="Personal access token with repo scope. Leave blank to use the server's GH_TOKEN / GITHUB_TOKEN env var."
-        />
+        <div className="flex items-start justify-between gap-2">
+          <FieldLabel
+            label="GitHub token"
+            hint="Personal access token with repo scope. Leave blank to use the server's GH_TOKEN / GITHUB_TOKEN env var."
+          />
+          {usingEnvToken && (
+            <span className="shrink-0 rounded-md border border-emerald-500/40 bg-emerald-500/10 px-1.5 py-0.5 text-[10px] font-medium text-emerald-700 dark:text-emerald-300">
+              Using server env var
+            </span>
+          )}
+        </div>
         <Input
           type="password"
           className="nodrag"
           value={config.github_token ?? ""}
           onChange={(e) => onUpdate({ github_token: e.target.value })}
-          placeholder="ghp_... (optional if server has GH_TOKEN)"
+          placeholder={
+            usingEnvToken
+              ? "using server's GH_TOKEN env var"
+              : "ghp_... (optional if server has GH_TOKEN)"
+          }
         />
       </div>
       <div className="grid gap-1.5">

studio/frontend/src/features/recipe-studio/recipe-studio-page.tsx

@@ -202,7 +202,10 @@ export function RecipeStudioPage({
     null,
   );
   const flowContainerRef = useRef<HTMLDivElement | null>(null);
-  const supportsEasyMode = initialPayload?.ui?.seed_source_type === "github_repo";
+  const supportsEasyMode =
+    initialPayload?.ui?.seed_source_type === "github_repo" ||
+    (initialPayload?.recipe?.seed_config as { source?: { seed_type?: string } } | undefined)
+      ?.source?.seed_type === "github_repo";
   const viewModeStorageKey = `recipe-studio:view-mode:${recipeId}`;
   const [activeView, setActiveViewState] = useState<RecipeStudioView>(() => {
     if (typeof window !== "undefined") {