Support optional shared online-OCR key via env var

app.py

@@ -10,6 +10,7 @@ and off unless you supply your own API key.
 
 import io
 import json
+import os
 import asyncio
 from pathlib import Path
 
@@ -100,7 +101,12 @@ async def capabilities():
             )
         except Exception:
             _CAPABILITIES["handwriting"] = False
-    return {"handwriting": bool(_CAPABILITIES["handwriting"])}
+    return {
+        "handwriting": bool(_CAPABILITIES["handwriting"]),
+        # True when this deployment provides a shared Gemini key (a Space secret),
+        # so the front-end can offer online OCR without the visitor's own key.
+        "online_demo": bool(os.environ.get("DEMO_GEMINI_KEY", "").strip()),
+    }
 
 
 @app.post("/api/upload")
@@ -129,6 +135,14 @@ async def upload(
 
     # Cheap validations BEFORE buffering the whole upload into memory, so a
     # request that will be rejected anyway doesn't pay a full file read.
+    #
+    # A deployment may provide a shared demo key via the DEMO_GEMINI_KEY env var
+    # (set as a Space secret, never committed to the repo). Fall back to it when
+    # the visitor turns on online OCR without supplying their own key, so the
+    # hosted demo works out of the box. The user's own key always takes
+    # precedence; this only fills in a blank.
+    if onl and not okey:
+        okey = os.environ.get("DEMO_GEMINI_KEY", "").strip()
     if onl and not okey:
         raise HTTPException(
             status_code=400,

static/index.html

@@ -32,13 +32,19 @@
         fetch("/api/capabilities")
           .then(function (r) { return r.json(); })
           .then(function (caps) {
-            if (!caps || caps.handwriting !== false) return;
-            var hw = document.getElementById("handwritingToggle");
-            if (hw) { hw.checked = false; hw.disabled = true; }
-            var row = document.getElementById("handwritingRow");
-            if (row) row.classList.add("is-unavailable");
-            var note = document.getElementById("hwUnavailable");
-            if (note) note.hidden = false;
+            if (!caps) return;
+            if (caps.handwriting === false) {
+              var hw = document.getElementById("handwritingToggle");
+              if (hw) { hw.checked = false; hw.disabled = true; }
+              var row = document.getElementById("handwritingRow");
+              if (row) row.classList.add("is-unavailable");
+              var note = document.getElementById("hwUnavailable");
+              if (note) note.hidden = false;
+            }
+            if (caps.online_demo === true) {
+              var on = document.getElementById("onlineDemoNote");
+              if (on) on.hidden = false;
+            }
           })
           .catch(function () {});
       });
@@ -180,6 +186,7 @@
                 <span class="slider" aria-hidden="true"></span>
               </label>
             </div>
+            <p class="hint hw-note" id="onlineDemoNote" hidden>This demo includes a Gemini key &mdash; just turn this on and leave the key field blank. Or paste your own key to use that instead.</p>
             <div class="setting setting-sub" id="onlineRow" hidden>
               <label class="setting-label" for="onlineKey">Gemini API key</label>
               <input type="password" id="onlineKey" class="select online-input" placeholder="paste key from aistudio.google.com" autocomplete="off" spellcheck="false" />