Add YouTube-access health check; confirm stale length-cap UI is gone

- New "Check YouTube access" button reports YT_PROXY/YT_COOKIES/YOUTUBE_API_KEY status,
the Space's egress IP (via proxy if set), and live YouTube reachability with a
green/red verdict pointing at tools/ when blocked
- run status notes when YT_PROXY is active
- (Re-architecture already removed the self-contradictory "Max video length (min)" slider,
the per-user "Proxy URL" field, and the "Whisper timing" label — verified absent)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app.py

@@ -88,6 +88,35 @@ def _resolve_api_key(ui_key: str | None) -> str | None:
     return key or None
 
 
+def check_access():
+    """Health check: which secrets are set, the egress IP, and YouTube reachability."""
+    import requests
+
+    proxy = _resolve_proxy()
+    proxies = {"http": proxy, "https": proxy} if proxy else None
+    lines = [
+        f"- **Proxy** (`YT_PROXY`): {'set ✅' if proxy else 'not set ⚪'}",
+        f"- **Cookies** (`YT_COOKIES`): {'set ✅' if os.environ.get('YT_COOKIES') else 'not set ⚪'}",
+        f"- **Data API key** (`YOUTUBE_API_KEY`): {'set ✅' if os.environ.get('YOUTUBE_API_KEY') else 'not set ⚪'}",
+    ]
+    try:
+        ip = requests.get("https://api.ipify.org", proxies=proxies, timeout=20).text.strip()
+        lines.append(f"- **Egress IP** {'(via proxy)' if proxy else '(Space direct)'}: `{ip}`")
+    except Exception as exc:
+        lines.append(f"- **Egress IP**: ❌ {type(exc).__name__}")
+    try:
+        r = requests.get("https://www.youtube.com/robots.txt", proxies=proxies, timeout=20)
+        lines.append(f"- **YouTube reachable**: ✅ HTTP {r.status_code}")
+        verdict = "### 🟢 YouTube is reachable — transcript + screenshots should work."
+    except Exception as exc:
+        lines.append(f"- **YouTube reachable**: ❌ {type(exc).__name__} (datacenter IP likely blocked)")
+        verdict = ("### 🔴 YouTube is NOT reachable from the Space.\n"
+                   "Set a residential **`YT_PROXY`** (e.g. the home-tunnel panel in "
+                   "[`tools/`](tools/README.md)). Comments still work via the Data API; "
+                   "transcript + screenshots need the proxy.")
+    return verdict + "\n\n" + "\n".join(lines)
+
+
 # ----------------------------------------------------------------------------- helpers
 def _ranking_rows(scored: list[dict]) -> list[list]:
     rows = []
@@ -140,6 +169,8 @@ def run_pipeline(topic, hf_token, yt_api_key, llm_model, vlm_model,
         api_key = _resolve_api_key(yt_api_key)
         cookiefile = _cookiefile(workdir)
         proxy = _resolve_proxy()
+        if proxy:
+            log.append("🔐 `YT_PROXY` is set — transcript + stream requests route through it.")
 
         # 1. Search ------------------------------------------------------------------
         progress(0.03, desc="Searching")
@@ -266,6 +297,10 @@ def build_ui():
                 lead = gr.Slider(0.0, 5.0, value=1.0, step=0.5, label="Lead offset (s)")
             max_shots = gr.Slider(1, 15, value=8, step=1, label="Max screenshots")
 
+        with gr.Row():
+            health_btn = gr.Button("🩺 Check YouTube access (proxy + reachability)")
+        health_md = gr.Markdown()
+
         run_btn = gr.Button("Generate tutorial", variant="primary")
 
         status_md = gr.Markdown(label="Status")
@@ -276,6 +311,7 @@ def build_ui():
         transcript_box = gr.Textbox(label="Transcript preview", lines=10, max_lines=20)
         docx_file = gr.File(label="Download tutorial (.docx)")
 
+        health_btn.click(check_access, outputs=health_md)
         run_btn.click(
             run_pipeline,
             inputs=[topic, hf_token, yt_api_key, llm_model, vlm_model,