Add client-side watchdog so a crashed generation can't wedge Generate

The button-reset step (_btn_ready) only fires via Gradio's .then()
chain, which requires the preceding step's SSE stream to report SOME
terminal status. A dropped connection (container crash-restart, HTTP/2
protocol error — both seen in this app's logs) delivers no status at
all, so the chain stalls forever and Generate stays disabled with no
way to retry.

Arm a client-side timeout (10 min, well past any normal generation)
right after the button disables, that force-resets it if still stuck.
Token-gated per click so a stale watchdog can't clobber a newer,
still-in-flight generation.

app.py

@@ -2645,6 +2645,31 @@ _GLOBAL_JS = """
     }
   };
 
+  // Force-reset a stuck "Generating…" button after a generous timeout.
+  // The normal reset path is a .then() step chained after the (possibly
+  // crash-prone) generate call — Gradio only fires .then() steps when the
+  // preceding step's SSE stream reports SOME terminal status. A dropped
+  // connection (container restart, HTTP/2 protocol error — both observed in
+  // this app) never delivers one, so the chain stalls forever and the button
+  // never re-enables. This watchdog is a client-side safety net that doesn't
+  // depend on the chain completing at all. Token-gated so a stale watchdog
+  // from an earlier click can't clobber a newer, still-in-flight generation.
+  window._armGenerateWatchdog = function(btnId, timeoutMs) {
+    const root = document.getElementById(btnId);
+    if (!root) return;
+    const btn = root.tagName === 'BUTTON' ? root : root.querySelector('button');
+    if (!btn) return;
+    btn._genToken = (btn._genToken || 0) + 1;
+    const token = btn._genToken;
+    setTimeout(function() {
+      if (btn._genToken === token && btn.disabled) {
+        btn.disabled = false;
+        btn.textContent = 'Generate';
+        console.log('[watchdog] ' + btnId + ' stuck disabled past ' + timeoutMs + 'ms — force re-enabled');
+      }
+    }, timeoutMs);
+  };
+
   // ── ZeroGPU quota attribution ──
   // HF Spaces run inside an iframe on huggingface.co. Gradio's own JS client
   // gets ZeroGPU auth headers (x-zerogpu-token, x-zerogpu-uuid) by sending a
@@ -3073,7 +3098,7 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                     taro_cf_dur  = gr.Slider(label="Crossfade Duration (s)", minimum=0, maximum=4, value=2, step=0.1, elem_id="taro_cf_dur")
                     taro_cf_db   = gr.Textbox(label="Crossfade Boost (dB)", value="3", elem_id="taro_cf_db")
                     taro_samples    = gr.Slider(label="Generations", minimum=1, maximum=MAX_SLOTS, value=1, step=1)
-                    taro_btn        = gr.Button("Generate", variant="primary")
+                    taro_btn        = gr.Button("Generate", variant="primary", elem_id="taro_btn")
 
                 with gr.Column(scale=1):
                     (_, taro_slot_vids,
@@ -3119,6 +3144,11 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                 fn=_btn_generating,
                 inputs=None,
                 outputs=[taro_btn],
+            ).then(
+                fn=None,
+                inputs=None,
+                outputs=[],
+                js="() => window._armGenerateWatchdog('taro_btn', 600000)",
             ).then(
                 fn=_run_taro,
                 inputs=[taro_video, taro_seed, taro_cfg, taro_steps, taro_mode,
@@ -3159,7 +3189,7 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                     mma_cf_dur   = gr.Slider(label="Crossfade Duration (s)", minimum=0, maximum=4, value=2, step=0.1, elem_id="mma_cf_dur")
                     mma_cf_db    = gr.Textbox(label="Crossfade Boost (dB)", value="3", elem_id="mma_cf_db")
                     mma_samples     = gr.Slider(label="Generations", minimum=1, maximum=MAX_SLOTS, value=1, step=1)
-                    mma_btn         = gr.Button("Generate", variant="primary")
+                    mma_btn         = gr.Button("Generate", variant="primary", elem_id="mma_btn")
 
                 with gr.Column(scale=1):
                     (_, mma_slot_vids,
@@ -3185,6 +3215,11 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                 fn=_btn_generating,
                 inputs=None,
                 outputs=[mma_btn],
+            ).then(
+                fn=None,
+                inputs=None,
+                outputs=[],
+                js="() => window._armGenerateWatchdog('mma_btn', 600000)",
             ).then(
                 fn=_run_mmaudio,
                 inputs=[mma_video, mma_prompt, mma_neg, mma_seed,
@@ -3224,7 +3259,7 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                     hf_cf_dur   = gr.Slider(label="Crossfade Duration (s)", minimum=0, maximum=4, value=2, step=0.1, elem_id="hf_cf_dur")
                     hf_cf_db    = gr.Textbox(label="Crossfade Boost (dB)", value="3", elem_id="hf_cf_db")
                     hf_samples      = gr.Slider(label="Generations", minimum=1, maximum=MAX_SLOTS, value=1, step=1)
-                    hf_btn          = gr.Button("Generate", variant="primary")
+                    hf_btn          = gr.Button("Generate", variant="primary", elem_id="hf_btn")
 
                 with gr.Column(scale=1):
                     (_, hf_slot_vids,
@@ -3250,6 +3285,11 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                 fn=_btn_generating,
                 inputs=None,
                 outputs=[hf_btn],
+            ).then(
+                fn=None,
+                inputs=None,
+                outputs=[],
+                js="() => window._armGenerateWatchdog('hf_btn', 600000)",
             ).then(
                 fn=_run_hunyuan,
                 inputs=[hf_video, hf_prompt, hf_neg, hf_seed,