feat(post): wire separate stems / normalise / mp3 export buttons in output panel (m5 g2)

app.py

@@ -53,6 +53,7 @@ import ace_pipeline
 import backend as be
 import lora_stack
 import modes
+import post_process
 import theme
 import ui
 
@@ -305,6 +306,39 @@ def on_draft_lyrics(
         raise gr.Error(str(e)) from e
 
 
+def on_separate_stems(audio_path):
+    """Run Demucs on the current Output audio and surface 4 stem files."""
+    if not audio_path:
+        raise gr.Error("Generate a song first.")
+    try:
+        stems = post_process.separate_stems(audio_path)
+    except Exception as e:
+        raise gr.Error(f"Demucs failed: {e}") from e
+    return gr.Files(value=list(stems.values()), visible=True)
+
+
+def on_normalise(audio_path):
+    """Run pyloudnorm at -14 LUFS and surface the normalised WAV."""
+    if not audio_path:
+        raise gr.Error("Generate a song first.")
+    try:
+        out = post_process.normalise_lufs(audio_path, target_lufs=-14.0)
+    except Exception as e:
+        raise gr.Error(f"Normalisation failed: {e}") from e
+    return gr.Audio(value=str(out), visible=True)
+
+
+def on_export_mp3(audio_path):
+    """Encode the current Output to MP3 320 k via ffmpeg and surface the file."""
+    if not audio_path:
+        raise gr.Error("Generate a song first.")
+    try:
+        out = post_process.to_mp3(audio_path, bitrate_kbps=320)
+    except Exception as e:
+        raise gr.Error(f"MP3 export failed: {e}") from e
+    return gr.File(value=str(out), visible=True)
+
+
 def on_edit_click(
     source_audio,
     sub_mode: str,
@@ -458,6 +492,22 @@ def build_app() -> gr.Blocks:
                         ],
                         outputs=[g["output_audio"], g["output_meta"]],
                     )
+                    # Post-processing actions (M5/G2)
+                    g["separate_stems_btn"].click(
+                        fn=on_separate_stems,
+                        inputs=[g["output_audio"]],
+                        outputs=[g["stem_files"]],
+                    )
+                    g["normalise_btn"].click(
+                        fn=on_normalise,
+                        inputs=[g["output_audio"]],
+                        outputs=[g["normalised_audio"]],
+                    )
+                    g["mp3_btn"].click(
+                        fn=on_export_mp3,
+                        inputs=[g["output_audio"]],
+                        outputs=[g["mp3_file"]],
+                    )
                 with gr.Group(visible=False, elem_classes=["ams-tab-pane"]) as pane_cover:
                     c = ui.build_cover_tab()
                     c["lora_preset"].change(
@@ -487,6 +537,22 @@ def build_app() -> gr.Blocks:
                         ],
                         outputs=[c["output_audio"], c["output_meta"]],
                     )
+                    # Post-processing actions (M5/G2)
+                    c["separate_stems_btn"].click(
+                        fn=on_separate_stems,
+                        inputs=[c["output_audio"]],
+                        outputs=[c["stem_files"]],
+                    )
+                    c["normalise_btn"].click(
+                        fn=on_normalise,
+                        inputs=[c["output_audio"]],
+                        outputs=[c["normalised_audio"]],
+                    )
+                    c["mp3_btn"].click(
+                        fn=on_export_mp3,
+                        inputs=[c["output_audio"]],
+                        outputs=[c["mp3_file"]],
+                    )
                 with gr.Group(visible=False, elem_classes=["ams-tab-pane"]) as pane_extend:
                     x = ui.build_extend_tab()
                     x["lora_preset"].change(
@@ -520,6 +586,22 @@ def build_app() -> gr.Blocks:
                         ],
                         outputs=[x["output_audio"], x["output_meta"]],
                     )
+                    # Post-processing actions (M5/G2)
+                    x["separate_stems_btn"].click(
+                        fn=on_separate_stems,
+                        inputs=[x["output_audio"]],
+                        outputs=[x["stem_files"]],
+                    )
+                    x["normalise_btn"].click(
+                        fn=on_normalise,
+                        inputs=[x["output_audio"]],
+                        outputs=[x["normalised_audio"]],
+                    )
+                    x["mp3_btn"].click(
+                        fn=on_export_mp3,
+                        inputs=[x["output_audio"]],
+                        outputs=[x["mp3_file"]],
+                    )
                 with gr.Group(visible=False, elem_classes=["ams-tab-pane"]) as pane_edit:
                     e = ui.build_edit_tab()
                     e["lora_preset"].change(
@@ -556,6 +638,22 @@ def build_app() -> gr.Blocks:
                         ],
                         outputs=[e["output_audio"], e["output_meta"]],
                     )
+                    # Post-processing actions (M5/G2)
+                    e["separate_stems_btn"].click(
+                        fn=on_separate_stems,
+                        inputs=[e["output_audio"]],
+                        outputs=[e["stem_files"]],
+                    )
+                    e["normalise_btn"].click(
+                        fn=on_normalise,
+                        inputs=[e["output_audio"]],
+                        outputs=[e["normalised_audio"]],
+                    )
+                    e["mp3_btn"].click(
+                        fn=on_export_mp3,
+                        inputs=[e["output_audio"]],
+                        outputs=[e["mp3_file"]],
+                    )
                 with gr.Group(visible=False, elem_classes=["ams-tab-pane"]) as pane_lyrics:
                     lyr = ui.build_lyrics_tab()
                     lyr["draft_btn"].click(

theme.py

@@ -914,6 +914,46 @@ main, .contain {{
   padding:0 12px 12px 12px !important;
 }}
 
+/* ============================================================
+ * Post-process action row (M5/G2) — sits below the Output Audio.
+ * Three compact mono pills (separate stems / normalise / mp3 export)
+ * that surface hidden gr.Files / gr.Audio / gr.File widgets once a
+ * post-process click handler returns. The bordered list chrome on
+ * stem_files + mp3_file matches the generic .ams-out treatment so
+ * the populated state reads as a continuation of the Output panel.
+ * ============================================================ */
+.ams-content .ams-post-actions {{
+  gap: 6px !important;
+  margin: 8px 0 0 0 !important;
+}}
+.ams-content .ams-post-btn {{
+  font-family: {FONT_MONO} !important;
+  font-size: 11px !important;
+  letter-spacing: 0.04em !important;
+  padding: 8px 10px !important;
+  background: #000 !important;
+  border: 1px solid {BORDER} !important;
+  color: {INK} !important;
+  border-radius: 3px !important;
+}}
+.ams-content .ams-post-btn:hover {{
+  border-color: {PRIMARY} !important;
+}}
+/* Stem files + mp3 file widgets — compact bordered list */
+.ams-content .ams-stem-files,
+.ams-content .ams-mp3-file {{
+  background: #000 !important;
+  border: 1px solid {BORDER} !important;
+  border-radius: 3px !important;
+  margin-top: 6px !important;
+}}
+@media (max-width: 640px) {{
+  .ams-content .ams-post-btn {{
+    font-size: 10px !important;
+    padding: 7px 8px !important;
+  }}
+}}
+
 /* Hide Gradio footer + the floating "Use via API" / settings panel */
 footer {{ display:none !important; }}
 .show-api {{ display:none !important; }}

ui.py

@@ -73,7 +73,7 @@ def _build_lora_accordion(components: dict[str, gr.components.Component]) -> Non
 
 
 def _build_output_panel(components: dict[str, gr.components.Component]) -> None:
-    """Shared OUTPUT (gr.Audio) + METADATA (gr.JSON) bordered panels.
+    """Shared OUTPUT (gr.Audio) + post-process actions + METADATA (gr.JSON).
 
     elem_classes on each output component give CSS hooks for the
     Brutalist Mono treatment (uppercase mono labels + bordered
@@ -83,6 +83,12 @@ def _build_output_panel(components: dict[str, gr.components.Component]) -> None:
     gr.JSON renders a dict directly as a syntax-highlighted, expandable
     tree. gr.Code(language="json") refuses dicts — it requires a
     pre-stringified blob — and crashes with "'dict' has no .strip()".
+
+    Below the Audio we expose three secondary post-process actions
+    (M5/G2): Demucs stem separation, pyloudnorm LUFS normalisation, and
+    ffmpeg MP3 export. Each emits to a hidden output (stem_files /
+    normalised_audio / mp3_file) that becomes visible only once the
+    click handler returns a populated value.
     """
     components["output_audio"] = gr.Audio(
         label="Output",
@@ -90,6 +96,39 @@ def _build_output_panel(components: dict[str, gr.components.Component]) -> None:
         interactive=False,
         elem_classes=["ams-out", "ams-out-audio"],
     )
+    with gr.Row(elem_classes=["ams-post-actions"]):
+        components["separate_stems_btn"] = gr.Button(
+            "↯ Separate stems",
+            variant="secondary",
+            elem_classes=["ams-post-btn"],
+        )
+        components["normalise_btn"] = gr.Button(
+            "▮ Normalise -14 LUFS",
+            variant="secondary",
+            elem_classes=["ams-post-btn"],
+        )
+        components["mp3_btn"] = gr.Button(
+            "↓ MP3 320k",
+            variant="secondary",
+            elem_classes=["ams-post-btn"],
+        )
+    components["stem_files"] = gr.Files(
+        label="Stems",
+        visible=False,
+        elem_classes=["ams-stem-files"],
+    )
+    components["normalised_audio"] = gr.Audio(
+        label="Normalised (-14 LUFS)",
+        type="filepath",
+        interactive=False,
+        visible=False,
+        elem_classes=["ams-out", "ams-out-normalised"],
+    )
+    components["mp3_file"] = gr.File(
+        label="MP3 download",
+        visible=False,
+        elem_classes=["ams-mp3-file"],
+    )
     components["output_meta"] = gr.JSON(
         label="Metadata",
         elem_classes=["ams-out", "ams-out-meta"],