feat: detect and slice audio attacks atomically and qualify sample editor workflows

screenshots/README.md

@@ -1,6 +1,7 @@
 # xtc screenshots
 
-All captures refreshed from the Phase 68 FLTK application on 2026-11-06.
+The main gallery was refreshed after Phase 68 on 2026-11-06. Two additional
+Phase 79 captures show the new sample editor and transient markers.
 These are actual rendered application windows and menus on a 1440 × 960 virtual
 X11 screen, without mockups, compositing or image edits.
 
@@ -35,6 +36,15 @@ See [COMPOSITION_WORKFLOWS.md](../docs/COMPOSITION_WORKFLOWS.md) for precise
 behavior, limits and commands. The screenshots illustrate implemented workflows;
 they do not establish feature parity with other DAWs.
 
+## Audio source editor (Phases 69–79)
+
+- [Frame selection, waveform, statistics and processing controls](sample-editor.png)
+- [Detected source attacks and clip slicing controls](sample-transients.png)
+
+These captures show the actual modal editor with the repository pluck WAV.
+Processing is staged locally; Save full copy and relink applies it to the project.
+See [AUDIO_EDITOR.md](../docs/AUDIO_EDITOR.md) for limits and frame/tick rounding.
+
 ## Refreshed application views
 
 All pre-existing images below were recaptured. Mixer playback meters come from
@@ -102,3 +112,6 @@ prerequisites, a running JACK server, Xvfb (`xvfb-run`), ImageMagick (`import`)
 PNGs. All demonstration edits and collection outputs use an automatically removed
 temporary directory; no preferences are saved. It neither installs dependencies
 nor starts/reconfigures the audio server.
+
+Set `XTC_CAPTURE_SAMPLE_ONLY=1` for the capture tool (or the make target) to write
+only the two sample-editor images while retaining the existing gallery.