diff --git a/docker-compose.prod.yml b/docker-compose.prod.yml
index 0d6a3f5..7ba76a6 100644
--- a/docker-compose.prod.yml
+++ b/docker-compose.prod.yml
@@ -7,10 +7,17 @@ services:
     expose:
       - "8000"
     # LTspice engine is GATED. The backend image ships Wine 11.10 + the prefix,
-    # and the host carries ./ltspice (exe/lib/examples), but LTspice v26 stalls
-    # at graphics init under headless Wine in this slim image (works on the dev
-    # desktop). Without LTSPICE_DIR the engine reports "unavailable" and fails
-    # fast instead of hanging. To resume debugging, uncomment the two blocks:
+    # the host carries ./ltspice (exe/lib/examples), but LTspice v26's threads
+    # spin in userspace during startup under headless Wine in this slim image
+    # (runs fine on the dev desktop). Without LTSPICE_DIR the engine reports
+    # "unavailable" and fails fast instead of hanging.
+    #
+    # Ruled out (don't re-tread): Wine version (11.10 matches dev), the ini
+    # first-run seed, the X display (Xvfb up), GL/EGL/vulkan libs, fonts,
+    # 32-bit subsystem, color depth, and the entire CUPS/print path (cupsd up,
+    # CUPS_SERVER, libcups removed -- all still spin). Next: a userspace
+    # backtrace of the spinning thread, or pivot to running mcltspice on a
+    # real desktop and calling it remotely. To resume, uncomment both blocks:
     # volumes:
     #   - ./ltspice:/opt/ltspice-src:ro
     # environment: