From f4dd819f6a636fcb79edd9b047b88208b79c4758 Mon Sep 17 00:00:00 2001
From: 7800uk <git@7800.io>
Date: Wed, 4 Nov 2026 00:11:34 +0000
Subject: [PATCH 1/8] test(showcase): use the option interface for renderer
 effects

neomacs-effects-apply, neomacs-effect-set and neomacs-effect-reset were
removed when effects became defcustoms, so the showcase signalled
void-function from its first section.

Set gallery and behavioural options with setopt. Use customize-set-variable
and custom-reevaluate-setting where the effect is only known at run time,
which is the Custom path the removal commit named as the replacement for
reset. Keep neomacs--effects-apply for whole profiles, which no option
expresses.

Also drop the removed effects profile from the neomacs-cursor-effect
docstring.
---
 lisp/term/neo-win.el             |  2 +-
 test/neomacs/neomacs-showcase.el | 86 ++++++++++++++++++++------------
 2 files changed, 54 insertions(+), 34 deletions(-)

diff --git a/lisp/term/neo-win.el b/lisp/term/neo-win.el
index a456d25103..e9a7505871 100644
--- a/lisp/term/neo-win.el
+++ b/lisp/term/neo-win.el
@@ -730,7 +730,7 @@ Applied at the render level."
 
 (defvar-local neomacs-cursor-effect nil
   "Per-buffer cursor effect profile.
-The value is one entry or a list of entries in `neomacs-effects' format.
+The value is one (EFFECT :PROPERTY VALUE ...) entry or a list of them.
 Only cursor effects are used when rendering this buffer's cursor.")
 
 ;; Provide the feature
diff --git a/test/neomacs/neomacs-showcase.el b/test/neomacs/neomacs-showcase.el
index 66fc4dc65c..c28d5b1452 100644
--- a/test/neomacs/neomacs-showcase.el
+++ b/test/neomacs/neomacs-showcase.el
@@ -4,6 +4,7 @@
 (require 'neomacs-webkit nil t)
 (require 'neomacs-video nil t)
 (require 'neomacs-image nil t)
+(require 'neomacs-effects nil t)
 
 (defvar showcase--log-file "/tmp/neomacs-showcase.log"
   "Path to the log file.")
@@ -304,6 +305,19 @@ The future of text editing is here.  It's called Neomacs.
     (push frame showcase--child-frames)
     frame))
 
+(defun showcase--effect-option (effect)
+  "Return the option `neomacs-effects' generates for gallery EFFECT."
+  (intern (format "neomacs-effect-%s" effect)))
+
+(defun showcase--effect-enable (effect)
+  "Turn on gallery EFFECT, for the callers that only know it at run time.
+`setopt' needs a literal variable name; the rest of this file uses it."
+  (customize-set-variable (showcase--effect-option effect) '(:enabled t)))
+
+(defun showcase--effect-reset (effect)
+  "Restore gallery EFFECT's standard value, which also reaches the renderer."
+  (custom-reevaluate-setting (showcase--effect-option effect)))
+
 (defun showcase--reset-all-effects ()
   "Disable every visual effect for a clean slate."
   (showcase--log "RESET-ALL-EFFECTS called (step=%d)" showcase--step)
@@ -319,7 +333,7 @@ The future of text editing is here.  It's called Neomacs.
       (ignore-errors (neomacs-webkit-close-all))))
   ;; Restore every renderer-defined default, then turn off the one shader
   ;; whose Rust default is intentionally enabled.
-  (neomacs-effects-apply '((cursor-color-cycle :enabled nil))))
+  (neomacs--effects-apply '((cursor-color-cycle :enabled nil))))
 
 (defun showcase--title-card (title &optional subtitle)
   "Show a title card with TITLE and optional SUBTITLE."
@@ -504,9 +518,9 @@ The future of text editing is here.  It's called Neomacs.
                   (goto-char (+ (match-beginning 0) 1)))
                 (redisplay t))))))))
   ;; Breathing border (purple, slow)
-  (neomacs-effect-set 'breathing-border
-                      :enabled t :color "#9966FF"
-                      :min-opacity 0.05 :max-opacity 0.4 :cycle-ms 4000))
+  (setopt neomacs-effect-breathing-border
+          '(:enabled t :color "#9966FF"
+            :min-opacity 0.05 :max-opacity 0.4 :cycle-ms 4000)))
 
 (defun showcase--section-cursor-anim ()
   "Demonstrate smooth cursor with spring physics and glow."
@@ -520,8 +534,10 @@ The future of text editing is here.  It's called Neomacs.
     (recenter)
     (redisplay t)
     ;; Enable smooth cursor + glow + line highlight
-    (neomacs-effect-set 'cursor-glow :enabled t :color "#4D99FF" :radius 40)
-    (neomacs-effect-set 'line-highlight :enabled t)
+    (setopt neomacs-effect-cursor-glow
+            '(:enabled t :color "#4D99FF" :radius 40))
+    (setopt neomacs-effect-line-highlight
+            '(:enabled t))
     ;; Animate cursor through positions
     (let ((delay 0.3))
       (showcase--schedule delay
@@ -596,8 +612,8 @@ The future of text editing is here.  It's called Neomacs.
         (showcase--schedule delay
           (lambda ()
             (showcase--log "  scroll effect: %s" effect)
-            (neomacs-effect-set 'scroll-transition
-                                :enabled t :effect effect)
+            (setopt neomacs-scroll-transition-enabled t
+                    neomacs-scroll-transition-effect effect)
             (message "Scroll Effect: %s" effect)))
         (showcase--schedule (+ delay 0.2)
           (lambda ()
@@ -640,10 +656,11 @@ The future of text editing is here.  It's called Neomacs.
           (showcase--schedule delay
             (lambda ()
               (when old
-                (neomacs-effect-reset old))
-              (neomacs-effect-set effect :enabled t)
+                (showcase--effect-reset old))
+              (showcase--effect-enable effect)
               (when (eq effect 'cursor-color-cycle)
-                (neomacs-effect-set 'cursor-glow :enabled t :radius 35))
+                (setopt neomacs-effect-cursor-glow
+                        '(:enabled t :radius 35)))
               (showcase--log "  cursor effect: %s" name)
               (message "Cursor Effect: %s" name))))
         (setq previous (cdr entry))
@@ -685,7 +702,7 @@ The future of text editing is here.  It's called Neomacs.
             (profile (cadr entry)))
         (showcase--schedule delay
           (lambda ()
-            (neomacs-effects-apply profile)
+            (neomacs--effects-apply profile)
             (showcase--log "  atmosphere: %s" name)
             (message "Atmosphere: %s" name))))
       (setq delay (+ delay 1.0)))))
@@ -702,37 +719,40 @@ The future of text editing is here.  It's called Neomacs.
     (let ((features '((0.2 "Line Numbers"
                        (display-line-numbers-mode 1))
                       (0.8 "Rainbow Indent Guides"
-                       (neomacs-effect-set 'indent-guides
-                                           :enabled t :rainbow-enabled t))
+                       (setopt neomacs-effect-indent-guides
+                               '(:enabled t :rainbow-enabled t)))
                       (1.4 "Line Highlight"
-                       (neomacs-effect-set 'line-highlight :enabled t))
+                       (setopt neomacs-effect-line-highlight
+                               '(:enabled t)))
                       (2.0 "Visible Whitespace"
-                       (neomacs-effect-set 'show-whitespace
-                                           :enabled t :color "#33FF66"))
+                       (setopt neomacs-effect-show-whitespace
+                               '(:enabled t :color "#33FF66")))
                       (2.6 "Minimap"
-                       (neomacs-effect-set 'minimap :enabled t))
+                       (setopt neomacs-effect-minimap
+                               '(:enabled t)))
                       (3.2 "Focus Mode"
-                       (neomacs-effect-set 'focus-mode
-                                           :enabled t :opacity 0.3))
+                       (setopt neomacs-effect-focus-mode
+                               '(:enabled t :opacity 0.3)))
                       (3.8 "Scroll Progress"
-                       (neomacs-effect-set 'scroll-progress :enabled t))
+                       (setopt neomacs-effect-scroll-progress
+                               '(:enabled t)))
                       (4.5 "Split + Inactive Dimming"
                        (progn
                          (split-window-right)
                          (other-window 1)
                          (switch-to-buffer (showcase--insert-prose-buffer))
                          (other-window 1)
-                         (neomacs-effect-set 'inactive-dim
-                                             :enabled t :opacity 0.2)))
+                         (setopt neomacs-effect-inactive-dim
+                                 '(:enabled t :opacity 0.2))))
                       (5.5 "Zen Mode"
                        (progn
                          (delete-other-windows)
-                         (neomacs-effect-reset 'focus-mode)
-                         (neomacs-effect-reset 'minimap)
+                         (showcase--effect-reset 'focus-mode)
+                         (showcase--effect-reset 'minimap)
                          (switch-to-buffer (showcase--insert-prose-buffer))
-                         (neomacs-effect-set 'zen-mode :enabled t
-                                             :content-width-pct 60
-                                             :margin-opacity 0.3))))))
+                         (setopt neomacs-effect-zen-mode
+                                 '(:enabled t :content-width-pct 60
+                                   :margin-opacity 0.3)))))))
       (dolist (feat features)
         (let ((d (nth 0 feat))
               (name (nth 1 feat))
@@ -991,9 +1011,9 @@ The future of text editing is here.  It's called Neomacs.
       (lambda ()
         (showcase--log "  window-trans: focus border")
         (message "Transition: Focus Gradient Border")
-        (neomacs-effect-set 'focus-gradient-border
-                            :enabled t :top-color "#4D99FF"
-                            :bot-color "#FF4DFF" :width 3 :opacity 0.8)))
+        (setopt neomacs-effect-focus-gradient-border
+                '(:enabled t :top-color "#4D99FF"
+                  :bot-color "#FF4DFF" :width 3 :opacity 0.8))))
     (showcase--schedule 4.3
       (lambda ()
         (other-window 1)))
@@ -1240,7 +1260,7 @@ The future of text editing is here.  It's called Neomacs.
       (insert (propertize "RETRO MODE ACTIVATED\n" 'face '(:height 2.0 :foreground "#4DFF4D" :weight bold)))
       (insert "\n")))
   ;; Stack retro effects in one renderer update.
-  (neomacs-effects-apply
+  (neomacs--effects-apply
    '((scanlines :enabled t :spacing 3 :opacity 0.12 :color "#000000")
      (dot-matrix :enabled t)
      (bg-pattern :style 1 :spacing 16 :color "#003300" :opacity 0.08)
@@ -1347,7 +1367,7 @@ The future of text editing is here.  It's called Neomacs.
                 (redisplay t))))))))
 
   ;; Stack the prettiest effects.
-  (neomacs-effects-apply
+  (neomacs--effects-apply
    '((aurora :enabled t :color1 "#33CC66" :color2 "#9966FF"
              :height 100 :opacity 0.2)
      (neon-border :enabled t)

From af0e223c4d539a2d96fb98050357894986d56da3 Mon Sep 17 00:00:00 2001
From: 7800uk <git@7800.io>
Date: Wed, 4 Nov 2026 00:11:34 +0000
Subject: [PATCH 2/8] docs(effects): say which settings reach the renderer

Options reach the renderer only through :set, so setq on a loaded option
changes the variable alone: in a batch run, scroll-transition stayed
disabled after setq and turned on after setopt. Correct the commentary and
the two transition defaults that suggested setq, rather than add watchers.
A watcher on 210 options would also fire on let-binding and on the
set-default inside every :set, and setq on a :set option does nothing in
GNU Emacs either.

Rename the private primitives in Rust comments and drop the removed
neomacs-effects profile.
---
 .../tests/child_frame_animation_test.rs            |  2 +-
 .../src/effect_config/tests/effect_config_test.rs  |  4 ++--
 crates/neomacs-display-protocol/src/motion_spec.rs |  2 +-
 .../src/tests/effect_config_test.rs                |  4 ++--
 .../neomacs-display-protocol/src/visual_config.rs  | 14 ++++++++------
 .../src/window_animation.rs                        |  2 +-
 lisp/neomacs-effects.el                            |  7 +++++--
 7 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/crates/neomacs-display-protocol/src/child_frame_animation/tests/child_frame_animation_test.rs b/crates/neomacs-display-protocol/src/child_frame_animation/tests/child_frame_animation_test.rs
index 1085f8154f..1177d7fb72 100644
--- a/crates/neomacs-display-protocol/src/child_frame_animation/tests/child_frame_animation_test.rs
+++ b/crates/neomacs-display-protocol/src/child_frame_animation/tests/child_frame_animation_test.rs
@@ -121,7 +121,7 @@ fn a_cubic_bezier_slot_carries_its_control_points_into_the_spec() {
 
 #[test]
 fn the_registry_carries_every_slot_and_the_slide_property() {
-    // `neomacs-effect-set` validates a property key against the value already
+    // `neomacs--effect-set` validates a property key against the value already
     // stored, so a property missing from the serialized shape makes switching
     // it from Lisp unreachable. Walking every name of the config struct and
     // round-tripping one value through the registry proves the opposite.
diff --git a/crates/neomacs-display-protocol/src/effect_config/tests/effect_config_test.rs b/crates/neomacs-display-protocol/src/effect_config/tests/effect_config_test.rs
index fc95a34974..14dac3ff6e 100644
--- a/crates/neomacs-display-protocol/src/effect_config/tests/effect_config_test.rs
+++ b/crates/neomacs-display-protocol/src/effect_config/tests/effect_config_test.rs
@@ -2648,7 +2648,7 @@ fn every_effect_in_the_registry_can_report_its_values() {
     // The registry is pure serde reflection over `VisualConfig`, and a property
     // that serializes to an object (anything but the `Duration` special case)
     // makes `effect_values` fail for the *whole* effect — which takes
-    // `neomacs-effect-get` down for it and `neomacs-effects-apply`, which walks
+    // `neomacs-effect-get` down for it and `neomacs--effects-apply`, which walks
     // every effect, down entirely. That failure is invisible from the Rust side
     // until someone asks from Lisp, so it is asserted here instead.
     let config = VisualConfig::default();
@@ -2730,7 +2730,7 @@ fn every_window_animation_slot_reaches_the_registry_as_scalars() {
     // break if a slot stored a `MotionSpec` directly: every variant but
     // `Instant` serializes to an object, which the registry cannot represent,
     // so `neomacs-effect-get` would fail for the slot — and
-    // `neomacs-effects-apply`, which walks every effect, with it.
+    // `neomacs--effects-apply`, which walks every effect, with it.
     assert!(sprung.effect_values("window-open").is_ok());
 }
 
diff --git a/crates/neomacs-display-protocol/src/motion_spec.rs b/crates/neomacs-display-protocol/src/motion_spec.rs
index be9fd2a614..1916357fff 100644
--- a/crates/neomacs-display-protocol/src/motion_spec.rs
+++ b/crates/neomacs-display-protocol/src/motion_spec.rs
@@ -275,7 +275,7 @@ impl<'de> serde::Deserialize<'de> for DevicePixels {
 /// that type is a *registry* field on four different configs, and the effect
 /// registry can only carry scalar property values. A data-carrying easing
 /// variant would serialize to an object and break `neomacs-effect-get` for
-/// whichever slot selected it -- and `neomacs-effects-apply`, which walks every
+/// whichever slot selected it -- and `neomacs--effects-apply`, which walks every
 /// effect, along with it. Keeping `TransitionEasing` fieldless makes that
 /// impossible by construction rather than by discipline.
 #[derive(Clone, Copy, Debug, PartialEq, serde::Serialize, serde::Deserialize)]
diff --git a/crates/neomacs-display-protocol/src/tests/effect_config_test.rs b/crates/neomacs-display-protocol/src/tests/effect_config_test.rs
index fc95a34974..14dac3ff6e 100644
--- a/crates/neomacs-display-protocol/src/tests/effect_config_test.rs
+++ b/crates/neomacs-display-protocol/src/tests/effect_config_test.rs
@@ -2648,7 +2648,7 @@ fn every_effect_in_the_registry_can_report_its_values() {
     // The registry is pure serde reflection over `VisualConfig`, and a property
     // that serializes to an object (anything but the `Duration` special case)
     // makes `effect_values` fail for the *whole* effect — which takes
-    // `neomacs-effect-get` down for it and `neomacs-effects-apply`, which walks
+    // `neomacs-effect-get` down for it and `neomacs--effects-apply`, which walks
     // every effect, down entirely. That failure is invisible from the Rust side
     // until someone asks from Lisp, so it is asserted here instead.
     let config = VisualConfig::default();
@@ -2730,7 +2730,7 @@ fn every_window_animation_slot_reaches_the_registry_as_scalars() {
     // break if a slot stored a `MotionSpec` directly: every variant but
     // `Instant` serializes to an object, which the registry cannot represent,
     // so `neomacs-effect-get` would fail for the slot — and
-    // `neomacs-effects-apply`, which walks every effect, with it.
+    // `neomacs--effects-apply`, which walks every effect, with it.
     assert!(sprung.effect_values("window-open").is_ok());
 }
 
diff --git a/crates/neomacs-display-protocol/src/visual_config.rs b/crates/neomacs-display-protocol/src/visual_config.rs
index 4959a16bed..2415e73063 100644
--- a/crates/neomacs-display-protocol/src/visual_config.rs
+++ b/crates/neomacs-display-protocol/src/visual_config.rs
@@ -92,9 +92,10 @@ impl Default for BufferTransitionConfig {
             // Off by default: switching buffers repaints instantly, matching
             // stock Emacs, the same choice ScrollTransitionConfig makes below.
             // Opt in at runtime with
-            //   (setq neomacs-buffer-transition-enabled t)
-            // or via the `neomacs-effects' profile. The effect/duration/easing
-            // below are the values used once it is enabled.
+            //   (setopt neomacs-buffer-transition-enabled t)
+            // or through Customize; a plain `setq' never reaches the renderer.
+            // The effect/duration/easing below are the values used once it is
+            // enabled.
             enabled: false,
             duration: Duration::from_millis(200),
             effect: TransitionEffect::Slide,
@@ -118,9 +119,10 @@ impl Default for ScrollTransitionConfig {
         Self {
             // Off by default: C-v/M-v (and other scrolls) update instantly,
             // matching stock Emacs. Opt in at runtime with
-            //   (setq neomacs-scroll-transition-enabled t)
-            // or via the `neomacs-effects' profile. The effect/duration/easing
-            // below are the values used once it is enabled.
+            //   (setopt neomacs-scroll-transition-enabled t)
+            // or through Customize; a plain `setq' never reaches the renderer.
+            // The effect/duration/easing below are the values used once it is
+            // enabled.
             enabled: false,
             duration: Duration::from_millis(150),
             effect: TransitionEffect::Slide,
diff --git a/crates/neomacs-display-protocol/src/window_animation.rs b/crates/neomacs-display-protocol/src/window_animation.rs
index 0c4b7caaf9..bb548f3a5f 100644
--- a/crates/neomacs-display-protocol/src/window_animation.rs
+++ b/crates/neomacs-display-protocol/src/window_animation.rs
@@ -13,7 +13,7 @@
 //! The effect registry reflects [`crate::visual_config::VisualConfig`] through
 //! serde and can carry only scalar property values. Every `MotionSpec` variant
 //! but `Instant` serializes to an *object*, so storing one here would make
-//! `neomacs-effect-get` fail for the slot -- and `neomacs-effects-apply`, which
+//! `neomacs-effect-get` fail for the slot -- and `neomacs--effects-apply`, which
 //! walks every effect, with it. [`WindowAnimation::motion`] converts to the
 //! form the compositor samples.
 //!
diff --git a/lisp/neomacs-effects.el b/lisp/neomacs-effects.el
index 274c5960ad..0aa3d03f38 100644
--- a/lisp/neomacs-effects.el
+++ b/lisp/neomacs-effects.el
@@ -6,8 +6,11 @@
 
 ;; Every renderer effect is configured through `defcustom', the way
 ;; `blink-cursor-interval' and friends are: one option per property, with a
-;; type, a docstring and a group.  There is no public setter function.  Setting
-;; an option with `setq' or through \\[customize] is the whole interface.
+;; type, a docstring and a group.  There is no public setter function: `setopt'
+;; and \\[customize] are the whole interface, because an option reaches the
+;; renderer through its `:set' function.  As with any GNU option that has one, a
+;; plain `setq' once this file is loaded changes the variable and nothing else;
+;; a value already set when this file loads is picked up by the `defcustom'.
 ;;
 ;; The properties themselves are defined in Rust and published by
 ;; `neomacs-effect-schema', which reports each property's kind, its bounds and,

From 048f65d373807d5962f66e6f0d6ffcf7cefc81f1 Mon Sep 17 00:00:00 2001
From: 7800uk <git@7800.io>
Date: Wed, 4 Nov 2026 00:11:34 +0000
Subject: [PATCH 3/8] fix(perf): probe the xwidget feature for webview
 capability

neomacs-webkit-create is not registered by any crate, so every artifact
reported webview as false. xwidget-internal is what the runtime provides
when the webview backend is present.
---
 crates/neomacs-perf/src/harness.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/neomacs-perf/src/harness.rs b/crates/neomacs-perf/src/harness.rs
index 735dacacb4..d9a2c88b3a 100644
--- a/crates/neomacs-perf/src/harness.rs
+++ b/crates/neomacs-perf/src/harness.rs
@@ -1574,7 +1574,7 @@ fn editor_capabilities(
         "--batch",
         "-Q",
         "--eval",
-        r#"(princ (format "%d,%d,%d,%d,%d,%d" (if (and (fboundp 'native-comp-available-p) (native-comp-available-p)) 1 0) (if (and (fboundp 'treesit-available-p) (treesit-available-p)) 1 0) (if (fboundp 'module-load) 1 0) (if (fboundp 'neomacs-video-load) 1 0) (if (fboundp 'neomacs-webkit-create) 1 0) (if (fboundp 'neomacs-terminal-create) 1 0)))"#,
+        r#"(princ (format "%d,%d,%d,%d,%d,%d" (if (and (fboundp 'native-comp-available-p) (native-comp-available-p)) 1 0) (if (and (fboundp 'treesit-available-p) (treesit-available-p)) 1 0) (if (fboundp 'module-load) 1 0) (if (fboundp 'neomacs-video-load) 1 0) (if (featurep 'xwidget-internal) 1 0) (if (fboundp 'neomacs-terminal-create) 1 0)))"#,
     ]);
     let output = command
         .output()

From 900100da707a03348c7ccd6d93b5a1f58c9795e4 Mon Sep 17 00:00:00 2001
From: 7800uk <git@7800.io>
Date: Wed, 4 Nov 2026 00:42:28 +0000
Subject: [PATCH 4/8] fix(effects): stop offering cubic-bezier for buffer and
 scroll easing

BufferTransitionConfig and ScrollTransitionConfig have nowhere to store
control points, so choosing cubic-bezier silently ran as linear. The window
and child-frame slots keep the choice because they carry the points.
---
 lisp/neomacs-effects.el | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lisp/neomacs-effects.el b/lisp/neomacs-effects.el
index 0aa3d03f38..01d53b149a 100644
--- a/lisp/neomacs-effects.el
+++ b/lisp/neomacs-effects.el
@@ -537,7 +537,7 @@ decorative."
   "Curve shape for a buffer switch."
   :type '(choice (const linear) (const ease-out-quad) (const ease-out-cubic)
                  (const ease-out-expo) (const ease-in-out-cubic)
-                 (const spring) (const cubic-bezier))
+                 (const spring))
   :group 'neomacs-transitions
   :set (lambda (symbol value)
          (set-default symbol value)
@@ -597,7 +597,7 @@ When nil the viewport jumps to its new position on the next frame."
   "Curve shape for a scroll."
   :type '(choice (const linear) (const ease-out-quad) (const ease-out-cubic)
                  (const ease-out-expo) (const ease-in-out-cubic)
-                 (const spring) (const cubic-bezier))
+                 (const spring))
   :group 'neomacs-transitions
   :set (lambda (symbol value)
          (set-default symbol value)

From 37c809881da4786a63e2caacf7e51344c717e4c3 Mon Sep 17 00:00:00 2001
From: 7800uk <git@7800.io>
Date: Wed, 4 Nov 2026 08:27:39 +0000
Subject: [PATCH 5/8] Revert "fix(perf): probe the xwidget feature for webview
 capability"

This reverts commit 1c13d7ce5b0863c7fafbbadeba88c8b53c48853c.
---
 crates/neomacs-perf/src/harness.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/neomacs-perf/src/harness.rs b/crates/neomacs-perf/src/harness.rs
index d9a2c88b3a..735dacacb4 100644
--- a/crates/neomacs-perf/src/harness.rs
+++ b/crates/neomacs-perf/src/harness.rs
@@ -1574,7 +1574,7 @@ fn editor_capabilities(
         "--batch",
         "-Q",
         "--eval",
-        r#"(princ (format "%d,%d,%d,%d,%d,%d" (if (and (fboundp 'native-comp-available-p) (native-comp-available-p)) 1 0) (if (and (fboundp 'treesit-available-p) (treesit-available-p)) 1 0) (if (fboundp 'module-load) 1 0) (if (fboundp 'neomacs-video-load) 1 0) (if (featurep 'xwidget-internal) 1 0) (if (fboundp 'neomacs-terminal-create) 1 0)))"#,
+        r#"(princ (format "%d,%d,%d,%d,%d,%d" (if (and (fboundp 'native-comp-available-p) (native-comp-available-p)) 1 0) (if (and (fboundp 'treesit-available-p) (treesit-available-p)) 1 0) (if (fboundp 'module-load) 1 0) (if (fboundp 'neomacs-video-load) 1 0) (if (fboundp 'neomacs-webkit-create) 1 0) (if (fboundp 'neomacs-terminal-create) 1 0)))"#,
     ]);
     let output = command
         .output()

From 99b7c75724b6a0868ba2d9f72fbc9ddfe2d1f639 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Sat, 7 Nov 2026 10:52:07 +0000
Subject: [PATCH 6/8] test(showcase): keep demo effects off the user's options

The showcase turned gallery effects on with customize-set-variable and
put them back with custom-reevaluate-setting. The first records a
customization; the second reapplies a saved value, so leaving an effect
turned a saved one back on. Section resets published a clean renderer
through neomacs--effects-apply and left the options at the demo values.

Remember the renderer and the option values before the first change.
Drive the demo through each option's :set function, and on quit write
the snapshot back with set-default so neither customized-value nor a
saved value is involved.

Co-authored-by: Eval Exec <execvy@gmail.com>
---
 test/neomacs/neomacs-showcase-effects-test.el | 222 +++++++++++++++++
 test/neomacs/neomacs-showcase.el              | 234 ++++++++++++++----
 2 files changed, 405 insertions(+), 51 deletions(-)
 create mode 100644 test/neomacs/neomacs-showcase-effects-test.el

diff --git a/test/neomacs/neomacs-showcase-effects-test.el b/test/neomacs/neomacs-showcase-effects-test.el
new file mode 100644
index 0000000000..ea5b1e78e4
--- /dev/null
+++ b/test/neomacs/neomacs-showcase-effects-test.el
@@ -0,0 +1,222 @@
+;;; neomacs-showcase-effects-test.el --- transient effect session regression -*- lexical-binding: t; -*-
+
+;; Run against the pinned GNU Emacs from parity-reference.toml:
+;;
+;;   src/emacs -Q --batch -l test/neomacs/neomacs-showcase-effects-test.el
+;;
+;; The Neomacs renderer subrs are stubbed with the same two rules the Rust
+;; side uses: `neomacs--effect-set' merges properties onto the current
+;; config, and `neomacs--effects-apply' starts from the Rust defaults and
+;; then applies the profile. `cursor-color-cycle' defaults to enabled.
+
+(defvar showcase-effects-test-failures nil)
+
+(defun showcase-effects-test-fail (fmt &rest args)
+  (let ((msg (apply #'format fmt args)))
+    (push msg showcase-effects-test-failures)
+    (princ (format "FAIL %s\n" msg))))
+
+(defun showcase-effects-test-enabled (plist)
+  (plist-get plist :enabled))
+
+(defun showcase-effects-test-reset-session ()
+  (when (boundp 'showcase--saved-renderer)
+    (setq showcase--saved-renderer nil))
+  (when (boundp 'showcase--saved-options)
+    (setq showcase--saved-options nil)))
+
+(defun showcase-effects-test-custom-clean (symbol)
+  (put symbol 'customized-value nil)
+  (put symbol 'theme-value nil)
+  (put symbol 'saved-value nil)
+  (put symbol 'custom-check-value nil))
+
+(defvar neo-test-config (make-hash-table :test #'eq))
+
+(defun neo-test-default (effect)
+  (if (eq effect 'cursor-color-cycle)
+      (list :enabled t)
+    (list :enabled nil)))
+
+(defun neomacs-effect-names (&optional scope)
+  (let ((shaders '(aurora breathing-border cursor-color-cycle cursor-firework
+                         cursor-glow focus-gradient-border focus-mode
+                         inactive-dim indent-guides line-highlight minimap
+                         scroll-progress show-whitespace zen-mode))
+        (behavior '(buffer-transition cursor-blink cursor-motion
+                                      cursor-size-transition scroll-transition
+                                      window-animations window-close
+                                      window-movement window-open
+                                      window-resize child-frame-animations
+                                      child-frame-close child-frame-movement
+                                      child-frame-open child-frame-resize)))
+    (cond ((eq scope 'shader) shaders)
+          ((eq scope 'behavior) behavior)
+          ((eq scope 'cursor) '(cursor-color-cycle cursor-firework cursor-glow))
+          (t (append shaders behavior)))))
+
+(defun neomacs-effect-schema (effect)
+  ;; These two publish :off / :slowdown, not :enabled. A stub :enabled
+  ;; entry makes `neomacs-effects--check-schema' warn about a symbol the
+  ;; real file deliberately does not define.
+  (if (memq effect '(window-animations child-frame-animations))
+      nil
+    '((:enabled boolean))))
+
+(defun neomacs-effect-get (effect)
+  (copy-sequence (or (gethash effect neo-test-config)
+                     (neo-test-default effect))))
+
+(defun neomacs--effect-set (effect &rest plist)
+  (let ((current (neomacs-effect-get effect)))
+    (while plist
+      (setq current (plist-put current (car plist) (cadr plist)))
+      (setq plist (cddr plist)))
+    (puthash effect current neo-test-config)
+    nil))
+
+(defun neomacs--effects-apply (profile)
+  (clrhash neo-test-config)
+  (dolist (effect (neomacs-effect-names))
+    (puthash effect (neo-test-default effect) neo-test-config))
+  (dolist (entry profile)
+    (apply #'neomacs--effect-set entry)))
+
+(defun showcase-effects-test-user-set (symbol value)
+  (let ((setter (get symbol 'custom-set)))
+    (if setter
+        (funcall setter symbol value)
+      (set-default symbol value))))
+
+(let* ((root (expand-file-name "../.." (file-name-directory load-file-name)))
+       (lisp (expand-file-name "lisp" root)))
+  ;; Load Neomacs's effects library by path. Do not put its `lisp/'
+  ;; directory on `load-path': that tree replaces GNU macros such as
+  ;; `defun' and the showcase then fails to expand.
+  (setq showcase--inhibit-init t)
+  (load (expand-file-name "neomacs-effects.el" lisp))
+  (load (expand-file-name "test/neomacs/neomacs-showcase.el" root)))
+
+(unless (boundp 'neomacs-effect-cursor-firework)
+  (showcase-effects-test-fail "gallery option neomacs-effect-cursor-firework was not defined"))
+
+;; A transient enable must not become a user customization, and leaving the
+;; effect must turn it off even when a saved Custom value says enabled.
+(let ((sym 'neomacs-effect-cursor-firework))
+  (showcase-effects-test-reset-session)
+  (showcase-effects-test-custom-clean sym)
+  (showcase-effects-test-user-set sym '(:enabled nil))
+  (put sym 'saved-value (list (list 'quote '(:enabled t))))
+  (showcase--effect-enable 'cursor-firework)
+  (when (get sym 'customized-value)
+    (showcase-effects-test-fail
+     "enable stored customized-value %S" (get sym 'customized-value)))
+  (when (get sym 'theme-value)
+    (showcase-effects-test-fail
+     "enable stored theme-value %S" (get sym 'theme-value)))
+  (unless (eq (showcase-effects-test-enabled (symbol-value sym)) t)
+    (showcase-effects-test-fail "enable left option %S" (symbol-value sym)))
+  (unless (eq (showcase-effects-test-enabled (neomacs-effect-get 'cursor-firework)) t)
+    (showcase-effects-test-fail
+     "enable left renderer %S" (neomacs-effect-get 'cursor-firework)))
+  (showcase--effect-reset 'cursor-firework)
+  (when (eq (showcase-effects-test-enabled (neomacs-effect-get 'cursor-firework)) t)
+    (showcase-effects-test-fail
+     "reset re-enabled firework from saved-value; renderer %S option %S"
+     (neomacs-effect-get 'cursor-firework) (symbol-value sym)))
+  (unless (equal (get sym 'saved-value) (list (list 'quote '(:enabled t))))
+    (showcase-effects-test-fail "reset rewrote saved-value %S" (get sym 'saved-value)))
+  (when (get sym 'customized-value)
+    (showcase-effects-test-fail
+     "reset stored customized-value %S" (get sym 'customized-value))))
+
+;; A section reset must leave the option and the renderer describing the
+;; same effect, and quitting must put the user's value back in both places.
+(let ((sym 'neomacs-effect-breathing-border)
+      (user '(:enabled t :color "#112233")))
+  (showcase-effects-test-reset-session)
+  (showcase-effects-test-custom-clean sym)
+  (showcase-effects-test-user-set sym user)
+  (showcase--reset-all-effects)
+  (let ((option (symbol-value sym))
+        (renderer (neomacs-effect-get 'breathing-border)))
+    (unless (eq (showcase-effects-test-enabled option)
+                (showcase-effects-test-enabled renderer))
+      (showcase-effects-test-fail
+       "reset-all desynced breathing-border option %S renderer %S"
+       option renderer)))
+  (when (get sym 'customized-value)
+    (showcase-effects-test-fail
+     "reset-all stored customized-value %S" (get sym 'customized-value)))
+  (showcase-quit)
+  (let ((option (symbol-value sym))
+        (renderer (neomacs-effect-get 'breathing-border)))
+    (unless (and (eq (showcase-effects-test-enabled option) t)
+                 (equal (plist-get option :color) "#112233"))
+      (showcase-effects-test-fail "quit left option %S" option))
+    (unless (and (eq (showcase-effects-test-enabled renderer) t)
+                 (equal (plist-get renderer :color) "#112233"))
+      (showcase-effects-test-fail "quit left renderer %S" renderer)))
+  (when (get sym 'customized-value)
+    (showcase-effects-test-fail
+     "quit stored customized-value %S" (get sym 'customized-value))))
+
+;; The one default-on shader is off for a clean section and back on after quit.
+(let ((sym 'neomacs-effect-cursor-color-cycle))
+  (showcase-effects-test-reset-session)
+  (showcase-effects-test-custom-clean sym)
+  (showcase-effects-test-user-set sym '(:enabled t))
+  (showcase--reset-all-effects)
+  (when (or (showcase-effects-test-enabled (symbol-value sym))
+            (showcase-effects-test-enabled (neomacs-effect-get 'cursor-color-cycle)))
+    (showcase-effects-test-fail
+     "clean slate left color-cycle option %S renderer %S"
+     (symbol-value sym) (neomacs-effect-get 'cursor-color-cycle)))
+  (showcase-quit)
+  (unless (and (eq (showcase-effects-test-enabled (symbol-value sym)) t)
+               (eq (showcase-effects-test-enabled
+                    (neomacs-effect-get 'cursor-color-cycle))
+                   t))
+    (showcase-effects-test-fail
+     "quit did not restore color-cycle option %S renderer %S"
+     (symbol-value sym) (neomacs-effect-get 'cursor-color-cycle))))
+
+;; A profile must not turn the renderer on while leaving the option off,
+;; and it must not wipe an effect the profile does not mention.
+(if (not (fboundp 'showcase--apply-profile))
+    (showcase-effects-test-fail "showcase--apply-profile is not defined")
+  (let ((highlight 'neomacs-effect-line-highlight)
+        (aurora 'neomacs-effect-aurora))
+    (showcase-effects-test-reset-session)
+    (showcase-effects-test-custom-clean highlight)
+    (showcase-effects-test-custom-clean aurora)
+    (showcase-effects-test-user-set highlight '(:enabled t))
+    (showcase--reset-all-effects)
+    (showcase--apply-profile '((aurora :enabled t :opacity 0.2)))
+    (when (or (showcase-effects-test-enabled (symbol-value highlight))
+              (showcase-effects-test-enabled (neomacs-effect-get 'line-highlight)))
+      (showcase-effects-test-fail
+       "profile resurrected line-highlight option %S renderer %S"
+       (symbol-value highlight) (neomacs-effect-get 'line-highlight)))
+    (unless (and (eq (showcase-effects-test-enabled (symbol-value aurora)) t)
+                 (eq (showcase-effects-test-enabled (neomacs-effect-get 'aurora)) t))
+      (showcase-effects-test-fail
+       "profile desynced aurora option %S renderer %S"
+       (symbol-value aurora) (neomacs-effect-get 'aurora)))
+    (when (get aurora 'customized-value)
+      (showcase-effects-test-fail
+       "profile stored customized-value %S" (get aurora 'customized-value)))
+    (showcase-quit)
+    (unless (and (eq (showcase-effects-test-enabled (symbol-value highlight)) t)
+                 (eq (showcase-effects-test-enabled (neomacs-effect-get 'line-highlight)) t))
+      (showcase-effects-test-fail
+       "quit lost line-highlight option %S renderer %S"
+       (symbol-value highlight) (neomacs-effect-get 'line-highlight)))
+    (when (showcase-effects-test-enabled (neomacs-effect-get 'aurora))
+      (showcase-effects-test-fail
+       "quit left aurora renderer %S" (neomacs-effect-get 'aurora)))))
+
+(when showcase-effects-test-failures
+  (princ (format "FAILED %d\n" (length showcase-effects-test-failures)))
+  (kill-emacs 1))
+(princ "PASS\n")
diff --git a/test/neomacs/neomacs-showcase.el b/test/neomacs/neomacs-showcase.el
index c28d5b1452..94dcabcc92 100644
--- a/test/neomacs/neomacs-showcase.el
+++ b/test/neomacs/neomacs-showcase.el
@@ -305,22 +305,145 @@ The future of text editing is here.  It's called Neomacs.
     (push frame showcase--child-frames)
     frame))
 
+(defvar showcase--saved-renderer nil
+  "Renderer plists captured before this demo changes an effect.
+Nil means no session is open.  Each element is (EFFECT . PLIST), as
+returned by `neomacs-effect-get'.")
+
+(defvar showcase--saved-options nil
+  "Option values captured with `showcase--saved-renderer'.
+Each element is (SYMBOL . VALUE).  Restoring writes these with
+`set-default' so a demo cannot mark them customized.")
+
 (defun showcase--effect-option (effect)
   "Return the option `neomacs-effects' generates for gallery EFFECT."
   (intern (format "neomacs-effect-%s" effect)))
 
+(defun showcase--plist-merge (base overlay)
+  "Return a plist of BASE with OVERLAY's properties written over it."
+  (setq base (copy-sequence (if (listp base) base nil)))
+  (while overlay
+    (setq base (plist-put base (car overlay) (cadr overlay)))
+    (setq overlay (cddr overlay)))
+  base)
+
+(defun showcase--each-effect-option (function)
+  "Call FUNCTION with each effect option that has a `:set' function."
+  (when (and (fboundp 'neomacs-effect-names) (fboundp 'neomacs-effect-get))
+    (dolist (effect (neomacs-effect-names))
+      (let ((gallery (showcase--effect-option effect)))
+        (if (and (boundp gallery) (get gallery 'custom-set))
+            (funcall function gallery)
+          (let ((plist (neomacs-effect-get effect)))
+            (while plist
+              (let ((symbol (intern (format "neomacs-%s-%s"
+                                            effect
+                                            (substring (symbol-name (car plist)) 1)))))
+                (when (and (boundp symbol) (get symbol 'custom-set))
+                  (funcall function symbol)))
+              (setq plist (cddr plist)))))))))
+
+(defun showcase--begin-effect-session ()
+  "Remember the renderer and the option values before the first demo change."
+  (when (and (not showcase--saved-renderer)
+             (fboundp 'neomacs-effect-names)
+             (fboundp 'neomacs-effect-get)
+             (fboundp 'neomacs--effects-apply))
+    (setq showcase--saved-renderer
+          (mapcar (lambda (effect)
+                    (cons effect (neomacs-effect-get effect)))
+                  (neomacs-effect-names)))
+    (setq showcase--saved-options nil)
+    (showcase--each-effect-option
+     (lambda (symbol)
+       (push (cons symbol (symbol-value symbol)) showcase--saved-options)))))
+
+(defun showcase--install-renderer-into-options ()
+  "Copy the current renderer into the option variables.
+Uses `set-default', not an option's `:set' function: the renderer was
+just published, and `:set' would publish it again and could record a
+customization."
+  (when (and (fboundp 'neomacs-effect-names) (fboundp 'neomacs-effect-get))
+    (dolist (effect (neomacs-effect-names))
+      (let ((plist (neomacs-effect-get effect))
+            (gallery (showcase--effect-option effect)))
+        (if (and (boundp gallery) (get gallery 'custom-set))
+            (set-default gallery (copy-sequence plist))
+          (while plist
+            (let ((symbol (intern (format "neomacs-%s-%s"
+                                          effect
+                                          (substring (symbol-name (car plist)) 1)))))
+              (when (and (boundp symbol) (get symbol 'custom-set))
+                (set-default symbol (cadr plist))))
+            (setq plist (cddr plist))))))))
+
+(defun showcase--option-set (symbol value)
+  "Set option SYMBOL to VALUE through its `:set' function.
+This updates the variable and the renderer together.  It does not call
+`customize-set-variable' or `custom-reevaluate-setting', so the change
+is not saved as the user's customization and a saved value is not
+reapplied."
+  (showcase--begin-effect-session)
+  (let ((setter (get symbol 'custom-set)))
+    (if setter
+        (funcall setter symbol value)
+      (set-default symbol value))))
+
+(defun showcase--gallery-set (effect plist)
+  "Set gallery EFFECT to PLIST, keeping its other properties.
+When the effect has an option, the option and the renderer receive the
+merged plist.  Otherwise only the renderer changes."
+  (let ((symbol (showcase--effect-option effect)))
+    (if (and (boundp symbol) (get symbol 'custom-set))
+        (showcase--option-set
+         symbol
+         (showcase--plist-merge (and (listp (symbol-value symbol))
+                                     (symbol-value symbol))
+                                plist))
+      (showcase--begin-effect-session)
+      (when (fboundp 'neomacs--effect-set)
+        (apply #'neomacs--effect-set effect plist)))))
+
+(defun showcase--apply-profile (profile)
+  "Apply each entry of PROFILE with `showcase--gallery-set'.
+PROFILE has the same shape `neomacs--effects-apply' accepts.  Unlike
+that subr, this does not rebuild every effect from the Rust defaults,
+so options the profile does not mention stay in sync with the renderer."
+  (dolist (entry profile)
+    (showcase--gallery-set (car entry) (cdr entry))))
+
 (defun showcase--effect-enable (effect)
-  "Turn on gallery EFFECT, for the callers that only know it at run time.
-`setopt' needs a literal variable name; the rest of this file uses it."
-  (customize-set-variable (showcase--effect-option effect) '(:enabled t)))
+  "Turn on gallery EFFECT without recording a user customization."
+  (showcase--gallery-set effect '(:enabled t)))
 
 (defun showcase--effect-reset (effect)
-  "Restore gallery EFFECT's standard value, which also reaches the renderer."
-  (custom-reevaluate-setting (showcase--effect-option effect)))
-
-(defun showcase--reset-all-effects ()
-  "Disable every visual effect for a clean slate."
-  (showcase--log "RESET-ALL-EFFECTS called (step=%d)" showcase--step)
+  "Turn gallery EFFECT off for the demo, ignoring any saved Custom value.
+The value from before the demo is put back by `showcase-quit'."
+  (showcase--gallery-set effect '(:enabled nil)))
+
+(defun showcase--demo-clean-effects ()
+  "Make the renderer, and the options, a clean demo slate.
+The slate is the Rust defaults with `cursor-color-cycle' forced off.
+The pre-demo renderer and option values stay in the session snapshot."
+  (showcase--begin-effect-session)
+  (when (fboundp 'neomacs--effects-apply)
+    (neomacs--effects-apply '((cursor-color-cycle :enabled nil)))
+    (showcase--install-renderer-into-options)))
+
+(defun showcase--end-effect-session ()
+  "Put back the renderer and the options captured for this demo."
+  (when showcase--saved-renderer
+    (neomacs--effects-apply
+     (mapcar (lambda (entry)
+               (cons (car entry) (copy-sequence (cdr entry))))
+             showcase--saved-renderer))
+    (dolist (cell showcase--saved-options)
+      (set-default (car cell) (cdr cell)))
+    (setq showcase--saved-renderer nil
+          showcase--saved-options nil)))
+
+(defun showcase--reset-demo-chrome ()
+  "Drop timers, child frames, and extra windows used by the demo."
   (showcase--cancel-timers)
   (showcase--cleanup-child-frames)
   (delete-other-windows)
@@ -330,10 +453,15 @@ The future of text editing is here.  It's called Neomacs.
       (ignore-errors (neomacs-video-stop-all))))
   (when (fboundp 'neomacs-webkit-close-all)
     (let ((inhibit-message t))
-      (ignore-errors (neomacs-webkit-close-all))))
-  ;; Restore every renderer-defined default, then turn off the one shader
-  ;; whose Rust default is intentionally enabled.
-  (neomacs--effects-apply '((cursor-color-cycle :enabled nil))))
+      (ignore-errors (neomacs-webkit-close-all)))))
+
+(defun showcase--reset-all-effects ()
+  "Disable every visual effect for a clean slate.
+The user's options and the pre-demo renderer are remembered and put
+back by `showcase-quit'.  Nothing here is recorded as a customization."
+  (showcase--log "RESET-ALL-EFFECTS called (step=%d)" showcase--step)
+  (showcase--reset-demo-chrome)
+  (showcase--demo-clean-effects))
 
 (defun showcase--title-card (title &optional subtitle)
   "Show a title card with TITLE and optional SUBTITLE."
@@ -518,9 +646,10 @@ The future of text editing is here.  It's called Neomacs.
                   (goto-char (+ (match-beginning 0) 1)))
                 (redisplay t))))))))
   ;; Breathing border (purple, slow)
-  (setopt neomacs-effect-breathing-border
-          '(:enabled t :color "#9966FF"
-            :min-opacity 0.05 :max-opacity 0.4 :cycle-ms 4000)))
+  (showcase--gallery-set
+   'breathing-border
+   '(:enabled t :color "#9966FF"
+     :min-opacity 0.05 :max-opacity 0.4 :cycle-ms 4000)))
 
 (defun showcase--section-cursor-anim ()
   "Demonstrate smooth cursor with spring physics and glow."
@@ -534,10 +663,9 @@ The future of text editing is here.  It's called Neomacs.
     (recenter)
     (redisplay t)
     ;; Enable smooth cursor + glow + line highlight
-    (setopt neomacs-effect-cursor-glow
-            '(:enabled t :color "#4D99FF" :radius 40))
-    (setopt neomacs-effect-line-highlight
-            '(:enabled t))
+    (showcase--gallery-set 'cursor-glow
+                           '(:enabled t :color "#4D99FF" :radius 40))
+    (showcase--gallery-set 'line-highlight '(:enabled t))
     ;; Animate cursor through positions
     (let ((delay 0.3))
       (showcase--schedule delay
@@ -612,8 +740,8 @@ The future of text editing is here.  It's called Neomacs.
         (showcase--schedule delay
           (lambda ()
             (showcase--log "  scroll effect: %s" effect)
-            (setopt neomacs-scroll-transition-enabled t
-                    neomacs-scroll-transition-effect effect)
+            (showcase--option-set 'neomacs-scroll-transition-enabled t)
+            (showcase--option-set 'neomacs-scroll-transition-effect effect)
             (message "Scroll Effect: %s" effect)))
         (showcase--schedule (+ delay 0.2)
           (lambda ()
@@ -659,8 +787,7 @@ The future of text editing is here.  It's called Neomacs.
                 (showcase--effect-reset old))
               (showcase--effect-enable effect)
               (when (eq effect 'cursor-color-cycle)
-                (setopt neomacs-effect-cursor-glow
-                        '(:enabled t :radius 35)))
+                (showcase--gallery-set 'cursor-glow '(:enabled t :radius 35)))
               (showcase--log "  cursor effect: %s" name)
               (message "Cursor Effect: %s" name))))
         (setq previous (cdr entry))
@@ -702,7 +829,7 @@ The future of text editing is here.  It's called Neomacs.
             (profile (cadr entry)))
         (showcase--schedule delay
           (lambda ()
-            (neomacs--effects-apply profile)
+            (showcase--apply-profile profile)
             (showcase--log "  atmosphere: %s" name)
             (message "Atmosphere: %s" name))))
       (setq delay (+ delay 1.0)))))
@@ -719,40 +846,38 @@ The future of text editing is here.  It's called Neomacs.
     (let ((features '((0.2 "Line Numbers"
                        (display-line-numbers-mode 1))
                       (0.8 "Rainbow Indent Guides"
-                       (setopt neomacs-effect-indent-guides
-                               '(:enabled t :rainbow-enabled t)))
+                       (showcase--gallery-set 'indent-guides
+                                              '(:enabled t :rainbow-enabled t)))
                       (1.4 "Line Highlight"
-                       (setopt neomacs-effect-line-highlight
-                               '(:enabled t)))
+                       (showcase--gallery-set 'line-highlight '(:enabled t)))
                       (2.0 "Visible Whitespace"
-                       (setopt neomacs-effect-show-whitespace
-                               '(:enabled t :color "#33FF66")))
+                       (showcase--gallery-set 'show-whitespace
+                                              '(:enabled t :color "#33FF66")))
                       (2.6 "Minimap"
-                       (setopt neomacs-effect-minimap
-                               '(:enabled t)))
+                       (showcase--gallery-set 'minimap '(:enabled t)))
                       (3.2 "Focus Mode"
-                       (setopt neomacs-effect-focus-mode
-                               '(:enabled t :opacity 0.3)))
+                       (showcase--gallery-set 'focus-mode
+                                              '(:enabled t :opacity 0.3)))
                       (3.8 "Scroll Progress"
-                       (setopt neomacs-effect-scroll-progress
-                               '(:enabled t)))
+                       (showcase--gallery-set 'scroll-progress '(:enabled t)))
                       (4.5 "Split + Inactive Dimming"
                        (progn
                          (split-window-right)
                          (other-window 1)
                          (switch-to-buffer (showcase--insert-prose-buffer))
                          (other-window 1)
-                         (setopt neomacs-effect-inactive-dim
-                                 '(:enabled t :opacity 0.2))))
+                         (showcase--gallery-set 'inactive-dim
+                                                '(:enabled t :opacity 0.2))))
                       (5.5 "Zen Mode"
                        (progn
                          (delete-other-windows)
                          (showcase--effect-reset 'focus-mode)
                          (showcase--effect-reset 'minimap)
                          (switch-to-buffer (showcase--insert-prose-buffer))
-                         (setopt neomacs-effect-zen-mode
-                                 '(:enabled t :content-width-pct 60
-                                   :margin-opacity 0.3)))))))
+                         (showcase--gallery-set
+                          'zen-mode
+                          '(:enabled t :content-width-pct 60
+                            :margin-opacity 0.3)))))))
       (dolist (feat features)
         (let ((d (nth 0 feat))
               (name (nth 1 feat))
@@ -1011,9 +1136,10 @@ The future of text editing is here.  It's called Neomacs.
       (lambda ()
         (showcase--log "  window-trans: focus border")
         (message "Transition: Focus Gradient Border")
-        (setopt neomacs-effect-focus-gradient-border
-                '(:enabled t :top-color "#4D99FF"
-                  :bot-color "#FF4DFF" :width 3 :opacity 0.8))))
+        (showcase--gallery-set
+         'focus-gradient-border
+         '(:enabled t :top-color "#4D99FF"
+           :bot-color "#FF4DFF" :width 3 :opacity 0.8))))
     (showcase--schedule 4.3
       (lambda ()
         (other-window 1)))
@@ -1259,8 +1385,8 @@ The future of text editing is here.  It's called Neomacs.
       (erase-buffer)
       (insert (propertize "RETRO MODE ACTIVATED\n" 'face '(:height 2.0 :foreground "#4DFF4D" :weight bold)))
       (insert "\n")))
-  ;; Stack retro effects in one renderer update.
-  (neomacs--effects-apply
+  ;; Stack retro effects without rebuilding the other options from defaults.
+  (showcase--apply-profile
    '((scanlines :enabled t :spacing 3 :opacity 0.12 :color "#000000")
      (dot-matrix :enabled t)
      (bg-pattern :style 1 :spacing 16 :color "#003300" :opacity 0.08)
@@ -1367,7 +1493,7 @@ The future of text editing is here.  It's called Neomacs.
                 (redisplay t))))))))
 
   ;; Stack the prettiest effects.
-  (neomacs--effects-apply
+  (showcase--apply-profile
    '((aurora :enabled t :color1 "#33CC66" :color2 "#9966FF"
              :height 100 :opacity 0.2)
      (neon-border :enabled t)
@@ -1453,7 +1579,8 @@ The future of text editing is here.  It's called Neomacs.
   (showcase--log "=== SHOWCASE QUIT ===")
   (showcase--stop-countdown)
   (showcase--cancel-seq-timers)
-  (showcase--reset-all-effects)
+  (showcase--reset-demo-chrome)
+  (showcase--end-effect-session)
   (when showcase--original-mode-line-format
     (set-default 'mode-line-format showcase--original-mode-line-format)
     (force-mode-line-update t))
@@ -1507,8 +1634,13 @@ The future of text editing is here.  It's called Neomacs.
         (message "Neomacs Showcase: a=run-all  n=next  p=prev  0-9=jump  q=quit"))
     (showcase-run-all)))
 
-;; Auto-initialize when loaded
-(showcase--init)
+(defvar showcase--inhibit-init nil
+  "When non-nil, loading this file does not start the demo.
+Tests bind this before loading so they can call the helpers.")
+
+;; Auto-initialize when loaded as a demo, not when a test is driving it.
+(unless showcase--inhibit-init
+  (showcase--init))
 
 (provide 'neomacs-showcase)
 ;;; neomacs-showcase.el ends here

From 91d33e57b0e9b7e5dccc06790ba8b3b94ee7a707 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Sat, 7 Nov 2026 10:52:07 +0000
Subject: [PATCH 7/8] docs(effects): point configuration at the defcustom
 interface

neomacs-effect-set, neomacs-effect-reset, and neomacs-effects-apply are
not defined. The animation page linked from the README, EFFECTS.md, and
the display-engine pipeline still called them. Describe setopt, and say
that a setq reaches the renderer only when it is made before
neomacs-effects.el loads.

Co-authored-by: Eval Exec <execvy@gmail.com>
---
 .../src/visual_config.rs                      |  8 +-
 docs/animations.md                            | 45 +++++----
 docs/design/display-crate-layout.md           |  2 +-
 docs/display-engine/DESIGN.md                 |  9 +-
 docs/display-engine/EFFECTS.md                | 94 +++++++++++--------
 5 files changed, 92 insertions(+), 66 deletions(-)

diff --git a/crates/neomacs-display-protocol/src/visual_config.rs b/crates/neomacs-display-protocol/src/visual_config.rs
index 2415e73063..fa2e92f39d 100644
--- a/crates/neomacs-display-protocol/src/visual_config.rs
+++ b/crates/neomacs-display-protocol/src/visual_config.rs
@@ -93,7 +93,9 @@ impl Default for BufferTransitionConfig {
             // stock Emacs, the same choice ScrollTransitionConfig makes below.
             // Opt in at runtime with
             //   (setopt neomacs-buffer-transition-enabled t)
-            // or through Customize; a plain `setq' never reaches the renderer.
+            // or through Customize. A plain `setq' after `neomacs-effects.el'
+            // has loaded never reaches the renderer; a value set before that
+            // load is applied by the `defcustom'.
             // The effect/duration/easing below are the values used once it is
             // enabled.
             enabled: false,
@@ -120,7 +122,9 @@ impl Default for ScrollTransitionConfig {
             // Off by default: C-v/M-v (and other scrolls) update instantly,
             // matching stock Emacs. Opt in at runtime with
             //   (setopt neomacs-scroll-transition-enabled t)
-            // or through Customize; a plain `setq' never reaches the renderer.
+            // or through Customize. A plain `setq' after `neomacs-effects.el'
+            // has loaded never reaches the renderer; a value set before that
+            // load is applied by the `defcustom'.
             // The effect/duration/easing below are the values used once it is
             // enabled.
             enabled: false,
diff --git a/docs/animations.md b/docs/animations.md
index 14f511ee63..d93a5c76af 100644
--- a/docs/animations.md
+++ b/docs/animations.md
@@ -90,23 +90,30 @@ orientation, and direction are independent typed settings:
 ## Configuration
 
 ```elisp
-;; One typed, name-based profile configures effects and animation policy.
-(neomacs-effects-apply
- '((cursor-motion :enabled t :speed 15.0
-                  :style critically-damped-spring :duration 0.15
-                  :trail-size 0.7)
-   (buffer-transition :enabled t :duration 0.2
-                      :effect slide :easing ease-out-quad
-                      :axis auto :direction forward)
-   (scroll-transition :enabled t :duration 0.15
-                      :effect page-curl :easing spring)))
-
-;; Incremental changes use the same names and properties.
-(neomacs-effect-set 'cursor-motion
-                    :speed 20.0 :style 'linear :duration 0.1)
-(neomacs-effect-set 'buffer-transition
-                    :effect 'page-curl
-                    :axis 'vertical :direction 'backward)
-(neomacs-effect-set 'scroll-transition
-                    :effect 'wobbly :easing 'ease-out-quad)
+;; Options reach the renderer through their :set function. setopt and
+;; Customize do that; a setq after neomacs-effects.el has loaded does not.
+(setopt neomacs-cursor-motion-enabled t
+        neomacs-cursor-motion-speed 15.0
+        neomacs-cursor-motion-style 'critically-damped-spring
+        neomacs-cursor-motion-duration 0.15
+        neomacs-cursor-motion-trail-size 0.7
+        neomacs-buffer-transition-enabled t
+        neomacs-buffer-transition-duration 0.2
+        neomacs-buffer-transition-effect 'slide
+        neomacs-buffer-transition-easing 'ease-out-quad
+        neomacs-buffer-transition-axis 'auto
+        neomacs-buffer-transition-direction 'forward
+        neomacs-scroll-transition-enabled t
+        neomacs-scroll-transition-duration 0.15
+        neomacs-scroll-transition-effect 'page-curl
+        neomacs-scroll-transition-easing 'spring)
+
+(setopt neomacs-cursor-motion-speed 20.0
+        neomacs-cursor-motion-style 'linear
+        neomacs-cursor-motion-duration 0.1
+        neomacs-buffer-transition-effect 'page-curl
+        neomacs-buffer-transition-axis 'vertical
+        neomacs-buffer-transition-direction 'backward
+        neomacs-scroll-transition-effect 'wobbly
+        neomacs-scroll-transition-easing 'ease-out-quad)
 ```
diff --git a/docs/design/display-crate-layout.md b/docs/design/display-crate-layout.md
index 496e405d6c..5d29809b77 100644
--- a/docs/design/display-crate-layout.md
+++ b/docs/design/display-crate-layout.md
@@ -131,7 +131,7 @@ Submodule charters — a new file needs one of these to belong:
 6. **A config value that Lisp can set must be scalar.** The effect registry is
    serde reflection over `VisualConfig` and carries only scalars plus
    `Duration`; a field that serializes to an object breaks
-   `neomacs-effects-apply` for every effect, not just its own.
+   `neomacs--effects-apply` for every effect, not just its own.
 6. **Lint suppressions are per item, never per crate.** A `#![allow(...)]` in a
    `lib.rs` covers code nobody has read yet, so the count it hides drifts:
    `neomacs-layout-engine`'s crate-wide `clippy::too_many_arguments` allow was
diff --git a/docs/display-engine/DESIGN.md b/docs/display-engine/DESIGN.md
index 8f0dd4e654..3ec591c3df 100644
--- a/docs/display-engine/DESIGN.md
+++ b/docs/display-engine/DESIGN.md
@@ -289,10 +289,11 @@ region, excluding mode-lines and fringes.
 ```
 Elisp                    Evaluator / protocol              Render thread
 ─────                    ────────────────────              ─────────────
-(neomacs-effect-set      validate named properties        ConfigCommand::
- 'cursor-glow              against VisualConfig             SetVisualConfig(snapshot)
- :enabled t                apply to cloned snapshot              ↓
- :radius 48)               commit atomically              effect/cursor/transition state
+(setopt                  option :set calls                ConfigCommand::
+  neomacs-effect-           neomacs--effect-set            SetVisualConfig(snapshot)
+  cursor-glow            validate named properties             ↓
+  '(:enabled t            against VisualConfig           effect/cursor/transition state
+    :radius 48))         commit atomically
 ```
 
 Each effect keeps its own typed property schema.  Profiles validate completely
diff --git a/docs/display-engine/EFFECTS.md b/docs/display-engine/EFFECTS.md
index 029e27f89a..052901178c 100644
--- a/docs/display-engine/EFFECTS.md
+++ b/docs/display-engine/EFFECTS.md
@@ -1,48 +1,62 @@
 # Renderer effects
 
-Neomacs exposes renderer effects through one name-based Elisp interface.  An
-effect has its own typed property set; unrelated effects do not pretend to
-share one universal options struct.
+Renderer effects are user options.  Behavioural effects — cursor motion,
+buffer and scroll transitions, window and child-frame animation — are one
+option per property.  A decorative effect is one option, `neomacs-effect-NAME`,
+whose value is a plist of that effect's properties.  `setopt` and Customize
+are the interface: both run the option's `:set` function, and that is what
+reaches the renderer.  A plain `setq` after `neomacs-effects.el` has loaded
+changes the variable only.  A value already set when that file loads is picked
+up by the `defcustom`.
 
 ```elisp
-(neomacs-effect-set 'cursor-glow
-                    :enabled t
-                    :color "#66CCFF"
-                    :radius 48)
+(setopt neomacs-effect-cursor-glow
+        '(:enabled t :color "#66CCFF" :radius 48))
 
 (neomacs-effect-get 'cursor-glow)
-(neomacs-effect-reset 'cursor-glow)
 (neomacs-effect-names)
 ```
 
+`neomacs-effect-set`, `neomacs-effect-reset`, and `neomacs-effects-apply` are
+not defined.
+
 `neomacs-effect-names` accepts an optional discovery scope: `shader` lists
 renderer shader configs, `cursor` lists configs valid in a buffer-local cursor
 profile, and `behavior` lists cursor/window animation policy.  With no scope it
 returns the complete `VisualConfig` registry.
 
-The same interface owns animation behavior that used to be split across
+The same options own animation behavior that used to be split across
 positional setters:
 
 ```elisp
-(neomacs-effect-set 'cursor-motion
-                    :enabled t :speed 2.4
-                    :style 'critically-damped-spring
-                    :duration 0.15 :trail-size 0.7)
-(neomacs-effect-set 'cursor-color-cycle :enabled t :fps 24)
-(neomacs-effect-set 'cursor-blink :enabled t :interval 0.5)
-(neomacs-effect-set 'cursor-size-transition :enabled t :duration 0.15)
-(neomacs-effect-set 'buffer-transition
-                    :enabled t :duration 0.2
-                    :effect 'slide :easing 'ease-out-quad
-                    :axis 'auto :direction 'forward)
-(neomacs-effect-set 'scroll-transition
-                    :enabled t :duration 0.15
-                    :effect 'page-curl :easing 'spring)
+(setopt neomacs-cursor-motion-enabled t
+        neomacs-cursor-motion-speed 2.4
+        neomacs-cursor-motion-style 'critically-damped-spring
+        neomacs-cursor-motion-duration 0.15
+        neomacs-cursor-motion-trail-size 0.7)
+(setopt neomacs-effect-cursor-color-cycle '(:enabled t :fps 24))
+(setopt neomacs-cursor-blink-enabled t
+        neomacs-cursor-blink-interval 0.5)
+(setopt neomacs-cursor-size-transition-enabled t
+        neomacs-cursor-size-transition-duration 0.15)
+(setopt neomacs-buffer-transition-enabled t
+        neomacs-buffer-transition-duration 0.2
+        neomacs-buffer-transition-effect 'slide
+        neomacs-buffer-transition-easing 'ease-out-quad
+        neomacs-buffer-transition-axis 'auto
+        neomacs-buffer-transition-direction 'forward)
+(setopt neomacs-scroll-transition-enabled t
+        neomacs-scroll-transition-duration 0.15
+        neomacs-scroll-transition-effect 'page-curl
+        neomacs-scroll-transition-easing 'spring)
 ```
 
-Unknown effects, unknown properties, invalid colors, wrong value types, and
-non-integral values for integer properties signal an Elisp error.  Property
-names use Lisp kebab-case and map to the Rust config field with the same name
+`neomacs--effect-set` rejects an unknown effect, an unknown property, an
+invalid color, a wrong value type, and a non-integral value for an integer
+property.  An option's `:set` function stores the Lisp value first and
+ignores that signal, so a rejected value changes the option and leaves the
+renderer as it was.  Property names use Lisp kebab-case and map to the Rust
+config field with the same name
 in snake_case.  Colors use sRGB `#RRGGBB` or `#RRGGBBAA` strings and are
 converted to and from the renderer's linear color storage at the protocol
 boundary.  Time fields whose names end in `-ms` are milliseconds, while Rust
@@ -80,25 +94,25 @@ Other motion styles remain available: `exponential`, `critically-damped-spring`,
 `ease-in-out-cubic`. The plain `ease-out-expo` style moves one rectangle;
 `neovide` independently animates its corners.
 
-### Applying profiles
+### Applying several effects
 
-`neomacs-effects-apply` replaces the complete profile, starting from the
-Rust-defined defaults and applying every entry before publishing anything:
+Set each option.  There is no public command that replaces the whole profile.
+`neomacs--effects-apply` is internal: it rebuilds the renderer from the Rust
+defaults plus the profile it is given, and it does not write the options, so
+calling it directly leaves Customize showing the previous values.  An invalid
+entry makes that subr signal and publish nothing.
 
 ```elisp
-(neomacs-effects-apply
- '((cursor-glow :enabled t :color "#66CCFF" :radius 48)
-   (rain-effect :enabled t :drop-count 30 :speed 120.0)))
+(setopt neomacs-effect-cursor-glow
+        '(:enabled t :color "#66CCFF" :radius 48)
+        neomacs-effect-rain-effect
+        '(:enabled t :drop-count 30 :speed 120.0))
 ```
 
-If any entry is invalid, neither evaluator state nor renderer state changes.
-An empty profile restores every Rust default.  `neomacs-effects`, the Custom
-option in `term/neo-win.el`, has the same format.
-
-`neomacs-cursor-effect` accepts one cursor-effect entry or a list of entries
-in this format as a buffer-local variable or window parameter.  The layout
-engine validates it through the same protocol registry used by global
-configuration.
+`neomacs-cursor-effect`, in `term/neo-win.el`, accepts one
+`(EFFECT :PROPERTY VALUE ...)` entry or a list of them as a buffer-local
+variable or window parameter.  The layout engine validates it through the
+same protocol registry used by the options above.
 
 ## Ownership and update flow
 

From 1498ec4ddb2fcd7f633e0169543b4be321979f28 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Sat, 7 Nov 2026 11:12:44 +0000
Subject: [PATCH 8/8] fix(showcase): show one atmosphere preset at a time

showcase--apply-profile merges, so each atmosphere preset left the
previous one enabled. Clear the demo slate before a preset, then apply
it through the option setters.

Require neomacs-effects when the renderer subr exists. Document that a
gallery setopt replaces the option plist while the renderer merges, and
that cursor blink follows blink-cursor-mode rather than those options.

Co-authored-by: Eval Exec <execvy@gmail.com>
---
 docs/display-engine/EFFECTS.md                | 18 +++++
 test/neomacs/neomacs-showcase-effects-test.el | 70 ++++++++++++++++++-
 test/neomacs/neomacs-showcase.el              | 27 ++++++-
 3 files changed, 109 insertions(+), 6 deletions(-)

diff --git a/docs/display-engine/EFFECTS.md b/docs/display-engine/EFFECTS.md
index 052901178c..0e8387e126 100644
--- a/docs/display-engine/EFFECTS.md
+++ b/docs/display-engine/EFFECTS.md
@@ -17,6 +17,13 @@ up by the `defcustom`.
 (neomacs-effect-names)
 ```
 
+A gallery assignment replaces the option's plist.  The renderer merges the
+properties it is given, so a later `(setopt neomacs-effect-cursor-glow
+'(:radius 40))` leaves glow enabled on screen while the option no longer
+records `:enabled`.  Saving that value and starting again applies only
+`:radius` onto the defaults, and the enablement is gone.  Include every
+property that should persist, or merge onto the current plist first.
+
 `neomacs-effect-set`, `neomacs-effect-reset`, and `neomacs-effects-apply` are
 not defined.
 
@@ -39,6 +46,17 @@ positional setters:
         neomacs-cursor-blink-interval 0.5)
 (setopt neomacs-cursor-size-transition-enabled t
         neomacs-cursor-size-transition-duration 0.15)
+```
+
+`neomacs-cursor-blink-enabled` and `neomacs-cursor-blink-interval` are not
+what a session keeps.  After the first frame, `neomacs--setup-cursor-blink`
+copies `blink-cursor-mode` and `blink-cursor-interval` into the renderer
+with `neomacs--effect-set`, and a later `blink-cursor-mode` change does
+that again.  The option variables stay as they were, so a `setopt` of them
+in an init file can disappear from the screen.  Set `blink-cursor-mode` and
+`blink-cursor-interval` for the blink that should persist.
+
+```elisp
 (setopt neomacs-buffer-transition-enabled t
         neomacs-buffer-transition-duration 0.2
         neomacs-buffer-transition-effect 'slide
diff --git a/test/neomacs/neomacs-showcase-effects-test.el b/test/neomacs/neomacs-showcase-effects-test.el
index ea5b1e78e4..850cfca4c0 100644
--- a/test/neomacs/neomacs-showcase-effects-test.el
+++ b/test/neomacs/neomacs-showcase-effects-test.el
@@ -39,10 +39,10 @@
     (list :enabled nil)))
 
 (defun neomacs-effect-names (&optional scope)
-  (let ((shaders '(aurora breathing-border cursor-color-cycle cursor-firework
+  (let (        (shaders '(aurora breathing-border cursor-color-cycle cursor-firework
                          cursor-glow focus-gradient-border focus-mode
-                         inactive-dim indent-guides line-highlight minimap
-                         scroll-progress show-whitespace zen-mode))
+                         inactive-dim indent-guides line-highlight matrix-rain
+                         minimap scroll-progress show-whitespace zen-mode))
         (behavior '(buffer-transition cursor-blink cursor-motion
                                       cursor-size-transition scroll-transition
                                       window-animations window-close
@@ -216,6 +216,70 @@
       (showcase-effects-test-fail
        "quit left aurora renderer %S" (neomacs-effect-get 'aurora)))))
 
+;; Atmosphere presets are shown one at a time.  Applying the next profile
+;; must turn the previous preset off in both the option and the renderer.
+(let ((aurora 'neomacs-effect-aurora)
+      (rain 'neomacs-effect-matrix-rain))
+  (showcase-effects-test-reset-session)
+  (showcase-effects-test-custom-clean aurora)
+  (showcase-effects-test-custom-clean rain)
+  (showcase-effects-test-user-set aurora '(:enabled nil))
+  (showcase--replace-profile '((aurora :enabled t :opacity 0.18)))
+  (showcase--replace-profile '((matrix-rain :enabled t :opacity 0.15)))
+  (when (or (eq (showcase-effects-test-enabled (symbol-value aurora)) t)
+            (eq (showcase-effects-test-enabled (neomacs-effect-get 'aurora)) t))
+    (showcase-effects-test-fail
+     "second preset left aurora option %S renderer %S"
+     (symbol-value aurora) (neomacs-effect-get 'aurora)))
+  (unless (and (eq (showcase-effects-test-enabled (symbol-value rain)) t)
+               (eq (showcase-effects-test-enabled (neomacs-effect-get 'matrix-rain)) t))
+    (showcase-effects-test-fail
+     "second preset desynced matrix-rain option %S renderer %S"
+     (symbol-value rain) (neomacs-effect-get 'matrix-rain)))
+  (when (or (get aurora 'customized-value) (get rain 'customized-value))
+    (showcase-effects-test-fail "replace-profile recorded a customization"))
+  (showcase-quit)
+  (when (eq (showcase-effects-test-enabled (neomacs-effect-get 'matrix-rain)) t)
+    (showcase-effects-test-fail
+     "quit left matrix-rain renderer %S" (neomacs-effect-get 'matrix-rain))))
+
+;; A gallery :set replaces the option plist and merges into the renderer.
+(let* ((sym 'neomacs-effect-cursor-glow)
+       (setter (get sym 'custom-set)))
+  (unless setter
+    (showcase-effects-test-fail "cursor-glow has no :set function"))
+  (when setter
+    (funcall setter sym '(:enabled t :color "#112233" :radius 48))
+    (funcall setter sym '(:radius 10))
+    (let ((option (symbol-value sym))
+          (renderer (neomacs-effect-get 'cursor-glow)))
+      (when (plist-member option :enabled)
+        (showcase-effects-test-fail
+         "partial plist kept :enabled in the option %S" option))
+      (unless (and (eq (plist-get renderer :enabled) t)
+                   (equal (plist-get renderer :color) "#112233")
+                   (eql (plist-get renderer :radius) 10))
+        (showcase-effects-test-fail
+         "renderer did not keep omitted glow properties %S" renderer)))))
+
+;; The effects library is required when the renderer subr exists, and the
+;; load stays quiet when that subr is absent.
+(cl-letf (((symbol-function 'require) (lambda (&rest _) nil)))
+  (condition-case err
+      (progn
+        (showcase--require-effects)
+        (showcase-effects-test-fail "missing neomacs-effects did not signal"))
+    (error
+     (unless (string-match-p "neomacs-effects" (error-message-string err))
+       (showcase-effects-test-fail "unexpected require error %S" err)))))
+(let ((orig (symbol-function 'neomacs--effect-set)))
+  (fmakunbound 'neomacs--effect-set)
+  (condition-case err
+      (showcase--require-effects)
+    (error
+     (showcase-effects-test-fail "require signaled without the subr: %S" err)))
+  (fset 'neomacs--effect-set orig))
+
 (when showcase-effects-test-failures
   (princ (format "FAILED %d\n" (length showcase-effects-test-failures)))
   (kill-emacs 1))
diff --git a/test/neomacs/neomacs-showcase.el b/test/neomacs/neomacs-showcase.el
index 94dcabcc92..3515671dba 100644
--- a/test/neomacs/neomacs-showcase.el
+++ b/test/neomacs/neomacs-showcase.el
@@ -4,7 +4,19 @@
 (require 'neomacs-webkit nil t)
 (require 'neomacs-video nil t)
 (require 'neomacs-image nil t)
-(require 'neomacs-effects nil t)
+
+(defun showcase--require-effects ()
+  "Load `neomacs-effects' when the renderer can be configured.
+WebKit, video, and image are optional.  The effect options are not:
+without them a later setter only changes a variable and the renderer
+never sees it.  When the renderer subr is absent, keep the load
+optional so this file can still be read."
+  (if (fboundp 'neomacs--effect-set)
+      (unless (require 'neomacs-effects nil t)
+        (error "Showcase needs library `neomacs-effects'"))
+    (require 'neomacs-effects nil t)))
+
+(showcase--require-effects)
 
 (defvar showcase--log-file "/tmp/neomacs-showcase.log"
   "Path to the log file.")
@@ -408,10 +420,19 @@ merged plist.  Otherwise only the renderer changes."
   "Apply each entry of PROFILE with `showcase--gallery-set'.
 PROFILE has the same shape `neomacs--effects-apply' accepts.  Unlike
 that subr, this does not rebuild every effect from the Rust defaults,
-so options the profile does not mention stay in sync with the renderer."
+so options the profile does not mention stay in sync with the renderer.
+Call `showcase--replace-profile' when the profile should be shown alone."
   (dolist (entry profile)
     (showcase--gallery-set (car entry) (cdr entry))))
 
+(defun showcase--replace-profile (profile)
+  "Show PROFILE alone on the demo slate.
+Clears every effect to the demo defaults, then applies PROFILE through
+the option setters.  The user's pre-demo values stay in the snapshot
+`showcase-quit' restores."
+  (showcase--demo-clean-effects)
+  (showcase--apply-profile profile))
+
 (defun showcase--effect-enable (effect)
   "Turn on gallery EFFECT without recording a user customization."
   (showcase--gallery-set effect '(:enabled t)))
@@ -829,7 +850,7 @@ back by `showcase-quit'.  Nothing here is recorded as a customization."
             (profile (cadr entry)))
         (showcase--schedule delay
           (lambda ()
-            (showcase--apply-profile profile)
+            (showcase--replace-profile profile)
             (showcase--log "  atmosphere: %s" name)
             (message "Atmosphere: %s" name))))
       (setq delay (+ delay 1.0)))))