Motion flavours, and Lift is shadow, rim or auto: auto on a dark page recedes the other panes (InactiveDim)

Motion off|crisp|smooth|bouncy|playful is one parameter set (animation.Motion)
every fx animation reads. One focus spring per pane drives both the lift and
the dim, at the flavour's pace; a grid snaps.

Lift drops glow and surface. A shadow falls on pane bodies and rails only,
capped so text and the selection keep min(contrast, 4.5); rim is a hairline
along the focused tag's top. auto is a shadow on a light page; on a dark page
the core recedes the unfocused panes' text (InactiveDim, ported from 2e4d97f,
default 30 under auto) with the same floor. Tests: focused text contrast is
never below unfocused in any style, dim or theme; the focused pane's cells and
tag are untouched by a dim.

Shared files: src/config.zig, src/builtins.zig, src/ninep/ctl.zig,
src/surface.zig, src/detached/wire.zig, docs/config.md,
test/snapshots/builtins.snap (one more wheel for the longer help).

1 files changed, 42 insertions, 8 deletions

diff --git a/src/config.zig b/src/config.zig
index f7e83e91..ed7bee92 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -116,6 +116,8 @@ pub const leader_path = paths: {
     if (builtins.capabilities.window_blur) table.set(.WindowBlur, null);
     if (builtins.capabilities.ligatures) table.set(.Ligatures, null);
     if (builtins.capabilities.lift) table.set(.Lift, null);
+    table.set(.Motion, null);
+    table.set(.InactiveDim, null);
     if (builtins.capabilities.panel_transitions) {
         table.set(.PanelSlide, "as");
         table.set(.PanelZoom, "az");
@@ -623,6 +625,13 @@ pub const Runtime = struct {
     /// docs/render-pipeline.md §9.1), or off. Opt-in until the focus lift's
     /// default is decided. Only a pixel shell draws it (`Capabilities.lift`).
     lift: LiftStyle = .off,
+    /// Blends the unfocused panes' text toward each cell's own ground,
+    /// percent (0 off): the focused pane wins by comparison, its tag tint
+    /// untouched. Kept above min(each cell's contrast, 4.5).
+    inactive_dim: u8 = 0,
+    /// How the fx track's animations move (animation.Motion): off for
+    /// reduced motion.
+    motion: animation.Motion.Flavour = .smooth,
 
     /// Builtins announce themselves on the message row.
     verbose: bool = true,
@@ -670,12 +679,15 @@ pub const Runtime = struct {
 
     pub const ShaderAnimation = enum { off, on, always };
 
-    /// shadow: a soft drop shadow. surface: the lifted pane's ground
-    /// lightens, as a raised surface does on a dark theme. rim: a soft light
-    /// along its top and left edges. glow: a faint halo in the theme's
-    /// accent. auto: shadow on a light page, surface and a faint rim on a
-    /// dark one.
-    pub const LiftStyle = enum(u8) { off, shadow, surface, rim, glow, auto };
+    /// shadow: a soft drop shadow. rim: a light hairline along the top of
+    /// the focused pane's tag rows. auto: a shadow on a light page; on a
+    /// dark one, where a shadow has nothing to darken, the other panes
+    /// recede instead (InactiveDim, at `auto_dim` unless it is set).
+    pub const LiftStyle = enum(u8) { off, shadow, rim, auto };
+    /// What `Lift auto` dims the unfocused panes by on a dark page when
+    /// InactiveDim is 0: enough to read at a glance (the user's own init
+    /// sets 35), not so much that they stop being worth reading.
+    pub const auto_dim: u8 = 30;
 
     /// Each pass the bundled Crt or a Shadertoy file.
     pub const Post = struct {
@@ -846,6 +858,10 @@ pub const Runtime = struct {
         dump_dir,
         /// A lift style, `on` (auto) or `off`; bare flips auto and off.
         lift,
+        /// A motion flavour.
+        motion,
+        /// A percentage, 0 through 100.
+        inactive_dim,
         transition: animation.Transition,
         scene: Scene,
         /// A Shadertoy file into the post chain or out of it; `off` empties
@@ -881,6 +897,8 @@ pub const Runtime = struct {
         .{ .word = "MessageAnimation", .action = .{ .toggle = .message_animation } },
         .{ .word = "Ligatures", .action = .{ .toggle = .ligatures }, .availability = .ligatures },
         .{ .word = "Lift", .action = .lift, .availability = .lift },
+        .{ .word = "Motion", .action = .motion },
+        .{ .word = "InactiveDim", .action = .inactive_dim },
         .{ .word = "MessageLinger", .action = .{ .message_ms = .linger } },
         .{ .word = "MessageFall", .action = .{ .message_ms = .fall } },
         .{ .word = "MessageDissolve", .action = .{ .message_ms = .dissolve } },
@@ -1074,6 +1092,16 @@ pub const Runtime = struct {
                 else
                     std.meta.stringToEnum(LiftStyle, text) orelse return false;
             },
+            .motion => {
+                const text = std.mem.trim(u8, argument orelse return false, " \t\r\n");
+                state.motion = std.meta.stringToEnum(animation.Motion.Flavour, text) orelse return false;
+            },
+            .inactive_dim => {
+                const text = std.mem.trim(u8, argument orelse return false, " \t\r\n%");
+                const percent = std.fmt.parseInt(u8, text, 10) catch return false;
+                if (percent > 100) return false;
+                state.inactive_dim = percent;
+            },
             .theme, .font => return false,
         }
         return true;
@@ -1247,6 +1275,8 @@ pub const Runtime = struct {
                 try out.print("{s} {s}\n", .{ setting.word, @tagName(state.lift) })
             else
                 try out.print("{s} unsupported\n", .{setting.word}),
+            .motion => try out.print("{s} {s}\n", .{ setting.word, @tagName(state.motion) }),
+            .inactive_dim => try out.print("{s} {d}\n", .{ setting.word, state.inactive_dim }),
         };
 
         if (context.startup_config_path) |path|
@@ -1514,7 +1544,9 @@ pub const Runtime = struct {
                 .dump_dir => "~/dumps",
                 .shader => "~/crt.glsl",
                 .shader_animation => "always",
-                .lift => "glow",
+                .lift => "rim",
+                .motion => "playful",
+                .inactive_dim => "35",
                 else => null,
             };
             try std.testing.expect(apply(&state, setting, argument));
@@ -1565,7 +1597,9 @@ pub const Runtime = struct {
                 },
                 .shader => "Shader ~/crt.glsl\n",
                 .shader_animation => "ShaderAnimation always\n",
-                .lift => "Lift glow\n",
+                .lift => "Lift rim\n",
+                .motion => "Motion playful\n",
+                .inactive_dim => "InactiveDim 35\n",
                 .theme, .font => unreachable,
             };
             try std.testing.expect(std.mem.indexOf(u8, report, expected) != null);