The board's symbol takes a tint — a 4×2 colour row under the picker's glyphs, and the glyph itself moves into the titlebar

iconColor stops being hand-written-only (user-ruled, superseding 03's
"schema yes, control no"): it rides StyleCommand.apply → applyStyle as
the third styled dimension — per-dimension no-op skip, one bracket, one
history step, ExpectedField.iconColor for staleness. The SymbolPicker
grows an opt-in colour row (leading None plus seven Palette.foregrounds
hues, None removes the key); the board popover is its one caller. The
window-title widget now draws the board's resolved glyph in that tint
beside the name. Doc realignment filed on the Redesign board (Minor).

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

KanbanTests/UndoWriteTests.swift

@@ -43,6 +43,7 @@ order: 3072
 project: lanework       # agent overlay
 background: {color: blue}
 icon: star
+iconColor: chalk
 created: 2026-01-01T09:00:00Z
 ---
 Styled body.
@@ -249,6 +250,27 @@ struct RestyleUndoTests {
         let undone = try document(fixture, card3Path)
         #expect(undone.background.value == "blue")
         #expect(undone.icon.value == "star", "a dimension the gesture did not touch is not touched back")
+        #expect(undone.iconColor.value == "chalk", "the third dimension rides the same rule")
+    }
+
+    @Test("The colour row's dimension round-trips: a tint undoes to the prior tint, and to absence where there was none")
+    func iconColorRoundTrip() throws {
+        let fixture = try makeBoard()
+        defer { fixture.tearDown() }
+        let (store, history) = try makeStore(fixture)
+
+        // card3 carries `iconColor: chalk`; card1 carries none.
+        store.applyStyle(to: .items([card3]), iconColor: .set("fern"))
+        #expect(try document(fixture, card3Path).iconColor.value == "fern")
+
+        history.undo()
+        #expect(try document(fixture, card3Path).iconColor.value == "chalk")
+        history.redo()
+        #expect(try document(fixture, card3Path).iconColor.value == "fern")
+
+        store.applyStyle(to: .items([card1]), iconColor: .set("carnation"))
+        history.undo()
+        #expect(try document(fixture, card1Path).iconColor.isMissing, "no prior tint undoes to no key at all")
     }
 
     @Test("A styling batch is one step, with a plural title")