test: improve coverage to 98.2%, add staticcheck to CI

- Fix comment typos (Intensty → Intensity)
- Add tests for createStringerPalette modes (background fill, smart mode)
- Add tests for ColorString variants, BytesToColor determinism
- Add tests for GetBackgroundColor mid-tone edge case
- Add tests for GenerateOKLCHPalette negative/large inputs
- Add Go 1.25 to CI matrix for compatibility testing
- Add staticcheck lint step to CI
- Fix goimports formatting in hash_test.go

.github/workflows/ci.yml

@@ -14,13 +14,18 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: ['1.26']
+        go-version: ['1.25', '1.26']
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
         with:
           go-version: ${{ matrix.go-version }}
       - run: go vet ./...
+      - name: staticcheck
+        if: matrix.go-version == '1.26'
+        run: |
+          go install honnef.co/go/tools/cmd/staticcheck@latest
+          staticcheck ./...
       - run: go test -race -coverprofile=coverage.txt ./...
       - name: Upload coverage
         if: matrix.go-version == '1.26'

colors.go

@@ -52,7 +52,7 @@ var (
 	OnCyan   = ColorString("\033[46m%s\033[0m")
 	OnWhite  = ColorString("\033[47m%s\033[0m")
 
-	//  High Intensty
+	//  High Intensity
 	IBlack  = ColorString("\033[0;90m%s\033[0m")
 	IRed    = ColorString("\033[0;91m%s\033[0m")
 	IGreen  = ColorString("\033[0;92m%s\033[0m")
@@ -62,7 +62,7 @@ var (
 	ICyan   = ColorString("\033[0;96m%s\033[0m")
 	IWhite  = ColorString("\033[0;97m%s\033[0m")
 
-	//  Bold High Intensty
+	//  Bold High Intensity
 	BIBlack  = ColorString("\033[1;90m%s\033[0m")
 	BIRed    = ColorString("\033[1;91m%s\033[0m")
 	BIGreen  = ColorString("\033[1;92m%s\033[0m")
@@ -72,7 +72,7 @@ var (
 	BICyan   = ColorString("\033[1;96m%s\033[0m")
 	BIWhite  = ColorString("\033[1;97m%s\033[0m")
 
-	//  High Intensty backgrounds
+	//  High Intensity backgrounds
 	OnIBlack  = ColorString("\033[0;100m%s\033[0m")
 	OnIRed    = ColorString("\033[0;101m%s\033[0m")
 	OnIGreen  = ColorString("\033[0;102m%s\033[0m")

hash_test.go

@@ -12,8 +12,8 @@ import (
 type testPalette []color.Color
 
 func (p testPalette) ToPalette() color.Palette { return color.Palette(p) }
-func (p testPalette) Get(i int) color.Color     { return p[i] }
+func (p testPalette) Get(i int) color.Color    { return p[i] }
-func (p testPalette) Len() int                   { return len(p) }
+func (p testPalette) Len() int                 { return len(p) }
 
 func newTestPalette() testPalette {
 	return testPalette{
@@ -153,6 +153,106 @@ func TestStringerPalette(t *testing.T) {
 	}
 }
 
+func TestCreateStringerPaletteBackgroundFill(t *testing.T) {
+	palette := newTestPalette()
+	sp := createStringerPalette(true, false, palette)
+	if len(sp) != len(palette) {
+		t.Fatalf("expected %d entries, got %d", len(palette), len(sp))
+	}
+	result := sp.GetString("test-bg")
+	if result == "" {
+		t.Fatal("GetString with background fill returned empty string")
+	}
+	if result == "test-bg" {
+		t.Fatal("GetString with background fill did not wrap with escape codes")
+	}
+}
+
+func TestCreateStringerPaletteDisableSmart(t *testing.T) {
+	palette := newTestPalette()
+	sp := createStringerPalette(false, true, palette)
+	if len(sp) != len(palette) {
+		t.Fatalf("expected %d entries, got %d", len(palette), len(sp))
+	}
+	result := sp.GetString("test-nosmart")
+	if result == "" {
+		t.Fatal("GetString with smart mode disabled returned empty string")
+	}
+}
+
+func TestCreateStringerPaletteMultipleSets(t *testing.T) {
+	p1 := newTestPalette()
+	p2 := testPalette{
+		simplecolor.FromRGBA(100, 100, 100, 255),
+		simplecolor.FromRGBA(200, 200, 200, 255),
+	}
+	sp := createStringerPalette(false, false, p1, p2)
+	if len(sp) != len(p1)+len(p2) {
+		t.Fatalf("expected %d entries, got %d", len(p1)+len(p2), len(sp))
+	}
+}
+
+func TestGetBackgroundColorMidTone(t *testing.T) {
+	// A mid-tone color to exercise the luminance threshold
+	mid := simplecolor.FromRGBA(128, 128, 128, 255)
+	bg := GetBackgroundColor(mid)
+	// Should return a valid color (either black or white)
+	r, g, b, _ := bg.RGBA()
+	isBlack := r == 0 && g == 0 && b == 0
+	isWhite := r == 255 && g == 255 && b == 255
+	if !isBlack && !isWhite {
+		t.Errorf("expected black or white background, got (%d,%d,%d)", r, g, b)
+	}
+}
+
+func TestColorStringVariants(t *testing.T) {
+	variants := []struct {
+		name string
+		fn   ColorStringer
+	}{
+		{"Green", Green},
+		{"Yellow", Yellow},
+		{"Purple", Purple},
+		{"Magenta", Magenta},
+		{"BBlue", BBlue},
+		{"UCyan", UCyan},
+		{"OnRed", OnRed},
+		{"IBlue", IBlue},
+		{"BICyan", BICyan},
+		{"OnIGreen", OnIGreen},
+	}
+	for _, v := range variants {
+		t.Run(v.name, func(t *testing.T) {
+			result := v.fn("test")
+			if result == "" {
+				t.Fatalf("%s returned empty string", v.name)
+			}
+			if result == "test" {
+				t.Fatalf("%s did not apply escape codes", v.name)
+			}
+		})
+	}
+}
+
+func TestHashBytesEmpty(t *testing.T) {
+	h := HashBytes(bytes.NewReader([]byte{}))
+	if h < 0 {
+		t.Errorf("HashBytes with empty input returned negative: %d", h)
+	}
+}
+
+func TestBytesToColorDeterministic(t *testing.T) {
+	palette := newTestPalette()
+	input := []byte("consistent-bytes")
+	c1 := BytesToColor(palette, bytes.NewReader(input))
+	c2 := BytesToColor(palette, bytes.NewReader(input))
+	r1, g1, b1, a1 := c1.RGBA()
+	r2, g2, b2, a2 := c2.RGBA()
+	if r1 != r2 || g1 != g2 || b1 != b2 || a1 != a2 {
+		t.Error("BytesToColor is not deterministic")
+	}
+}
+
 func TestDifferentInputsDifferentColors(t *testing.T) {
 	palette := newTestPalette()
 	type rgba struct{ r, g, b, a uint32 }

oklch_test.go

@@ -55,6 +55,27 @@ func TestGenerateOKLCHPaletteSingle(t *testing.T) {
 	}
 }
 
+func TestGenerateOKLCHPaletteNegative(t *testing.T) {
+	palette := GenerateOKLCHPalette(-5, 0.7, 0.15)
+	if len(palette) != 0 {
+		t.Errorf("expected empty palette for negative n, got %d colors", len(palette))
+	}
+}
+
+func TestGenerateOKLCHPaletteLarge(t *testing.T) {
+	palette := GenerateOKLCHPalette(360, 0.7, 0.15)
+	if len(palette) != 360 {
+		t.Fatalf("expected 360 colors, got %d", len(palette))
+	}
+	// Hue step should be ~1° for 360 colors
+	c0 := palette[0].ToOKLCH()
+	c1 := palette[1].ToOKLCH()
+	step := c1.H - c0.H
+	if math.Abs(step-1.0) > 1.0 {
+		t.Errorf("expected ~1° hue step, got %f°", step)
+	}
+}
+
 func TestGenerateOKLCHPaletteDistinct(t *testing.T) {
 	palette := GenerateOKLCHPalette(6, 0.7, 0.15)
 	// All colors should be distinct