refactor(tui): simplify viewport sizing defaults

2 files changed, 50 insertions, 21 deletions

diff --git a/internal/tui/common/viewport.go b/internal/tui/common/viewport.go
index e1729db..099a4e1 100644
--- a/internal/tui/common/viewport.go
+++ b/internal/tui/common/viewport.go
@@ -1,33 +1,13 @@
 package common
 
-import (
-	"os"
-
-	xterm "github.com/charmbracelet/x/term"
-)
-
 const (
 	defaultViewportWidth  = 80
 	defaultViewportHeight = 24
 )
 
 // EffectiveViewport returns a usable terminal viewport size. Missing or invalid
-// dimensions are resolved from the active terminal when possible.
+// dimensions fall back to defaults.
 func EffectiveViewport(width, height int) (int, int) {
-	if width > 0 && height > 0 {
-		return width, height
-	}
-
-	termWidth, termHeight, err := xterm.GetSize(os.Stdout.Fd())
-	if err == nil {
-		if width <= 0 && termWidth > 0 {
-			width = termWidth
-		}
-		if height <= 0 && termHeight > 0 {
-			height = termHeight
-		}
-	}
-
 	if width <= 0 {
 		width = defaultViewportWidth
 	}
diff --git a/internal/tui/common/viewport_test.go b/internal/tui/common/viewport_test.go
new file mode 100644
index 0000000..c90f046
--- /dev/null
+++ b/internal/tui/common/viewport_test.go
@@ -0,0 +1,49 @@
+package common
+
+import "testing"
+
+func TestEffectiveViewport(t *testing.T) {
+	tests := []struct {
+		name       string
+		width      int
+		height     int
+		wantWidth  int
+		wantHeight int
+	}{
+		{
+			name:       "provided dimensions",
+			width:      120,
+			height:     40,
+			wantWidth:  120,
+			wantHeight: 40,
+		},
+		{
+			name:       "both missing use defaults",
+			width:      0,
+			height:     0,
+			wantWidth:  defaultViewportWidth,
+			wantHeight: defaultViewportHeight,
+		},
+		{
+			name:       "missing height uses default",
+			width:      100,
+			height:     0,
+			wantWidth:  100,
+			wantHeight: defaultViewportHeight,
+		},
+		{
+			name:       "missing width uses default",
+			width:      -1,
+			height:     30,
+			wantWidth:  defaultViewportWidth,
+			wantHeight: 30,
+		},
+	}
+
+	for _, tt := range tests {
+		gotWidth, gotHeight := EffectiveViewport(tt.width, tt.height)
+		if gotWidth != tt.wantWidth || gotHeight != tt.wantHeight {
+			t.Fatalf("%s: got (%d,%d), want (%d,%d)", tt.name, gotWidth, gotHeight, tt.wantWidth, tt.wantHeight)
+		}
+	}
+}