test(tui): add tier 1 unit tests for pure logic functions

Cover search filtering, intent matching, card affordances, checklist
parsing, template slot discovery/resolve, date grouping, and truncation.

internal/tui/fill_test.go

@@ -0,0 +1,81 @@
+package tui
+
+import (
+	"testing"
+)
+
+func TestDiscoverSlots(t *testing.T) {
+	tests := []struct {
+		name      string
+		body      string
+		wantNames []string
+	}{
+		{"no slots", "plain text", nil},
+		{"single slot", "Hello ${name}", []string{"name"}},
+		{"multiple slots", "${greeting} ${name}, welcome to ${place}", []string{"greeting", "name", "place"}},
+		{"duplicate slot deduped", "${x} and ${x} again", []string{"x"}},
+		{"adjacent slots", "${a}${b}", []string{"a", "b"}},
+		{"nested braces ignored", "${{bad}}", nil},
+		{"empty body", "", nil},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := discoverSlots(tt.body)
+			if len(tt.wantNames) == 0 && len(got) == 0 {
+				return
+			}
+			if len(got) != len(tt.wantNames) {
+				t.Fatalf("got %d slots, want %d", len(got), len(tt.wantNames))
+			}
+			for i, s := range got {
+				if s.Name != tt.wantNames[i] {
+					t.Fatalf("slot[%d].Name = %q, want %q", i, s.Name, tt.wantNames[i])
+				}
+			}
+		})
+	}
+}
+
+func TestResolve(t *testing.T) {
+	tests := []struct {
+		name  string
+		body  string
+		slots []fillSlot
+		want  string
+	}{
+		{
+			"all filled",
+			"Hello ${name}, welcome to ${place}",
+			[]fillSlot{{Name: "name", Value: "Alice"}, {Name: "place", Value: "Nib"}},
+			"Hello Alice, welcome to Nib",
+		},
+		{
+			"unfilled stays as placeholder",
+			"${greeting} ${name}",
+			[]fillSlot{{Name: "greeting", Value: "Hi"}, {Name: "name"}},
+			"Hi ${name}",
+		},
+		{
+			"no slots",
+			"plain text",
+			nil,
+			"plain text",
+		},
+		{
+			"repeated slot filled everywhere",
+			"${x} and ${x}",
+			[]fillSlot{{Name: "x", Value: "Y"}},
+			"Y and Y",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f := fillModel{body: tt.body, slots: tt.slots}
+			if got := f.resolve(); got != tt.want {
+				t.Fatalf("resolve() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}