2 files changed, 155 insertions, 0 deletions
diff --git a/internal/handlers/handlers.go b/internal/handlers/handlers.go
index e70650d..c5df00d 100644
--- a/internal/handlers/handlers.go
+++ b/internal/handlers/handlers.go
@@ -1251,6 +1251,34 @@ func templateFuncMap() template.FuncMap {
 	return template.FuncMap{
 		"subtract": func(a, b int) int { return a - b },
 		"add":      func(a, b int) int { return a + b },
+		// slug turns a free-text name into an id-safe fragment, so a template
+		// can give a section a stable anchor and target it by selector. Store
+		// names are user data ("Trader Joe's", "Hardware Store") and go
+		// straight into element ids, so anything outside [a-z0-9-] has to go.
+		"slug": func(s string) string {
+			var b strings.Builder
+			lastDash := true // leading dashes are suppressed
+			for _, r := range strings.ToLower(s) {
+				switch {
+				case (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9'):
+					b.WriteRune(r)
+					lastDash = false
+				default:
+					// Collapse any run of separators/punctuation into one dash.
+					if !lastDash {
+						b.WriteByte('-')
+						lastDash = true
+					}
+				}
+			}
+			out := strings.Trim(b.String(), "-")
+			if out == "" {
+				// An empty id would make every such section share the same
+				// (invalid) anchor, so give it something addressable.
+				return "unnamed"
+			}
+			return out
+		},
 		// multiDayLabel returns the "(starts/ends HH:MM)" suffix for a
 		// multi-day calendar event's row on the day it's rendered, or ""
 		// for a normal item or a "spans" (pass-through) day, which shows
diff --git a/internal/handlers/shopping_template_test.go b/internal/handlers/shopping_template_test.go
new file mode 100644
index 0000000..06f63b3
--- /dev/null
+++ b/internal/handlers/shopping_template_test.go
@@ -0,0 +1,127 @@
+package handlers
+
+import (
+	"bytes"
+	"html/template"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"task-dashboard/internal/models"
+)
+
+// renderShoppingTab renders the real shopping-tab template with the real func
+// map, so these assertions cover what actually ships rather than a stand-in.
+func renderShoppingTab(t *testing.T, data any) string {
+	t.Helper()
+	dir := filepath.Join("..", "..", "web", "templates")
+
+	tmpl, err := template.New("").Funcs(templateFuncMap()).ParseGlob(filepath.Join(dir, "*.html"))
+	if err != nil {
+		t.Fatalf("parsing top-level templates: %v", err)
+	}
+	if _, err := tmpl.ParseGlob(filepath.Join(dir, "partials", "*.html")); err != nil {
+		t.Fatalf("parsing partials: %v", err)
+	}
+
+	var buf bytes.Buffer
+	if err := tmpl.ExecuteTemplate(&buf, "shopping-tab", data); err != nil {
+		t.Fatalf("executing shopping-tab: %v", err)
+	}
+	return buf.String()
+}
+
+func twoStoreTabData() any {
+	return struct {
+		Stores  []models.ShoppingStore
+		Grouped bool
+	}{
+		Stores: []models.ShoppingStore{
+			{Name: "Costco", Categories: []models.ShoppingCategory{
+				{Name: "", Items: []models.UnifiedShoppingItem{
+					{ID: "user-1", Name: "Milk", Store: "Costco", Source: "user"},
+				}},
+			}},
+			{Name: "Hardware Store", Categories: []models.ShoppingCategory{
+				{Name: "", Items: []models.UnifiedShoppingItem{
+					{ID: "user-2", Name: "Screws", Store: "Hardware Store", Source: "user"},
+				}},
+			}},
+		},
+		Grouped: true,
+	}
+}
+
+// The inline per-store add form used to submit with a bare
+// hx-swap="innerHTML". Because that form lives *inside* the swap target
+// (#shopping-items-list), submitting it destroys the form mid-request and the
+// page ends up scrolled to the bottom instead of staying where the user was.
+// The quick-add form at the top already pinned this with an explicit
+// scroll: modifier; the per-store forms did not.
+func TestShoppingTab_InlineAddScrollsToItsOwnStore(t *testing.T) {
+	html := renderShoppingTab(t, twoStoreTabData())
+
+	for _, want := range []string{
+		`id="store-costco"`,
+		`id="store-hardware-store"`,
+		`scroll:#store-costco:top`,
+		`scroll:#store-hardware-store:top`,
+	} {
+		if !strings.Contains(html, want) {
+			t.Errorf("rendered shopping tab is missing %q", want)
+		}
+	}
+}
+
+// Every inline add form must carry a scroll target. A form without one is the
+// bug, and it is easy to reintroduce by adding a new store section by copy.
+func TestShoppingTab_EveryInlineAddFormHasAScrollTarget(t *testing.T) {
+	html := renderShoppingTab(t, twoStoreTabData())
+
+	// Count the class attribute specifically — a bare "inline-add-form" also
+	// matches the string literal in the page's own JS handler.
+	forms := strings.Count(html, `class="inline-add-form`)
+	scrolls := strings.Count(html, "scroll:#store-")
+	if forms == 0 {
+		t.Fatal("expected at least one inline add form in the grouped view")
+	}
+	if forms != scrolls {
+		t.Errorf("found %d inline add forms but %d scroll targets; every form needs one",
+			forms, scrolls)
+	}
+}
+
+func TestSlug(t *testing.T) {
+	slug, ok := templateFuncMap()["slug"].(func(string) string)
+	if !ok {
+		t.Fatal("templateFuncMap has no slug function of type func(string) string")
+	}
+
+	cases := []struct{ in, want string }{
+		{"Costco", "costco"},
+		{"Hardware Store", "hardware-store"},
+		{"Trader Joe's", "trader-joe-s"},
+		{"  Spaced  Out  ", "spaced-out"},
+		{"Multiple---Dashes", "multiple-dashes"},
+		// Non-ASCII is treated as a separator rather than transliterated. That
+		// keeps the id valid without pulling in a transliteration table; the
+		// result only has to be stable and unique, not pretty.
+		{"Ünïcode Störe", "n-code-st-re"},
+		{"", "unnamed"},
+		{"!!!", "unnamed"},
+	}
+	for _, c := range cases {
+		if got := slug(c.in); got != c.want {
+			t.Errorf("slug(%q) = %q, want %q", c.in, got, c.want)
+		}
+	}
+}
+
+// Two stores whose names differ only by punctuation must not collide into the
+// same element id, or the scroll target becomes ambiguous.
+func TestSlug_DistinguishesSimilarNames(t *testing.T) {
+	slug := templateFuncMap()["slug"].(func(string) string)
+	if slug("Store A") == slug("Store B") {
+		t.Error("distinct store names produced the same slug")
+	}
+}