feat: navigate individual sections

internal/web/handler_test.go

@@ -443,3 +443,139 @@ func TestGroupNotesByFolder(t *testing.T) {
 		t.Fatalf("unexpected notes group: %+v", groups[1])
 	}
 }
+
+func TestHandlerNotes_SectionLinks(t *testing.T) {
+	env := newTestEnv(t)
+
+	sectionNote := &note.Note{
+		ID:        "s1",
+		Title:     "Sections",
+		Content:   "# Sections\nIntro\n## 2026-01-01 - First\nFirst body\n## Glossary\nTerm A\n## Glossary\nTerm B\n",
+		Path:      "notes/sections.md",
+		UpdatedAt: time.Date(2026, 1, 4, 10, 0, 0, 0, time.UTC),
+	}
+
+	if err := env.storage.Create(sectionNote); err != nil {
+		t.Fatalf("create note: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodGet, "/notes/s1", nil)
+	rec := httptest.NewRecorder()
+
+	env.handler.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected status 200, got %d", rec.Code)
+	}
+
+	body := rec.Body.String()
+	if !strings.Contains(body, `href="/notes/s1/sections/2026-01-01-first"`) {
+		t.Fatalf("expected link for first section")
+	}
+	if !strings.Contains(body, `href="/notes/s1/sections/glossary"`) {
+		t.Fatalf("expected link for glossary section")
+	}
+	if !strings.Contains(body, `href="/notes/s1/sections/glossary-2"`) {
+		t.Fatalf("expected link for duplicate glossary section")
+	}
+}
+
+func TestHandlerNotes_SectionRoute(t *testing.T) {
+	env := newTestEnv(t)
+
+	sectionNote := &note.Note{
+		ID:        "s1",
+		Title:     "Sections",
+		Content:   "# Sections\nIntro\n## 2026-01-01 - First\nFirst body\n## Glossary\nTerm A\n## Glossary\nTerm B\n",
+		Path:      "notes/sections.md",
+		UpdatedAt: time.Date(2026, 1, 4, 10, 0, 0, 0, time.UTC),
+	}
+
+	if err := env.storage.Create(sectionNote); err != nil {
+		t.Fatalf("create note: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodGet, "/notes/s1/sections/glossary", nil)
+	rec := httptest.NewRecorder()
+
+	env.handler.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected status 200, got %d", rec.Code)
+	}
+
+	body := rec.Body.String()
+	if !strings.Contains(body, "<h2>Glossary</h2>") {
+		t.Fatalf("expected glossary heading to be rendered")
+	}
+	if !strings.Contains(body, "Term A") {
+		t.Fatalf("expected first glossary content")
+	}
+	if strings.Contains(body, "First body") {
+		t.Fatalf("expected other section content to be excluded")
+	}
+	if strings.Contains(body, "Term B") {
+		t.Fatalf("expected second glossary content to be excluded")
+	}
+}
+
+func TestHandlerNotes_SectionRoute_Duplicate(t *testing.T) {
+	env := newTestEnv(t)
+
+	sectionNote := &note.Note{
+		ID:        "s1",
+		Title:     "Sections",
+		Content:   "# Sections\nIntro\n## Glossary\nTerm A\n## Glossary\nTerm B\n",
+		Path:      "notes/sections.md",
+		UpdatedAt: time.Date(2026, 1, 4, 10, 0, 0, 0, time.UTC),
+	}
+
+	if err := env.storage.Create(sectionNote); err != nil {
+		t.Fatalf("create note: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodGet, "/notes/s1/sections/glossary-2", nil)
+	rec := httptest.NewRecorder()
+
+	env.handler.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected status 200, got %d", rec.Code)
+	}
+
+	body := rec.Body.String()
+	if !strings.Contains(body, "<h2>Glossary</h2>") {
+		t.Fatalf("expected glossary heading to be rendered")
+	}
+	if !strings.Contains(body, "Term B") {
+		t.Fatalf("expected second glossary content")
+	}
+	if strings.Contains(body, "Term A") {
+		t.Fatalf("expected first glossary content to be excluded")
+	}
+}
+
+func TestHandlerNotes_SectionRoute_NotFound(t *testing.T) {
+	env := newTestEnv(t)
+
+	sectionNote := &note.Note{
+		ID:        "s1",
+		Title:     "Sections",
+		Content:   "# Sections\n## Alpha\nA\n",
+		Path:      "notes/sections.md",
+		UpdatedAt: time.Date(2026, 1, 4, 10, 0, 0, 0, time.UTC),
+	}
+
+	if err := env.storage.Create(sectionNote); err != nil {
+		t.Fatalf("create note: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodGet, "/notes/s1/sections/missing", nil)
+	rec := httptest.NewRecorder()
+
+	env.handler.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusNotFound {
+		t.Fatalf("expected status 404, got %d", rec.Code)
+	}
+}