diff --git a/classes/chat_context_test.go b/classes/chat_context_test.go
index 843a834..49f644a 100644
--- a/classes/chat_context_test.go
+++ b/classes/chat_context_test.go
@@ -96,6 +96,35 @@ func TestChatContext(t *testing.T) {
 		t.Error("CanActFor is not self-only")
 	}
 
+	// Moderators delete other people's messages in group conversations
+	// (# ogólny) only, and only while they are chat-group members too
+	// (D-10, D-24).
+	for _, mc := range []struct {
+		name     string
+		userID   uint
+		convType string
+		want     bool
+	}{
+		{"moderator in group", 7, "group", true},
+		{"moderator in dm", 7, "dm", false},
+		{"moderator, unknown type", 7, "", false},
+		{"non-moderator in group", 8, "group", false},
+		{"moderator outside the chat group", 9, "group", false},
+		{"no user", 0, "group", false},
+	} {
+		got, err := c.CanModerateMessage(ctx, mc.userID, mc.convType)
+		if err != nil || got != mc.want {
+			t.Errorf("%s: CanModerateMessage = %v, %v, want %v", mc.name, got, err, mc.want)
+		}
+	}
+	if _, err := c.CanModerateMessage(ctx, 13, "group"); err == nil {
+		t.Error("CanModerateMessage with a failing check returned no error")
+	}
+	noMods := classes.NewChatContext(&gorm.DB{}, "studenci", "").WithMembership(members)
+	if ok, err := noMods.CanModerateMessage(ctx, 7, "group"); ok || err != nil {
+		t.Errorf("CanModerateMessage without a moderator group = %v, %v, want false", ok, err)
+	}
+
 	load := classes.ChatContextLoader(func() string { return "studenci" }, func() string { return "moderatorzy" })
 	if got, err := load(ctx, &gorm.DB{}, 2); got != nil || err != nil {
 		t.Errorf("loader(2) = %v, %v, want nil, nil", got, err)
diff --git a/controllers/api/chat_embeds_test.go b/controllers/api/chat_embeds_test.go
new file mode 100644
index 0000000..f5b5a56
--- /dev/null
+++ b/controllers/api/chat_embeds_test.go
@@ -0,0 +1,161 @@
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"git.golem15.com/golem15/summercms/modules/bouncer"
+	"gorm.io/gorm"
+)
+
+func embedHandlers() *Handlers {
+	return &Handlers{DB: func() *gorm.DB { return nil }, ChatGroup: "studenci", ChatModeratorGroup: "moderatorzy"}
+}
+
+func serveEmbed(t *testing.T, fn http.HandlerFunc, method, target, body string, userID uint) (int, map[string]any) {
+	t.Helper()
+	req := httptest.NewRequest(method, target, strings.NewReader(body))
+	if userID != 0 {
+		req = req.WithContext(bouncer.WithUser(req.Context(), &bouncer.Principal{ID: userID}))
+	}
+	rec := httptest.NewRecorder()
+	fn(rec, req)
+	var out map[string]any
+	if err := json.Unmarshal(rec.Body.Bytes(), &out); err != nil {
+		t.Fatalf("%s %s: body is not JSON: %v\n%s", method, target, err, rec.Body.String())
+	}
+	return rec.Code, out
+}
+
+// TestChatEmbedRefs: the resolver accepts deadline, class and reading refs
+// with a positive id, collapses duplicates and takes at most 50 distinct
+// refs; materials and quizzes are not embed types (D-14).
+func TestChatEmbedRefs(t *testing.T) {
+	ok := []embedRef{{"deadline", 1}, {"class", 2}, {"reading", 3}, {"deadline", 1}}
+	got, errs := parseEmbedRefs(ok)
+	if len(errs) != 0 {
+		t.Fatalf("valid refs refused: %v", errs)
+	}
+	if want := []embedRef{{"deadline", 1}, {"class", 2}, {"reading", 3}}; fmt.Sprint(got) != fmt.Sprint(want) {
+		t.Errorf("refs = %v, want %v (duplicates collapse, order kept)", got, want)
+	}
+	for name, refs := range map[string][]embedRef{
+		"material": {{"material", 1}},
+		"quiz":     {{"quiz", 1}},
+		"empty":    {{"", 1}},
+		"id 0":     {{"deadline", 0}},
+		"51 refs":  manyRefs(51),
+	} {
+		if _, errs := parseEmbedRefs(refs); len(errs) == 0 {
+			t.Errorf("%s: accepted, want a validation error", name)
+		}
+	}
+	if _, errs := parseEmbedRefs(manyRefs(50)); len(errs) != 0 {
+		t.Errorf("50 refs refused: %v", errs)
+	}
+	dup := append(manyRefs(50), manyRefs(50)...)
+	if got, errs := parseEmbedRefs(dup); len(errs) != 0 || len(got) != 50 {
+		t.Errorf("50 distinct refs sent twice = %d refs, %v; want 50 and no error", len(got), errs)
+	}
+	if embedKey("deadline", 12) != "deadline:12" || embedKey("class", 3) != "class:3" {
+		t.Errorf("embedKey = %q / %q", embedKey("deadline", 12), embedKey("class", 3))
+	}
+	if embedSearchLimit != 20 {
+		t.Errorf("embedSearchLimit = %d, want 20", embedSearchLimit)
+	}
+}
+
+func manyRefs(n int) []embedRef {
+	out := make([]embedRef, n)
+	for i := range out {
+		out[i] = embedRef{Type: "reading", ID: uint(i + 1)}
+	}
+	return out
+}
+
+// TestEscapeLike: %, _ and the backslash escape character are matched
+// literally in an ILIKE pattern.
+func TestEscapeLike(t *testing.T) {
+	for in, want := range map[string]string{
+		`50%_a\b`:   `50\%\_a\\b`,
+		"plain":     "plain",
+		"":          "",
+		"Wstęp_100": `Wstęp\_100`,
+	} {
+		if got := escapeLike(in); got != want {
+			t.Errorf("escapeLike(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
+func TestChatEmbedsUnauthenticated(t *testing.T) {
+	code, body := serveEmbed(t, embedHandlers().ChatEmbeds, http.MethodGet, "/?type=deadline", "", 0)
+	if code != http.StatusUnauthorized || body["error"] != true {
+		t.Errorf("GET /chat/embeds without a principal = %d %v, want 401", code, body)
+	}
+}
+
+func TestResolveChatEmbedsUnauthenticated(t *testing.T) {
+	code, body := serveEmbed(t, embedHandlers().ResolveChatEmbeds, http.MethodPost, "/", `{"refs":[{"type":"deadline","id":1}]}`, 0)
+	if code != http.StatusUnauthorized || body["error"] != true {
+		t.Errorf("POST /chat/embeds/resolve without a principal = %d %v, want 401", code, body)
+	}
+}
+
+// TestChatEmbedsInvalid: the search validates type and q before the
+// database (422 without one).
+func TestChatEmbedsInvalid(t *testing.T) {
+	h := embedHandlers()
+	for target, field := range map[string]string{
+		"/":               "type",
+		"/?type=material": "type",
+		"/?type=deadline&q=" + strings.Repeat("ą", 101): "q",
+	} {
+		code, body := serveEmbed(t, h.ChatEmbeds, http.MethodGet, target, "", 7)
+		if code != http.StatusUnprocessableEntity {
+			t.Errorf("%s = %d %v, want 422", target, code, body)
+			continue
+		}
+		if errs, _ := body["errors"].(map[string]any); errs[field] == nil {
+			t.Errorf("%s: errors %v have no %s", target, body["errors"], field)
+		}
+	}
+	code, _ := serveEmbed(t, h.ChatEmbeds, http.MethodGet, "/?type=reading&q="+strings.Repeat("ą", 100), "", 7)
+	if code != http.StatusServiceUnavailable {
+		t.Errorf("100-rune q = %d, want to pass validation (503 without a database)", code)
+	}
+}
+
+// TestResolveChatEmbedsInvalid: an unsupported type, id 0, too many refs,
+// an unknown field or a malformed body is 422 before the database.
+func TestResolveChatEmbedsInvalid(t *testing.T) {
+	h := embedHandlers()
+	many, _ := json.Marshal(map[string]any{"refs": manyRefs(51)})
+	for name, body := range map[string]string{
+		"material":      `{"refs":[{"type":"material","id":1}]}`,
+		"id 0":          `{"refs":[{"type":"deadline","id":0}]}`,
+		"51 refs":       string(many),
+		"unknown field": `{"refs":[],"extra":1}`,
+		"not an object": `[1]`,
+		"malformed":     `{`,
+		"empty body":    ``,
+	} {
+		code, out := serveEmbed(t, h.ResolveChatEmbeds, http.MethodPost, "/", body, 7)
+		if code != http.StatusUnprocessableEntity {
+			t.Errorf("%s = %d %v, want 422", name, code, out)
+		}
+	}
+}
+
+// TestResolveChatEmbedsNoDatabase: valid refs pass validation and need the
+// database (503 without one).
+func TestResolveChatEmbedsNoDatabase(t *testing.T) {
+	code, body := serveEmbed(t, embedHandlers().ResolveChatEmbeds, http.MethodPost, "/", `{"refs":[{"type":"deadline","id":1},{"type":"class","id":2},{"type":"reading","id":3}]}`, 7)
+	if code != http.StatusServiceUnavailable {
+		t.Errorf("valid refs without a database = %d %v, want 503", code, body)
+	}
+}
diff --git a/controllers/api/handlers_test.go b/controllers/api/handlers_test.go
index bae042d..086397b 100644
--- a/controllers/api/handlers_test.go
+++ b/controllers/api/handlers_test.go
@@ -60,6 +60,37 @@ func handlers(h *api.Handlers) map[string]http.HandlerFunc {
 	}
 }
 
+// bodyRequest is a handler that validates its query or body before the
+// database, with a request that passes that validation.
+type bodyRequest struct {
+	fn     http.HandlerFunc
+	method string
+	target string
+	body   string
+}
+
+func bodyHandlers(h *api.Handlers) map[string]bodyRequest {
+	return map[string]bodyRequest{
+		"chat-embeds":  {h.ChatEmbeds, http.MethodGet, "/?type=deadline&q=esej", ""},
+		"chat-resolve": {h.ResolveChatEmbeds, http.MethodPost, "/", `{"refs":[{"type":"reading","id":1}]}`},
+	}
+}
+
+func serveBody(t *testing.T, b bodyRequest, user *bouncer.Principal) (int, map[string]any) {
+	t.Helper()
+	req := httptest.NewRequest(b.method, b.target, strings.NewReader(b.body))
+	if user != nil {
+		req = req.WithContext(bouncer.WithUser(req.Context(), user))
+	}
+	rec := httptest.NewRecorder()
+	b.fn(rec, req)
+	var body map[string]any
+	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
+		t.Fatalf("%s %s: body is not JSON: %v\n%s", b.method, b.target, err, rec.Body.String())
+	}
+	return rec.Code, body
+}
+
 func TestEveryHandlerNeedsACaller(t *testing.T) {
 	for name, fn := range handlers(noDB()) {
 		code, body := serve(t, fn, http.MethodGet, "/", nil, map[string]string{"id": "1"})
@@ -67,6 +98,12 @@ func TestEveryHandlerNeedsACaller(t *testing.T) {
 			t.Errorf("%s without a principal = %d %v, want 401", name, code, body)
 		}
 	}
+	for name, b := range bodyHandlers(noDB()) {
+		code, body := serveBody(t, b, nil)
+		if code != http.StatusUnauthorized || body["error"] != true {
+			t.Errorf("%s without a principal = %d %v, want 401", name, code, body)
+		}
+	}
 }
 
 func TestEveryHandlerNeedsADatabase(t *testing.T) {
@@ -77,6 +114,12 @@ func TestEveryHandlerNeedsADatabase(t *testing.T) {
 			t.Errorf("%s without a database = %d %v, want 503", name, code, body)
 		}
 	}
+	for name, b := range bodyHandlers(noDB()) {
+		code, body := serveBody(t, b, user)
+		if code != http.StatusServiceUnavailable {
+			t.Errorf("%s without a database = %d %v, want 503", name, code, body)
+		}
+	}
 	// A nil DB func is the same as an unpublished database.
 	code, _ := serve(t, (&api.Handlers{}).Meetings, http.MethodGet, "/", user, nil)
 	if code != http.StatusServiceUnavailable {