diff --git a/internal/channels/zalo/factory_test.go b/internal/channels/zalo/factory_test.go
new file mode 100644
index 00000000..5d8e6a4c
--- /dev/null
+++ b/internal/channels/zalo/factory_test.go
@@ -0,0 +1,191 @@
+package zalo
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/nextlevelbuilder/goclaw/internal/bus"
+	"github.com/nextlevelbuilder/goclaw/internal/config"
+)
+
+// TestFactory_ValidCredsProducesChannel verifies Factory constructs a live
+// Channel when credentials and config JSON are well-formed.
+func TestFactory_ValidCredsProducesChannel(t *testing.T) {
+	creds := []byte(`{"token":"fake-zalo-token","webhook_secret":"hook-sec"}`)
+	cfg := []byte(`{"dm_policy":"open","media_max_mb":7,"allow_from":["+84900000000"],"webhook_url":"https://example.test/hook","block_reply":true}`)
+
+	mb := bus.New()
+	ch, err := Factory("my-zalo", creds, cfg, mb, nil)
+	if err != nil {
+		t.Fatalf("Factory error: %v", err)
+	}
+	if ch == nil {
+		t.Fatal("Factory returned nil channel")
+	}
+	if ch.Name() != "my-zalo" {
+		t.Errorf("Name() = %q, want my-zalo", ch.Name())
+	}
+	zc, ok := ch.(*Channel)
+	if !ok {
+		t.Fatalf("unexpected channel type %T", ch)
+	}
+	if zc.token != "fake-zalo-token" {
+		t.Errorf("token = %q, want fake-zalo-token", zc.token)
+	}
+	if zc.dmPolicy != "open" {
+		t.Errorf("dmPolicy = %q, want open", zc.dmPolicy)
+	}
+	if zc.mediaMaxMB != 7 {
+		t.Errorf("mediaMaxMB = %d, want 7", zc.mediaMaxMB)
+	}
+	if zc.blockReply == nil || !*zc.blockReply {
+		t.Errorf("blockReply = %v, want true", zc.blockReply)
+	}
+}
+
+// TestFactory_ErrorCases covers the error branches in order:
+// - missing token in creds
+// - malformed creds JSON
+// - malformed config JSON
+// - empty creds bytes (missing required token after unmarshal)
+func TestFactory_ErrorCases(t *testing.T) {
+	mb := bus.New()
+	cases := []struct {
+		name    string
+		creds   []byte
+		cfg     []byte
+		wantSub string
+	}{
+		{
+			name:    "missing token",
+			creds:   []byte(`{"webhook_secret":"x"}`),
+			cfg:     []byte(`{}`),
+			wantSub: "token is required",
+		},
+		{
+			name:    "malformed creds",
+			creds:   []byte(`{not-json`),
+			cfg:     []byte(`{}`),
+			wantSub: "decode zalo credentials",
+		},
+		{
+			name:    "malformed config",
+			creds:   []byte(`{"token":"t"}`),
+			cfg:     []byte(`{malformed`),
+			wantSub: "decode zalo config",
+		},
+		{
+			name:    "empty creds bytes",
+			creds:   nil,
+			cfg:     []byte(`{}`),
+			wantSub: "token is required",
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := Factory("zalo-x", tc.creds, tc.cfg, mb, nil)
+			if err == nil {
+				t.Fatal("expected error, got nil")
+			}
+			if !strings.Contains(err.Error(), tc.wantSub) {
+				t.Errorf("err = %v, want substring %q", err, tc.wantSub)
+			}
+		})
+	}
+}
+
+// TestNew_DefaultsWhenFieldsUnset verifies New() applies defaults:
+// - dm_policy defaults to "pairing"
+// - media_max_mb defaults to defaultMediaMaxMB when ≤0
+func TestNew_DefaultsWhenFieldsUnset(t *testing.T) {
+	mb := bus.New()
+	ch, err := New(config.ZaloConfig{Token: "t"}, mb, nil)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	if ch.dmPolicy != "pairing" {
+		t.Errorf("dmPolicy = %q, want pairing (default)", ch.dmPolicy)
+	}
+	if ch.mediaMaxMB != defaultMediaMaxMB {
+		t.Errorf("mediaMaxMB = %d, want %d", ch.mediaMaxMB, defaultMediaMaxMB)
+	}
+	// block_reply should be nil (inherit gateway default).
+	if got := ch.BlockReplyEnabled(); got != nil {
+		t.Errorf("BlockReplyEnabled() = %v, want nil", got)
+	}
+}
+
+// TestNew_EmptyTokenRejected verifies New() rejects empty token.
+func TestNew_EmptyTokenRejected(t *testing.T) {
+	mb := bus.New()
+	if _, err := New(config.ZaloConfig{}, mb, nil); err == nil {
+		t.Fatal("expected error on empty token, got nil")
+	}
+}
+
+// TestNew_CustomValuesPreserved verifies caller-provided values stick.
+func TestNew_CustomValuesPreserved(t *testing.T) {
+	mb := bus.New()
+	blockReply := false
+	ch, err := New(config.ZaloConfig{
+		Token:      "xyz",
+		DMPolicy:   "open",
+		MediaMaxMB: 12,
+		BlockReply: &blockReply,
+	}, mb, nil)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	if ch.dmPolicy != "open" {
+		t.Errorf("dmPolicy = %q, want open", ch.dmPolicy)
+	}
+	if ch.mediaMaxMB != 12 {
+		t.Errorf("mediaMaxMB = %d, want 12", ch.mediaMaxMB)
+	}
+	if got := ch.BlockReplyEnabled(); got == nil || *got != false {
+		t.Errorf("BlockReplyEnabled() = %v, want false pointer", got)
+	}
+}
+
+// TestFactoryConfigWithoutOptionals verifies minimal config still parses —
+// zero values for non-required fields are accepted.
+func TestFactoryConfigWithoutOptionals(t *testing.T) {
+	mb := bus.New()
+	creds := []byte(`{"token":"t"}`)
+	cfg := []byte(`{}`)
+
+	ch, err := Factory("zalo", creds, cfg, mb, nil)
+	if err != nil {
+		t.Fatalf("Factory: %v", err)
+	}
+	zc := ch.(*Channel)
+	if zc.dmPolicy != "pairing" {
+		t.Errorf("dmPolicy = %q, want pairing (default)", zc.dmPolicy)
+	}
+}
+
+// Sanity guard: factory must accept the same JSON shapes that
+// zaloInstanceConfig declares; ensure deserialization matches struct tags.
+func TestZaloInstanceConfigRoundTrip(t *testing.T) {
+	src := zaloInstanceConfig{
+		DMPolicy:   "pairing",
+		WebhookURL: "https://example.test",
+		MediaMaxMB: 3,
+		AllowFrom:  []string{"user1", "user2"},
+	}
+	data, err := json.Marshal(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got zaloInstanceConfig
+	if err := json.Unmarshal(data, &got); err != nil {
+		t.Fatal(err)
+	}
+	if got.DMPolicy != src.DMPolicy || got.MediaMaxMB != src.MediaMaxMB {
+		t.Errorf("round-trip mismatch: got %+v, want %+v", got, src)
+	}
+	if len(got.AllowFrom) != 2 {
+		t.Errorf("AllowFrom len = %d, want 2", len(got.AllowFrom))
+	}
+}
diff --git a/internal/channels/zalo/zalo.go b/internal/channels/zalo/zalo.go
index d04ae19d..aafa53a2 100644
--- a/internal/channels/zalo/zalo.go
+++ b/internal/channels/zalo/zalo.go
@@ -24,7 +24,6 @@ import (
 )
 
 const (
-	apiBase            = "https://bot-api.zaloplatforms.com"
 	defaultPollTimeout = 30
 	maxTextLength      = 2000
 	defaultMediaMaxMB  = 5
@@ -32,6 +31,10 @@ const (
 	pairingDebounce    = 60 * time.Second
 )
 
+// apiBase is the Zalo Bot API root. Declared as a variable so tests can
+// override it with an httptest.NewServer URL.
+var apiBase = "https://bot-api.zaloplatforms.com"
+
 // Channel connects to the Zalo OA Bot API.
 type Channel struct {
 	*channels.BaseChannel
diff --git a/internal/channels/zalo/zalo_test.go b/internal/channels/zalo/zalo_test.go
new file mode 100644
index 00000000..a03c1c0b
--- /dev/null
+++ b/internal/channels/zalo/zalo_test.go
@@ -0,0 +1,534 @@
+package zalo
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/nextlevelbuilder/goclaw/internal/bus"
+	"github.com/nextlevelbuilder/goclaw/internal/config"
+)
+
+// swapAPIBase points zalo.apiBase at a test server for the duration of t.
+// Restores original value automatically via t.Cleanup.
+func swapAPIBase(t *testing.T, url string) {
+	t.Helper()
+	original := apiBase
+	apiBase = url
+	t.Cleanup(func() { apiBase = original })
+}
+
+// newTestChannel returns a Channel wired to the given mock server URL.
+// Token is fixed to "t" so callers can predict the URL path:
+//
+//	<base>/bott/<method>
+func newTestChannel(t *testing.T, srvURL string) *Channel {
+	t.Helper()
+	swapAPIBase(t, srvURL)
+	mb := bus.New()
+	ch, err := New(config.ZaloConfig{Token: "t", DMPolicy: "open"}, mb, nil)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	ch.SetRunning(true)
+	return ch
+}
+
+// TestCallAPI_SuccessRoutesOKResponse verifies callAPI marshals the body,
+// hits the correct path with the bot token, and returns apiResp.Result.
+func TestCallAPI_SuccessRoutesOKResponse(t *testing.T) {
+	var gotPath, gotMethod, gotCT string
+	var gotBody map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotPath = r.URL.Path
+		gotMethod = r.Method
+		gotCT = r.Header.Get("Content-Type")
+		raw, _ := io.ReadAll(r.Body)
+		_ = json.Unmarshal(raw, &gotBody)
+		_, _ = w.Write([]byte(`{"ok":true,"result":{"id":"bot-1","name":"Zalobot"}}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+
+	raw, err := ch.callAPI("getMe", nil)
+	if err != nil {
+		t.Fatalf("callAPI: %v", err)
+	}
+	if gotMethod != http.MethodPost {
+		t.Errorf("method = %q, want POST", gotMethod)
+	}
+	if gotPath != "/bott/getMe" {
+		t.Errorf("path = %q, want /bott/getMe", gotPath)
+	}
+	// No body → Content-Type should not be set by callAPI.
+	if gotCT != "" {
+		t.Errorf("content-type = %q, want empty (no body sent)", gotCT)
+	}
+	// Verify raw result is forwarded verbatim.
+	if !strings.Contains(string(raw), `"bot-1"`) {
+		t.Errorf("raw result = %s, want bot-1", raw)
+	}
+}
+
+// TestCallAPI_ErrorResponseSurfaces verifies callAPI returns an error when
+// the upstream reports ok=false.
+func TestCallAPI_ErrorResponseSurfaces(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":false,"error_code":1001,"description":"bad token"}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	_, err := ch.callAPI("getMe", nil)
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+	if !strings.Contains(err.Error(), "1001") || !strings.Contains(err.Error(), "bad token") {
+		t.Errorf("err = %v, want both code and description", err)
+	}
+}
+
+// TestCallAPI_MalformedJSONReturnsError verifies malformed upstream JSON
+// surfaces an unmarshal error.
+func TestCallAPI_MalformedJSONReturnsError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`not-json`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	_, err := ch.callAPI("getMe", nil)
+	if err == nil {
+		t.Fatal("expected unmarshal error, got nil")
+	}
+}
+
+// TestGetMe_ParsesBotInfo verifies getMe returns the zaloBotInfo struct.
+func TestGetMe_ParsesBotInfo(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":true,"result":{"id":"bot-xyz","name":"TestBot"}}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	info, err := ch.getMe()
+	if err != nil {
+		t.Fatalf("getMe: %v", err)
+	}
+	if info.ID != "bot-xyz" || info.Name != "TestBot" {
+		t.Errorf("info = %+v, want bot-xyz/TestBot", info)
+	}
+}
+
+// TestGetMe_UnmarshalError surfaces decode errors when result is malformed.
+func TestGetMe_UnmarshalError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":true,"result":"not-an-object"}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	if _, err := ch.getMe(); err == nil {
+		t.Fatal("expected unmarshal error, got nil")
+	}
+}
+
+// TestGetUpdates_ParsesUpdateArray verifies getUpdates decodes the updates array.
+func TestGetUpdates_ParsesUpdateArray(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":true,"result":[{"event_name":"message.text.received","message":{"message_id":"m1","text":"hi","from":{"id":"user1"},"chat":{"id":"user1"}}}]}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	updates, err := ch.getUpdates(10)
+	if err != nil {
+		t.Fatalf("getUpdates: %v", err)
+	}
+	if len(updates) != 1 {
+		t.Fatalf("updates len = %d, want 1", len(updates))
+	}
+	if updates[0].EventName != "message.text.received" {
+		t.Errorf("EventName = %q", updates[0].EventName)
+	}
+	if updates[0].Message == nil || updates[0].Message.Text != "hi" {
+		t.Errorf("Message = %+v", updates[0].Message)
+	}
+}
+
+// TestGetUpdates_UnmarshalError verifies a malformed result surfaces an error.
+func TestGetUpdates_UnmarshalError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":true,"result":"string-instead-of-array"}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	if _, err := ch.getUpdates(5); err == nil {
+		t.Fatal("expected unmarshal error, got nil")
+	}
+}
+
+// TestSendMessage_PostsBodyWithParams verifies sendMessage forwards chat_id
+// and text through callAPI as a JSON body.
+func TestSendMessage_PostsBodyWithParams(t *testing.T) {
+	var got map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		raw, _ := io.ReadAll(r.Body)
+		_ = json.Unmarshal(raw, &got)
+		_, _ = w.Write([]byte(`{"ok":true,"result":{}}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	if err := ch.sendMessage("user-1", "hello"); err != nil {
+		t.Fatalf("sendMessage: %v", err)
+	}
+	if got["chat_id"] != "user-1" {
+		t.Errorf("chat_id = %v, want user-1", got["chat_id"])
+	}
+	if got["text"] != "hello" {
+		t.Errorf("text = %v, want hello", got["text"])
+	}
+}
+
+// TestSendPhoto_OmitsEmptyCaption verifies sendPhoto only adds "caption"
+// when it is non-empty (KISS: don't transmit empty fields).
+func TestSendPhoto_OmitsEmptyCaption(t *testing.T) {
+	var gotBodies []map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		raw, _ := io.ReadAll(r.Body)
+		m := map[string]any{}
+		_ = json.Unmarshal(raw, &m)
+		gotBodies = append(gotBodies, m)
+		_, _ = w.Write([]byte(`{"ok":true,"result":{}}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	if err := ch.sendPhoto("chat-1", "https://cdn.example.test/a.jpg", ""); err != nil {
+		t.Fatalf("sendPhoto: %v", err)
+	}
+	if err := ch.sendPhoto("chat-1", "https://cdn.example.test/b.jpg", "caption"); err != nil {
+		t.Fatalf("sendPhoto (w/ caption): %v", err)
+	}
+	if len(gotBodies) != 2 {
+		t.Fatalf("want 2 bodies, got %d", len(gotBodies))
+	}
+	if _, present := gotBodies[0]["caption"]; present {
+		t.Errorf("first call should omit caption, got %v", gotBodies[0]["caption"])
+	}
+	if gotBodies[1]["caption"] != "caption" {
+		t.Errorf("second call caption = %v, want caption", gotBodies[1]["caption"])
+	}
+}
+
+// TestSendChunkedText_ChunksLongContent verifies long text is split into
+// multiple sendMessage calls via ChunkMarkdown + maxTextLength.
+func TestSendChunkedText_ChunksLongContent(t *testing.T) {
+	var callCount int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		atomic.AddInt32(&callCount, 1)
+		_, _ = w.Write([]byte(`{"ok":true,"result":{}}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	// Build text larger than maxTextLength (2000) to force chunking.
+	long := strings.Repeat("a", maxTextLength*2+10)
+	if err := ch.sendChunkedText("chat-x", long); err != nil {
+		t.Fatalf("sendChunkedText: %v", err)
+	}
+	if got := atomic.LoadInt32(&callCount); got < 2 {
+		t.Errorf("expected ≥2 chunked sends, got %d", got)
+	}
+}
+
+// TestSendChunkedText_PropagatesFirstError verifies that if the first
+// chunk fails, the method returns the error without attempting later chunks.
+func TestSendChunkedText_PropagatesFirstError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":false,"error_code":500,"description":"boom"}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	err := ch.sendChunkedText("chat-x", "short enough")
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+}
+
+// TestSend_NotRunningRejects verifies Send errors when the channel is not running.
+func TestSend_NotRunningRejects(t *testing.T) {
+	mb := bus.New()
+	ch, err := New(config.ZaloConfig{Token: "t"}, mb, nil)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	// channel is NOT Start()ed → IsRunning() is false.
+	err = ch.Send(context.Background(), bus.OutboundMessage{
+		ChatID:  "x",
+		Content: "hi",
+	})
+	if err == nil {
+		t.Fatal("expected error when not running, got nil")
+	}
+	if !strings.Contains(err.Error(), "not running") {
+		t.Errorf("err = %v, want 'not running'", err)
+	}
+}
+
+// TestSend_PlainTextGoesThroughSendMessage verifies Send routes plain text
+// through sendChunkedText → sendMessage → callAPI.
+func TestSend_PlainTextGoesThroughSendMessage(t *testing.T) {
+	var got map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		raw, _ := io.ReadAll(r.Body)
+		_ = json.Unmarshal(raw, &got)
+		_, _ = w.Write([]byte(`{"ok":true,"result":{}}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	err := ch.Send(context.Background(), bus.OutboundMessage{
+		ChatID:  "user-7",
+		Content: "**hello** world",
+	})
+	if err != nil {
+		t.Fatalf("Send: %v", err)
+	}
+	// Content should have markdown stripped (StripMarkdown drops **…**).
+	if text, _ := got["text"].(string); strings.Contains(text, "**") {
+		t.Errorf("markdown not stripped: %q", text)
+	}
+	if got["chat_id"] != "user-7" {
+		t.Errorf("chat_id = %v, want user-7", got["chat_id"])
+	}
+}
+
+// TestSend_PhotoExtractionRoutesToSendPhoto verifies [photo:URL] is
+// extracted and sent via sendPhoto instead of sendMessage.
+func TestSend_PhotoExtractionRoutesToSendPhoto(t *testing.T) {
+	var lastPath string
+	var lastBody map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		lastPath = r.URL.Path
+		raw, _ := io.ReadAll(r.Body)
+		lastBody = map[string]any{}
+		_ = json.Unmarshal(raw, &lastBody)
+		_, _ = w.Write([]byte(`{"ok":true,"result":{}}`))
+	}))
+	defer srv.Close()
+
+	ch := newTestChannel(t, srv.URL)
+	err := ch.Send(context.Background(), bus.OutboundMessage{
+		ChatID:  "user-8",
+		Content: "look at this [photo:https://cdn.example/test.jpg] nice pic",
+	})
+	if err != nil {
+		t.Fatalf("Send: %v", err)
+	}
+	if !strings.HasSuffix(lastPath, "/sendPhoto") {
+		t.Errorf("path = %q, want sendPhoto", lastPath)
+	}
+	if lastBody["photo"] != "https://cdn.example/test.jpg" {
+		t.Errorf("photo = %v", lastBody["photo"])
+	}
+}
+
+// TestStop_SignalsLoopAndTogglesRunning verifies Stop closes stopCh and
+// flips IsRunning() back to false.
+func TestStop_SignalsLoopAndTogglesRunning(t *testing.T) {
+	mb := bus.New()
+	ch, err := New(config.ZaloConfig{Token: "t"}, mb, nil)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	ch.SetRunning(true)
+	if err := ch.Stop(context.Background()); err != nil {
+		t.Fatalf("Stop: %v", err)
+	}
+	if ch.IsRunning() {
+		t.Error("IsRunning still true after Stop")
+	}
+	// stopCh should be closed — reading from a closed channel returns zero value
+	// immediately instead of blocking.
+	select {
+	case <-ch.stopCh:
+	case <-time.After(100 * time.Millisecond):
+		t.Error("stopCh not closed after Stop")
+	}
+}
+
+// TestProcessUpdate_DispatchesByEventName covers the event switch: text,
+// image, and unknown events. Verifies HandleMessage is invoked for known
+// events (observed indirectly through bus inbound queue).
+func TestProcessUpdate_DispatchesByEventName(t *testing.T) {
+	mb := bus.New()
+	ch, err := New(config.ZaloConfig{Token: "t", DMPolicy: "open"}, mb, nil)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+
+	// Unknown event → no-op, no panic.
+	ch.processUpdate(zaloUpdate{EventName: "message.unknown"})
+
+	// Text event with nil message → handler guard returns early without
+	// panicking (nil pointer check).
+	ch.processUpdate(zaloUpdate{EventName: "message.text.received"})
+
+	// Image event with nil message → same guard.
+	ch.processUpdate(zaloUpdate{EventName: "message.image.received"})
+
+	// Text event with populated message → should flow through handleTextMessage.
+	// We cannot easily assert the bus side without draining it, but the call
+	// should not panic and should route through the happy path.
+	ch.processUpdate(zaloUpdate{
+		EventName: "message.text.received",
+		Message: &zaloMessage{
+			MessageID: "m1",
+			Text:      "hello",
+			From:      zaloFrom{ID: "u1"},
+			Chat:      zaloChat{ID: "u1"},
+		},
+	})
+}
+
+// TestHandleTextMessage_EmptySenderDropped verifies messages with empty
+// sender IDs are dropped (logged warning, no bus publish).
+func TestHandleTextMessage_EmptySenderDropped(t *testing.T) {
+	mb := bus.New()
+	ch, err := New(config.ZaloConfig{Token: "t", DMPolicy: "open"}, mb, nil)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	// No panic expected.
+	ch.handleTextMessage(&zaloMessage{
+		MessageID: "m",
+		Text:      "hi",
+		From:      zaloFrom{ID: ""}, // missing sender
+		Chat:      zaloChat{ID: ""},
+	})
+}
+
+// TestHandleImageMessage_EmptySenderDropped mirrors the text variant guard.
+func TestHandleImageMessage_EmptySenderDropped(t *testing.T) {
+	mb := bus.New()
+	ch, err := New(config.ZaloConfig{Token: "t", DMPolicy: "open"}, mb, nil)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	ch.handleImageMessage(&zaloMessage{
+		MessageID: "m",
+		From:      zaloFrom{ID: ""},
+	})
+}
+
+// TestDownloadMedia_SuccessWritesTempFile verifies downloadMedia fetches
+// the URL and persists a temp file with matching extension.
+func TestDownloadMedia_SuccessWritesTempFile(t *testing.T) {
+	payload := bytes.Repeat([]byte("x"), 128)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "image/png")
+		_, _ = w.Write(payload)
+	}))
+	defer srv.Close()
+
+	mb := bus.New()
+	ch, _ := New(config.ZaloConfig{Token: "t"}, mb, nil)
+	path, err := ch.downloadMedia(srv.URL + "/photo")
+	if err != nil {
+		t.Fatalf("downloadMedia: %v", err)
+	}
+	defer os.Remove(path)
+
+	if !strings.HasSuffix(path, ".png") {
+		t.Errorf("path ext = %q, want .png (from Content-Type)", path)
+	}
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(data, payload) {
+		t.Errorf("file content len = %d, want %d", len(data), len(payload))
+	}
+}
+
+// TestDownloadMedia_HTTPErrorReturnsError verifies non-200 responses error out.
+func TestDownloadMedia_HTTPErrorReturnsError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, "not found", http.StatusNotFound)
+	}))
+	defer srv.Close()
+
+	ch, _ := New(config.ZaloConfig{Token: "t"}, bus.New(), nil)
+	if _, err := ch.downloadMedia(srv.URL); err == nil {
+		t.Fatal("expected error on 404, got nil")
+	}
+}
+
+// TestDownloadMedia_EmptyResponseReturnsError verifies zero-byte responses
+// are treated as errors (don't leave empty temp files behind).
+func TestDownloadMedia_EmptyResponseReturnsError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "image/jpeg")
+		// no body
+	}))
+	defer srv.Close()
+
+	ch, _ := New(config.ZaloConfig{Token: "t"}, bus.New(), nil)
+	if _, err := ch.downloadMedia(srv.URL); err == nil {
+		t.Fatal("expected empty-response error, got nil")
+	}
+}
+
+// TestDownloadMedia_FallbackJPEGExtension verifies an unknown content-type
+// defaults to .jpg extension.
+func TestDownloadMedia_FallbackJPEGExtension(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Intentionally no Content-Type → default to .jpg
+		_, _ = w.Write([]byte("binary-bytes"))
+	}))
+	defer srv.Close()
+
+	ch, _ := New(config.ZaloConfig{Token: "t"}, bus.New(), nil)
+	path, err := ch.downloadMedia(srv.URL)
+	if err != nil {
+		t.Fatalf("downloadMedia: %v", err)
+	}
+	defer os.Remove(path)
+	if !strings.HasSuffix(path, ".jpg") {
+		t.Errorf("path = %q, want .jpg default", path)
+	}
+}
+
+// TestZaloAPIResponse_Roundtrip sanity-checks the wire-type tags.
+func TestZaloAPIResponse_Roundtrip(t *testing.T) {
+	src := zaloAPIResponse{
+		OK:          true,
+		Result:      json.RawMessage(`{"id":"x"}`),
+		ErrorCode:   0,
+		Description: "",
+	}
+	data, err := json.Marshal(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got zaloAPIResponse
+	if err := json.Unmarshal(data, &got); err != nil {
+		t.Fatal(err)
+	}
+	if !got.OK {
+		t.Error("OK field lost in round-trip")
+	}
+}
diff --git a/internal/providers/adapter_codex_test.go b/internal/providers/adapter_codex_test.go
new file mode 100644
index 00000000..fe2967c6
--- /dev/null
+++ b/internal/providers/adapter_codex_test.go
@@ -0,0 +1,342 @@
+package providers
+
+import (
+	"encoding/json"
+	"errors"
+	"strings"
+	"testing"
+)
+
+// erroringTokenSource is a TokenSource that can return a configured error.
+// Separate from codex_test.go's staticTokenSource (which returns nil error).
+type erroringTokenSource struct {
+	token string
+	err   error
+}
+
+func (s *erroringTokenSource) Token() (string, error) {
+	return s.token, s.err
+}
+
+// TestCodexAdapter_Defaults verifies empty BaseURL/Model get defaults and that
+// Name() + Capabilities() expose expected Responses-API values.
+func TestCodexAdapter_Defaults(t *testing.T) {
+	a, err := NewCodexAdapter(ProviderConfig{})
+	if err != nil {
+		t.Fatalf("NewCodexAdapter error: %v", err)
+	}
+	if a.Name() != "codex" {
+		t.Errorf("Name() = %q, want codex", a.Name())
+	}
+	caps := a.Capabilities()
+	if !caps.Streaming || !caps.ToolCalling || !caps.StreamWithTools {
+		t.Errorf("expected full streaming+tools+stream-with-tools, got %+v", caps)
+	}
+	if !caps.Thinking || !caps.Vision {
+		t.Errorf("expected Thinking+Vision, got %+v", caps)
+	}
+	if caps.MaxContextWindow != 1_000_000 {
+		t.Errorf("MaxContextWindow = %d, want 1_000_000", caps.MaxContextWindow)
+	}
+	if caps.TokenizerID != "o200k_base" {
+		t.Errorf("TokenizerID = %q, want o200k_base", caps.TokenizerID)
+	}
+}
+
+// TestCodexAdapter_BaseURLTrimmed verifies trailing slashes are stripped from
+// the base URL (important because codex_build.go appends a path).
+func TestCodexAdapter_BaseURLTrimmed(t *testing.T) {
+	a, err := NewCodexAdapter(ProviderConfig{BaseURL: "https://example.test/api/"})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	ca, ok := a.(*CodexAdapter)
+	if !ok {
+		t.Fatalf("unexpected type %T", a)
+	}
+	if ca.apiBase != "https://example.test/api" {
+		t.Errorf("apiBase = %q, want trimmed", ca.apiBase)
+	}
+}
+
+// TestCodexAdapter_ExtractsTokenSource verifies the token source is pulled
+// from ExtraOpts["token_source"].
+func TestCodexAdapter_ExtractsTokenSource(t *testing.T) {
+	ts := &erroringTokenSource{token: "tok-ok"}
+	a, err := NewCodexAdapter(ProviderConfig{
+		ExtraOpts: map[string]any{"token_source": TokenSource(ts)},
+	})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	_, headers, err := a.ToRequest(ChatRequest{
+		Messages: []Message{{Role: "user", Content: "hi"}},
+	})
+	if err != nil {
+		t.Fatalf("ToRequest: %v", err)
+	}
+	if got := headers.Get("Authorization"); got != "Bearer tok-ok" {
+		t.Errorf("Authorization = %q, want Bearer tok-ok", got)
+	}
+	if got := headers.Get("OpenAI-Beta"); got != "responses=v1" {
+		t.Errorf("OpenAI-Beta = %q, want responses=v1", got)
+	}
+}
+
+// TestCodexAdapter_ToRequest_NoTokenSource verifies a missing token source
+// omits the Authorization header (caller is responsible for auth) rather
+// than erroring or panicking.
+func TestCodexAdapter_ToRequest_NoTokenSource(t *testing.T) {
+	a, _ := NewCodexAdapter(ProviderConfig{})
+	body, headers, err := a.ToRequest(ChatRequest{
+		Messages: []Message{{Role: "user", Content: "hi"}},
+	})
+	if err != nil {
+		t.Fatalf("ToRequest: %v", err)
+	}
+	if headers.Get("Authorization") != "" {
+		t.Errorf("Authorization should be empty with no token source, got %q", headers.Get("Authorization"))
+	}
+	if !strings.HasPrefix(headers.Get("Content-Type"), "application/json") {
+		t.Errorf("Content-Type missing: %q", headers.Get("Content-Type"))
+	}
+	if len(body) == 0 {
+		t.Error("empty body")
+	}
+}
+
+// TestCodexAdapter_ToRequest_TokenSourceError verifies a Token() error
+// surfaces from ToRequest (don't silently build an unauthenticated request).
+func TestCodexAdapter_ToRequest_TokenSourceError(t *testing.T) {
+	boom := errors.New("token expired")
+	ts := &erroringTokenSource{err: boom}
+	a, _ := NewCodexAdapter(ProviderConfig{
+		ExtraOpts: map[string]any{"token_source": TokenSource(ts)},
+	})
+	_, _, err := a.ToRequest(ChatRequest{
+		Messages: []Message{{Role: "user", Content: "hi"}},
+	})
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+	if !errors.Is(err, boom) {
+		t.Errorf("err = %v, want wrapped %v", err, boom)
+	}
+}
+
+// TestCodexAdapter_FromResponse_TextAndUsage verifies a simple "message" item
+// with "output_text" content parses correctly plus usage accounting including
+// reasoning token detail.
+func TestCodexAdapter_FromResponse_TextAndUsage(t *testing.T) {
+	a, _ := NewCodexAdapter(ProviderConfig{})
+	raw := []byte(`{
+		"id":"resp_1",
+		"object":"response",
+		"status":"completed",
+		"output":[
+			{"type":"message","role":"assistant","content":[{"type":"output_text","text":"hello"}]}
+		],
+		"usage":{
+			"input_tokens":10,
+			"output_tokens":3,
+			"total_tokens":13,
+			"output_tokens_details":{"reasoning_tokens":2}
+		}
+	}`)
+	resp, err := a.FromResponse(raw)
+	if err != nil {
+		t.Fatalf("FromResponse: %v", err)
+	}
+	if resp.Content != "hello" {
+		t.Errorf("Content = %q, want hello", resp.Content)
+	}
+	if resp.FinishReason != "stop" {
+		t.Errorf("FinishReason = %q, want stop", resp.FinishReason)
+	}
+	if resp.Usage == nil || resp.Usage.TotalTokens != 13 {
+		t.Errorf("Usage TotalTokens = %+v, want 13", resp.Usage)
+	}
+	if resp.Usage == nil || resp.Usage.ThinkingTokens != 2 {
+		t.Errorf("Usage ThinkingTokens = %+v, want 2", resp.Usage)
+	}
+}
+
+// TestCodexAdapter_FromResponse_FunctionCallAndIncomplete covers two branches:
+// - a function_call output item populates ToolCalls and bumps FinishReason to "tool_calls"
+// - status="incomplete" overrides FinishReason to "length"
+func TestCodexAdapter_FromResponse_FunctionCallAndIncomplete(t *testing.T) {
+	a, _ := NewCodexAdapter(ProviderConfig{})
+
+	t.Run("function_call sets tool_calls finish", func(t *testing.T) {
+		raw := []byte(`{
+			"id":"resp_2",
+			"status":"completed",
+			"output":[
+				{"type":"function_call","call_id":"fc_abc","name":"lookup","arguments":"{\"q\":\"hi\"}"}
+			]
+		}`)
+		resp, err := a.FromResponse(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if len(resp.ToolCalls) != 1 {
+			t.Fatalf("ToolCalls len = %d, want 1", len(resp.ToolCalls))
+		}
+		tc := resp.ToolCalls[0]
+		if tc.Name != "lookup" {
+			t.Errorf("ToolCall.Name = %q, want lookup", tc.Name)
+		}
+		if q, _ := tc.Arguments["q"].(string); q != "hi" {
+			t.Errorf("Arguments[q] = %v, want hi", tc.Arguments["q"])
+		}
+		if resp.FinishReason != "tool_calls" {
+			t.Errorf("FinishReason = %q, want tool_calls", resp.FinishReason)
+		}
+	})
+
+	t.Run("status=incomplete sets length finish", func(t *testing.T) {
+		raw := []byte(`{
+			"id":"resp_3",
+			"status":"incomplete",
+			"output":[
+				{"type":"message","role":"assistant","content":[{"type":"output_text","text":"partial"}]}
+			]
+		}`)
+		resp, err := a.FromResponse(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if resp.FinishReason != "length" {
+			t.Errorf("FinishReason = %q, want length", resp.FinishReason)
+		}
+	})
+
+	t.Run("reasoning summary populates Thinking", func(t *testing.T) {
+		raw := []byte(`{
+			"id":"resp_4",
+			"status":"completed",
+			"output":[
+				{"type":"reasoning","summary":[{"type":"text","text":"step1 "},{"type":"text","text":"step2"}]}
+			]
+		}`)
+		resp, err := a.FromResponse(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if resp.Thinking != "step1 step2" {
+			t.Errorf("Thinking = %q, want %q", resp.Thinking, "step1 step2")
+		}
+	})
+}
+
+// TestCodexAdapter_FromResponse_MalformedReturnsError verifies malformed JSON
+// errors out instead of panicking.
+func TestCodexAdapter_FromResponse_MalformedReturnsError(t *testing.T) {
+	a, _ := NewCodexAdapter(ProviderConfig{})
+	if _, err := a.FromResponse([]byte(`{not`)); err == nil {
+		t.Fatal("expected error, got nil")
+	}
+}
+
+// TestCodexAdapter_FromStreamChunk covers the three event-dispatch branches in
+// adapter_codex.go: output_text.delta, response.completed, unknown → skip.
+func TestCodexAdapter_FromStreamChunk(t *testing.T) {
+	a, _ := NewCodexAdapter(ProviderConfig{})
+
+	t.Run("done literal", func(t *testing.T) {
+		sc, err := a.FromStreamChunk([]byte("[DONE]"))
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc == nil || !sc.Done {
+			t.Errorf("want Done, got %+v", sc)
+		}
+	})
+
+	t.Run("text delta", func(t *testing.T) {
+		raw := []byte(`{"type":"response.output_text.delta","delta":"tok"}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc == nil || sc.Content != "tok" {
+			t.Errorf("want Content=tok, got %+v", sc)
+		}
+	})
+
+	t.Run("empty text delta skipped", func(t *testing.T) {
+		raw := []byte(`{"type":"response.output_text.delta","delta":""}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc != nil {
+			t.Errorf("empty delta should yield nil, got %+v", sc)
+		}
+	})
+
+	t.Run("completed event signals done", func(t *testing.T) {
+		raw := []byte(`{"type":"response.completed"}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc == nil || !sc.Done {
+			t.Errorf("want Done on completed, got %+v", sc)
+		}
+	})
+
+	t.Run("failed event signals done", func(t *testing.T) {
+		raw := []byte(`{"type":"response.failed"}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc == nil || !sc.Done {
+			t.Errorf("want Done on failed, got %+v", sc)
+		}
+	})
+
+	t.Run("unknown event skipped", func(t *testing.T) {
+		raw := []byte(`{"type":"response.reasoning.delta","text":"thinking"}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc != nil {
+			t.Errorf("unknown event should yield nil, got %+v", sc)
+		}
+	})
+
+	t.Run("malformed returns nil", func(t *testing.T) {
+		// Decoder intentionally swallows malformed chunks.
+		sc, err := a.FromStreamChunk([]byte(`not-json`))
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc != nil {
+			t.Errorf("want nil, got %+v", sc)
+		}
+	})
+}
+
+// TestCodexAdapter_ToRequest_StreamOption verifies stream option flows into body.
+func TestCodexAdapter_ToRequest_StreamOption(t *testing.T) {
+	a, _ := NewCodexAdapter(ProviderConfig{})
+	body, _, err := a.ToRequest(ChatRequest{
+		Messages: []Message{{Role: "user", Content: "hi"}},
+		Options:  map[string]any{"stream": false},
+	})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	var m map[string]any
+	_ = json.Unmarshal(body, &m)
+	// Responses-API marshals the stream flag; codex sets stream in buildRequestBody.
+	if s, ok := m["stream"].(bool); !ok || s != false {
+		t.Errorf("stream = %v, want false", m["stream"])
+	}
+}
+
+// ensure the adapter satisfies the interface at compile time.
+var _ ProviderAdapter = (*CodexAdapter)(nil)
diff --git a/internal/providers/adapter_dashscope_test.go b/internal/providers/adapter_dashscope_test.go
new file mode 100644
index 00000000..3c243539
--- /dev/null
+++ b/internal/providers/adapter_dashscope_test.go
@@ -0,0 +1,122 @@
+package providers
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+// TestDashScopeAdapter_Basics verifies:
+// - Name() returns "dashscope" (NOT openai — wire format differs conceptually)
+// - StreamWithTools is overridden to false (DashScope falls back to non-stream for tool calls)
+// - Other capabilities inherit from OpenAI
+func TestDashScopeAdapter_Basics(t *testing.T) {
+	a, err := NewDashScopeAdapter(ProviderConfig{APIKey: "sk-ds"})
+	if err != nil {
+		t.Fatalf("NewDashScopeAdapter error: %v", err)
+	}
+	if a.Name() != "dashscope" {
+		t.Errorf("Name() = %q, want dashscope", a.Name())
+	}
+	caps := a.Capabilities()
+	if caps.StreamWithTools {
+		t.Error("DashScope must NOT support StreamWithTools (non-stream fallback on tool calls)")
+	}
+	if !caps.Streaming {
+		t.Error("expected Streaming=true (inherited)")
+	}
+	if !caps.ToolCalling {
+		t.Error("expected ToolCalling=true (inherited)")
+	}
+}
+
+// TestDashScopeAdapter_DefaultsApplied verifies BaseURL and Model defaults
+// are injected when the caller leaves them empty.
+func TestDashScopeAdapter_DefaultsApplied(t *testing.T) {
+	a, err := NewDashScopeAdapter(ProviderConfig{APIKey: "sk-ds"})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	body, _, err := a.ToRequest(ChatRequest{
+		Messages: []Message{{Role: "user", Content: "ping"}},
+	})
+	if err != nil {
+		t.Fatalf("ToRequest: %v", err)
+	}
+	var m map[string]any
+	_ = json.Unmarshal(body, &m)
+	model, _ := m["model"].(string)
+	if model == "" {
+		t.Fatal("model missing from request body")
+	}
+	// Default model constant is dashscopeDefaultModel — confirm it flowed through.
+	if model != dashscopeDefaultModel {
+		t.Errorf("model = %q, want %q (default)", model, dashscopeDefaultModel)
+	}
+}
+
+// TestDashScopeAdapter_ToRequestDelegates verifies the adapter produces the
+// same wire format as OpenAIAdapter for equivalent input (since DashScope is
+// an OpenAI-compatible endpoint).
+func TestDashScopeAdapter_ToRequestDelegates(t *testing.T) {
+	a, _ := NewDashScopeAdapter(ProviderConfig{APIKey: "sk", Model: "qwen-plus"})
+	body, headers, err := a.ToRequest(ChatRequest{
+		Messages: []Message{{Role: "user", Content: "hello qwen"}},
+	})
+	if err != nil {
+		t.Fatalf("ToRequest: %v", err)
+	}
+	if !strings.HasPrefix(headers.Get("Authorization"), "Bearer sk") {
+		t.Errorf("Authorization = %q, want Bearer sk...", headers.Get("Authorization"))
+	}
+	var m map[string]any
+	_ = json.Unmarshal(body, &m)
+	if m["model"] != "qwen-plus" {
+		t.Errorf("model = %v, want qwen-plus", m["model"])
+	}
+}
+
+// TestDashScopeAdapter_FromResponseDelegates verifies response parsing
+// works against the OpenAI-compat shape.
+func TestDashScopeAdapter_FromResponseDelegates(t *testing.T) {
+	a, _ := NewDashScopeAdapter(ProviderConfig{APIKey: "sk"})
+	raw := []byte(`{
+		"choices":[{"index":0,"message":{"role":"assistant","content":"hi"},"finish_reason":"stop"}],
+		"usage":{"prompt_tokens":3,"completion_tokens":1,"total_tokens":4}
+	}`)
+	resp, err := a.FromResponse(raw)
+	if err != nil {
+		t.Fatalf("FromResponse: %v", err)
+	}
+	if resp.Content != "hi" {
+		t.Errorf("Content = %q, want hi", resp.Content)
+	}
+	if resp.Usage == nil || resp.Usage.TotalTokens != 4 {
+		t.Errorf("Usage TotalTokens = %v, want 4", resp.Usage)
+	}
+}
+
+// TestDashScopeAdapter_FromStreamChunkDelegates verifies stream chunk parsing
+// reuses OpenAI logic end-to-end.
+func TestDashScopeAdapter_FromStreamChunkDelegates(t *testing.T) {
+	a, _ := NewDashScopeAdapter(ProviderConfig{APIKey: "sk"})
+
+	sc, err := a.FromStreamChunk([]byte("[DONE]"))
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if sc == nil || !sc.Done {
+		t.Errorf("want Done, got %+v", sc)
+	}
+
+	sc2, err := a.FromStreamChunk([]byte(`{"choices":[{"delta":{"content":"x"}}]}`))
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if sc2 == nil || sc2.Content != "x" {
+		t.Errorf("want Content=x, got %+v", sc2)
+	}
+}
+
+// ensure adapter satisfies the interface at compile time.
+var _ ProviderAdapter = (*DashScopeAdapter)(nil)
diff --git a/internal/providers/adapter_openai_test.go b/internal/providers/adapter_openai_test.go
new file mode 100644
index 00000000..c7cfcb4f
--- /dev/null
+++ b/internal/providers/adapter_openai_test.go
@@ -0,0 +1,245 @@
+package providers
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+// TestOpenAIAdapter_Basics verifies Name() and Capabilities() delegate to the
+// wrapped OpenAIProvider rather than returning zero values.
+func TestOpenAIAdapter_Basics(t *testing.T) {
+	a, err := NewOpenAIAdapter(ProviderConfig{
+		APIKey:  "sk-fake",
+		BaseURL: "https://api.openai.com/v1",
+		Model:   "gpt-4o-mini",
+	})
+	if err != nil {
+		t.Fatalf("NewOpenAIAdapter error: %v", err)
+	}
+	if a.Name() != "openai" {
+		t.Errorf("Name() = %q, want openai", a.Name())
+	}
+	caps := a.Capabilities()
+	if !caps.Streaming {
+		t.Error("expected Streaming=true")
+	}
+	if !caps.ToolCalling {
+		t.Error("expected ToolCalling=true")
+	}
+	if caps.TokenizerID == "" {
+		t.Error("expected non-empty TokenizerID")
+	}
+}
+
+// TestOpenAIAdapter_ToRequest_DefaultStreamAndAuth verifies defaults:
+// - stream=true (when not set in Options)
+// - Authorization "Bearer <key>" for non-Azure endpoints
+// - Content-Type header present
+// - resolved model travels into the body
+func TestOpenAIAdapter_ToRequest_DefaultStreamAndAuth(t *testing.T) {
+	a, _ := NewOpenAIAdapter(ProviderConfig{
+		APIKey:  "sk-abc",
+		BaseURL: "https://api.openai.com/v1",
+		Model:   "gpt-4o-mini",
+	})
+
+	req := ChatRequest{
+		Messages: []Message{{Role: "user", Content: "hi"}},
+	}
+	body, headers, err := a.ToRequest(req)
+	if err != nil {
+		t.Fatalf("ToRequest error: %v", err)
+	}
+
+	if got := headers.Get("Content-Type"); !strings.HasPrefix(got, "application/json") {
+		t.Errorf("Content-Type = %q, want application/json", got)
+	}
+	if got := headers.Get("Authorization"); got != "Bearer sk-abc" {
+		t.Errorf("Authorization = %q, want %q", got, "Bearer sk-abc")
+	}
+	if got := headers.Get("api-key"); got != "" {
+		t.Errorf("api-key should be empty for non-Azure, got %q", got)
+	}
+
+	var m map[string]any
+	if err := json.Unmarshal(body, &m); err != nil {
+		t.Fatalf("body unmarshal: %v", err)
+	}
+	if m["stream"] != true {
+		t.Errorf("stream = %v, want true", m["stream"])
+	}
+	if m["model"] == "" || m["model"] == nil {
+		t.Errorf("model missing from body: %v", m["model"])
+	}
+}
+
+// TestOpenAIAdapter_ToRequest_AzureUsesAPIKeyHeader verifies Azure endpoints
+// use the "api-key" header instead of Authorization Bearer.
+func TestOpenAIAdapter_ToRequest_AzureUsesAPIKeyHeader(t *testing.T) {
+	a, _ := NewOpenAIAdapter(ProviderConfig{
+		APIKey:  "az-key-42",
+		BaseURL: "https://my-resource.openai.azure.com/openai",
+		Model:   "gpt-4o",
+	})
+
+	_, headers, err := a.ToRequest(ChatRequest{
+		Messages: []Message{{Role: "user", Content: "hi"}},
+	})
+	if err != nil {
+		t.Fatalf("ToRequest error: %v", err)
+	}
+
+	if got := headers.Get("api-key"); got != "az-key-42" {
+		t.Errorf("api-key = %q, want az-key-42", got)
+	}
+	if got := headers.Get("Authorization"); got != "" {
+		t.Errorf("Authorization should be empty for Azure, got %q", got)
+	}
+}
+
+// TestOpenAIAdapter_ToRequest_StreamFalseOption verifies the stream option
+// flows through to the request body.
+func TestOpenAIAdapter_ToRequest_StreamFalseOption(t *testing.T) {
+	a, _ := NewOpenAIAdapter(ProviderConfig{
+		APIKey:  "sk-x",
+		BaseURL: "https://api.openai.com/v1",
+		Model:   "gpt-4o-mini",
+	})
+
+	body, _, err := a.ToRequest(ChatRequest{
+		Messages: []Message{{Role: "user", Content: "hi"}},
+		Options:  map[string]any{"stream": false},
+	})
+	if err != nil {
+		t.Fatalf("ToRequest error: %v", err)
+	}
+	var m map[string]any
+	_ = json.Unmarshal(body, &m)
+	if m["stream"] != false {
+		t.Errorf("stream = %v, want false", m["stream"])
+	}
+}
+
+// TestOpenAIAdapter_FromResponse_ParsesContentAndUsage verifies a canonical
+// OpenAI chat-completions response parses into ChatResponse with content and
+// non-zero usage numbers.
+func TestOpenAIAdapter_FromResponse_ParsesContentAndUsage(t *testing.T) {
+	a, _ := NewOpenAIAdapter(ProviderConfig{APIKey: "k", BaseURL: "https://api.openai.com/v1"})
+	raw := []byte(`{
+		"id":"chatcmpl-1",
+		"object":"chat.completion",
+		"choices":[{"index":0,"message":{"role":"assistant","content":"hi there"},"finish_reason":"stop"}],
+		"usage":{"prompt_tokens":10,"completion_tokens":2,"total_tokens":12}
+	}`)
+	resp, err := a.FromResponse(raw)
+	if err != nil {
+		t.Fatalf("FromResponse error: %v", err)
+	}
+	if resp.Content != "hi there" {
+		t.Errorf("Content = %q, want %q", resp.Content, "hi there")
+	}
+	if resp.FinishReason != "stop" {
+		t.Errorf("FinishReason = %q, want stop", resp.FinishReason)
+	}
+	if resp.Usage == nil || resp.Usage.TotalTokens != 12 {
+		t.Errorf("Usage = %+v, want TotalTokens=12", resp.Usage)
+	}
+}
+
+// TestOpenAIAdapter_FromResponse_MalformedReturnsError verifies malformed JSON
+// surfaces a decode error rather than panicking.
+func TestOpenAIAdapter_FromResponse_MalformedReturnsError(t *testing.T) {
+	a, _ := NewOpenAIAdapter(ProviderConfig{APIKey: "k"})
+	if _, err := a.FromResponse([]byte(`{not-json`)); err == nil {
+		t.Fatal("expected error on malformed JSON, got nil")
+	}
+}
+
+// TestOpenAIAdapter_FromStreamChunk covers the three main chunk shapes:
+// - "[DONE]" → Done=true
+// - content delta → Content set
+// - reasoning delta → Thinking set
+// - empty/unknown → nil (skip)
+func TestOpenAIAdapter_FromStreamChunk(t *testing.T) {
+	a, _ := NewOpenAIAdapter(ProviderConfig{APIKey: "k"})
+
+	t.Run("done sentinel", func(t *testing.T) {
+		sc, err := a.FromStreamChunk([]byte("[DONE]"))
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc == nil || !sc.Done {
+			t.Errorf("want Done=true, got %+v", sc)
+		}
+	})
+
+	t.Run("content delta", func(t *testing.T) {
+		raw := []byte(`{"choices":[{"delta":{"content":"hello"}}]}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc == nil || sc.Content != "hello" {
+			t.Errorf("want Content=hello, got %+v", sc)
+		}
+	})
+
+	t.Run("reasoning_content delta", func(t *testing.T) {
+		raw := []byte(`{"choices":[{"delta":{"reasoning_content":"thinking..."}}]}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc == nil || sc.Thinking != "thinking..." {
+			t.Errorf("want Thinking=thinking..., got %+v", sc)
+		}
+	})
+
+	t.Run("reasoning fallback field", func(t *testing.T) {
+		raw := []byte(`{"choices":[{"delta":{"reasoning":"alt"}}]}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc == nil || sc.Thinking != "alt" {
+			t.Errorf("want Thinking=alt, got %+v", sc)
+		}
+	})
+
+	t.Run("empty choices skipped", func(t *testing.T) {
+		raw := []byte(`{"choices":[]}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc != nil {
+			t.Errorf("want nil skip, got %+v", sc)
+		}
+	})
+
+	t.Run("empty delta skipped", func(t *testing.T) {
+		raw := []byte(`{"choices":[{"delta":{}}]}`)
+		sc, err := a.FromStreamChunk(raw)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc != nil {
+			t.Errorf("want nil skip (no content), got %+v", sc)
+		}
+	})
+
+	t.Run("malformed json returns nil", func(t *testing.T) {
+		// Decoder swallows malformed chunks so streaming doesn't die.
+		sc, err := a.FromStreamChunk([]byte(`{broken`))
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if sc != nil {
+			t.Errorf("want nil on malformed, got %+v", sc)
+		}
+	})
+}
+
+// ensure the adapter satisfies the interface at compile time.
+var _ ProviderAdapter = (*OpenAIAdapter)(nil)
diff --git a/internal/providers/adapter_registry_test.go b/internal/providers/adapter_registry_test.go
new file mode 100644
index 00000000..ffe53f6d
--- /dev/null
+++ b/internal/providers/adapter_registry_test.go
@@ -0,0 +1,148 @@
+package providers
+
+import (
+	"errors"
+	"net/http"
+	"sync"
+	"testing"
+)
+
+// TestAdapterRegistry_RegisterAndGet verifies basic registry store/lookup.
+func TestAdapterRegistry_RegisterAndGet(t *testing.T) {
+	r := NewAdapterRegistry()
+	if r == nil {
+		t.Fatal("NewAdapterRegistry returned nil")
+	}
+
+	// Register a fake factory returning a stub adapter.
+	r.Register("stub", func(cfg ProviderConfig) (ProviderAdapter, error) {
+		return &stubAdapter{name: "stub"}, nil
+	})
+
+	got, err := r.Get("stub", ProviderConfig{Name: "stub"})
+	if err != nil {
+		t.Fatalf("Get returned error: %v", err)
+	}
+	if got.Name() != "stub" {
+		t.Errorf("Get Name() = %q, want %q", got.Name(), "stub")
+	}
+}
+
+// TestAdapterRegistry_GetUnknown verifies lookup of an unregistered name
+// surfaces an error without panicking.
+func TestAdapterRegistry_GetUnknown(t *testing.T) {
+	r := NewAdapterRegistry()
+	_, err := r.Get("missing", ProviderConfig{})
+	if err == nil {
+		t.Fatal("expected error for unknown provider, got nil")
+	}
+}
+
+// TestAdapterRegistry_RegisterOverwrite verifies re-registering replaces the factory.
+func TestAdapterRegistry_RegisterOverwrite(t *testing.T) {
+	r := NewAdapterRegistry()
+	r.Register("x", func(cfg ProviderConfig) (ProviderAdapter, error) {
+		return &stubAdapter{name: "v1"}, nil
+	})
+	r.Register("x", func(cfg ProviderConfig) (ProviderAdapter, error) {
+		return &stubAdapter{name: "v2"}, nil
+	})
+	got, _ := r.Get("x", ProviderConfig{})
+	if got.Name() != "v2" {
+		t.Errorf("Get Name() = %q, want v2 (latest registration wins)", got.Name())
+	}
+}
+
+// TestAdapterRegistry_FactoryErrorSurfaces verifies factory errors propagate.
+func TestAdapterRegistry_FactoryErrorSurfaces(t *testing.T) {
+	r := NewAdapterRegistry()
+	want := errors.New("factory boom")
+	r.Register("boom", func(cfg ProviderConfig) (ProviderAdapter, error) {
+		return nil, want
+	})
+	_, err := r.Get("boom", ProviderConfig{})
+	if !errors.Is(err, want) {
+		t.Errorf("Get err = %v, want %v", err, want)
+	}
+}
+
+// TestAdapterRegistry_ConcurrentRegister verifies the registry is safe under
+// concurrent read+write access (RWMutex contract).
+func TestAdapterRegistry_ConcurrentRegister(t *testing.T) {
+	r := NewAdapterRegistry()
+	// Pre-register baseline so Get path exists during concurrent writes.
+	r.Register("base", func(cfg ProviderConfig) (ProviderAdapter, error) {
+		return &stubAdapter{name: "base"}, nil
+	})
+
+	var wg sync.WaitGroup
+	for i := 0; i < 32; i++ {
+		wg.Add(2)
+		go func(id int) {
+			defer wg.Done()
+			r.Register("base", func(cfg ProviderConfig) (ProviderAdapter, error) {
+				return &stubAdapter{name: "base"}, nil
+			})
+		}(i)
+		go func() {
+			defer wg.Done()
+			_, _ = r.Get("base", ProviderConfig{})
+		}()
+	}
+	wg.Wait()
+
+	got, err := r.Get("base", ProviderConfig{})
+	if err != nil {
+		t.Fatalf("post-concurrent Get error: %v", err)
+	}
+	if got.Name() != "base" {
+		t.Errorf("final Name() = %q, want base", got.Name())
+	}
+}
+
+// TestDefaultAdapterRegistry verifies the default registry contains all
+// built-in adapters and each resolves without error.
+func TestDefaultAdapterRegistry(t *testing.T) {
+	r := DefaultAdapterRegistry()
+	if r == nil {
+		t.Fatal("DefaultAdapterRegistry returned nil")
+	}
+
+	// Codex adapter doesn't need API key (token comes from TokenSource).
+	cases := []struct {
+		name string
+		cfg  ProviderConfig
+	}{
+		{"anthropic", ProviderConfig{APIKey: "fake"}},
+		{"openai", ProviderConfig{APIKey: "fake"}},
+		{"dashscope", ProviderConfig{APIKey: "fake"}},
+		{"codex", ProviderConfig{}},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			a, err := r.Get(tc.name, tc.cfg)
+			if err != nil {
+				t.Fatalf("Get(%q) returned error: %v", tc.name, err)
+			}
+			if a == nil {
+				t.Fatalf("Get(%q) returned nil adapter", tc.name)
+			}
+			if a.Name() == "" {
+				t.Errorf("Get(%q) Name() is empty", tc.name)
+			}
+		})
+	}
+}
+
+// stubAdapter is a minimal ProviderAdapter used by registry tests.
+type stubAdapter struct {
+	name string
+}
+
+func (s *stubAdapter) Name() string                       { return s.name }
+func (s *stubAdapter) Capabilities() ProviderCapabilities { return ProviderCapabilities{} }
+func (s *stubAdapter) ToRequest(ChatRequest) ([]byte, http.Header, error) {
+	return nil, nil, nil
+}
+func (s *stubAdapter) FromResponse([]byte) (*ChatResponse, error)    { return nil, nil }
+func (s *stubAdapter) FromStreamChunk([]byte) (*StreamChunk, error) { return nil, nil }
diff --git a/scripts/coverage_thresholds.json b/scripts/coverage_thresholds.json
index cf7ab03f..fea910b7 100644
--- a/scripts/coverage_thresholds.json
+++ b/scripts/coverage_thresholds.json
@@ -15,7 +15,7 @@
   "internal/channels/telegram/voiceguard": 100,
   "internal/channels/typing": 91.80327868852459,
   "internal/channels/whatsapp": 21.323529411764707,
-  "internal/channels/zalo": 7.203389830508475,
+  "internal/channels/zalo": 65.2542372881356,
   "internal/channels/zalo/personal": 0,
   "internal/channels/zalo/personal/protocol": 19.56989247311828,
   "internal/channels/zalo/personal/zalomethods": 0,
@@ -39,7 +39,7 @@
   "internal/permissions": 98.18181818181819,
   "internal/pipeline": 76.90417690417691,
   "internal/providerresolve": 88.88888888888889,
-  "internal/providers": 56.99965433805738,
+  "internal/providers": 62.15,
   "internal/providers/acp": 0,
   "internal/safego": 100,
   "internal/sandbox": 6.593406593406593,