diff --git a/pkg/dispatch/service/dispatch_engine.go b/pkg/dispatch/service/dispatch_engine.go
index 125f212..eb3a8bc 100644
--- a/pkg/dispatch/service/dispatch_engine.go
+++ b/pkg/dispatch/service/dispatch_engine.go
@@ -17,8 +17,10 @@ import (
 	"github.com/EvolutionAPI/evo-bot-runtime/pkg/pipeline/model"
 )
 
-// DispatchEngine segments the AI response, appends the message signature,
-// and sends each part sequentially via HTTP postback.
+// DispatchEngine segments the AI response and sends each part sequentially
+// via HTTP postback, unmodified — it does not apply BotConfig.MessageSignature
+// (the CRM applies the agent-bot display-name prefix centrally; see
+// dispatch_engine_test.go for the contract this must not regress).
 // Swap the dispatch backend by providing a different implementation at main.go wiring.
 type DispatchEngine interface {
 	Dispatch(
@@ -81,10 +83,10 @@ func (d *dispatchEngineImpl) Dispatch(
 
 	parts := segmentContent(residual, cfg)
 
-	// Prepend signature to the first part (FR-21)
-	if cfg.MessageSignature != "" && len(parts) > 0 {
-		parts[0] = cfg.MessageSignature + parts[0]
-	}
+	// FR-21's agent-bot display-name prefix is no longer applied here: the CRM
+	// now applies it once, centrally, for every outgoing AgentBot message
+	// (including this postback), so doing it here too would double-prefix it.
+	// cfg.MessageSignature is kept on BotConfig for callers that still read it.
 
 	start := time.Now()
 
diff --git a/pkg/dispatch/service/dispatch_engine_test.go b/pkg/dispatch/service/dispatch_engine_test.go
index 08f799f..e16ceaf 100644
--- a/pkg/dispatch/service/dispatch_engine_test.go
+++ b/pkg/dispatch/service/dispatch_engine_test.go
@@ -6,7 +6,6 @@ import (
 	"errors"
 	"net/http"
 	"net/http/httptest"
-	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -39,7 +38,13 @@ func collectParts(t *testing.T) (*httptest.Server, *[]string, *sync.Mutex) {
 	return server, &parts, &mu
 }
 
-func TestDispatch_MultiPart_SignatureOnFirstOnly(t *testing.T) {
+// MessageSignature is no longer applied here: the CRM now prefixes the
+// agent-bot display name once, centrally, for every outgoing AgentBot
+// message (see Message#apply_agent_bot_signature on the CRM side) — doing
+// it here too would double-prefix it. BotConfig still carries the field
+// for callers that read it for other purposes, but Dispatch must leave
+// content untouched regardless of its value.
+func TestDispatch_MultiPart_SignatureNotAppliedByBotRuntime(t *testing.T) {
 	server, partsPtr, mu := collectParts(t)
 
 	eng := service.NewDispatchEngine("")
@@ -61,17 +66,17 @@ func TestDispatch_MultiPart_SignatureOnFirstOnly(t *testing.T) {
 	copy(parts, *partsPtr)
 	mu.Unlock()
 
-	if len(parts) <= 1 {
-		t.Fatalf("segmentation must produce multiple parts, got %d", len(parts))
+	// "hello world this is test" (limit 15) → ["hello world", "this is test"]
+	// (greedy word-packing; see segmentContent). Asserting the full parts,
+	// not just the signature's absence, so a future regression that drops or
+	// mangles segmented content can't hide behind a passing "no [bot]" check.
+	want := []string{"hello world", "this is test"}
+	if len(parts) != len(want) {
+		t.Fatalf("segmentation must produce %d parts, got %d: %q", len(want), len(parts), parts)
 	}
-
-	// Signature only on first part
-	if !strings.HasPrefix(parts[0], "[bot] ") {
-		t.Errorf("signature must be prepended to first part: %q", parts[0])
-	}
-	for i, p := range parts[1:] {
-		if strings.Contains(p, "[bot]") {
-			t.Errorf("signature must NOT be on part %d: %q", i+1, p)
+	for i, p := range parts {
+		if p != want[i] {
+			t.Errorf("part %d = %q, want %q (MessageSignature must not be applied by bot_runtime)", i, p, want[i])
 		}
 	}
 }
@@ -98,9 +103,9 @@ func TestDispatch_NoSegmentation_SinglePart(t *testing.T) {
 	if len(parts) != 1 {
 		t.Fatalf("disabled segmentation must produce exactly one part, got %d", len(parts))
 	}
-	want := "—signature full response here"
+	want := "full response here"
 	if parts[0] != want {
-		t.Errorf("parts[0] = %q, want %q", parts[0], want)
+		t.Errorf("parts[0] = %q, want %q (MessageSignature must not be applied by bot_runtime)", parts[0], want)
 	}
 }
 
@@ -146,32 +151,6 @@ func TestDispatch_Cancellation_ReturnsInterrupted(t *testing.T) {
 	}
 }
 
-func TestDispatch_EmptySignature_NoSuffix(t *testing.T) {
-	server, partsPtr, mu := collectParts(t)
-
-	eng := service.NewDispatchEngine("")
-	cfg := model.BotConfig{
-		TextSegmentationEnabled: false,
-		MessageSignature:        "", // empty — no suffix
-	}
-
-	if err := eng.Dispatch(context.Background(), 4, 4, "no signature here", cfg, server.URL); err != nil {
-		t.Fatalf("Dispatch returned unexpected error: %v", err)
-	}
-
-	mu.Lock()
-	parts := make([]string, len(*partsPtr))
-	copy(parts, *partsPtr)
-	mu.Unlock()
-
-	if len(parts) != 1 {
-		t.Fatalf("expected 1 part, got %d", len(parts))
-	}
-	if parts[0] != "no signature here" {
-		t.Errorf("parts[0] = %q, want %q (empty signature must not append anything)", parts[0], "no signature here")
-	}
-}
-
 func TestDispatch_NonOKResponse_ReturnsError(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusInternalServerError)
diff --git a/test/e2e/e2e_test.go b/test/e2e/e2e_test.go
index 0fb2e1c..cdbb904 100644
--- a/test/e2e/e2e_test.go
+++ b/test/e2e/e2e_test.go
@@ -612,8 +612,11 @@ func TestE2E_PipelineIsolation(t *testing.T) {
 
 // TestE2E_DispatchSegmentation verifies that BotConfig segmentation fields are
 // threaded correctly from the event through the pipeline to the dispatch engine,
-// and that the AI response is split into the expected parts with the signature
-// appended only to the last one.
+// and that the AI response is split into the expected parts. MessageSignature
+// is set on the event to prove bot_runtime does NOT act on it — the CRM applies
+// the agent-bot display-name prefix once, centrally, on every postback it
+// receives (see Message#apply_agent_bot_signature on the CRM side), so
+// bot_runtime must leave segment content untouched regardless of this field.
 //
 // dispatch_engine_test.go covers segmentation in isolation. This is the first
 // test to exercise the full chain: BotConfig in the HTTP event → pipelineEntry →
@@ -621,7 +624,6 @@ func TestE2E_PipelineIsolation(t *testing.T) {
 //
 // Content: "hello world foo bar", limit=10 chars per segment.
 // segmentContent produces ["hello", "world foo", "bar"].
-// With signature " [sig]" appended to the last part: "bar [sig]".
 func TestE2E_DispatchSegmentation(t *testing.T) {
 	h := newHarness(t)
 	contactID, convID := nextPair()
@@ -650,12 +652,11 @@ func TestE2E_DispatchSegmentation(t *testing.T) {
 		t.Fatalf("postback called %d times, want 3 (one per segment)", n)
 	}
 
-	// EVO-558: the signature is prepended to the first segment only.
-	want := []string{" [sig]hello", "world foo", "bar"}
+	want := []string{"hello", "world foo", "bar"}
 	for i, body := range h.pbServer.allBodies() {
 		got := decodePostbackContent(body)
 		if got != want[i] {
-			t.Errorf("segment[%d] = %q, want %q", i, got, want[i])
+			t.Errorf("segment[%d] = %q, want %q (MessageSignature must not be applied by bot_runtime)", i, got, want[i])
 		}
 	}
 }