diff --git a/CHANGELOG.md b/CHANGELOG.md
index b51faadd..234cdcf0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- **fix(sessions): preserve distinct retried messages when merging transcripts** ([#2027](https://github.com/nesquena/hermes-webui/issues/2027)). Messaging session transcript merges now use `id`/`message_id` when present before falling back to the legacy role/content/timestamp/tool metadata key, so repeated turns with identical visible text are not silently collapsed.
+
 ## [v0.51.40] — 2026-05-11 — Release P (4-PR contributor batch — quota subprocess hardening + env-lock prewarm + cron one-shot warning + Xiaomi env key)
 
 ### Fixed
@@ -22,7 +26,6 @@
 
 - 4 PRs from 3 different authors. `api/providers.py` was touched by #2030 (+110/-7 in quota probe path) and #2034 (+1 in `_PROVIDER_ENV_VAR` map) with disjoint hunks. `CHANGELOG.md` Unreleased section was the only true conflict (#2033 + #2034 both added bullets); resolved by keeping both entries. Stage merge otherwise clean.
 
-
 ## [v0.51.39] — 2026-05-10 — Release O (4-PR contributor batch — Railway docker fix + Stop-button race + provider resolver + live context tracking)
 
 ### Fixed
diff --git a/api/routes.py b/api/routes.py
index f825d77c..bd3486bf 100644
--- a/api/routes.py
+++ b/api/routes.py
@@ -3081,13 +3081,18 @@ def handle_get(handler, parsed) -> bool:
                             str(m.get("role") or ""),
                             str(m.get("content") or ""),
                         )):
-                            key = (
-                                str(msg.get("role") or ""),
-                                str(msg.get("content") or ""),
-                                str(msg.get("timestamp") or ""),
-                                str(msg.get("tool_call_id") or ""),
-                                str(msg.get("tool_name") or msg.get("name") or ""),
-                            )
+                            message_identity = msg.get("id") or msg.get("message_id")
+                            if message_identity:
+                                key = ("message_id", str(message_identity))
+                            else:
+                                key = (
+                                    "legacy",
+                                    str(msg.get("role") or ""),
+                                    str(msg.get("content") or ""),
+                                    str(msg.get("timestamp") or ""),
+                                    str(msg.get("tool_call_id") or ""),
+                                    str(msg.get("tool_name") or msg.get("name") or ""),
+                                )
                             if key in seen_message_keys:
                                 continue
                             seen_message_keys.add(key)
diff --git a/tests/test_session_lineage_full_transcript.py b/tests/test_session_lineage_full_transcript.py
index 7efc6d18..63cdd203 100644
--- a/tests/test_session_lineage_full_transcript.py
+++ b/tests/test_session_lineage_full_transcript.py
@@ -59,3 +59,67 @@ def test_session_endpoint_merges_sidecar_and_lineage_messages_for_cli_sessions(m
         "tip assistant",
         "sidecar tail",
     ]
+
+
+def test_session_endpoint_preserves_distinct_messages_with_different_ids(monkeypatch):
+    class DummySession:
+        def __init__(self):
+            self.messages = [
+                {
+                    "id": "sidecar-retry",
+                    "role": "user",
+                    "content": "retry the same request",
+                    "timestamp": 2.0,
+                }
+            ]
+            self.tool_calls = []
+            self.active_stream_id = None
+            self.pending_user_message = None
+            self.pending_attachments = []
+            self.pending_started_at = None
+            self.context_length = 0
+            self.threshold_tokens = 0
+            self.last_prompt_tokens = 0
+            self.model = "openai/gpt-5"
+            self.session_id = "tip"
+
+        def compact(self):
+            return {"session_id": "tip", "title": "Tip", "model": "openai/gpt-5"}
+
+    captured = {}
+
+    monkeypatch.setattr(routes, "get_session", lambda sid, metadata_only=False: DummySession())
+    monkeypatch.setattr(routes, "_clear_stale_stream_state", lambda s: None)
+    monkeypatch.setattr(routes, "_lookup_cli_session_metadata", lambda sid: {"session_source": "messaging"})
+    monkeypatch.setattr(routes, "_is_messaging_session_record", lambda s: True)
+    monkeypatch.setattr(
+        routes,
+        "get_cli_session_messages",
+        lambda sid: [
+            {"role": "user", "content": "root user", "timestamp": 1.0},
+            {
+                "id": "cli-retry",
+                "role": "user",
+                "content": "retry the same request",
+                "timestamp": 2.0,
+            },
+        ],
+    )
+    monkeypatch.setattr(routes, "_resolve_effective_session_model_for_display", lambda s: getattr(s, "model", None))
+    monkeypatch.setattr(routes, "_resolve_effective_session_model_provider_for_display", lambda s: None)
+    monkeypatch.setattr(routes, "_merge_cli_sidebar_metadata", lambda raw, meta: raw)
+    monkeypatch.setattr(routes, "redact_session_data", lambda raw: raw)
+    monkeypatch.setattr(routes, "j", lambda handler, payload, status=200: captured.setdefault("payload", payload))
+
+    class Handler:
+        pass
+
+    class Parsed:
+        path = "/api/session"
+        query = "session_id=tip"
+
+    routes.handle_get(Handler(), Parsed())
+
+    session = captured["payload"]["session"]
+    retry_messages = [m for m in session["messages"] if m.get("content") == "retry the same request"]
+    assert [m.get("id") for m in retry_messages] == ["cli-retry", "sidecar-retry"]