diff --git a/api/compression_anchor.py b/api/compression_anchor.py
index 3a457d57..f251851c 100644
--- a/api/compression_anchor.py
+++ b/api/compression_anchor.py
@@ -53,6 +53,24 @@ def _content_has_part_type(content, part_types):
     )
 
 
+def _is_context_compression_marker(message):
+    """Return true for synthetic compression/reference cards, not user turns."""
+    if not isinstance(message, dict):
+        return False
+    role = message.get("role")
+    if not role or role == "tool":
+        return False
+    text = _content_text(
+        message.get("content", ""),
+        part_types={"text", "input_text", "output_text"},
+    ).lower().lstrip()
+    return (
+        text.startswith("[context compaction")
+        or text.startswith("context compaction")
+        or text.startswith("[your active task list was preserved across context compression]")
+    )
+
+
 def visible_messages_for_anchor(messages, *, auto_compression: bool = False):
     """Return transcript messages that can anchor compression UI metadata.
 
@@ -70,6 +88,8 @@ def visible_messages_for_anchor(messages, *, auto_compression: bool = False):
         role = message.get("role")
         if not role or role == "tool":
             continue
+        if _is_context_compression_marker(message):
+            continue
 
         content = message.get("content", "")
         has_attachments = bool(message.get("attachments"))
diff --git a/api/models.py b/api/models.py
index 6ff74869..1a22ec9d 100644
--- a/api/models.py
+++ b/api/models.py
@@ -377,6 +377,11 @@ class Session:
                  compression_anchor_message_key=None,
                  compression_anchor_summary=None,
                  pre_compression_snapshot: bool=False,
+                 context_engine=None,
+                 compression_anchor_engine=None,
+                 compression_anchor_mode=None,
+                 compression_anchor_details=None,
+                 context_engine_state=None,
                  context_length=None, threshold_tokens=None,
                  last_prompt_tokens=None,
                  gateway_routing=None, gateway_routing_history=None,
@@ -417,6 +422,11 @@ class Session:
         self.compression_anchor_message_key = compression_anchor_message_key
         self.compression_anchor_summary = compression_anchor_summary
         self.pre_compression_snapshot = bool(pre_compression_snapshot)
+        self.context_engine = context_engine
+        self.compression_anchor_engine = compression_anchor_engine
+        self.compression_anchor_mode = compression_anchor_mode
+        self.compression_anchor_details = compression_anchor_details if isinstance(compression_anchor_details, dict) else {}
+        self.context_engine_state = context_engine_state if isinstance(context_engine_state, dict) else {}
         self.context_length = context_length
         self.threshold_tokens = threshold_tokens
         self.last_prompt_tokens = last_prompt_tokens
@@ -474,6 +484,8 @@ class Session:
             'pending_user_message', 'pending_attachments', 'pending_started_at',
             'compression_anchor_visible_idx', 'compression_anchor_message_key',
             'compression_anchor_summary', 'pre_compression_snapshot',
+            'context_engine', 'compression_anchor_engine', 'compression_anchor_mode',
+            'compression_anchor_details', 'context_engine_state',
             'context_length', 'threshold_tokens', 'last_prompt_tokens',
             'gateway_routing', 'gateway_routing_history', 'llm_title_generated',
             'parent_session_id',
@@ -641,6 +653,11 @@ class Session:
             'compression_anchor_message_key': self.compression_anchor_message_key,
             'compression_anchor_summary': self.compression_anchor_summary,
             'pre_compression_snapshot': self.pre_compression_snapshot,
+            'context_engine': self.context_engine,
+            'compression_anchor_engine': self.compression_anchor_engine,
+            'compression_anchor_mode': self.compression_anchor_mode,
+            'compression_anchor_details': self.compression_anchor_details,
+            'context_engine_state': self.context_engine_state,
             'context_length': self.context_length,
             'threshold_tokens': self.threshold_tokens,
             'last_prompt_tokens': self.last_prompt_tokens,
diff --git a/static/i18n.js b/static/i18n.js
index c9e92360..4982119c 100644
--- a/static/i18n.js
+++ b/static/i18n.js
@@ -196,6 +196,8 @@ const LOCALES = {
     conversation_cleared: 'Conversation cleared',
     command_label: 'Command',
     context_compaction_label: 'Context compaction',
+    retrieval_context_label: 'Indexed context',
+    retrieval_context_preview: 'Earlier messages are stored and retrievable with context tools',
     preserved_task_list_label: 'Preserved task list',
     reference_only_label: 'Reference only',
     model_usage: 'Usage: /model <name>',
@@ -1417,6 +1419,8 @@ const LOCALES = {
     conversation_cleared: 'Conversazione cancellata',
     command_label: 'Comando',
     context_compaction_label: 'Compattazione contesto',
+    retrieval_context_label: 'Contesto indicizzato',
+    retrieval_context_preview: 'I messaggi precedenti sono archiviati e recuperabili con gli strumenti di contesto',
     preserved_task_list_label: 'Lista task preservata',
     reference_only_label: 'Solo riferimento',
     model_usage: 'Uso: /model <nome>',
@@ -2630,6 +2634,8 @@ const LOCALES = {
     conversation_cleared: '会話をクリアしました',
     command_label: 'コマンド',
     context_compaction_label: 'コンテキスト圧縮',
+    retrieval_context_label: 'インデックス済みコンテキスト',
+    retrieval_context_preview: '以前のメッセージは保存され、コンテキストツールで取得できます',
     preserved_task_list_label: '保持されたタスクリスト',
     reference_only_label: '参照専用',
     model_usage: '使い方: /model <名前>',
@@ -3883,6 +3889,8 @@ const LOCALES = {
     compress_failed_label: 'Ошибка сжатия',
     compress_running_label: 'Сжатие…',
     context_compaction_label: 'Сжатие контекста',
+    retrieval_context_label: 'Индексированный контекст',
+    retrieval_context_preview: 'Предыдущие сообщения сохранены и доступны через инструменты контекста',
     preserved_task_list_label: 'Сохранённый список задач',
     focus_label: 'Фокус',
     model_search_no_results: 'Модели не найдены',
@@ -4992,6 +5000,8 @@ const LOCALES = {
     conversation_cleared: 'Conversación borrada',
     command_label: 'Comando',
     context_compaction_label: 'Compacción de contexto',
+    retrieval_context_label: 'Contexto indexado',
+    retrieval_context_preview: 'Los mensajes anteriores se almacenan y se pueden recuperar con herramientas de contexto',
     preserved_task_list_label: 'Lista de tareas conservada',
     reference_only_label: 'Solo referencia',
     model_usage: 'Uso: /model <name>',
@@ -6118,6 +6128,8 @@ const LOCALES = {
     conversation_cleared: 'Konversation gelöscht',
     command_label: 'Befehl',
     context_compaction_label: 'Kontextkomprimierung',
+    retrieval_context_label: 'Indizierter Kontext',
+    retrieval_context_preview: 'Frühere Nachrichten sind gespeichert und über Kontextwerkzeuge abrufbar',
     preserved_task_list_label: 'Beibehaltene Aufgabenliste',
     reference_only_label: 'Nur Referenz',
     model_usage: 'Nutzung: /model <name>',
@@ -7295,6 +7307,8 @@ const LOCALES = {
     conversation_cleared: '对话已清空',
     command_label: '命令',
     context_compaction_label: '上下文压缩',
+    retrieval_context_label: '已索引上下文',
+    retrieval_context_preview: '较早消息已存储，可通过上下文工具检索',
     preserved_task_list_label: '保留的任务列表',
     reference_only_label: '仅供参考',
     model_usage: '用法：/model <name>',
@@ -10715,6 +10729,8 @@ const LOCALES = {
     conversation_cleared: '대화를 지웠습니다',
     command_label: '명령',
     context_compaction_label: 'Context compaction',
+    retrieval_context_label: 'Indexed context',
+    retrieval_context_preview: 'Earlier messages are stored and retrievable with context tools',
     preserved_task_list_label: '보존된 작업 목록',
     reference_only_label: 'Reference only',
     model_usage: 'Usage: /model <name>',
diff --git a/static/messages.js b/static/messages.js
index 6842bbb9..0cb687ee 100644
--- a/static/messages.js
+++ b/static/messages.js
@@ -1846,6 +1846,9 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
           phase:'done',
           automatic:true,
           message,
+          engine:d.engine,
+          mode:d.mode,
+          details:d.details,
           summary:{headline:message},
           continuationSessionId:continuationSid,
         };
diff --git a/static/ui.js b/static/ui.js
index 8da479ab..b5bc8684 100644
--- a/static/ui.js
+++ b/static/ui.js
@@ -5096,9 +5096,10 @@ function _autoCompressionBaseDetail(state){
     : (String(state&&state.message||fallback).trim()||fallback);
 }
 function _autoCompressionPreviewText(state){
+  const copy=_engineAwareCompressionCopy(String(state&&state.engine||_compressionEngineForSession()).toLowerCase(), String(state&&state.mode||_compressionModeForSession()).toLowerCase());
   const running=state&&state.phase==='running';
   const detail=_autoCompressionBaseDetail(state);
-  if(!running) return (String(state&&state.summary?.headline||detail).trim()||detail);
+  if(!running) return (String(state&&state.summary?.headline||copy.preview||detail).trim()||detail);
   const elapsedLabel=_compressionElapsedLabel(state);
   return [detail, elapsedLabel].filter(Boolean).join(' · ');
 }
@@ -5112,13 +5113,14 @@ function _autoCompressionDetailText(state){
   return [base,handoff].filter(Boolean).join('\n');
 }
 function _autoCompressionCardsHtml(state){
+  const copy=_engineAwareCompressionCopy(String(state&&state.engine||_compressionEngineForSession()).toLowerCase(), String(state&&state.mode||_compressionModeForSession()).toLowerCase());
   const running=state&&state.phase==='running';
   const preview=_autoCompressionPreviewText(state);
   const cardDetail=_autoCompressionDetailText(state);
   return `
     <div class="tool-card-row compression-card-row" data-compression-card="1">
       ${_compressionStatusCardHtml({
-        statusLabel: t('auto_compress_label'),
+        statusLabel: (String(state&&state.engine||'').toLowerCase()==='lcm'||String(state&&state.mode||'').toLowerCase()==='lossless_retrieval')?copy.label:t('auto_compress_label'),
         previewText: preview,
         detail: cardDetail,
         icon: running ? '<span class="tool-card-running-dot"></span>' : li('check',13),
@@ -5286,14 +5288,15 @@ function _latestCompressionReferenceMessage(messages, summaryText=''){
   return {message:null, rawIdx:-1};
 }
 function _compressionReferenceCardHtml(text, open=false){
+  const copy=_engineAwareCompressionCopy();
   const preview=text.split(/\n+/).filter(Boolean).slice(0,2).join(' ');
   return `
     <div class="tool-card-row compression-card-row" data-compression-card="1" data-raw-text="${esc(text)}">
       <div class="tool-card tool-card-compress-reference${open?' open':''}">
         <div class="tool-card-header" onclick="this.closest('.tool-card').classList.toggle('open')">
           <span class="tool-card-icon">${li('star',13)}</span>
-          <span class="tool-card-name">${esc(t('context_compaction_label'))}</span>
-          <span class="tool-card-preview">${esc(t('reference_only_label'))} · ${esc(preview)}</span>
+          <span class="tool-card-name">${esc(copy.label)}</span>
+          <span class="tool-card-preview">${esc(copy.preview)} · ${esc(preview)}</span>
           <span class="tool-card-toggle">${li('chevron-right',12)}</span>
           <button class="msg-copy-btn msg-action-btn tool-card-copy compression-reference-copy" title="${t('copy')}" onclick="copyMsg(this);event.stopPropagation()">${li('copy',13)}</button>
         </div>
@@ -5367,6 +5370,31 @@ function _formatMessageFooterTimestamp(tsVal){
   const opts={month:'short', day:'numeric', hour:'numeric', minute:'2-digit'};
   return fmt?fmt(date,opts):date.toLocaleString([], opts);
 }
+function _compressionEngineForSession(){
+  return String(
+    (S.session&&(
+      S.session.compression_anchor_engine
+      || S.session.context_engine
+    )) || 'compressor'
+  ).trim().toLowerCase() || 'compressor';
+}
+function _compressionModeForSession(){
+  return String(
+    (S.session&&S.session.compression_anchor_mode) || 'summary_compaction'
+  ).trim().toLowerCase() || 'summary_compaction';
+}
+function _engineAwareCompressionCopy(engine=_compressionEngineForSession(), mode=_compressionModeForSession()){
+  if(engine==='lcm'||mode==='lossless_retrieval'){
+    return {
+      label:t('retrieval_context_label'),
+      preview:t('retrieval_context_preview'),
+    };
+  }
+  return {
+    label:t('context_compaction_label'),
+    preview:t('reference_only_label'),
+  };
+}
 function _compressionStatusCardHtml({
   statusLabel,
   previewText,
@@ -5946,6 +5974,7 @@ function renderMessages(options){
   }
   function _insertCompressionLikeNodeByRawIdx(node, rawIdx){
     if(!node) return;
+    if(rawIdx<firstRenderedRawIdx) return;
     if(!renderVisWithIdx.length){
       inner.appendChild(node);
       return;
diff --git a/tests/test_auto_compression_card.py b/tests/test_auto_compression_card.py
index 23576ff2..f49463d6 100644
--- a/tests/test_auto_compression_card.py
+++ b/tests/test_auto_compression_card.py
@@ -1,5 +1,7 @@
 from pathlib import Path
 
+from api.compression_anchor import visible_messages_for_anchor
+from api.models import Session
 from api.streaming import _is_fallback_lifecycle_message
 
 
@@ -459,6 +461,76 @@ def test_reference_message_inserted_before_future_assistant_anchor():
     assert helper.index("blocks.insertBefore(node, anchorSeg);") < helper.index("const userRow=userRows.get(anchorRawIdx);")
 
 
+def test_frontend_uses_context_engine_metadata_for_indexed_context_copy():
+    src = _read("static/ui.js")
+    i18n = _read("static/i18n.js")
+
+    assert "function _compressionEngineForSession" in src
+    assert "S.session.compression_anchor_engine" in src
+    assert "S.session.context_engine" in src
+    assert "function _compressionModeForSession" in src
+    assert "S.session.compression_anchor_mode" in src
+    assert "function _engineAwareCompressionCopy" in src
+    assert "mode==='lossless_retrieval'" in src
+    assert "t('retrieval_context_label')" in src
+    assert "t('retrieval_context_preview')" in src
+    assert "retrieval_context_label" in i18n
+    assert "retrieval_context_preview" in i18n
+
+
+def test_session_model_round_trips_context_engine_metadata(tmp_path, monkeypatch):
+    import api.models as models
+
+    state_dir = tmp_path / "state"
+    session_dir = state_dir / "sessions"
+    session_dir.mkdir(parents=True)
+    monkeypatch.setattr(models, "SESSION_DIR", session_dir)
+    monkeypatch.setattr(models, "SESSION_INDEX_FILE", state_dir / "session_index.json")
+
+    session = Session(
+        session_id="lcm_metadata",
+        workspace=str(tmp_path),
+        context_engine="lcm",
+        compression_anchor_engine="lcm",
+        compression_anchor_mode="lossless_retrieval",
+        compression_anchor_details={"retrieval_tools": ["lcm_grep"]},
+        context_engine_state={"status": "indexed"},
+    )
+    session.save(touch_updated_at=False)
+
+    loaded = Session.load("lcm_metadata")
+    assert loaded.context_engine == "lcm"
+    assert loaded.compression_anchor_engine == "lcm"
+    assert loaded.compression_anchor_mode == "lossless_retrieval"
+    assert loaded.compression_anchor_details == {"retrieval_tools": ["lcm_grep"]}
+    assert loaded.context_engine_state == {"status": "indexed"}
+
+
+def test_backend_auto_anchor_count_excludes_compaction_marker_cards():
+    messages = [
+        {"role": "user", "content": "before compression"},
+        {"role": "assistant", "content": "[CONTEXT COMPACTION — REFERENCE ONLY] summary"},
+        {"role": "assistant", "content": "after compression"},
+        {"role": "tool", "content": "hidden tool output"},
+        {"role": "user", "content": "[Your active task list was preserved across context compression]"},
+    ]
+
+    visible = visible_messages_for_anchor(messages, auto_compression=True)
+
+    assert [m["content"] for m in visible] == ["before compression", "after compression"]
+
+
+def test_frontend_reference_insertion_skips_when_reference_is_before_render_window():
+    src = _read("static/ui.js")
+    start = src.find("function _insertCompressionLikeNodeByRawIdx")
+    assert start != -1, "raw-index insertion helper not found"
+    end = src.find("const preservedOnlyNode=", start)
+    assert end != -1, "raw-index insertion helper end not found"
+    helper = src[start:end]
+
+    assert "if(rawIdx<firstRenderedRawIdx) return;" in helper
+
+
 def test_reference_message_selection_prefers_latest_matching_marker():
     src = _read("static/ui.js")
     start = src.find("function _latestCompressionReferenceMessage")