Removed the Mendel flag user_history_cache_full_sentence.

This flag is now only enabled on canary and has never been pushed to prod.
We found that this model makes the suggestion pretty aggressive, which is inconsistent with the fact that users prefer exact match results.

We will merge this flag to the upcoming model to remember inner segment boundary information.

PiperOrigin-RevId: 820500823

Author: taku910

src/prediction/user_history_predictor.cc

@@ -2024,13 +2024,9 @@ void UserHistoryPredictor::InsertHistoryForConversionSegments(
     const ConversionRequest& request, bool is_suggestion_selected,
     uint64_t last_access_time, const SegmentsForLearning& learning_segments,
     UserHistoryPredictor::RevertEntries* revert_entries) {
-  const commands::DecoderExperimentParams& params =
-      request.request().decoder_experiment_params();
-
   // Inserts all_key/all_value.
   // We don't insert it for mobile.
-  if ((params.user_history_cache_full_sentence() ||
-       !IsMixedConversionEnabled(request)) &&
+  if (!IsMixedConversionEnabled(request) &&
       learning_segments.conversion_segments.size() > 1) {
     Insert(request, 0, 0, learning_segments.conversion_segments_key,
            learning_segments.conversion_segments_value, "",

src/prediction/user_history_predictor_test.cc

@@ -3434,78 +3434,72 @@ TEST_F(UserHistoryPredictorTest, GetInputKeyFromSegmentsKana) {
 }
 
 TEST_F(UserHistoryPredictorTest, RealtimeConversionInnerSegment) {
-  for (bool cache_full_sentence : {true, false}) {
-    for (bool mixed_conversion : {true, false}) {
-      UserHistoryPredictor* predictor =
-          GetUserHistoryPredictorWithClearedHistory();
-
-      SegmentsProxy segments_proxy;
-      std::vector<Result> results;
-
-      request_.set_mixed_conversion(mixed_conversion);
-      request_.mutable_decoder_experiment_params()
-          ->set_user_history_cache_full_sentence(cache_full_sentence);
-
-      const bool cache_full_sentence_expected =
-          (!mixed_conversion || cache_full_sentence);
-
-      {
-        constexpr absl::string_view kKey = "わたしのなまえはなかのです";
-        constexpr absl::string_view kValue = "私の名前は中野です";
-        const ConversionRequest convreq1 =
-            SetUpInputForPrediction(kKey, &composer_, &segments_proxy);
-        segments_proxy.AddCandidate(0, kValue);
-        // "わたしの, 私の", "わたし, 私"
-        segments_proxy.PushBackInnerSegmentBoundary(0, 0, 12, 6, 9, 3);
-        // "なまえは, 名前は", "なまえ, 名前"
-        segments_proxy.PushBackInnerSegmentBoundary(0, 0, 12, 9, 9, 6);
-        // "なかのです, 中野です", "なかの, 中野"
-        segments_proxy.PushBackInnerSegmentBoundary(0, 0, 15, 12, 9, 6);
-        predictor->Finish(convreq1, segments_proxy.MakeLearningResults(),
-                          kRevertId);
+  for (bool mixed_conversion : {true, false}) {
+    UserHistoryPredictor* predictor =
+        GetUserHistoryPredictorWithClearedHistory();
 
-        UserHistoryPredictorTestPeer predictor_peer(*predictor);
-        auto* entry = predictor_peer.dic_()->MutableLookupWithoutInsert(
-            UserHistoryPredictor::Fingerprint(kKey, kValue));
-        if (cache_full_sentence_expected) {
-          EXPECT_TRUE(entry);
-        } else {
-          EXPECT_FALSE(entry);
-        }
-      }
-      segments_proxy.Clear();
+    SegmentsProxy segments_proxy;
+    std::vector<Result> results;
 
-      const ConversionRequest convreq2 =
-          SetUpInputForPrediction("なかの", &composer_, &segments_proxy);
-      results = predictor->Predict(convreq2);
-      EXPECT_FALSE(results.empty());
-      EXPECT_TRUE(FindCandidateByValue("中野", results));
-      EXPECT_FALSE(FindCandidateByValue("中野です", results));
-      segments_proxy.Clear();
+    request_.set_mixed_conversion(mixed_conversion);
+    const bool cache_full_sentence_expected = !mixed_conversion;
 
-      const ConversionRequest convreq3 =
-          SetUpInputForPrediction("なかので", &composer_, &segments_proxy);
-      results = predictor->Predict(convreq3);
-      EXPECT_FALSE(results.empty());
-      EXPECT_TRUE(FindCandidateByValue("中野です", results));
+    {
+      constexpr absl::string_view kKey = "わたしのなまえはなかのです";
+      constexpr absl::string_view kValue = "私の名前は中野です";
+      const ConversionRequest convreq1 =
+          SetUpInputForPrediction(kKey, &composer_, &segments_proxy);
+      segments_proxy.AddCandidate(0, kValue);
+      // "わたしの, 私の", "わたし, 私"
+      segments_proxy.PushBackInnerSegmentBoundary(0, 0, 12, 6, 9, 3);
+      // "なまえは, 名前は", "なまえ, 名前"
+      segments_proxy.PushBackInnerSegmentBoundary(0, 0, 12, 9, 9, 6);
+      // "なかのです, 中野です", "なかの, 中野"
+      segments_proxy.PushBackInnerSegmentBoundary(0, 0, 15, 12, 9, 6);
+      predictor->Finish(convreq1, segments_proxy.MakeLearningResults(),
+                        kRevertId);
 
-      segments_proxy.Clear();
-      const ConversionRequest convreq4 =
-          SetUpInputForPrediction("なまえ", &composer_, &segments_proxy);
-      results = predictor->Predict(convreq4);
-      EXPECT_FALSE(results.empty());
-      EXPECT_TRUE(FindCandidateByValue("名前", results));
-      // Do not suggest the phrase ends with [content_word + function_word].
-      EXPECT_FALSE(FindCandidateByValue("名前は", results));
-      EXPECT_FALSE(FindCandidateByValue("名前は中野です", results));
-      if (mixed_conversion) {
-        // prefer exact match.
-        EXPECT_FALSE(FindCandidateByValue("名前は中野", results));
+      UserHistoryPredictorTestPeer predictor_peer(*predictor);
+      auto* entry = predictor_peer.dic_()->MutableLookupWithoutInsert(
+          UserHistoryPredictor::Fingerprint(kKey, kValue));
+      if (cache_full_sentence_expected) {
+        EXPECT_TRUE(entry);
       } else {
-        // prefer prediction.
-        EXPECT_TRUE(FindCandidateByValue("名前は中野", results));
+        EXPECT_FALSE(entry);
       }
     }
+    segments_proxy.Clear();
+
+    const ConversionRequest convreq2 =
+        SetUpInputForPrediction("なかの", &composer_, &segments_proxy);
+    results = predictor->Predict(convreq2);
+    EXPECT_FALSE(results.empty());
+    EXPECT_TRUE(FindCandidateByValue("中野", results));
+    EXPECT_FALSE(FindCandidateByValue("中野です", results));
+    segments_proxy.Clear();
+
+    const ConversionRequest convreq3 =
+        SetUpInputForPrediction("なかので", &composer_, &segments_proxy);
+    results = predictor->Predict(convreq3);
+    EXPECT_FALSE(results.empty());
+    EXPECT_TRUE(FindCandidateByValue("中野です", results));
+
+    segments_proxy.Clear();
+    const ConversionRequest convreq4 =
+        SetUpInputForPrediction("なまえ", &composer_, &segments_proxy);
+    results = predictor->Predict(convreq4);
+    EXPECT_FALSE(results.empty());
+    EXPECT_TRUE(FindCandidateByValue("名前", results));
+    // Do not suggest the phrase ends with [content_word + function_word].
+    EXPECT_FALSE(FindCandidateByValue("名前は", results));
+    EXPECT_FALSE(FindCandidateByValue("名前は中野です", results));
+    if (mixed_conversion) {
+      // prefer exact match.
+      EXPECT_FALSE(FindCandidateByValue("名前は中野", results));
+    } else {
+      // prefer prediction.
+      EXPECT_TRUE(FindCandidateByValue("名前は中野", results));
+    }
   }
 }
 

src/protocol/commands.proto

@@ -642,11 +642,6 @@ message DecoderExperimentParams {
   // This parameter is only used in mixed conversion mode.
   optional int32 user_history_suppress_min_length = 130 [default = 0];
 
-  // Caches full sentences consisting of multiple segments in user history
-  // learning. This mode is enabled on desktop, but we want to enable it on all
-  // devices to unify and simplify the implementation.
-  optional bool user_history_cache_full_sentence = 131 [default = false];
-
   // Demotes the partial candidates so that the top_n results must
   // be non-partial candidates.
   optional int32 demote_partial_candidate_top_n = 126 [default = 0];