diff --git a/otherarch/acestep/ace-qwen3.cpp b/otherarch/acestep/ace-qwen3.cpp
index 8d964bef6..286393c42 100644
--- a/otherarch/acestep/ace-qwen3.cpp
+++ b/otherarch/acestep/ace-qwen3.cpp
@@ -589,10 +589,21 @@ struct MetadataFSM {
         value_acc.clear();
     }
 
-    // Force FSM to only allow a specific language value
-    void force_language(BPETokenizer & bpe, const std::string & lang) {
-        language_tree = PrefixTree();
-        build_value_tree(bpe, language_tree, "language:", {lang});
+    // Force a user-supplied metadata value. The constrained token sequence is
+    // emitted into the CoT, so the LM sees it before generating lyrics/codes.
+    void force_field(BPETokenizer & bpe, State value_state, const std::string & value) {
+        PrefixTree * tree = nullptr;
+        const char * prefix = nullptr;
+        switch (value_state) {
+            case BPM_VALUE:      tree = &bpm_tree;       prefix = "bpm:"; break;
+            case DURATION_VALUE: tree = &duration_tree;  prefix = "duration:"; break;
+            case KEYSCALE_VALUE: tree = &keyscale_tree;  prefix = "keyscale:"; break;
+            case LANGUAGE_VALUE: tree = &language_tree;  prefix = "language:"; break;
+            case TIMESIG_VALUE:  tree = &timesig_tree;   prefix = "timesignature:"; break;
+            default: return;
+        }
+        *tree = PrefixTree();
+        build_value_tree(bpe, *tree, prefix, {value});
     }
 
     const std::vector<int> * current_name_tokens() const {
@@ -787,11 +798,15 @@ static void parse_phase1_into_aces(
         if (!parse_cot_and_lyrics(texts[i], &parsed))
             fprintf(stderr, "WARNING: batch %d CoT parse incomplete\n", i);
         aces[i] = base;
-        if (parsed.bpm > 0) aces[i].bpm = parsed.bpm;
-        if (parsed.duration > 0) aces[i].duration = parsed.duration;
-        if (!parsed.keyscale.empty()) aces[i].keyscale = parsed.keyscale;
-        if (!parsed.timesignature.empty()) aces[i].timesignature = parsed.timesignature;
-        if (!parsed.vocal_language.empty()) aces[i].vocal_language = parsed.vocal_language;
+        // User-supplied metadata is authoritative. Phase 1 only fills fields
+        // that were absent from the request.
+        if (parsed.bpm > 0 && base.bpm <= 0) aces[i].bpm = parsed.bpm;
+        if (parsed.duration > 0 && base.duration <= 0) aces[i].duration = parsed.duration;
+        if (!parsed.keyscale.empty() && base.keyscale.empty()) aces[i].keyscale = parsed.keyscale;
+        if (!parsed.timesignature.empty() && base.timesignature.empty()) aces[i].timesignature = parsed.timesignature;
+        if (!parsed.vocal_language.empty() &&
+            (base.vocal_language.empty() || base.vocal_language == "unknown"))
+            aces[i].vocal_language = parsed.vocal_language;
         if (!parsed.caption.empty()) aces[i].caption = parsed.caption;
         if (merge_lyrics && !parsed.lyrics.empty()) aces[i].lyrics = parsed.lyrics;
         if (aces[i].duration <= 0) aces[i].duration = 120.0f;
@@ -1391,6 +1406,24 @@ std::string acestep_prepare_request(const music_generation_inputs inputs)
     ace.timesignature  = req.timesignature;
     ace.vocal_language = req.vocal_language;
 
+    auto force_known_metadata = [&](MetadataFSM & target, const AcePrompt & values) {
+        if (values.bpm > 0)
+            target.force_field(acestep_bpe, MetadataFSM::BPM_VALUE,
+                               std::to_string(values.bpm));
+        if (values.duration > 0)
+            target.force_field(acestep_bpe, MetadataFSM::DURATION_VALUE,
+                               std::to_string((int)values.duration));
+        if (!values.keyscale.empty())
+            target.force_field(acestep_bpe, MetadataFSM::KEYSCALE_VALUE,
+                               values.keyscale);
+        if (!values.vocal_language.empty() && values.vocal_language != "unknown")
+            target.force_field(acestep_bpe, MetadataFSM::LANGUAGE_VALUE,
+                               values.vocal_language);
+        if (!values.timesignature.empty())
+            target.force_field(acestep_bpe, MetadataFSM::TIMESIG_VALUE,
+                               values.timesignature);
+    };
+
     bool user_has_codes = !req.audio_codes.empty();
     bool need_lm_codes  = inputs.gen_codes && !user_has_codes;
 
@@ -1421,10 +1454,10 @@ std::string acestep_prepare_request(const music_generation_inputs inputs)
             + std::string(req.instrumental ? "true" : "false");
         prompt = build_custom_prompt(acestep_bpe, sys, user_msg.c_str());
 
-        // FSM: reset then optionally force language (shared for both paths)
+        // Inject supplied metadata into the generated CoT so lyrics are planned
+        // for the requested duration/tempo/key rather than newly guessed values.
         fsm.reset();
-        if (use_fsm && ace.vocal_language != "unknown" && !ace.vocal_language.empty())
-            fsm.force_language(acestep_bpe, ace.vocal_language);
+        if (use_fsm) force_known_metadata(fsm, ace);
 
         // Phase 1: N lyrics + metadata generations (always batched, N=batch_size)
         fprintf(stderr, "[Simple] %zu tokens, N=%d, seeds: %lld..%lld\n",
@@ -1446,8 +1479,7 @@ std::string acestep_prepare_request(const music_generation_inputs inputs)
             MetadataFSM caption_fsm;
             caption_fsm.init(acestep_bpe, acestep_llm.cfg.vocab_size, true);
             caption_fsm.reset();
-            if (aces[0].vocal_language != "unknown" && !aces[0].vocal_language.empty())
-                caption_fsm.force_language(acestep_bpe, aces[0].vocal_language);
+            if (use_fsm) force_known_metadata(caption_fsm, aces[0]);
 
             auto caption_texts = generate_phase1_batch(
                 &acestep_llm, &acestep_bpe, prompt, 768,
@@ -1485,6 +1517,7 @@ std::string acestep_prepare_request(const music_generation_inputs inputs)
                 prompt.size(), phase1cfg, batch_size, seed, seed + batch_size - 1);
 
         fsm.reset();
+        if (use_fsm) force_known_metadata(fsm, ace);
         auto phase1_texts = generate_phase1_batch(
             &acestep_llm, &acestep_bpe, prompt, 2048, temperature, top_p, top_k, rep_pen,
             seed, batch_size, use_fsm ? &fsm : nullptr, false,