truncation: fixed runner truncation logic + removed server truncation (#12839)

This PR consolidates all embedding prompt-length checking, truncation, and prompt token counting into the runner to ensure a single source of truth.

runner/ollamarunner/runner.go

@@ -146,12 +146,12 @@ func (s *Server) NewSequence(prompt string, images []llm.ImageData, params NewSe
 	params.numKeep = min(params.numKeep, s.cache.numCtx-1)
 
 	if int32(len(inputs)) > s.cache.numCtx {
-		discard := int32(len(inputs)) - s.cache.numCtx
-
 		if !params.truncate {
 			return nil, errorInputTooLong
 		}
 
+		discard := int32(len(inputs)) - s.cache.numCtx
+
 		promptStart := params.numKeep + discard
 
 		// If we need to truncate in the middle of a unbreakable batch, remove the entire batch
@@ -996,13 +996,13 @@ func (s *Server) embeddings(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
 	seq, err := s.NewSequence(req.Content, nil, NewSequenceParams{
 		embedding: true,
-
-		// TODO (jmorganca): this should be provided by the server via the
-		// request options and truncated here in the runner, instead of relying on
-		// the server's truncate logic
-		truncate: true,
+		truncate:  false,
 	})
 	if err != nil {
+		if errors.Is(err, errorInputTooLong) {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
 		http.Error(w, fmt.Sprintf("failed to create new sequence: %v", err), http.StatusInternalServerError)
 		return
 	}
@@ -1043,7 +1043,8 @@ func (s *Server) embeddings(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := json.NewEncoder(w).Encode(&llm.EmbeddingResponse{
-		Embedding: <-seq.embedding,
+		Embedding:       <-seq.embedding,
+		PromptEvalCount: seq.numPromptInputs,
 	}); err != nil {
 		http.Error(w, fmt.Sprintf("failed to encode response: %v", err), http.StatusInternalServerError)
 	}