refactor: replace history_split with current_input_file configuration

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/httpapi/openai/chat/chat_history_test.go

@@ -272,14 +272,13 @@ func TestChatCompletionsSkipsHistoryWhenDisabled(t *testing.T) {
 	}
 }
 
-func TestChatCompletionsHistorySplitPersistsHistoryText(t *testing.T) {
+func TestChatCompletionsCurrentInputFilePersistsNeutralPrompt(t *testing.T) {
 	historyStore := newTestChatHistoryStore(t)
 	ds := &inlineUploadDSStub{}
 	h := &Handler{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		Auth:        streamStatusAuthStub{},
 		DS:          ds,
@@ -308,19 +307,19 @@ func TestChatCompletionsHistorySplitPersistsHistoryText(t *testing.T) {
 	if err != nil {
 		t.Fatalf("expected detail item, got %v", err)
 	}
-	if full.HistoryText == "" {
-		t.Fatalf("expected history text to be persisted")
-	}
-	if !strings.Contains(full.HistoryText, "first user turn") || !strings.Contains(full.HistoryText, "tool result") {
-		t.Fatalf("expected earlier turns in history text, got %q", full.HistoryText)
-	}
-	if strings.Contains(full.HistoryText, "latest user turn") {
-		t.Fatalf("expected latest turn to stay out of persisted history text, got %q", full.HistoryText)
+	if full.HistoryText != "" {
+		t.Fatalf("expected current input file flow to leave history text empty, got %q", full.HistoryText)
 	}
 	if len(ds.uploadCalls) != 1 {
-		t.Fatalf("expected history upload to happen, got %d", len(ds.uploadCalls))
+		t.Fatalf("expected current input upload to happen, got %d", len(ds.uploadCalls))
 	}
-	if full.HistoryText != string(ds.uploadCalls[0].Data) {
-		t.Fatalf("expected persisted history text to match uploaded HISTORY.txt contents")
+	if ds.uploadCalls[0].Filename != "IGNORE.txt" {
+		t.Fatalf("expected IGNORE.txt upload, got %q", ds.uploadCalls[0].Filename)
+	}
+	if len(full.Messages) != 1 {
+		t.Fatalf("expected neutral prompt to be the only persisted message, got %#v", full.Messages)
+	}
+	if !strings.Contains(full.Messages[0].Content, "Answer the latest user request directly.") {
+		t.Fatalf("expected neutral prompt to be persisted, got %#v", full.Messages[0])
 	}
 }

internal/httpapi/openai/chat/handler.go

@@ -42,20 +42,17 @@ func (h *Handler) compatStripReferenceMarkers() bool {
 	return shared.CompatStripReferenceMarkers(h.Store)
 }
 
-func (h *Handler) applyHistorySplit(ctx context.Context, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) (promptcompat.StandardRequest, error) {
+func (h *Handler) applyCurrentInputFile(ctx context.Context, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) (promptcompat.StandardRequest, error) {
 	if h == nil {
 		return stdReq, nil
 	}
 	stdReq = shared.ApplyThinkingInjection(h.Store, stdReq)
 	svc := history.Service{Store: h.Store, DS: h.DS}
 	out, err := svc.ApplyCurrentInputFile(ctx, a, stdReq)
-	if err != nil {
-		return stdReq, err
+	if err != nil || out.CurrentInputFileApplied {
+		return out, err
 	}
-	if out.CurrentInputFileApplied {
-		return out, nil
-	}
-	return svc.Apply(ctx, a, out)
+	return out, nil
 }
 
 func (h *Handler) preprocessInlineFileInputs(ctx context.Context, a *auth.RequestAuth, req map[string]any) error {
@@ -91,7 +88,7 @@ func writeOpenAIInlineFileError(w http.ResponseWriter, err error) {
 	files.WriteInlineFileError(w, err)
 }
 
-func mapHistorySplitError(err error) (int, string) {
+func mapCurrentInputFileError(err error) (int, string) {
 	return history.MapError(err)
 }
 

internal/httpapi/openai/chat/handler_chat.go

@@ -68,9 +68,9 @@ func (h *Handler) ChatCompletions(w http.ResponseWriter, r *http.Request) {
 		writeOpenAIError(w, http.StatusBadRequest, err.Error())
 		return
 	}
-	stdReq, err = h.applyHistorySplit(r.Context(), a, stdReq)
+	stdReq, err = h.applyCurrentInputFile(r.Context(), a, stdReq)
 	if err != nil {
-		status, message := mapHistorySplitError(err)
+		status, message := mapCurrentInputFileError(err)
 		writeOpenAIError(w, status, message)
 		return
 	}

internal/httpapi/openai/chat/vercel_prepare_test.go

@@ -87,7 +87,7 @@ func TestStreamLeaseTTL(t *testing.T) {
 	}
 }
 
-func TestHandleVercelStreamPrepareAppliesHistorySplit(t *testing.T) {
+func TestHandleVercelStreamPrepareAppliesCurrentInputFile(t *testing.T) {
 	t.Setenv("VERCEL", "1")
 	t.Setenv("DS2API_VERCEL_INTERNAL_SECRET", "stream-secret")
 
@@ -95,8 +95,7 @@ func TestHandleVercelStreamPrepareAppliesHistorySplit(t *testing.T) {
 	h := &Handler{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		Auth: streamStatusAuthStub{},
 		DS:   ds,
@@ -119,7 +118,7 @@ func TestHandleVercelStreamPrepareAppliesHistorySplit(t *testing.T) {
 		t.Fatalf("expected 200, got %d body=%s", rec.Code, rec.Body.String())
 	}
 	if len(ds.uploadCalls) != 1 {
-		t.Fatalf("expected 1 history upload, got %d", len(ds.uploadCalls))
+		t.Fatalf("expected 1 current input upload, got %d", len(ds.uploadCalls))
 	}
 
 	var body map[string]any
@@ -131,11 +130,11 @@ func TestHandleVercelStreamPrepareAppliesHistorySplit(t *testing.T) {
 		t.Fatalf("expected payload object, got %#v", body["payload"])
 	}
 	promptText, _ := payload["prompt"].(string)
-	if !strings.Contains(promptText, "latest user turn") {
-		t.Fatalf("expected latest user turn in prompt, got %s", promptText)
+	if !strings.Contains(promptText, "Answer the latest user request directly.") {
+		t.Fatalf("expected neutral prompt, got %s", promptText)
 	}
-	if strings.Contains(promptText, "first user turn") {
-		t.Fatalf("expected historical turns removed from prompt, got %s", promptText)
+	if strings.Contains(promptText, "first user turn") || strings.Contains(promptText, "latest user turn") {
+		t.Fatalf("expected original turns hidden from prompt, got %s", promptText)
 	}
 	refIDs, _ := payload["ref_file_ids"].([]any)
 	if len(refIDs) == 0 || refIDs[0] != "file-inline-1" {
@@ -143,7 +142,7 @@ func TestHandleVercelStreamPrepareAppliesHistorySplit(t *testing.T) {
 	}
 }
 
-func TestHandleVercelStreamPrepareMapsHistorySplitManagedAuthFailureTo401(t *testing.T) {
+func TestHandleVercelStreamPrepareMapsCurrentInputFileManagedAuthFailureTo401(t *testing.T) {
 	t.Setenv("VERCEL", "1")
 	t.Setenv("DS2API_VERCEL_INTERNAL_SECRET", "stream-secret")
 
@@ -153,8 +152,7 @@ func TestHandleVercelStreamPrepareMapsHistorySplitManagedAuthFailureTo401(t *tes
 	h := &Handler{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		Auth: streamStatusManagedAuthStub{},
 		DS:   ds,

internal/httpapi/openai/chat/vercel_stream.go

@@ -69,9 +69,9 @@ func (h *Handler) handleVercelStreamPrepare(w http.ResponseWriter, r *http.Reque
 		writeOpenAIError(w, http.StatusBadRequest, "stream must be true")
 		return
 	}
-	stdReq, err = h.applyHistorySplit(r.Context(), a, stdReq)
+	stdReq, err = h.applyCurrentInputFile(r.Context(), a, stdReq)
 	if err != nil {
-		status, message := mapHistorySplitError(err)
+		status, message := mapCurrentInputFileError(err)
 		writeOpenAIError(w, status, message)
 		return
 	}

internal/httpapi/openai/history/current_input_file.go

@@ -28,8 +28,7 @@ func (s Service) ApplyCurrentInputFile(ctx context.Context, a *auth.RequestAuth,
 	if index < 0 {
 		return stdReq, nil
 	}
-	historySplitReached := s.Store.HistorySplitEnabled() && wouldSplitHistory(stdReq.Messages, s.Store.HistorySplitTriggerAfterTurns())
-	if len([]rune(text)) < threshold && !historySplitReached {
+	if len([]rune(text)) < threshold {
 		return stdReq, nil
 	}
 	fileText := promptcompat.BuildOpenAICurrentInputContextTranscript(stdReq.Messages)
@@ -84,11 +83,6 @@ func latestUserInputForFile(messages []any) (int, string) {
 	return -1, ""
 }
 
-func wouldSplitHistory(messages []any, triggerAfterTurns int) bool {
-	_, historyMessages := SplitOpenAIHistoryMessages(messages, triggerAfterTurns)
-	return len(historyMessages) > 0
-}
-
 func currentInputFilePrompt() string {
 	return "The current request and prior conversation context have already been provided. Answer the latest user request directly."
 }

internal/httpapi/openai/history/history_split.go

@@ -2,60 +2,21 @@ package history
 
 import (
 	"context"
-	"errors"
-	"fmt"
 	"strings"
 
 	"ds2api/internal/auth"
-	dsclient "ds2api/internal/deepseek/client"
 	"ds2api/internal/httpapi/openai/shared"
 	"ds2api/internal/promptcompat"
 )
 
-const (
-	historySplitFilename    = "HISTORY.txt"
-	historySplitContentType = "text/plain; charset=utf-8"
-	historySplitPurpose     = "assistants"
-)
-
 type Service struct {
 	Store shared.ConfigReader
 	DS    shared.DeepSeekCaller
 }
 
+// Apply is retained for legacy compatibility only. The active split path is
+// current input file handling in ApplyCurrentInputFile.
 func (s Service) Apply(ctx context.Context, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) (promptcompat.StandardRequest, error) {
-	if s.DS == nil || s.Store == nil || a == nil || !s.Store.HistorySplitEnabled() {
-		return stdReq, nil
-	}
-
-	promptMessages, historyMessages := SplitOpenAIHistoryMessages(stdReq.Messages, s.Store.HistorySplitTriggerAfterTurns())
-	if len(historyMessages) == 0 {
-		return stdReq, nil
-	}
-
-	historyText := promptcompat.BuildOpenAIHistoryTranscript(historyMessages)
-	if strings.TrimSpace(historyText) == "" {
-		return stdReq, errors.New("history split produced empty transcript")
-	}
-
-	result, err := s.DS.UploadFile(ctx, a, dsclient.UploadFileRequest{
-		Filename:    historySplitFilename,
-		ContentType: historySplitContentType,
-		Purpose:     historySplitPurpose,
-		Data:        []byte(historyText),
-	}, 3)
-	if err != nil {
-		return stdReq, fmt.Errorf("upload history file: %w", err)
-	}
-	fileID := strings.TrimSpace(result.ID)
-	if fileID == "" {
-		return stdReq, errors.New("upload history file returned empty file id")
-	}
-
-	stdReq.Messages = promptMessages
-	stdReq.HistoryText = historyText
-	stdReq.RefFileIDs = prependUniqueRefFileID(stdReq.RefFileIDs, fileID)
-	stdReq.FinalPrompt, stdReq.ToolNames = promptcompat.BuildOpenAIPrompt(promptMessages, stdReq.ToolsRaw, "", stdReq.ToolChoice, stdReq.Thinking)
 	return stdReq, nil
 }
 

internal/httpapi/openai/history_split_test.go

@@ -60,9 +60,9 @@ func (streamStatusManagedAuthStub) DetermineCaller(_ *http.Request) (*auth.Reque
 
 func (streamStatusManagedAuthStub) Release(_ *auth.RequestAuth) {}
 
-func TestBuildOpenAIHistoryTranscriptUsesInjectedFileWrapper(t *testing.T) {
+func TestBuildOpenAICurrentInputContextTranscriptUsesInjectedFileWrapper(t *testing.T) {
 	_, historyMessages := splitOpenAIHistoryMessages(historySplitTestMessages(), 1)
-	transcript := buildOpenAIHistoryTranscript(historyMessages)
+	transcript := buildOpenAICurrentInputContextTranscript(historyMessages)
 
 	if !strings.HasPrefix(transcript, "[file content end]\n\n") {
 		t.Fatalf("expected injected file wrapper prefix, got %q", transcript)
@@ -107,7 +107,7 @@ func TestSplitOpenAIHistoryMessagesUsesLatestUserTurn(t *testing.T) {
 		t.Fatalf("expected middle user turn to be moved into history, got %s", promptText)
 	}
 
-	historyText := buildOpenAIHistoryTranscript(historyMessages)
+	historyText := buildOpenAICurrentInputContextTranscript(historyMessages)
 	if !strings.Contains(historyText, "middle user turn") {
 		t.Fatalf("expected middle user turn in split history, got %s", historyText)
 	}
@@ -116,13 +116,13 @@ func TestSplitOpenAIHistoryMessagesUsesLatestUserTurn(t *testing.T) {
 	}
 }
 
-func TestApplyHistorySplitSkipsFirstTurn(t *testing.T) {
+func TestApplyCurrentInputFileSkipsShortInputWhenThresholdNotReached(t *testing.T) {
 	ds := &inlineUploadDSStub{}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
+			currentInputMin:     10,
 		},
 		DS: ds,
 	}
@@ -137,9 +137,9 @@ func TestApplyHistorySplitSkipsFirstTurn(t *testing.T) {
 		t.Fatalf("normalize failed: %v", err)
 	}
 
-	out, err := h.applyHistorySplit(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
+	out, err := h.applyCurrentInputFile(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
 	if err != nil {
-		t.Fatalf("apply history split failed: %v", err)
+		t.Fatalf("apply current input file failed: %v", err)
 	}
 	if len(ds.uploadCalls) != 0 {
 		t.Fatalf("expected no upload on first turn, got %d", len(ds.uploadCalls))
@@ -153,10 +153,8 @@ func TestApplyThinkingInjectionAppendsLatestUserPrompt(t *testing.T) {
 	ds := &inlineUploadDSStub{}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
-			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
-			thinkingInjection:   boolPtr(true),
+			wideInput:         true,
+			thinkingInjection: boolPtr(true),
 		},
 		DS: ds,
 	}
@@ -171,7 +169,7 @@ func TestApplyThinkingInjectionAppendsLatestUserPrompt(t *testing.T) {
 		t.Fatalf("normalize failed: %v", err)
 	}
 
-	out, err := h.applyHistorySplit(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
+	out, err := h.applyCurrentInputFile(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
 	if err != nil {
 		t.Fatalf("apply thinking injection failed: %v", err)
 	}
@@ -204,7 +202,7 @@ func TestApplyThinkingInjectionUsesCustomPrompt(t *testing.T) {
 		t.Fatalf("normalize failed: %v", err)
 	}
 
-	out, err := h.applyHistorySplit(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
+	out, err := h.applyCurrentInputFile(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
 	if err != nil {
 		t.Fatalf("apply thinking injection failed: %v", err)
 	}
@@ -213,12 +211,11 @@ func TestApplyThinkingInjectionUsesCustomPrompt(t *testing.T) {
 	}
 }
 
-func TestApplyHistorySplitDirectPassThroughWhenBothSplitsDisabled(t *testing.T) {
+func TestApplyCurrentInputFileDisabledPassThrough(t *testing.T) {
 	ds := &inlineUploadDSStub{}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: false,
 			currentInputEnabled: false,
 		},
 		DS: ds,
@@ -232,9 +229,9 @@ func TestApplyHistorySplitDirectPassThroughWhenBothSplitsDisabled(t *testing.T)
 		t.Fatalf("normalize failed: %v", err)
 	}
 
-	out, err := h.applyHistorySplit(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
+	out, err := h.applyCurrentInputFile(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
 	if err != nil {
-		t.Fatalf("apply history split failed: %v", err)
+		t.Fatalf("apply current input file failed: %v", err)
 	}
 	if len(ds.uploadCalls) != 0 {
 		t.Fatalf("expected no uploads when both split modes are disabled, got %d", len(ds.uploadCalls))
@@ -252,8 +249,6 @@ func TestApplyCurrentInputFileUploadsFirstTurnWithInjectedWrapper(t *testing.T)
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
 			currentInputEnabled: true,
 			currentInputMin:     10,
 			thinkingInjection:   boolPtr(true),
@@ -271,7 +266,7 @@ func TestApplyCurrentInputFileUploadsFirstTurnWithInjectedWrapper(t *testing.T)
 		t.Fatalf("normalize failed: %v", err)
 	}
 
-	out, err := h.applyHistorySplit(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
+	out, err := h.applyCurrentInputFile(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
 	if err != nil {
 		t.Fatalf("apply current input file failed: %v", err)
 	}
@@ -309,15 +304,13 @@ func TestApplyCurrentInputFileUploadsFirstTurnWithInjectedWrapper(t *testing.T)
 	}
 }
 
-func TestApplyCurrentInputFileReplacesHistorySplitWithFullContextFile(t *testing.T) {
+func TestApplyCurrentInputFileUploadsFullContextFile(t *testing.T) {
 	ds := &inlineUploadDSStub{}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
 			currentInputEnabled: true,
-			currentInputMin:     1000,
+			currentInputMin:     0,
 			thinkingInjection:   boolPtr(true),
 		},
 		DS: ds,
@@ -331,12 +324,12 @@ func TestApplyCurrentInputFileReplacesHistorySplitWithFullContextFile(t *testing
 		t.Fatalf("normalize failed: %v", err)
 	}
 
-	out, err := h.applyHistorySplit(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
+	out, err := h.applyCurrentInputFile(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
 	if err != nil {
 		t.Fatalf("apply current input file failed: %v", err)
 	}
 	if !out.CurrentInputFileApplied {
-		t.Fatalf("expected current input file to replace history split")
+		t.Fatalf("expected current input file to apply")
 	}
 	if len(ds.uploadCalls) != 1 {
 		t.Fatalf("expected one current input upload, got %d", len(ds.uploadCalls))
@@ -351,9 +344,6 @@ func TestApplyCurrentInputFileReplacesHistorySplitWithFullContextFile(t *testing
 			t.Fatalf("expected full context file to contain %q, got %q", want, uploadedText)
 		}
 	}
-	if out.HistoryText != "" {
-		t.Fatalf("expected no HISTORY transcript when current input file replaces split, got %q", out.HistoryText)
-	}
 	if strings.Contains(out.FinalPrompt, "first user turn") || strings.Contains(out.FinalPrompt, "latest user turn") || strings.Contains(out.FinalPrompt, "CURRENT_USER_INPUT.txt") || strings.Contains(out.FinalPrompt, "IGNORE.txt") || strings.Contains(out.FinalPrompt, "Read that file") {
 		t.Fatalf("expected live prompt to use only a neutral continuation instruction, got %s", out.FinalPrompt)
 	}
@@ -362,13 +352,12 @@ func TestApplyCurrentInputFileReplacesHistorySplitWithFullContextFile(t *testing
 	}
 }
 
-func TestApplyHistorySplitCarriesHistoryText(t *testing.T) {
+func TestApplyCurrentInputFileLeavesHistoryTextEmpty(t *testing.T) {
 	ds := &inlineUploadDSStub{}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		DS: ds,
 	}
@@ -381,25 +370,24 @@ func TestApplyHistorySplitCarriesHistoryText(t *testing.T) {
 		t.Fatalf("normalize failed: %v", err)
 	}
 
-	out, err := h.applyHistorySplit(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
+	out, err := h.applyCurrentInputFile(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
 	if err != nil {
-		t.Fatalf("apply history split failed: %v", err)
+		t.Fatalf("apply current input file failed: %v", err)
 	}
 	if len(ds.uploadCalls) != 1 {
 		t.Fatalf("expected 1 upload call, got %d", len(ds.uploadCalls))
 	}
-	if out.HistoryText != string(ds.uploadCalls[0].Data) {
-		t.Fatalf("expected history text to be preserved on normalized request")
+	if out.HistoryText != "" {
+		t.Fatalf("expected current input file flow to leave history text empty, got %q", out.HistoryText)
 	}
 }
 
-func TestChatCompletionsHistorySplitUploadsHistoryFileAndKeepsLatestPrompt(t *testing.T) {
+func TestChatCompletionsCurrentInputFileUploadsContextAndKeepsNeutralPrompt(t *testing.T) {
 	ds := &inlineUploadDSStub{}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		Auth: streamStatusAuthStub{},
 		DS:   ds,
@@ -423,7 +411,7 @@ func TestChatCompletionsHistorySplitUploadsHistoryFileAndKeepsLatestPrompt(t *te
 		t.Fatalf("expected 1 upload call, got %d", len(ds.uploadCalls))
 	}
 	upload := ds.uploadCalls[0]
-	if upload.Filename != "HISTORY.txt" {
+	if upload.Filename != "IGNORE.txt" {
 		t.Fatalf("unexpected upload filename: %q", upload.Filename)
 	}
 	if upload.Purpose != "assistants" {
@@ -433,32 +421,31 @@ func TestChatCompletionsHistorySplitUploadsHistoryFileAndKeepsLatestPrompt(t *te
 	if !strings.Contains(historyText, "[file content end]") || !strings.Contains(historyText, "[file name]: IGNORE") {
 		t.Fatalf("expected injected IGNORE wrapper, got %s", historyText)
 	}
-	if strings.Contains(historyText, "latest user turn") {
-		t.Fatalf("expected latest turn to remain live, got %s", historyText)
+	if !strings.Contains(historyText, "latest user turn") {
+		t.Fatalf("expected full context to include latest turn, got %s", historyText)
 	}
 	if ds.completionReq == nil {
 		t.Fatal("expected completion payload to be captured")
 	}
 	promptText, _ := ds.completionReq["prompt"].(string)
-	if !strings.Contains(promptText, "latest user turn") {
-		t.Fatalf("expected latest turn in completion prompt, got %s", promptText)
+	if !strings.Contains(promptText, "Answer the latest user request directly.") {
+		t.Fatalf("expected neutral completion prompt, got %s", promptText)
 	}
-	if strings.Contains(promptText, "first user turn") {
-		t.Fatalf("expected historical turns removed from completion prompt, got %s", promptText)
+	if strings.Contains(promptText, "first user turn") || strings.Contains(promptText, "latest user turn") {
+		t.Fatalf("expected prompt to hide original turns, got %s", promptText)
 	}
 	refIDs, _ := ds.completionReq["ref_file_ids"].([]any)
 	if len(refIDs) == 0 || refIDs[0] != "file-inline-1" {
-		t.Fatalf("expected uploaded history file to be first ref_file_id, got %#v", ds.completionReq["ref_file_ids"])
+		t.Fatalf("expected uploaded current input file to be first ref_file_id, got %#v", ds.completionReq["ref_file_ids"])
 	}
 }
 
-func TestResponsesHistorySplitUploadsHistoryAndKeepsLatestPrompt(t *testing.T) {
+func TestResponsesCurrentInputFileUploadsContextAndKeepsNeutralPrompt(t *testing.T) {
 	ds := &inlineUploadDSStub{}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		Auth: streamStatusAuthStub{},
 		DS:   ds,
@@ -487,23 +474,22 @@ func TestResponsesHistorySplitUploadsHistoryAndKeepsLatestPrompt(t *testing.T) {
 		t.Fatal("expected completion payload to be captured")
 	}
 	promptText, _ := ds.completionReq["prompt"].(string)
-	if !strings.Contains(promptText, "latest user turn") {
-		t.Fatalf("expected latest turn in completion prompt, got %s", promptText)
+	if !strings.Contains(promptText, "Answer the latest user request directly.") {
+		t.Fatalf("expected neutral completion prompt, got %s", promptText)
 	}
-	if strings.Contains(promptText, "first user turn") {
-		t.Fatalf("expected historical turns removed from completion prompt, got %s", promptText)
+	if strings.Contains(promptText, "first user turn") || strings.Contains(promptText, "latest user turn") {
+		t.Fatalf("expected prompt to hide original turns, got %s", promptText)
 	}
 }
 
-func TestChatCompletionsHistorySplitMapsManagedAuthFailureTo401(t *testing.T) {
+func TestChatCompletionsCurrentInputFileMapsManagedAuthFailureTo401(t *testing.T) {
 	ds := &inlineUploadDSStub{
 		uploadErr: &dsclient.RequestFailure{Op: "upload file", Kind: dsclient.FailureManagedUnauthorized, Message: "expired token"},
 	}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		Auth: streamStatusManagedAuthStub{},
 		DS:   ds,
@@ -528,15 +514,14 @@ func TestChatCompletionsHistorySplitMapsManagedAuthFailureTo401(t *testing.T) {
 	}
 }
 
-func TestResponsesHistorySplitMapsDirectAuthFailureTo401(t *testing.T) {
+func TestResponsesCurrentInputFileMapsDirectAuthFailureTo401(t *testing.T) {
 	ds := &inlineUploadDSStub{
 		uploadErr: &dsclient.RequestFailure{Op: "upload file", Kind: dsclient.FailureDirectUnauthorized, Message: "invalid token"},
 	}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		Auth: streamStatusAuthStub{},
 		DS:   ds,
@@ -563,13 +548,12 @@ func TestResponsesHistorySplitMapsDirectAuthFailureTo401(t *testing.T) {
 	}
 }
 
-func TestChatCompletionsHistorySplitUploadFailureReturnsInternalServerError(t *testing.T) {
+func TestChatCompletionsCurrentInputFileUploadFailureReturnsInternalServerError(t *testing.T) {
 	ds := &inlineUploadDSStub{uploadErr: errors.New("boom")}
 	h := &openAITestSurface{
 		Store: mockOpenAIConfig{
 			wideInput:           true,
-			historySplitEnabled: true,
-			historySplitTurns:   1,
+			currentInputEnabled: true,
 		},
 		Auth: streamStatusAuthStub{},
 		DS:   ds,
@@ -591,7 +575,7 @@ func TestChatCompletionsHistorySplitUploadFailureReturnsInternalServerError(t *t
 	}
 }
 
-func TestHistorySplitWorksAcrossAutoDeleteModes(t *testing.T) {
+func TestCurrentInputFileWorksAcrossAutoDeleteModes(t *testing.T) {
 	for _, mode := range []string{"none", "single", "all"} {
 		t.Run(mode, func(t *testing.T) {
 			ds := &inlineUploadDSStub{}
@@ -599,8 +583,7 @@ func TestHistorySplitWorksAcrossAutoDeleteModes(t *testing.T) {
 				Store: mockOpenAIConfig{
 					wideInput:           true,
 					autoDeleteMode:      mode,
-					historySplitEnabled: true,
-					historySplitTurns:   1,
+					currentInputEnabled: true,
 				},
 				Auth: streamStatusAuthStub{},
 				DS:   ds,
@@ -621,13 +604,13 @@ func TestHistorySplitWorksAcrossAutoDeleteModes(t *testing.T) {
 				t.Fatalf("expected 200, got %d body=%s", rec.Code, rec.Body.String())
 			}
 			if len(ds.uploadCalls) != 1 {
-				t.Fatalf("expected history split upload for mode=%s, got %d", mode, len(ds.uploadCalls))
+				t.Fatalf("expected current input upload for mode=%s, got %d", mode, len(ds.uploadCalls))
 			}
 			if ds.completionReq == nil {
 				t.Fatalf("expected completion payload for mode=%s", mode)
 			}
 			promptText, _ := ds.completionReq["prompt"].(string)
-			if !strings.Contains(promptText, "latest user turn") || strings.Contains(promptText, "first user turn") {
+			if !strings.Contains(promptText, "Answer the latest user request directly.") || strings.Contains(promptText, "first user turn") || strings.Contains(promptText, "latest user turn") {
 				t.Fatalf("unexpected prompt for mode=%s: %s", mode, promptText)
 			}
 		})

internal/httpapi/openai/responses/handler.go

@@ -36,20 +36,17 @@ func (h *Handler) compatStripReferenceMarkers() bool {
 	return shared.CompatStripReferenceMarkers(h.Store)
 }
 
-func (h *Handler) applyHistorySplit(ctx context.Context, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) (promptcompat.StandardRequest, error) {
+func (h *Handler) applyCurrentInputFile(ctx context.Context, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) (promptcompat.StandardRequest, error) {
 	if h == nil {
 		return stdReq, nil
 	}
 	stdReq = shared.ApplyThinkingInjection(h.Store, stdReq)
 	svc := history.Service{Store: h.Store, DS: h.DS}
 	out, err := svc.ApplyCurrentInputFile(ctx, a, stdReq)
-	if err != nil {
-		return stdReq, err
+	if err != nil || out.CurrentInputFileApplied {
+		return out, err
 	}
-	if out.CurrentInputFileApplied {
-		return out, nil
-	}
-	return svc.Apply(ctx, a, out)
+	return out, nil
 }
 
 func (h *Handler) preprocessInlineFileInputs(ctx context.Context, a *auth.RequestAuth, req map[string]any) error {
@@ -89,7 +86,7 @@ func writeOpenAIInlineFileError(w http.ResponseWriter, err error) {
 	files.WriteInlineFileError(w, err)
 }
 
-func mapHistorySplitError(err error) (int, string) {
+func mapCurrentInputFileError(err error) (int, string) {
 	return history.MapError(err)
 }
 

internal/httpapi/openai/responses/responses_handler.go

@@ -85,9 +85,9 @@ func (h *Handler) Responses(w http.ResponseWriter, r *http.Request) {
 		writeOpenAIError(w, http.StatusBadRequest, err.Error())
 		return
 	}
-	stdReq, err = h.applyHistorySplit(r.Context(), a, stdReq)
+	stdReq, err = h.applyCurrentInputFile(r.Context(), a, stdReq)
 	if err != nil {
-		status, message := mapHistorySplitError(err)
+		status, message := mapCurrentInputFileError(err)
 		writeOpenAIError(w, status, message)
 		return
 	}

internal/httpapi/openai/test_bridge_test.go

@@ -83,17 +83,14 @@ func (h *openAITestSurface) ChatCompletions(w http.ResponseWriter, r *http.Reque
 	h.chatHandler().ChatCompletions(w, r)
 }
 
-func (h *openAITestSurface) applyHistorySplit(ctx context.Context, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) (promptcompat.StandardRequest, error) {
+func (h *openAITestSurface) applyCurrentInputFile(ctx context.Context, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) (promptcompat.StandardRequest, error) {
 	stdReq = shared.ApplyThinkingInjection(h.Store, stdReq)
 	svc := history.Service{Store: h.Store, DS: h.DS}
 	out, err := svc.ApplyCurrentInputFile(ctx, a, stdReq)
-	if err != nil {
-		return stdReq, err
+	if err != nil || out.CurrentInputFileApplied {
+		return out, err
 	}
-	if out.CurrentInputFileApplied {
-		return out, nil
-	}
-	return svc.Apply(ctx, a, out)
+	return out, nil
 }
 
 func (h *openAITestSurface) preprocessInlineFileInputs(ctx context.Context, a *auth.RequestAuth, req map[string]any) error {
@@ -114,8 +111,8 @@ func splitOpenAIHistoryMessages(messages []any, triggerAfterTurns int) ([]any, [
 	return history.SplitOpenAIHistoryMessages(messages, triggerAfterTurns)
 }
 
-func buildOpenAIHistoryTranscript(messages []any) string {
-	return promptcompat.BuildOpenAIHistoryTranscript(messages)
+func buildOpenAICurrentInputContextTranscript(messages []any) string {
+	return promptcompat.BuildOpenAICurrentInputContextTranscript(messages)
 }
 
 func writeOpenAIError(w http.ResponseWriter, status int, message string) {