增加不同上下文模式

internal/httpapi/admin/handler_settings_test.go

@@ -75,6 +75,12 @@ func TestGetSettingsIncludesHistorySplitDefaults(t *testing.T) {
 	if got := boolFrom(thinkingInjection["enabled"]); !got {
 		t.Fatalf("expected thinking_injection.enabled=true, body=%v", body)
 	}
+	if got, _ := thinkingInjection["prompt"].(string); got != "" {
+		t.Fatalf("expected empty custom thinking prompt, got %q body=%v", got, body)
+	}
+	if got, _ := thinkingInjection["default_prompt"].(string); got == "" {
+		t.Fatalf("expected default thinking prompt, body=%v", body)
+	}
 }
 
 func TestUpdateSettingsValidation(t *testing.T) {
@@ -264,6 +270,7 @@ func TestUpdateSettingsThinkingInjection(t *testing.T) {
 	payload := map[string]any{
 		"thinking_injection": map[string]any{
 			"enabled": false,
+			"prompt":  " custom thinking prompt ",
 		},
 	}
 	b, _ := json.Marshal(payload)
@@ -280,6 +287,9 @@ func TestUpdateSettingsThinkingInjection(t *testing.T) {
 	if h.Store.ThinkingInjectionEnabled() {
 		t.Fatal("expected thinking injection accessor to reflect disabled config")
 	}
+	if got := h.Store.ThinkingInjectionPrompt(); got != "custom thinking prompt" {
+		t.Fatalf("expected custom thinking prompt, got %q", got)
+	}
 }
 
 func TestUpdateSettingsAutoDeleteMode(t *testing.T) {

internal/httpapi/admin/settings/handler_settings_parse.go

@@ -199,6 +199,9 @@ func parseSettingsUpdateRequest(req map[string]any) (*config.AdminConfig, *confi
 			b := boolFrom(v)
 			cfg.Enabled = &b
 		}
+		if v, exists := raw["prompt"]; exists {
+			cfg.Prompt = strings.TrimSpace(fmt.Sprintf("%v", v))
+		}
 		thinkingInjCfg = cfg
 	}
 

internal/httpapi/admin/settings/handler_settings_read.go

@@ -6,6 +6,7 @@ import (
 
 	authn "ds2api/internal/auth"
 	"ds2api/internal/config"
+	"ds2api/internal/promptcompat"
 )
 
 func (h *Handler) getSettings(w http.ResponseWriter, _ *http.Request) {
@@ -39,7 +40,9 @@ func (h *Handler) getSettings(w http.ResponseWriter, _ *http.Request) {
 			"min_chars": h.Store.CurrentInputFileMinChars(),
 		},
 		"thinking_injection": map[string]any{
-			"enabled": h.Store.ThinkingInjectionEnabled(),
+			"enabled":        h.Store.ThinkingInjectionEnabled(),
+			"prompt":         h.Store.ThinkingInjectionPrompt(),
+			"default_prompt": promptcompat.DefaultThinkingInjectionPrompt,
 		},
 		"model_aliases":     snap.ModelAliases,
 		"env_backed":        h.Store.IsEnvBacked(),

internal/httpapi/admin/settings/handler_settings_write.go

@@ -89,6 +89,7 @@ func (h *Handler) updateSettings(w http.ResponseWriter, r *http.Request) {
 		}
 		if thinkingInjCfg != nil {
 			c.ThinkingInjection.Enabled = thinkingInjCfg.Enabled
+			c.ThinkingInjection.Prompt = thinkingInjCfg.Prompt
 		}
 		if aliasMap != nil {
 			c.ModelAliases = aliasMap

internal/httpapi/admin/shared/deps.go

@@ -38,6 +38,7 @@ type ConfigStore interface {
 	CurrentInputFileEnabled() bool
 	CurrentInputFileMinChars() int
 	ThinkingInjectionEnabled() bool
+	ThinkingInjectionPrompt() string
 	CompatStripReferenceMarkers() bool
 	AutoDeleteSessions() bool
 }

internal/httpapi/openai/chat/test_helpers_test.go

@@ -23,6 +23,7 @@ type mockOpenAIConfig struct {
 	currentInputEnabled bool
 	currentInputMin     int
 	thinkingInjection   *bool
+	thinkingPrompt      string
 }
 
 func (m mockOpenAIConfig) ModelAliases() map[string]string { return m.aliases }
@@ -58,6 +59,7 @@ func (m mockOpenAIConfig) ThinkingInjectionEnabled() bool {
 	}
 	return *m.thinkingInjection
 }
+func (m mockOpenAIConfig) ThinkingInjectionPrompt() string { return m.thinkingPrompt }
 
 type streamStatusAuthStub struct{}
 

internal/httpapi/openai/deps_injection_test.go

@@ -19,6 +19,7 @@ type mockOpenAIConfig struct {
 	currentInputEnabled bool
 	currentInputMin     int
 	thinkingInjection   *bool
+	thinkingPrompt      string
 }
 
 func (m mockOpenAIConfig) ModelAliases() map[string]string { return m.aliases }
@@ -54,6 +55,7 @@ func (m mockOpenAIConfig) ThinkingInjectionEnabled() bool {
 	}
 	return *m.thinkingInjection
 }
+func (m mockOpenAIConfig) ThinkingInjectionPrompt() string { return m.thinkingPrompt }
 
 func TestNormalizeOpenAIChatRequestWithConfigInterface(t *testing.T) {
 	cfg := mockOpenAIConfig{

internal/httpapi/openai/history_split_test.go

@@ -183,6 +183,36 @@ func TestApplyThinkingInjectionAppendsLatestUserPrompt(t *testing.T) {
 	}
 }
 
+func TestApplyThinkingInjectionUsesCustomPrompt(t *testing.T) {
+	ds := &inlineUploadDSStub{}
+	h := &openAITestSurface{
+		Store: mockOpenAIConfig{
+			wideInput:         true,
+			thinkingInjection: boolPtr(true),
+			thinkingPrompt:    "custom thinking format",
+		},
+		DS: ds,
+	}
+	req := map[string]any{
+		"model": "deepseek-v4-flash",
+		"messages": []any{
+			map[string]any{"role": "user", "content": "hello"},
+		},
+	}
+	stdReq, err := promptcompat.NormalizeOpenAIChatRequest(h.Store, req, "")
+	if err != nil {
+		t.Fatalf("normalize failed: %v", err)
+	}
+
+	out, err := h.applyHistorySplit(context.Background(), &auth.RequestAuth{DeepSeekToken: "token"}, stdReq)
+	if err != nil {
+		t.Fatalf("apply thinking injection failed: %v", err)
+	}
+	if !strings.Contains(out.FinalPrompt, "hello\n\ncustom thinking format") {
+		t.Fatalf("expected custom thinking injection after latest user message, got %s", out.FinalPrompt)
+	}
+}
+
 func TestApplyHistorySplitDirectPassThroughWhenBothSplitsDisabled(t *testing.T) {
 	ds := &inlineUploadDSStub{}
 	h := &openAITestSurface{

internal/httpapi/openai/shared/deps.go

@@ -48,6 +48,7 @@ type ConfigReader interface {
 	CurrentInputFileEnabled() bool
 	CurrentInputFileMinChars() int
 	ThinkingInjectionEnabled() bool
+	ThinkingInjectionPrompt() string
 }
 
 type Deps struct {

internal/httpapi/openai/shared/thinking_injection.go

@@ -6,7 +6,7 @@ func ApplyThinkingInjection(store ConfigReader, stdReq promptcompat.StandardRequ
 	if store == nil || !store.ThinkingInjectionEnabled() || !stdReq.Thinking {
 		return stdReq
 	}
-	messages, changed := promptcompat.AppendThinkingInjectionToLatestUser(stdReq.Messages)
+	messages, changed := promptcompat.AppendThinkingInjectionPromptToLatestUser(stdReq.Messages, store.ThinkingInjectionPrompt())
 	if !changed {
 		return stdReq
 	}