refactor: remove legacy history split configuration and integrate current input file handling into the completion runtime pipeline.

internal/httpapi/admin/handler_settings_test.go

@@ -208,9 +208,6 @@ func TestUpdateSettingsCurrentInputFile(t *testing.T) {
 	if !h.Store.CurrentInputFileEnabled() {
 		t.Fatal("expected current input file accessor to stay enabled")
 	}
-	if h.Store.HistorySplitEnabled() {
-		t.Fatal("expected history split accessor to stay disabled")
-	}
 }
 
 func TestUpdateSettingsCurrentInputFilePartialUpdatePreservesEnabled(t *testing.T) {

internal/httpapi/admin/shared/deps.go

@@ -33,8 +33,6 @@ type ConfigStore interface {
 	RuntimeGlobalMaxInflight(defaultSize int) int
 	RuntimeTokenRefreshIntervalHours() int
 	AutoDeleteMode() string
-	HistorySplitEnabled() bool
-	HistorySplitTriggerAfterTurns() int
 	CurrentInputFileEnabled() bool
 	CurrentInputFileMinChars() int
 	ThinkingInjectionEnabled() bool