feat: implement history split functionality to optimize context usage and add corresponding UI settings

internal/config/codec.go

@@ -51,6 +51,9 @@ func (c Config) MarshalJSON() ([]byte, error) {
 		m["embeddings"] = c.Embeddings
 	}
 	m["auto_delete"] = c.AutoDelete
+	if c.HistorySplit.Enabled != nil || c.HistorySplit.TriggerAfterTurns != nil {
+		m["history_split"] = c.HistorySplit
+	}
 	if c.VercelSyncHash != "" {
 		m["_vercel_sync_hash"] = c.VercelSyncHash
 	}
@@ -122,6 +125,10 @@ func (c *Config) UnmarshalJSON(b []byte) error {
 			if err := json.Unmarshal(v, &c.AutoDelete); err != nil {
 				return fmt.Errorf("invalid field %q: %w", k, err)
 			}
+		case "history_split":
+			if err := json.Unmarshal(v, &c.HistorySplit); err != nil {
+				return fmt.Errorf("invalid field %q: %w", k, err)
+			}
 		case "_vercel_sync_hash":
 			if err := json.Unmarshal(v, &c.VercelSyncHash); err != nil {
 				return fmt.Errorf("invalid field %q: %w", k, err)
@@ -156,9 +163,13 @@ func (c Config) Clone() Config {
 			WideInputStrictOutput: cloneBoolPtr(c.Compat.WideInputStrictOutput),
 			StripReferenceMarkers: cloneBoolPtr(c.Compat.StripReferenceMarkers),
 		},
-		Responses:        c.Responses,
-		Embeddings:       c.Embeddings,
-		AutoDelete:       c.AutoDelete,
+		Responses:  c.Responses,
+		Embeddings: c.Embeddings,
+		AutoDelete: c.AutoDelete,
+		HistorySplit: HistorySplitConfig{
+			Enabled:           cloneBoolPtr(c.HistorySplit.Enabled),
+			TriggerAfterTurns: cloneIntPtr(c.HistorySplit.TriggerAfterTurns),
+		},
 		VercelSyncHash:   c.VercelSyncHash,
 		VercelSyncTime:   c.VercelSyncTime,
 		AdditionalFields: map[string]any{},
@@ -188,6 +199,14 @@ func cloneBoolPtr(in *bool) *bool {
 	return &v
 }
 
+func cloneIntPtr(in *int) *int {
+	if in == nil {
+		return nil
+	}
+	v := *in
+	return &v
+}
+
 func parseConfigString(raw string) (Config, error) {
 	var cfg Config
 	candidates := []string{raw}

internal/config/config.go

@@ -8,22 +8,23 @@ import (
 )
 
 type Config struct {
-	Keys             []string          `json:"keys,omitempty"`
-	APIKeys          []APIKey          `json:"api_keys,omitempty"`
-	Accounts         []Account         `json:"accounts,omitempty"`
-	Proxies          []Proxy           `json:"proxies,omitempty"`
-	ClaudeMapping    map[string]string `json:"claude_mapping,omitempty"`
-	ClaudeModelMap   map[string]string `json:"claude_model_mapping,omitempty"`
-	ModelAliases     map[string]string `json:"model_aliases,omitempty"`
-	Admin            AdminConfig       `json:"admin,omitempty"`
-	Runtime          RuntimeConfig     `json:"runtime,omitempty"`
-	Compat           CompatConfig      `json:"compat,omitempty"`
-	Responses        ResponsesConfig   `json:"responses,omitempty"`
-	Embeddings       EmbeddingsConfig  `json:"embeddings,omitempty"`
-	AutoDelete       AutoDeleteConfig  `json:"auto_delete"`
-	VercelSyncHash   string            `json:"_vercel_sync_hash,omitempty"`
-	VercelSyncTime   int64             `json:"_vercel_sync_time,omitempty"`
-	AdditionalFields map[string]any    `json:"-"`
+	Keys             []string           `json:"keys,omitempty"`
+	APIKeys          []APIKey           `json:"api_keys,omitempty"`
+	Accounts         []Account          `json:"accounts,omitempty"`
+	Proxies          []Proxy            `json:"proxies,omitempty"`
+	ClaudeMapping    map[string]string  `json:"claude_mapping,omitempty"`
+	ClaudeModelMap   map[string]string  `json:"claude_model_mapping,omitempty"`
+	ModelAliases     map[string]string  `json:"model_aliases,omitempty"`
+	Admin            AdminConfig        `json:"admin,omitempty"`
+	Runtime          RuntimeConfig      `json:"runtime,omitempty"`
+	Compat           CompatConfig       `json:"compat,omitempty"`
+	Responses        ResponsesConfig    `json:"responses,omitempty"`
+	Embeddings       EmbeddingsConfig   `json:"embeddings,omitempty"`
+	AutoDelete       AutoDeleteConfig   `json:"auto_delete"`
+	HistorySplit     HistorySplitConfig `json:"history_split"`
+	VercelSyncHash   string             `json:"_vercel_sync_hash,omitempty"`
+	VercelSyncTime   int64              `json:"_vercel_sync_time,omitempty"`
+	AdditionalFields map[string]any     `json:"-"`
 }
 
 type Account struct {
@@ -148,3 +149,8 @@ type AutoDeleteConfig struct {
 	Mode     string `json:"mode,omitempty"`
 	Sessions bool   `json:"sessions,omitempty"`
 }
+
+type HistorySplitConfig struct {
+	Enabled           *bool `json:"enabled,omitempty"`
+	TriggerAfterTurns *int  `json:"trigger_after_turns,omitempty"`
+}

internal/config/config_edge_test.go

@@ -154,6 +154,10 @@ func TestConfigJSONRoundtrip(t *testing.T) {
 		AutoDelete: AutoDeleteConfig{
 			Mode: "single",
 		},
+		HistorySplit: HistorySplitConfig{
+			Enabled:           &trueVal,
+			TriggerAfterTurns: func() *int { v := 2; return &v }(),
+		},
 		Runtime: RuntimeConfig{
 			TokenRefreshIntervalHours: 12,
 		},
@@ -193,6 +197,12 @@ func TestConfigJSONRoundtrip(t *testing.T) {
 	if decoded.AutoDelete.Mode != "single" {
 		t.Fatalf("unexpected auto delete mode: %#v", decoded.AutoDelete.Mode)
 	}
+	if decoded.HistorySplit.Enabled == nil || !*decoded.HistorySplit.Enabled {
+		t.Fatalf("unexpected history split enabled: %#v", decoded.HistorySplit.Enabled)
+	}
+	if decoded.HistorySplit.TriggerAfterTurns == nil || *decoded.HistorySplit.TriggerAfterTurns != 2 {
+		t.Fatalf("unexpected history split trigger_after_turns: %#v", decoded.HistorySplit.TriggerAfterTurns)
+	}
 	if decoded.Compat.WideInputStrictOutput == nil || !*decoded.Compat.WideInputStrictOutput {
 		t.Fatalf("unexpected compat wide_input_strict_output: %#v", decoded.Compat.WideInputStrictOutput)
 	}
@@ -249,6 +259,8 @@ func TestConfigUnmarshalJSONPreservesUnknownFields(t *testing.T) {
 
 func TestConfigCloneIsDeepCopy(t *testing.T) {
 	falseVal := false
+	trueVal := true
+	turns := 2
 	cfg := Config{
 		Keys:     []string{"key1"},
 		Accounts: []Account{{Email: "user@test.com", Token: "token"}},
@@ -258,6 +270,10 @@ func TestConfigCloneIsDeepCopy(t *testing.T) {
 		Compat: CompatConfig{
 			StripReferenceMarkers: &falseVal,
 		},
+		HistorySplit: HistorySplitConfig{
+			Enabled:           &trueVal,
+			TriggerAfterTurns: &turns,
+		},
 		AdditionalFields: map[string]any{"custom": "value"},
 	}
 
@@ -270,6 +286,12 @@ func TestConfigCloneIsDeepCopy(t *testing.T) {
 	if cfg.Compat.StripReferenceMarkers != nil {
 		*cfg.Compat.StripReferenceMarkers = true
 	}
+	if cfg.HistorySplit.Enabled != nil {
+		*cfg.HistorySplit.Enabled = false
+	}
+	if cfg.HistorySplit.TriggerAfterTurns != nil {
+		*cfg.HistorySplit.TriggerAfterTurns = 5
+	}
 
 	// Cloned should not be affected
 	if cloned.Keys[0] != "key1" {
@@ -284,6 +306,12 @@ func TestConfigCloneIsDeepCopy(t *testing.T) {
 	if cloned.Compat.StripReferenceMarkers == nil || *cloned.Compat.StripReferenceMarkers {
 		t.Fatalf("clone compat was affected: %#v", cloned.Compat.StripReferenceMarkers)
 	}
+	if cloned.HistorySplit.Enabled == nil || !*cloned.HistorySplit.Enabled {
+		t.Fatalf("clone history split enabled was affected: %#v", cloned.HistorySplit.Enabled)
+	}
+	if cloned.HistorySplit.TriggerAfterTurns == nil || *cloned.HistorySplit.TriggerAfterTurns != 2 {
+		t.Fatalf("clone history split trigger was affected: %#v", cloned.HistorySplit.TriggerAfterTurns)
+	}
 }
 
 func TestConfigCloneNilMaps(t *testing.T) {

internal/config/store_accessors.go

@@ -174,3 +174,21 @@ func (s *Store) RuntimeTokenRefreshIntervalHours() int {
 func (s *Store) AutoDeleteSessions() bool {
 	return s.AutoDeleteMode() != "none"
 }
+
+func (s *Store) HistorySplitEnabled() bool {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	if s.cfg.HistorySplit.Enabled == nil {
+		return true
+	}
+	return *s.cfg.HistorySplit.Enabled
+}
+
+func (s *Store) HistorySplitTriggerAfterTurns() int {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	if s.cfg.HistorySplit.TriggerAfterTurns == nil || *s.cfg.HistorySplit.TriggerAfterTurns <= 0 {
+		return 1
+	}
+	return *s.cfg.HistorySplit.TriggerAfterTurns
+}

internal/config/store_accessors_test.go

@@ -0,0 +1,27 @@
+package config
+
+import "testing"
+
+func TestStoreHistorySplitAccessors(t *testing.T) {
+	store := &Store{cfg: Config{}}
+	if !store.HistorySplitEnabled() {
+		t.Fatal("expected history split enabled by default")
+	}
+	if got := store.HistorySplitTriggerAfterTurns(); got != 1 {
+		t.Fatalf("default history split trigger_after_turns=%d want=1", got)
+	}
+
+	enabled := false
+	turns := 3
+	store.cfg.HistorySplit = HistorySplitConfig{
+		Enabled:           &enabled,
+		TriggerAfterTurns: &turns,
+	}
+
+	if store.HistorySplitEnabled() {
+		t.Fatal("expected history split disabled after override")
+	}
+	if got := store.HistorySplitTriggerAfterTurns(); got != 3 {
+		t.Fatalf("history split trigger_after_turns=%d want=3", got)
+	}
+}

internal/config/validation.go

@@ -24,6 +24,9 @@ func ValidateConfig(c Config) error {
 	if err := ValidateAutoDeleteConfig(c.AutoDelete); err != nil {
 		return err
 	}
+	if err := ValidateHistorySplitConfig(c.HistorySplit); err != nil {
+		return err
+	}
 	if err := ValidateAccountProxyReferences(c.Accounts, c.Proxies); err != nil {
 		return err
 	}
@@ -111,6 +114,15 @@ func ValidateAutoDeleteConfig(autoDelete AutoDeleteConfig) error {
 	return ValidateAutoDeleteMode(autoDelete.Mode)
 }
 
+func ValidateHistorySplitConfig(historySplit HistorySplitConfig) error {
+	if historySplit.TriggerAfterTurns != nil {
+		if err := ValidateIntRange("history_split.trigger_after_turns", *historySplit.TriggerAfterTurns, 1, 1000, true); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func ValidateIntRange(name string, value, min, max int, required bool) error {
 	if value == 0 && !required {
 		return nil

internal/config/validation_test.go

@@ -39,6 +39,13 @@ func TestValidateConfigRejectsInvalidValues(t *testing.T) {
 			cfg:  Config{AutoDelete: AutoDeleteConfig{Mode: "maybe"}},
 			want: "auto_delete.mode",
 		},
+		{
+			name: "history split",
+			cfg: Config{HistorySplit: HistorySplitConfig{
+				TriggerAfterTurns: intPtr(0),
+			}},
+			want: "history_split.trigger_after_turns",
+		},
 	}
 
 	for _, tc := range tests {
@@ -59,3 +66,5 @@ func TestValidateConfigAcceptsLegacyAutoDeleteSessions(t *testing.T) {
 		t.Fatalf("expected legacy auto_delete.sessions config to remain valid, got %v", err)
 	}
 }
+
+func intPtr(v int) *int { return &v }