refactor: remove configurable toolcall policy and fix to feature matching with high-confidence early emit

internal/config/codec.go

@@ -38,9 +38,6 @@ func (c Config) MarshalJSON() ([]byte, error) {
 	if c.Compat.WideInputStrictOutput != nil {
 		m["compat"] = c.Compat
 	}
-	if strings.TrimSpace(c.Toolcall.Mode) != "" || strings.TrimSpace(c.Toolcall.EarlyEmitConfidence) != "" {
-		m["toolcall"] = c.Toolcall
-	}
 	if c.Responses.StoreTTLSeconds > 0 {
 		m["responses"] = c.Responses
 	}
@@ -98,9 +95,7 @@ func (c *Config) UnmarshalJSON(b []byte) error {
 				return fmt.Errorf("invalid field %q: %w", k, err)
 			}
 		case "toolcall":
-			if err := json.Unmarshal(v, &c.Toolcall); err != nil {
-				return fmt.Errorf("invalid field %q: %w", k, err)
-			}
+			// Legacy field ignored. Toolcall policy is fixed and no longer configurable.
 		case "responses":
 			if err := json.Unmarshal(v, &c.Responses); err != nil {
 				return fmt.Errorf("invalid field %q: %w", k, err)
@@ -143,7 +138,6 @@ func (c Config) Clone() Config {
 		Compat: CompatConfig{
 			WideInputStrictOutput: cloneBoolPtr(c.Compat.WideInputStrictOutput),
 		},
-		Toolcall:         c.Toolcall,
 		Responses:        c.Responses,
 		Embeddings:       c.Embeddings,
 		AutoDelete:       c.AutoDelete,

internal/config/config.go

@@ -9,7 +9,6 @@ type Config struct {
 	Admin            AdminConfig       `json:"admin,omitempty"`
 	Runtime          RuntimeConfig     `json:"runtime,omitempty"`
 	Compat           CompatConfig      `json:"compat,omitempty"`
-	Toolcall         ToolcallConfig    `json:"toolcall,omitempty"`
 	Responses        ResponsesConfig   `json:"responses,omitempty"`
 	Embeddings       EmbeddingsConfig  `json:"embeddings,omitempty"`
 	AutoDelete       AutoDeleteConfig  `json:"auto_delete"`
@@ -68,11 +67,6 @@ type RuntimeConfig struct {
 	TokenRefreshIntervalHours int `json:"token_refresh_interval_hours,omitempty"`
 }
 
-type ToolcallConfig struct {
-	Mode                string `json:"mode,omitempty"`
-	EarlyEmitConfidence string `json:"early_emit_confidence,omitempty"`
-}
-
 type ResponsesConfig struct {
 	StoreTTLSeconds int `json:"store_ttl_seconds,omitempty"`
 }

internal/config/store_accessors.go

@@ -43,23 +43,11 @@ func (s *Store) CompatWideInputStrictOutput() bool {
 }
 
 func (s *Store) ToolcallMode() string {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-	mode := strings.TrimSpace(strings.ToLower(s.cfg.Toolcall.Mode))
-	if mode == "" {
-		return "feature_match"
-	}
-	return mode
+	return "feature_match"
 }
 
 func (s *Store) ToolcallEarlyEmitConfidence() string {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-	level := strings.TrimSpace(strings.ToLower(s.cfg.Toolcall.EarlyEmitConfidence))
-	if level == "" {
-		return "high"
-	}
-	return level
+	return "high"
 }
 
 func (s *Store) ResponsesStoreTTLSeconds() int {