refactor: improve thinking logic

internal/thinking/provider/claude/apply.go

@@ -0,0 +1,116 @@
+// Package claude implements thinking configuration scaffolding for Claude models.
+//
+// Claude models use the thinking.budget_tokens format with values in the range
+// 1024-128000. Some Claude models support ZeroAllowed (sonnet-4-5, opus-4-5),
+// while older models do not.
+// See: _bmad-output/planning-artifacts/architecture.md#Epic-6
+package claude
+
+import (
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/thinking"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+// Applier implements thinking.ProviderApplier for Claude models.
+// This applier is stateless and holds no configuration.
+type Applier struct{}
+
+// NewApplier creates a new Claude thinking applier.
+func NewApplier() *Applier {
+	return &Applier{}
+}
+
+func init() {
+	thinking.RegisterProvider("claude", NewApplier())
+}
+
+// Apply applies thinking configuration to Claude request body.
+//
+// IMPORTANT: This method expects config to be pre-validated by thinking.ValidateConfig.
+// ValidateConfig handles:
+//   - Mode conversion (Level→Budget, Auto→Budget)
+//   - Budget clamping to model range
+//   - ZeroAllowed constraint enforcement
+//
+// Apply only processes ModeBudget and ModeNone; other modes are passed through unchanged.
+//
+// Expected output format when enabled:
+//
+//	{
+//	  "thinking": {
+//	    "type": "enabled",
+//	    "budget_tokens": 16384
+//	  }
+//	}
+//
+// Expected output format when disabled:
+//
+//	{
+//	  "thinking": {
+//	    "type": "disabled"
+//	  }
+//	}
+func (a *Applier) Apply(body []byte, config thinking.ThinkingConfig, modelInfo *registry.ModelInfo) ([]byte, error) {
+	if modelInfo == nil {
+		return body, nil
+	}
+	if modelInfo.Thinking == nil {
+		if modelInfo.Type == "" {
+			modelID := modelInfo.ID
+			if modelID == "" {
+				modelID = "unknown"
+			}
+			return nil, thinking.NewThinkingErrorWithModel(thinking.ErrThinkingNotSupported, "thinking not supported for this model", modelID)
+		}
+		return applyCompatibleClaude(body, config)
+	}
+
+	// Only process ModeBudget and ModeNone; other modes pass through
+	// (caller should use ValidateConfig first to normalize modes)
+	if config.Mode != thinking.ModeBudget && config.Mode != thinking.ModeNone {
+		return body, nil
+	}
+
+	if len(body) == 0 || !gjson.ValidBytes(body) {
+		body = []byte(`{}`)
+	}
+
+	// Budget is expected to be pre-validated by ValidateConfig (clamped, ZeroAllowed enforced)
+	// Decide enabled/disabled based on budget value
+	if config.Budget == 0 {
+		result, _ := sjson.SetBytes(body, "thinking.type", "disabled")
+		result, _ = sjson.DeleteBytes(result, "thinking.budget_tokens")
+		return result, nil
+	}
+
+	result, _ := sjson.SetBytes(body, "thinking.type", "enabled")
+	result, _ = sjson.SetBytes(result, "thinking.budget_tokens", config.Budget)
+	return result, nil
+}
+
+func applyCompatibleClaude(body []byte, config thinking.ThinkingConfig) ([]byte, error) {
+	if config.Mode != thinking.ModeBudget && config.Mode != thinking.ModeNone && config.Mode != thinking.ModeAuto {
+		return body, nil
+	}
+
+	if len(body) == 0 || !gjson.ValidBytes(body) {
+		body = []byte(`{}`)
+	}
+
+	switch config.Mode {
+	case thinking.ModeNone:
+		result, _ := sjson.SetBytes(body, "thinking.type", "disabled")
+		result, _ = sjson.DeleteBytes(result, "thinking.budget_tokens")
+		return result, nil
+	case thinking.ModeAuto:
+		result, _ := sjson.SetBytes(body, "thinking.type", "enabled")
+		result, _ = sjson.DeleteBytes(result, "thinking.budget_tokens")
+		return result, nil
+	default:
+		result, _ := sjson.SetBytes(body, "thinking.type", "enabled")
+		result, _ = sjson.SetBytes(result, "thinking.budget_tokens", config.Budget)
+		return result, nil
+	}
+}