feat(agent): introduce ThinkingLevel for agent instance configuration

- Added ThinkingLevel field to AgentInstance to support model-specific thinking configurations.
- Implemented parseThinkingLevel function to normalize thinking level strings for compatibility.
- Updated NewAgentInstance function to initialize ThinkingLevel from model config.

This change enhances the agent's ability to adapt its thinking parameters based on the model's configuration, improving overall performance and flexibility.

pkg/agent/instance.go

@@ -26,6 +26,7 @@ type AgentInstance struct {
 	MaxIterations             int
 	MaxTokens                 int
 	Temperature               float64
+	ThinkingLevel             ThinkingLevel // Default from model config at creation (main compatibility).
 	ContextWindow             int
 	SummarizeMessageThreshold int
 	SummarizeTokenPercent     int
@@ -124,6 +125,12 @@ func NewAgentInstance(
 		temperature = *defaults.Temperature
 	}
 
+	var thinkingLevelStr string
+	if mc, err := cfg.GetModelConfig(model); err == nil {
+		thinkingLevelStr = mc.ThinkingLevel
+	}
+	thinkingLevel := parseThinkingLevel(thinkingLevelStr)
+
 	summarizeMessageThreshold := defaults.SummarizeMessageThreshold
 	if summarizeMessageThreshold == 0 {
 		summarizeMessageThreshold = 20
@@ -209,6 +216,7 @@ func NewAgentInstance(
 		MaxIterations:             maxIter,
 		MaxTokens:                 maxTokens,
 		Temperature:               temperature,
+		ThinkingLevel:             thinkingLevel,
 		ContextWindow:             maxTokens,
 		SummarizeMessageThreshold: summarizeMessageThreshold,
 		SummarizeTokenPercent:     summarizeTokenPercent,

pkg/agent/thinking.go

@@ -8,6 +8,29 @@ import (
 	"github.com/sipeed/picoclaw/pkg/config"
 )
 
+// ThinkingLevel controls how the provider sends thinking parameters (main compatibility).
+// Session-level resolution uses string internally; this type is used for agent default from model config.
+type ThinkingLevel string
+
+const (
+	ThinkingOff      ThinkingLevel = "off"
+	ThinkingLow      ThinkingLevel = "low"
+	ThinkingMedium   ThinkingLevel = "medium"
+	ThinkingHigh     ThinkingLevel = "high"
+	ThinkingXHigh    ThinkingLevel = "xhigh"
+	ThinkingAdaptive ThinkingLevel = "adaptive"
+)
+
+// parseThinkingLevel normalizes a config string to a ThinkingLevel (main compatibility).
+// Case-insensitive and whitespace-tolerant. Returns ThinkingOff for unknown or empty.
+func parseThinkingLevel(level string) ThinkingLevel {
+	if normalized, ok := normalizeThinkingLevel(level); ok {
+		return ThinkingLevel(normalized)
+	}
+	return ThinkingOff
+}
+
+// Unexported string constants for internal use (session, downgrade, aliases).
 const (
 	thinkingOff      = "off"
 	thinkingMinimal  = "minimal"
@@ -51,6 +74,10 @@ func resolveThinkingLevel(cfg *config.Config, agent *AgentInstance, sessionKey s
 	if modelLevel := modelThinkingLevel(cfg, agent.Model); modelLevel != "" {
 		return modelLevel
 	}
+	// Main compatibility: fall back to agent default (from model config at creation).
+	if agent.ThinkingLevel != ThinkingOff {
+		return string(agent.ThinkingLevel)
+	}
 	if cfg != nil {
 		if level, ok := normalizeThinkingLevel(cfg.Agents.Defaults.Thinking); ok {
 			return level