feat: Add ExtraFields support via provider_options complementing extra_body

This change enables passing custom parameters to OpenAI-compatible API
providers through Fantasy's ExtraFields mechanism, working alongside
Kujtim's SDK-level extra_body support.

Key changes:
- Extract extra_fields from provider_options (not extra_body)
- Apply via Fantasy's ExtraFields (per-call level)
- Works alongside extra_body (SDK level) for complementary behavior
- Merged with upstream/crush-fantasy parameter update fix

This creates two complementary mechanisms:
1. extra_body: SDK-level defaults (Kujtim's approach) - provider-wide
2. provider_options.extra_fields: Fantasy-level per-call (this PR)

Example config for Z.AI GLM thinking mode:
{
  "providers": {
    "z.ai": {
      "provider_options": {
        "extra_fields": {
          "thinking": {
            "type": "enabled",
            "budget_tokens": 26214
          }
        }
      }
    }
  }
}

The extra_fields are passed through Fantasy's ExtraFields to the
OpenAI SDK's SetExtraFields() method, enabling per-call customization.

Co-authored-by: Kujtim Hoxha <[email protected]>

Author: Jesssullivan

go.mod

@@ -50,6 +50,11 @@ require (
 	mvdan.cc/sh/v3 v3.12.1-0.20250902163504-3cf4fd5717a5
 )
 
+require (
+	github.com/anthropics/anthropic-sdk-go v1.14.0 // indirect
+	google.golang.org/genai v1.32.0 // indirect
+)
+
 require (
 	cloud.google.com/go v0.116.0 // indirect
 	cloud.google.com/go/auth v0.17.0 // indirect
@@ -58,7 +63,6 @@ require (
 	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.17.0 // indirect
 	github.com/Azure/azure-sdk-for-go/sdk/internal v1.10.0 // indirect
 	github.com/andybalholm/cascadia v1.3.3 // indirect
-	github.com/anthropics/anthropic-sdk-go v1.14.0 // indirect
 	github.com/aws/aws-sdk-go-v2 v1.39.3 // indirect
 	github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.6.3 // indirect
 	github.com/aws/aws-sdk-go-v2/config v1.27.27 // indirect
@@ -158,7 +162,6 @@ require (
 	golang.org/x/text v0.30.0
 	golang.org/x/time v0.12.0 // indirect
 	google.golang.org/api v0.239.0 // indirect
-	google.golang.org/genai v1.32.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20250603155806-513f23925822 // indirect
 	google.golang.org/grpc v1.74.2 // indirect
 	google.golang.org/protobuf v1.36.10 // indirect

internal/agent/coordinator.go

@@ -142,6 +142,7 @@ func getProviderOptions(model Model, providerCfg config.ProviderConfig) fantasy.
 	cfgOpts := []byte("{}")
 	providerCfgOpts := []byte("{}")
 	catwalkOpts := []byte("{}")
+	extraBodyOpts := []byte("{}")
 
 	if model.ModelCfg.ProviderOptions != nil {
 		data, err := json.Marshal(model.ModelCfg.ProviderOptions)
@@ -164,9 +165,29 @@ func getProviderOptions(model Model, providerCfg config.ProviderConfig) fantasy.
 		}
 	}
 
+	// Extract extra_fields from provider_options and apply via Fantasy's ExtraFields mechanism
+	// This is separate from extra_body (which applies at SDK level via WithJSONSet)
+	// Use provider_options.extra_fields for per-call customization (e.g., Z.AI GLM thinking mode)
+	if providerCfg.ProviderOptions != nil {
+		if extraFieldsRaw, hasExtraFields := providerCfg.ProviderOptions["extra_fields"]; hasExtraFields {
+			if extraFieldsMap, ok := extraFieldsRaw.(map[string]any); ok && len(extraFieldsMap) > 0 {
+				extraBodyData := map[string]any{
+					"extra_fields": extraFieldsMap,
+				}
+				data, err := json.Marshal(extraBodyData)
+				if err == nil {
+					extraBodyOpts = data
+				} else {
+					slog.Warn("Failed to marshal extra_fields from provider_options", "error", err)
+				}
+			}
+		}
+	}
+
 	readers := []io.Reader{
 		bytes.NewReader(catwalkOpts),
 		bytes.NewReader(providerCfgOpts),
+		bytes.NewReader(extraBodyOpts),
 		bytes.NewReader(cfgOpts),
 	}
 

internal/config/load.go

@@ -500,6 +500,21 @@ func (c *Config) configureSelectedModels(knownProviders []catwalk.Provider) erro
 				large.ReasoningEffort = largeModelSelected.ReasoningEffort
 			}
 			large.Think = largeModelSelected.Think
+			if largeModelSelected.Temperature != nil {
+				large.Temperature = largeModelSelected.Temperature
+			}
+			if largeModelSelected.TopP != nil {
+				large.TopP = largeModelSelected.TopP
+			}
+			if largeModelSelected.TopK != nil {
+				large.TopK = largeModelSelected.TopK
+			}
+			if largeModelSelected.FrequencyPenalty != nil {
+				large.FrequencyPenalty = largeModelSelected.FrequencyPenalty
+			}
+			if largeModelSelected.PresencePenalty != nil {
+				large.PresencePenalty = largeModelSelected.PresencePenalty
+			}
 		}
 	}
 	smallModelSelected, smallModelConfigured := c.Models[SelectedModelTypeSmall]
@@ -525,7 +540,24 @@ func (c *Config) configureSelectedModels(knownProviders []catwalk.Provider) erro
 			} else {
 				small.MaxTokens = model.DefaultMaxTokens
 			}
-			small.ReasoningEffort = smallModelSelected.ReasoningEffort
+			if smallModelSelected.ReasoningEffort != "" {
+				small.ReasoningEffort = smallModelSelected.ReasoningEffort
+			}
+			if smallModelSelected.Temperature != nil {
+				small.Temperature = smallModelSelected.Temperature
+			}
+			if smallModelSelected.TopP != nil {
+				small.TopP = smallModelSelected.TopP
+			}
+			if smallModelSelected.TopK != nil {
+				small.TopK = smallModelSelected.TopK
+			}
+			if smallModelSelected.FrequencyPenalty != nil {
+				small.FrequencyPenalty = smallModelSelected.FrequencyPenalty
+			}
+			if smallModelSelected.PresencePenalty != nil {
+				small.PresencePenalty = smallModelSelected.PresencePenalty
+			}
 			small.Think = smallModelSelected.Think
 		}
 	}