fix(runtime): remove gpt-5.1 minimal effort variant

Stop advertising and mapping the unsupported gpt-5.1-minimal variant in the model registry and Codex executor, and align bare gpt-5.1 requests to use medium reasoning effort like Codex CLI while preserving minimal for gpt-5.

Author: ben-vargas

internal/registry/model_definitions.go

@@ -430,19 +430,6 @@ func GetOpenAIModels() []*ModelInfo {
 			MaxCompletionTokens: 128000,
 			SupportedParameters: []string{"tools"},
 		},
-		{
-			ID:                  "gpt-5.1-minimal",
-			Object:              "model",
-			Created:             time.Now().Unix(),
-			OwnedBy:             "openai",
-			Type:                "openai",
-			Version:             "gpt-5.1-2025-11-12",
-			DisplayName:         "GPT 5 Minimal",
-			Description:         "Stable version of GPT 5, The best model for coding and agentic tasks across domains.",
-			ContextLength:       400000,
-			MaxCompletionTokens: 128000,
-			SupportedParameters: []string{"tools"},
-		},
 		{
 			ID:                  "gpt-5.1-low",
 			Object:              "model",

internal/runtime/executor/codex_executor.go

@@ -85,14 +85,12 @@ func (e *CodexExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, re
 		default:
 			body, _ = sjson.SetBytes(body, "reasoning.effort", "medium")
 		}
-	} else if util.InArray([]string{"gpt-5.1", "gpt-5.1-minimal", "gpt-5.1-low", "gpt-5.1-medium", "gpt-5.1-high"}, req.Model) {
+	} else if util.InArray([]string{"gpt-5.1", "gpt-5.1-low", "gpt-5.1-medium", "gpt-5.1-high"}, req.Model) {
 		body, _ = sjson.SetBytes(body, "model", "gpt-5.1")
 		switch req.Model {
-		case "gpt-5.1-minimal":
-			body, _ = sjson.SetBytes(body, "reasoning.effort", "minimal")
 		case "gpt-5.1-low":
 			body, _ = sjson.SetBytes(body, "reasoning.effort", "low")
-		case "gpt-5.1-medium":
+		case "gpt-5.1-medium", "gpt-5.1":
 			body, _ = sjson.SetBytes(body, "reasoning.effort", "medium")
 		case "gpt-5.1-high":
 			body, _ = sjson.SetBytes(body, "reasoning.effort", "high")
@@ -239,14 +237,12 @@ func (e *CodexExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Au
 		case "gpt-5-codex-mini-high":
 			body, _ = sjson.SetBytes(body, "reasoning.effort", "high")
 		}
-	} else if util.InArray([]string{"gpt-5.1", "gpt-5.1-minimal", "gpt-5.1-low", "gpt-5.1-medium", "gpt-5.1-high"}, req.Model) {
+	} else if util.InArray([]string{"gpt-5.1", "gpt-5.1-low", "gpt-5.1-medium", "gpt-5.1-high"}, req.Model) {
 		body, _ = sjson.SetBytes(body, "model", "gpt-5.1")
 		switch req.Model {
-		case "gpt-5.1-minimal":
-			body, _ = sjson.SetBytes(body, "reasoning.effort", "minimal")
 		case "gpt-5.1-low":
 			body, _ = sjson.SetBytes(body, "reasoning.effort", "low")
-		case "gpt-5.1-medium":
+		case "gpt-5.1-medium", "gpt-5.1":
 			body, _ = sjson.SetBytes(body, "reasoning.effort", "medium")
 		case "gpt-5.1-high":
 			body, _ = sjson.SetBytes(body, "reasoning.effort", "high")