diff --git a/internal/registry/model_definitions.go b/internal/registry/model_definitions.go
index bbc49dc8..d66adeb5 100644
--- a/internal/registry/model_definitions.go
+++ b/internal/registry/model_definitions.go
@@ -417,6 +417,162 @@ func GetOpenAIModels() []*ModelInfo {
 			MaxCompletionTokens: 128000,
 			SupportedParameters: []string{"tools"},
 		},
+		{
+			ID:                  "gpt-5.1",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5",
+			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-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",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Low",
+			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-medium",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Medium",
+			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-high",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 High",
+			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-codex",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Codex",
+			Description:         "Stable version of GPT 5 Codex, The best model for coding and agentic tasks across domains.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5.1-codex-low",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Codex Low",
+			Description:         "Stable version of GPT 5 Codex, The best model for coding and agentic tasks across domains.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5.1-codex-medium",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Codex Medium",
+			Description:         "Stable version of GPT 5 Codex, The best model for coding and agentic tasks across domains.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5.1-codex-high",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Codex High",
+			Description:         "Stable version of GPT 5 Codex, The best model for coding and agentic tasks across domains.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5.1-codex-mini",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Codex Mini",
+			Description:         "Stable version of GPT 5 Codex Mini: cheaper, faster, but less capable version of GPT 5 Codex.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5.1-codex-mini-medium",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Codex Mini Medium",
+			Description:         "Stable version of GPT 5 Codex Mini: cheaper, faster, but less capable version of GPT 5 Codex.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
+		{
+			ID:                  "gpt-5.1-codex-mini-high",
+			Object:              "model",
+			Created:             time.Now().Unix(),
+			OwnedBy:             "openai",
+			Type:                "openai",
+			Version:             "gpt-5.1-2025-11-12",
+			DisplayName:         "GPT 5 Codex Mini High",
+			Description:         "Stable version of GPT 5 Codex Mini: cheaper, faster, but less capable version of GPT 5 Codex.",
+			ContextLength:       400000,
+			MaxCompletionTokens: 128000,
+			SupportedParameters: []string{"tools"},
+		},
 	}
 }
 
diff --git a/internal/runtime/executor/codex_executor.go b/internal/runtime/executor/codex_executor.go
index 947bff88..34c17724 100644
--- a/internal/runtime/executor/codex_executor.go
+++ b/internal/runtime/executor/codex_executor.go
@@ -85,6 +85,38 @@ 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) {
+		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":
+			body, _ = sjson.SetBytes(body, "reasoning.effort", "medium")
+		case "gpt-5.1-high":
+			body, _ = sjson.SetBytes(body, "reasoning.effort", "high")
+		}
+	} else if util.InArray([]string{"gpt-5.1-codex", "gpt-5.1-codex-low", "gpt-5.1-codex-medium", "gpt-5.1-codex-high"}, req.Model) {
+		body, _ = sjson.SetBytes(body, "model", "gpt-5.1-codex")
+		switch req.Model {
+		case "gpt-5.1-codex-low":
+			body, _ = sjson.SetBytes(body, "reasoning.effort", "low")
+		case "gpt-5.1-codex-medium":
+			body, _ = sjson.SetBytes(body, "reasoning.effort", "medium")
+		case "gpt-5.1-codex-high":
+			body, _ = sjson.SetBytes(body, "reasoning.effort", "high")
+		}
+	} else if util.InArray([]string{"gpt-5.1-codex-mini", "gpt-5.1-codex-mini-medium", "gpt-5.1-codex-mini-high"}, req.Model) {
+		body, _ = sjson.SetBytes(body, "model", "gpt-5.1-codex-mini")
+		switch req.Model {
+		case "gpt-5.1-codex-mini-medium":
+			body, _ = sjson.SetBytes(body, "reasoning.effort", "medium")
+		case "gpt-5.1-codex-mini-high":
+			body, _ = sjson.SetBytes(body, "reasoning.effort", "high")
+		default:
+			body, _ = sjson.SetBytes(body, "reasoning.effort", "medium")
+		}
 	}
 
 	body, _ = sjson.SetBytes(body, "stream", true)
diff --git a/internal/runtime/executor/token_helpers.go b/internal/runtime/executor/token_helpers.go
index c196bd00..f4236f9b 100644
--- a/internal/runtime/executor/token_helpers.go
+++ b/internal/runtime/executor/token_helpers.go
@@ -16,6 +16,8 @@ func tokenizerForModel(model string) (tokenizer.Codec, error) {
 		return tokenizer.Get(tokenizer.Cl100kBase)
 	case strings.HasPrefix(sanitized, "gpt-5"):
 		return tokenizer.ForModel(tokenizer.GPT5)
+	case strings.HasPrefix(sanitized, "gpt-5.1"):
+		return tokenizer.ForModel(tokenizer.GPT5)
 	case strings.HasPrefix(sanitized, "gpt-4.1"):
 		return tokenizer.ForModel(tokenizer.GPT41)
 	case strings.HasPrefix(sanitized, "gpt-4o"):