Add first-class ChatGPT subscription provider support

crates/common/src/configuration.rs

@@ -370,6 +370,8 @@ pub enum LlmProviderType {
     AmazonBedrock,
     #[serde(rename = "plano")]
     Plano,
+    #[serde(rename = "chatgpt")]
+    ChatGPT,
 }
 
 impl Display for LlmProviderType {
@@ -391,6 +393,7 @@ impl Display for LlmProviderType {
             LlmProviderType::Qwen => write!(f, "qwen"),
             LlmProviderType::AmazonBedrock => write!(f, "amazon_bedrock"),
             LlmProviderType::Plano => write!(f, "plano"),
+            LlmProviderType::ChatGPT => write!(f, "chatgpt"),
         }
     }
 }
@@ -457,6 +460,7 @@ pub struct LlmProvider {
     pub base_url_path_prefix: Option<String>,
     pub internal: Option<bool>,
     pub passthrough_auth: Option<bool>,
+    pub headers: Option<HashMap<String, String>>,
 }
 
 pub trait IntoModels {
@@ -500,6 +504,7 @@ impl Default for LlmProvider {
             base_url_path_prefix: None,
             internal: None,
             passthrough_auth: None,
+            headers: None,
         }
     }
 }

crates/common/src/llm_providers.rs

@@ -277,6 +277,7 @@ mod tests {
             internal: None,
             stream: None,
             passthrough_auth: None,
+            headers: None,
         }
     }
 

crates/hermesllm/src/bin/provider_models.yaml

@@ -328,7 +328,11 @@ providers:
   - xiaomi/mimo-v2-flash
   - xiaomi/mimo-v2-omni
   - xiaomi/mimo-v2-pro
+  chatgpt:
+  - chatgpt/gpt-5.4
+  - chatgpt/gpt-5.3-codex
+  - chatgpt/gpt-5.2
 metadata:
-  total_providers: 11
-  total_models: 316
+  total_providers: 12
+  total_models: 319
   last_updated: 2026-04-03T23:14:46.956158+00:00

crates/hermesllm/src/clients/endpoints.rs

@@ -192,7 +192,9 @@ impl SupportedAPIsFromClient {
                 // For Responses API, check if provider supports it, otherwise translate to chat/completions
                 match provider_id {
                     // Providers that support /v1/responses natively
-                    ProviderId::OpenAI | ProviderId::XAI => route_by_provider("/responses"),
+                    ProviderId::OpenAI | ProviderId::XAI | ProviderId::ChatGPT => {
+                        route_by_provider("/responses")
+                    }
                     // All other providers: translate to /chat/completions
                     _ => route_by_provider("/chat/completions"),
                 }

crates/hermesllm/src/providers/id.rs

@@ -44,6 +44,7 @@ pub enum ProviderId {
     Zhipu,
     Qwen,
     AmazonBedrock,
+    ChatGPT,
 }
 
 impl TryFrom<&str> for ProviderId {
@@ -71,6 +72,7 @@ impl TryFrom<&str> for ProviderId {
             "qwen" => Ok(ProviderId::Qwen),
             "amazon_bedrock" => Ok(ProviderId::AmazonBedrock),
             "amazon" => Ok(ProviderId::AmazonBedrock), // alias
+            "chatgpt" => Ok(ProviderId::ChatGPT),
             _ => Err(format!("Unknown provider: {}", value)),
         }
     }
@@ -95,6 +97,7 @@ impl ProviderId {
             ProviderId::Moonshotai => "moonshotai",
             ProviderId::Zhipu => "z-ai",
             ProviderId::Qwen => "qwen",
+            ProviderId::ChatGPT => "chatgpt",
             _ => return Vec::new(),
         };
 
@@ -148,7 +151,8 @@ impl ProviderId {
                 | ProviderId::Ollama
                 | ProviderId::Moonshotai
                 | ProviderId::Zhipu
-                | ProviderId::Qwen,
+                | ProviderId::Qwen
+                | ProviderId::ChatGPT,
                 SupportedAPIsFromClient::AnthropicMessagesAPI(_),
             ) => SupportedUpstreamAPIs::OpenAIChatCompletions(OpenAIApi::ChatCompletions),
 
@@ -167,13 +171,14 @@ impl ProviderId {
                 | ProviderId::Ollama
                 | ProviderId::Moonshotai
                 | ProviderId::Zhipu
-                | ProviderId::Qwen,
+                | ProviderId::Qwen
+                | ProviderId::ChatGPT,
                 SupportedAPIsFromClient::OpenAIChatCompletions(_),
             ) => SupportedUpstreamAPIs::OpenAIChatCompletions(OpenAIApi::ChatCompletions),
 
-            // OpenAI Responses API - OpenAI and xAI support this natively
+            // OpenAI Responses API - OpenAI, xAI, and ChatGPT support this natively
             (
-                ProviderId::OpenAI | ProviderId::XAI,
+                ProviderId::OpenAI | ProviderId::XAI | ProviderId::ChatGPT,
                 SupportedAPIsFromClient::OpenAIResponsesAPI(_),
             ) => SupportedUpstreamAPIs::OpenAIResponsesAPI(OpenAIApi::Responses),
 
@@ -234,6 +239,7 @@ impl Display for ProviderId {
             ProviderId::Zhipu => write!(f, "zhipu"),
             ProviderId::Qwen => write!(f, "qwen"),
             ProviderId::AmazonBedrock => write!(f, "amazon_bedrock"),
+            ProviderId::ChatGPT => write!(f, "chatgpt"),
         }
     }
 }

crates/hermesllm/src/providers/request.rs

@@ -89,6 +89,41 @@ impl ProviderRequestType {
                 req.web_search_options = None;
             }
         }
+
+        // ChatGPT requires instructions, store=false, and input as a list
+        if provider_id == ProviderId::ChatGPT {
+            if let Self::ResponsesAPIRequest(req) = self {
+                use crate::apis::openai_responses::{
+                    InputItem, InputMessage, InputParam, MessageContent, MessageRole,
+                };
+
+                const CHATGPT_BASE_INSTRUCTIONS: &str =
+                    "You are Codex, based on GPT-5. You are running as a coding agent in the Codex CLI on a user's computer.";
+                match &req.instructions {
+                    Some(existing) if existing.contains(CHATGPT_BASE_INSTRUCTIONS) => {}
+                    Some(existing) => {
+                        req.instructions =
+                            Some(format!("{}\n\n{}", CHATGPT_BASE_INSTRUCTIONS, existing));
+                    }
+                    None => {
+                        req.instructions = Some(CHATGPT_BASE_INSTRUCTIONS.to_string());
+                    }
+                }
+                req.store = Some(false);
+                req.stream = Some(true);
+
+                // ChatGPT backend requires input to be a list, not a plain string
+                if let InputParam::Text(text) = &req.input {
+                    req.input = InputParam::Items(vec![InputItem::Message(InputMessage {
+                        role: MessageRole::User,
+                        content: MessageContent::Text(text.clone()),
+                    })]);
+                }
+                if let InputParam::SingleItem(item) = &req.input {
+                    req.input = InputParam::Items(vec![item.clone()]);
+                }
+            }
+        }
     }
 }
 

crates/llm_gateway/src/stream_context.rs

@@ -229,6 +229,14 @@ impl StreamContext {
             }
         }
 
+        // Apply any extra headers configured on the provider (e.g., ChatGPT-Account-Id, originator)
+        let headers = self.llm_provider().headers.clone();
+        if let Some(headers) = headers {
+            for (key, value) in &headers {
+                self.set_http_request_header(key, Some(value));
+            }
+        }
+
         Ok(())
     }