Support provider-level extraHeaders

Sent on completion and models list requests, model-level extraHeaders
win on conflicts.

Closes #517

Author: ericdallo

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Support provider-level `extraHeaders`, sent on completion and models list requests. #517
+
 ## 0.144.0
 
 - Add built-in variants for `glm-5.2` (case-insensitive): `none`, `medium`, `high`.

docs/config.json

@@ -650,6 +650,14 @@
             "okhttp"
           ]
         },
+        "extraHeaders": {
+          "type": "object",
+          "description": "Additional HTTP headers to include in all requests to this provider (completions and models list fetching). Model-level extraHeaders take precedence on conflicts.",
+          "markdownDescription": "Additional HTTP headers to include in all requests to this provider (completions and models list fetching). Model-level `extraHeaders` take precedence on conflicts.",
+          "additionalProperties": {
+            "type": "string"
+          }
+        },
         "retryRules": {
           "type": "array",
           "description": "Custom retry rules. Each rule can match by HTTP status code and/or error text regex pattern. When matched, the request is retried with exponential backoff.",

docs/config/models.md

@@ -368,6 +368,7 @@ Schema:
 | `thinkTagEnd`                     | string  | Optional override the think end tag for openai-chat (Default: "</think>") api                                | No       |
 | `httpClient`                      | map     | Allow customize the http-client for this provider requests, like changing http version                       | No       |
 | `retryRules`                      | array   | Custom retry rules that match by HTTP status and/or error pattern (see [Retry Rules](#retry-rules))    | No       |
+| `extraHeaders`                    | map     | Extra headers sent on all requests to this provider (completion and models list fetch). Model-level `extraHeaders` win on conflicts | No       |
 | `models`                          | map     | Key: model name, value: its config                                                                           | Yes      |
 | `models <model> extraPayload`     | map     | Extra payload sent in body to LLM                                                                            | No       |
 | `models <model> extraHeaders`     | map     | Extra headers sent to LLM request                                                                            | No       |

src/eca/config.clj

@@ -540,6 +540,7 @@
    :stringfy-key
    [[:agent]
     [:providers]
+    [:providers :ANY :extraHeaders]
     [:providers :ANY :models]
     [:providers :ANY :models :ANY :extraHeaders]
     [:providers :ANY :models :ANY :variants]

src/eca/llm_api.clj

@@ -236,7 +236,8 @@
               (catch Exception e
                 (logger/warn logger-tag "on-history-sanitized callback failed" {:exception (ex-message e)}))))
         extra-payload (extra-payload-considering-variant model-config variant api-handler reason?)
-        extra-headers (:extraHeaders model-config)
+        extra-headers (merge (:extraHeaders provider-config)
+                             (:extraHeaders model-config))
         reasoning-history (or (:reasoningHistory model-config) :all)
         [auth-type api-key] (llm-util/provider-api-key provider provider-auth config)
         api-url (llm-util/provider-api-url provider config)

src/eca/models.clj

@@ -45,17 +45,19 @@
     nil))
 
 (defn ^:private models-endpoint-headers
-  [provider auth-type api-type api-key]
+  [provider auth-type api-type api-key extra-headers]
   (let [oauth? (= :auth/oauth auth-type)
         anthropic? (= "anthropic" api-type)]
     (client/merge-llm-headers
-     (assoc-some
-      (cond-> {"Content-Type" "application/json"}
-        (= "github-copilot" provider) (merge (llm-util/copilot-ide-headers)))
-      "anthropic-version" (when anthropic? "2023-06-01")
-      "x-api-key" (when (and api-key anthropic? (not oauth?)) api-key)
-      "Authorization" (when (and api-key (or oauth? (not anthropic?))) (str "Bearer " api-key))
-      "anthropic-beta" (when (and anthropic? oauth?) "oauth-2025-04-20")))))
+     (merge
+      (assoc-some
+       (cond-> {"Content-Type" "application/json"}
+         (= "github-copilot" provider) (merge (llm-util/copilot-ide-headers)))
+       "anthropic-version" (when anthropic? "2023-06-01")
+       "x-api-key" (when (and api-key anthropic? (not oauth?)) api-key)
+       "Authorization" (when (and api-key (or oauth? (not anthropic?))) (str "Bearer " api-key))
+       "anthropic-beta" (when (and anthropic? oauth?) "oauth-2025-04-20"))
+      extra-headers))))
 
 (defn ^:private fetch-models-dev-data []
   (let [{:keys [status body]} (http/get models-dev-api-url
@@ -280,11 +282,11 @@
 (defn ^:private fetch-provider-native-models
   "Fetches models from provider's native /models endpoint.
    Returns a map of model-id -> {} on success, nil on failure."
-  [{:keys [api-url auth-type api-key api-type provider]}]
+  [{:keys [api-url auth-type api-key api-type provider extra-headers]}]
   (when-let [models-path (provider-models-endpoint-path api-type)]
     (let [url (shared/join-api-url api-url models-path)
           rid (llm-util/gen-rid)
-          headers (models-endpoint-headers provider auth-type api-type api-key)]
+          headers (models-endpoint-headers provider auth-type api-type api-key extra-headers)]
       (try
         (logger/debug logger-tag (format "[%s] Provider '%s': Fetching models from %s" rid provider url))
         (let [{:keys [status body]} (http/get url
@@ -339,7 +341,8 @@
                                 :api-url api-url
                                 :auth-type auth-type
                                 :api-key api-key
-                                :api-type api-type})))]
+                                :api-type api-type
+                                :extra-headers (:extraHeaders provider-config)})))]
         (logger/debug logger-tag
                       (format "Provider '%s': Discovered %d models"
                               provider (count models)))

test/eca/llm_api_test.clj

@@ -417,6 +417,32 @@
       (is (= 300 (:stream-idle-timeout-seconds @captured*))
           "anthropic handler should receive :stream-idle-timeout-seconds from top-level config"))))
 
+(deftest prompt-merges-provider-and-model-extra-headers-test
+  (testing "provider-level extraHeaders are sent and model-level ones win on conflicts"
+    (let [captured* (atom nil)]
+      (with-redefs [llm-providers.openai/create-response!
+                    (fn [opts _callbacks] (reset! captured* opts) :ok)]
+        (#'eca.llm-api/prompt!
+         {:provider "openai"
+          :model "gpt-5.2"
+          :model-capabilities {:tools true
+                               :reason? false
+                               :web-search false
+                               :model-name "gpt-5.2"}
+          :user-messages [{:role "user" :content [{:type :text :text "hi"}]}]
+          :past-messages []
+          :tools []
+          :provider-auth {:api-key "test-key"}
+          :config {:providers {"openai" {:url "https://api.openai.com"
+                                         :key "test-key"
+                                         :extraHeaders {"Ocp-Apim-Subscription-Key" "prov-secret"
+                                                        "X-Shared" "provider"}
+                                         :models {"gpt-5.2" {:extraHeaders {"X-Shared" "model"}}}}}}
+          :sync? false}))
+      (is (= {"Ocp-Apim-Subscription-Key" "prov-secret"
+              "X-Shared" "model"}
+             (:extra-headers @captured*))))))
+
 (deftest retry-delay-ms-test
   ;; Formula: (quot capped 2) + rand(0, capped)
   ;; Range: [capped/2, capped/2 + capped) = [capped/2, capped*3/2)

test/eca/models_test.clj

@@ -436,6 +436,26 @@
         (is (re-find #"^copilot-chat/" (get-in @request* [1 :headers "editor-plugin-version"])))
         (is (= "vscode-chat" (get-in @request* [1 :headers "copilot-integration-id"])))))))
 
+(deftest fetch-provider-models-sends-provider-extra-headers-test
+  (testing "Provider-level extraHeaders are sent on the native /models fetch"
+    (let [request* (atom nil)]
+      (with-redefs [http/get (fn [url opts]
+                               (reset! request* [url opts])
+                               {:status 200
+                                :body {:data [{:id "gpt-5.2"}]}})]
+        (is (match?
+             {"my-gateway" {"gpt-5.2" {}}}
+             (#'models/fetch-provider-models-with-priority
+              {:providers {"my-gateway" {:api "openai-chat"
+                                         :url "https://gateway.example.com"
+                                         :key "sk-test"
+                                         :extraHeaders {"Ocp-Apim-Subscription-Key" "apim-secret"}}}}
+              {}
+              {})))
+        (is (= "https://gateway.example.com/models" (first @request*)))
+        (is (= "apim-secret" (get-in @request* [1 :headers "Ocp-Apim-Subscription-Key"])))
+        (is (= "Bearer sk-test" (get-in @request* [1 :headers "Authorization"])))))))
+
 (deftest fetch-provider-models-with-priority-fallback-test
   (let [models-dev-data {"native-provider" {"api" "https://api.openai.com"
                                             "models" {"from-models-dev" {"id" "from-models-dev"}}}}]