Improve error handling for incompatible models messages in chat.

Related to #209

Author: ericdallo

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Improve error handleing for incompatible models messages in chat. #209
+
 ## 0.87.2
 
 - Fix openai-chat tool call + support for Mistral API #233

docs/protocol.md

@@ -505,7 +505,7 @@ interface ChatPromptResponse {
     /**
      * What the server is doing after receing this prompt
      */
-    status: 'prompting' | 'login';
+    status: 'prompting' | 'login' | 'error';
 }
 ```
 

src/eca/features/chat.clj

@@ -16,11 +16,11 @@
    [eca.features.tools :as f.tools]
    [eca.features.tools.mcp :as f.mcp]
    [eca.llm-api :as llm-api]
+   [eca.llm-util :as llm-util]
    [eca.logger :as logger]
    [eca.messenger :as messenger]
    [eca.metrics :as metrics]
-   [eca.shared :as shared :refer [assoc-some future*]]
-   [eca.llm-util :as llm-util]))
+   [eca.shared :as shared :refer [assoc-some future*]]))
 
 (set! *warn-on-reflection* true)
 
@@ -1006,6 +1006,22 @@
                   nil)))
           {:new-messages (get-in @db* [:chats chat-id :messages])})))))
 
+(defn ^:private assert-compatible-apis-between-models!
+  "Ensure new request is compatible with last api used.
+   E.g. Anthropic is not compatible with openai and vice versa."
+  [db chat-id provider config]
+  (let [current-api (:api (llm-api/provider->api-handler provider config))
+        last-api (get-in db [:chats chat-id :last-api])]
+    (cond
+      (not last-api) nil
+      (not current-api) nil
+
+      (or (and (= :anthropic current-api)
+               (not= :anthropic last-api))
+          (and (not= :anthropic current-api)
+               (= :anthropic last-api)))
+      (throw (ex-info "Incompatible past messages in chat.\nAnthropic models are only compatible with other Anthropic models, switch models or start a new chat." {})))))
+
 (defn ^:private prompt-messages!
   "Send user messages to LLM with hook processing.
    source-type controls hook behavior.
@@ -1075,6 +1091,7 @@
             on-usage-updated (fn [usage]
                                (when-let [usage (shared/usage-msg->usage usage full-model chat-ctx)]
                                  (send-content! chat-ctx :system (merge {:type :usage} usage))))]
+        (assert-compatible-apis-between-models! db chat-id provider config)
         (when-not (get-in db [:chats chat-id :title])
           (future* config
             (when-let [{:keys [output-text]} (llm-api/sync-prompt!
@@ -1109,6 +1126,7 @@
                                           (doseq [message user-messages]
                                             (add-to-history!
                                              (assoc message :content-id (:user-content-id chat-ctx))))
+                                          (swap! db* assoc-in [:chats chat-id :last-api] (:api (llm-api/provider->api-handler provider config)))
                                           (send-content! chat-ctx :system {:type :progress
                                                                            :state :running
                                                                            :text "Generating"}))
@@ -1349,17 +1367,24 @@
     (send-content! chat-ctx :user {:type :text
                                    :content-id (:user-content-id chat-ctx)
                                    :text (str message "\n")})
-    (case (:type decision)
-      :mcp-prompt (send-mcp-prompt! decision chat-ctx)
-      :eca-command (handle-command! decision chat-ctx)
-      :prompt-message (prompt-messages! user-messages :prompt-message chat-ctx))
-    (metrics/count-up! "prompt-received"
-                       {:full-model full-model
-                        :behavior behavior}
-                       metrics)
-    {:chat-id chat-id
-     :model full-model
-     :status :prompting}))
+    (try
+      (case (:type decision)
+        :mcp-prompt (send-mcp-prompt! decision chat-ctx)
+        :eca-command (handle-command! decision chat-ctx)
+        :prompt-message (prompt-messages! user-messages :prompt-message chat-ctx))
+      (metrics/count-up! "prompt-received"
+                         {:full-model full-model
+                          :behavior behavior}
+                         metrics)
+      {:chat-id chat-id
+       :model full-model
+       :status :prompting}
+      (catch Exception e
+        (send-content! chat-ctx :system {:type :text :text (str "Error: " (ex-message e))})
+        (finish-chat-prompt! :idle chat-ctx)
+        {:chat-id chat-id
+         :model full-model
+         :status :error}))))
 
 (defn tool-call-approve [{:keys [chat-id tool-call-id save]} db* messenger metrics]
   (let [chat-ctx {:chat-id chat-id

src/eca/llm_api.clj

@@ -62,6 +62,27 @@
 (defn ^:private real-model-name [model model-capabilities]
   (or (:model-name model-capabilities) model))
 
+(defn provider->api-handler [provider config]
+  (cond
+    (= "openai" provider) {:api :openai-responses
+                           :handler llm-providers.openai/create-response!}
+    (= "anthropic" provider) {:api :anthropic
+                              :handler llm-providers.anthropic/chat!}
+    (= "github-copilot" provider) {:api :openai-chat
+                                   :handler llm-providers.openai-chat/chat-completion!}
+    (= "google" provider) {:api :openai-chat
+                           :handler llm-providers.openai-chat/chat-completion!}
+    (= "ollama" provider) {:api :ollama
+                           :handler llm-providers.ollama/chat!}
+    :else (case (get-in config [:providers provider :api])
+            ("openai-responses" "openai") {:api :openai-responses
+                                           :handler llm-providers.openai/create-response!}
+            "anthropic" {:api :anthropic
+                         :handler llm-providers.anthropic/chat!}
+            "openai-chat" {:api :openai-chat
+                           :handler llm-providers.openai-chat/chat-completion!}
+            nil)))
+
 (defn ^:private prompt!
   [{:keys [provider model model-capabilities instructions user-messages config
            on-message-received on-error on-prepare-tool-call on-tools-called on-reason on-usage-updated
@@ -78,6 +99,7 @@
         extra-payload (:extraPayload model-config)
         [auth-type api-key] (llm-util/provider-api-key provider provider-auth config)
         api-url (llm-util/provider-api-url provider config)
+        {:keys [handler]} (provider->api-handler provider config)
         callbacks (when-not sync?
                     {:on-message-received on-message-received
                      :on-error on-error
@@ -89,7 +111,7 @@
       (when-not api-url (throw (ex-info (format "API url not found.\nMake sure you have provider '%s' configured properly." provider) {})))
       (cond
         (= "openai" provider)
-        (llm-providers.openai/create-response!
+        (handler
          {:model real-model
           :instructions instructions
           :user-messages user-messages
@@ -107,7 +129,7 @@
          callbacks)
 
         (= "anthropic" provider)
-        (llm-providers.anthropic/chat!
+        (handler
          {:model real-model
           :instructions instructions
           :user-messages user-messages
@@ -124,7 +146,7 @@
          callbacks)
 
         (= "github-copilot" provider)
-        (llm-providers.openai-chat/chat-completion!
+        (handler
          {:model real-model
           :instructions instructions
           :user-messages user-messages
@@ -146,7 +168,7 @@
          callbacks)
 
         (= "google" provider)
-        (llm-providers.openai-chat/chat-completion!
+        (handler
          {:model real-model
           :instructions instructions
           :user-messages user-messages
@@ -166,7 +188,7 @@
          callbacks)
 
         (= "ollama" provider)
-        (llm-providers.ollama/chat!
+        (handler
          {:api-url api-url
           :reason? (:reason? model-capabilities)
           :supports-image? supports-image?
@@ -178,18 +200,12 @@
           :extra-payload extra-payload}
          callbacks)
 
-        model-config
-        (let [provider-fn (case (:api provider-config)
-                            ("openai-responses"
-                             "openai") llm-providers.openai/create-response!
-                            "anthropic" llm-providers.anthropic/chat!
-                            "openai-chat" llm-providers.openai-chat/chat-completion!
-                            (on-error {:message (format "Unknown model %s for provider %s" (:api provider-config) provider)}))
-              url-relative-path (:completionUrlRelativePath provider-config)
+        (and model-config handler)
+        (let [url-relative-path (:completionUrlRelativePath provider-config)
               think-tag-start (:thinkTagStart provider-config)
               think-tag-end (:thinkTagEnd provider-config)
               http-client (:httpClient provider-config)]
-          (provider-fn
+          (handler
            {:model real-model
             :instructions instructions
             :user-messages user-messages