Fix potential infinite auto-compact loop on context overflow

Add auto-compacted? one-shot guard to prevent Compact → Resume →
Overflow → Compact loops when context overflow persists after
compaction. Mirrors the existing auto-continued? pattern.

#391

🤖 Generated with [eca](https://eca.dev)

Co-Authored-By: eca <git@eca.dev>

Author: ericdallo

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Fix exceptions on openai responses models when creating tasks.
+- Fix potential infinite auto-compact loop when context overflow persists after compaction. #391
 
 ## 0.123.2
 

src/eca/features/chat.clj

@@ -391,7 +391,7 @@
                                     :text "Continue with the task. The previous user request was:"}]}]
                        user-messages)
                :auto-compact
-               chat-ctx))))
+               (assoc chat-ctx :auto-compacted? true)))))
     nil))
 
 (defn ^:private assert-compatible-apis-between-models!
@@ -527,7 +527,8 @@
                   (when (= :idle (get-in @db* [:chats chat-id :status]))
                     (db/update-workspaces-cache! @db* metrics)))))))
         (lifecycle/send-content! chat-ctx :system {:type :progress :state :running :text "Waiting model"})
-        (if (lifecycle/auto-compact? chat-id agent full-model config @db*)
+        (if (and (lifecycle/auto-compact? chat-id agent full-model config @db*)
+                 (not (:auto-compacted? chat-ctx)))
           (trigger-auto-compact! chat-ctx all-tools user-messages)
           (future* config
             (try
@@ -636,7 +637,8 @@
                                              (do (swap! db* update-in [:chats chat-id] dissoc :compact-done?)
                                                  (lifecycle/finish-chat-prompt! :idle chat-ctx)
                                                  nil)
-                                             (if (lifecycle/auto-compact? chat-id agent full-model config @db*)
+                                             (if (and (lifecycle/auto-compact? chat-id agent full-model config @db*)
+                                                      (not (:auto-compacted? chat-ctx)))
                                                (trigger-auto-compact! chat-ctx tc-all-tools tc-user-messages)
                                                (do
                                                  (consume-steer-message! chat-id db* chat-ctx add-to-history!)
@@ -742,7 +744,8 @@
                                   compacting? (or (get-in db [:chats chat-id :compacting?])
                                                   (get-in db [:chats chat-id :auto-compacting?]))]
                               (if (and (= :context-overflow error-type)
-                                       (not compacting?))
+                                       (not compacting?)
+                                       (not (:auto-compacted? chat-ctx)))
                                 (do
                                   (logger/warn logger-tag "Context overflow detected, pruning tool results and auto-compacting"
                                                {:chat-id chat-id})

test/eca/features/chat_test.clj

@@ -197,6 +197,44 @@
                 :role :system}]}
              (h/messages)))))))
 
+(deftest context-overflow-auto-compact-guard-test
+  (testing "context overflow after auto-compact reports error instead of looping"
+    (h/reset-components!)
+    (let [api-call-count* (atom 0)
+          auto-compact-count* (atom 0)]
+      (with-redefs-fn
+        {#'f.chat/trigger-auto-compact!
+         (fn [chat-ctx _all-tools user-messages]
+           (swap! auto-compact-count* inc)
+           (#'f.chat/prompt-messages!
+            user-messages
+            :auto-compact
+            (assoc chat-ctx :auto-compacted? true)))}
+        (fn []
+          (let [{:keys [chat-id]}
+                (prompt!
+                 {:message "Do something"}
+                 {:all-tools-mock (constantly [])
+                  :api-mock
+                  (fn [{:keys [on-error]}]
+                    (swap! api-call-count* inc)
+                    (on-error {:error/type :context-overflow
+                               :message "token limit exceeded"}))})]
+            (is (= 1 @auto-compact-count*)
+                "auto-compact should trigger exactly once, not loop")
+            (is (= 2 @api-call-count*)
+                "LLM should be called exactly twice: initial prompt and resume after compact")
+            (is (match?
+                 {:chat-content-received
+                  (m/embeds [{:role :system
+                              :content {:type :text
+                                        :text "Context window exceeded. Auto-compacting conversation..."}}
+                             {:role :system
+                              :content {:type :text
+                                        :text "\n\ntoken limit exceeded"}}])}
+                 (h/messages))
+                "Should show auto-compact attempt and then the final error")))))))
+
 (defn ^:private make-tool-output-msg [id text]
   {:role "tool_call_output"
    :content {:id id