fix: truncate oversized failed tool output

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Truncate oversized failed tool output, preserving full logs on disk instead of overflowing the model context.
+
 ## 0.147.3
 
 - Fix remote server silently falling back to HTTP when the TLS private key is in SEC1 EC format; validate keys before caching and log HTTP fallback. #521

src/eca/features/tools/util.clj

@@ -242,13 +242,14 @@
   [result config tool-call-id]
   (let [max-lines (get-in config [:toolCall :outputTruncation :lines])
         max-size-kb (get-in config [:toolCall :outputTruncation :sizeKb])]
-    (if (or (nil? max-lines) (nil? max-size-kb) (:error result))
+    (if (or (nil? max-lines) (nil? max-size-kb))
       result
       (let [full-text (contents->text (:contents result))]
         (if (exceeds-truncation-limits? full-text max-lines max-size-kb)
           (let [saved-path (cache/save-tool-call-output! tool-call-id full-text)
                 truncated (truncate-text full-text max-lines max-size-kb)
-                notice (str "\n\n[OUTPUT TRUNCATED] The tool call succeeded but the output was truncated. "
+                outcome (if (:error result) "failed" "succeeded")
+                notice (str "\n\n[OUTPUT TRUNCATED] The tool call " outcome " and the output was truncated. "
                             "Full output saved to: " saved-path "\n"
                             "Use `eca__grep` or `eca__read_file` with offset/limit to view specific sections. Do not full read the file.")]
             (assoc result :contents [{:type :text

test/eca/features/tools/util_test.clj

@@ -66,12 +66,18 @@
       (is (string/includes? output-text "[OUTPUT TRUNCATED]"))
       (is (false? (:error truncated))))))
 
-(deftest maybe-truncate-output-skips-error-results-test
-  (testing "does not truncate error results"
+(deftest maybe-truncate-output-truncates-error-results-test
+  (testing "truncates error results and preserves the failure status"
     (let [long-text (string/join "\n" (repeat 5000 "error line"))
           result {:error true :contents [{:type :text :text long-text}]}
-          config (config-with-truncation 100 1)]
-      (is (= result (tools.util/maybe-truncate-output result config "call-err"))))))
+          config (config-with-truncation 100 1)
+          truncated (tools.util/maybe-truncate-output result config "call-err")
+          output-text (-> truncated :contents first :text)]
+      (is (true? (:error truncated)))
+      (is (string/includes? output-text "[OUTPUT TRUNCATED]"))
+      (is (string/includes? output-text "The tool call failed"))
+      (is (string/includes? output-text "Full output saved to:"))
+      (is (not (string/includes? output-text (string/join "\n" (repeat 5000 "error line"))))))))
 
 (deftest maybe-truncate-output-nil-config-test
   (testing "returns result unchanged when truncation config is nil"