fix(caching): keep structured function_call_output text in semantic prompts

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm-rust/crates/cache/src/semantic.rs

@@ -199,10 +199,13 @@ fn collect_input_text(value: &Value, parts: &mut Vec<String>) {
                 return;
             }
             for key in ["text", "output", "input_text", "output_text"] {
-                if let Some(Value::String(text)) = map.get(key)
-                    && push_trimmed(text, parts)
-                {
-                    return;
+                match map.get(key) {
+                    Some(nested @ Value::Array(_)) => {
+                        collect_input_text(nested, parts);
+                        return;
+                    }
+                    Some(Value::String(text)) if push_trimmed(text, parts) => return,
+                    _ => {}
                 }
             }
         }

litellm-rust/crates/cache/tests/semantic.rs

@@ -240,6 +240,14 @@ fn prompt_from_messages_reads_messages_only(
     ])),
     Some("update the config\n{\"name\":\"write_file\",\"arguments\":\"{\\\"path\\\":\\\"a.yaml\\\"}\"}\nok"),
 )]
+#[case::responses_structured_function_call_output(
+    None,
+    Some(json!([
+        {"type": "function_call", "call_id": "c1", "name": "write_file", "arguments": "{}"},
+        {"type": "function_call_output", "call_id": "c1", "output": [{"type": "input_text", "text": "denied"}]},
+    ])),
+    Some("{\"name\":\"write_file\",\"arguments\":\"{}\"}\ndenied"),
+)]
 fn prompt_from_context_matches_python(
     #[case] messages: Option<Value>,
     #[case] input: Option<Value>,

litellm/caching/redis_semantic_cache.py

@@ -299,6 +299,9 @@ class RedisSemanticCache(BaseCache):
 
             for text_key in ("text", "output", "input_text", "output_text"):
                 text_value = value.get(text_key)
+                if isinstance(text_value, (list, tuple)):
+                    cls._collect_responses_input_text(text_value, prompt_parts)
+                    return
                 if isinstance(text_value, str):
                     stripped_text = text_value.strip()
                     if stripped_text:

tests/unit/caching/test_redis_semantic_cache.py

@@ -614,6 +614,27 @@ def test_redis_semantic_cache_prompt_extraction_keeps_responses_function_calls()
     assert prompt == 'update the config\n{"name":"write_file","arguments":"{\\"path\\":\\"a.yaml\\"}"}\nok'
 
 
+def test_redis_semantic_cache_prompt_extraction_keeps_structured_function_call_outputs():
+    from litellm.caching.redis_semantic_cache import RedisSemanticCache
+
+    def prompt_for(output_text: str) -> str | None:
+        return RedisSemanticCache._get_prompt_from_kwargs(
+            input=[
+                {"type": "message", "role": "user", "content": [{"type": "input_text", "text": "write hello"}]},
+                {"type": "function_call", "call_id": "c1", "name": "write_file", "arguments": '{"path":"a.txt"}'},
+                {
+                    "type": "function_call_output",
+                    "call_id": "c1",
+                    "output": [{"type": "input_text", "text": output_text}],
+                },
+            ]
+        )
+
+    expected_call = '{"name":"write_file","arguments":"{\\"path\\":\\"a.txt\\"}"}'
+    assert prompt_for("wrote 5 bytes") == f"write hello\n{expected_call}\nwrote 5 bytes"
+    assert prompt_for("wrote 5 bytes") != prompt_for("PermissionError")
+
+
 def test_redis_semantic_cache_prompt_extraction_handles_model_objects():
     from litellm.caching.redis_semantic_cache import RedisSemanticCache