fix(caching): read list-form function_call_output text in semantic cache prompts

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

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

@@ -184,6 +184,10 @@ fn collect_input_text(value: &Value, parts: &mut Vec<String>) {
                 collect_input_text(content, parts);
                 return;
             }
+            if let Some(output) = map.get("output").filter(|output| output.is_array()) {
+                collect_input_text(output, parts);
+                return;
+            }
             for key in ["text", "output", "input_text", "output_text"] {
                 if let Some(Value::String(text)) = map.get(key)
                     && push_trimmed(text, parts)

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

@@ -191,6 +191,15 @@ fn prompt_from_messages_reads_messages_only(
     ])),
     Some("model dump prompt\ndict prompt\ninline prompt"),
 )]
+#[case::function_call_output_blocks(
+    None,
+    Some(json!([
+        {"role": "user", "content": "update the config"},
+        {"type": "function_call", "call_id": "c1", "name": "write_file", "arguments": "{\"path\": \"a\"}"},
+        {"type": "function_call_output", "call_id": "c1", "output": [{"type": "input_text", "text": "wrote a"}]},
+    ])),
+    Some("update the config\nwrote a"),
+)]
 #[case::object_content(
     None,
     Some(json!({"content": [{"text": "object content prompt"}]})),

litellm/caching/redis_semantic_cache.py

@@ -296,6 +296,11 @@ class RedisSemanticCache(BaseCache):
                 cls._collect_responses_input_text(content, prompt_parts)
                 return
 
+            output = value.get("output")
+            if isinstance(output, list):
+                cls._collect_responses_input_text(output, prompt_parts)
+                return
+
             for text_key in ("text", "output", "input_text", "output_text"):
                 text_value = value.get(text_key)
                 if isinstance(text_value, str):

tests/unit/caching/test_redis_semantic_cache.py

@@ -568,6 +568,20 @@ def test_redis_semantic_cache_set_cache_flattens_structured_responses_input():
     )
 
 
+def test_redis_semantic_cache_prompt_extraction_reads_function_call_output_blocks():
+    from litellm.caching.redis_semantic_cache import RedisSemanticCache
+
+    prompt = RedisSemanticCache._get_prompt_from_kwargs(
+        input=[
+            {"role": "user", "content": "update the config"},
+            {"type": "function_call", "call_id": "c1", "name": "write_file", "arguments": '{"path": "a"}'},
+            {"type": "function_call_output", "call_id": "c1", "output": [{"type": "input_text", "text": "wrote a"}]},
+        ]
+    )
+
+    assert prompt == "update the config\nwrote a"
+
+
 def test_redis_semantic_cache_prompt_extraction_prefers_messages():
     from litellm.caching.redis_semantic_cache import RedisSemanticCache