Chat API: skip tool calls with missing function names (#4159)

* Chat API: skip tool calls with missing function names

Some providers send empty or absent function names in streaming
tool call deltas. Previously these produced invalid output items.

- Don't overwrite accumulated state.name with empty deltas
- Skip tool calls that never received a valid name (instead of
  falling back to 'unknown_tool')
- Apply the same defensive guard in finalize_tools and the
  non-streaming path

* Address review: defer empty-name skip to finalization

Require both call_id and name before triggering should_add,
instead of skipping eagerly when name is absent in the first
delta.  This handles providers that send id before name,
as suggested in the Codex review.

* Guard legacy function_call against empty name

Return Option<Value> from chat_legacy_function_call_to_response_item,
returning None when function_call.name is missing or empty. This covers
the legacy message.function_call path that the original guard missed.

* Remove unreachable unknown_tool fallback

---------

Co-authored-by: Jason <farion1231@gmail.com>

src-tauri/src/proxy/providers/transform_codex_chat.rs

@@ -1398,6 +1398,14 @@ fn chat_tool_calls_to_response_output_items(
 
     if let Some(tool_calls) = message.get("tool_calls").and_then(|v| v.as_array()) {
         for (index, tool_call) in tool_calls.iter().enumerate() {
+            // Skip tool calls with missing function names (defensive: some models
+            // may generate tool calls without providing a valid name)
+            let function = tool_call.get("function").unwrap_or(&Value::Null);
+            let name = function.get("name").and_then(|v| v.as_str()).unwrap_or("");
+            if name.is_empty() {
+                log::warn!("[Codex] Skipping tool call with missing name");
+                continue;
+            }
             output.push(chat_tool_call_to_response_item(
                 tool_call,
                 index,
@@ -1406,11 +1414,13 @@ fn chat_tool_calls_to_response_output_items(
             ));
         }
     } else if let Some(function_call) = message.get("function_call") {
-        output.push(chat_legacy_function_call_to_response_item(
+        if let Some(item) = chat_legacy_function_call_to_response_item(
             function_call,
             reasoning,
             tool_context,
-        ));
+        ) {
+            output.push(item);
+        }
     }
 
     output
@@ -1448,7 +1458,7 @@ fn chat_legacy_function_call_to_response_item(
     function_call: &Value,
     reasoning: Option<&str>,
     tool_context: &CodexToolContext,
-) -> Value {
+) -> Option<Value> {
     let call_id = function_call
         .get("id")
         .and_then(|v| v.as_str())
@@ -1458,10 +1468,18 @@ fn chat_legacy_function_call_to_response_item(
         .get("name")
         .and_then(|v| v.as_str())
         .unwrap_or("");
+
+    // Skip legacy function calls with missing names (defensive: some models
+    // may generate function_call without providing a valid name)
+    if name.is_empty() {
+        log::warn!("[Codex] Skipping legacy function_call with missing name");
+        return None;
+    }
+
     let arguments = canonicalize_tool_arguments(function_call.get("arguments"));
 
     let item_id = response_tool_call_item_id_from_chat_name(call_id, name, tool_context);
-    response_tool_call_item_from_chat_name(
+    Some(response_tool_call_item_from_chat_name(
         &item_id,
         "completed",
         call_id,
@@ -1469,7 +1487,7 @@ fn chat_legacy_function_call_to_response_item(
         &arguments,
         reasoning,
         tool_context,
-    )
+    ))
 }
 
 pub(crate) fn response_tool_call_item_id_from_chat_name(