refactor(sse): dedup fallback tool_call id helper

open-sse/translator/helpers/toolCallHelper.ts

@@ -2,6 +2,12 @@
 
 const ALPHANUM9 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
+// Fallback streaming tool_call id when a provider response omits one (index optional).
+// `call_<ts>` when no index is given; `call_<index>_<ts>` when an index is supplied.
+export function fallbackToolCallId(index?: number): string {
+  return index === undefined ? `call_${Date.now()}` : `call_${index}_${Date.now()}`;
+}
+
 // Generate unique tool call ID (default long form)
 export function generateToolCallId() {
   return `call_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 9)}`;

open-sse/translator/response/kiro-to-openai.ts

@@ -4,6 +4,7 @@
  */
 import { register } from "../registry.ts";
 import { FORMATS } from "../formats.ts";
+import { fallbackToolCallId } from "../helpers/toolCallHelper.ts";
 
 /**
  * Parse Kiro SSE event and convert to OpenAI format
@@ -116,7 +117,7 @@ export function convertKiroToOpenAI(chunk, state) {
   // Handle tool use events
   if (eventType === "toolUseEvent" || data.toolUseEvent) {
     const toolUse = data.toolUseEvent || data;
-    const toolCallId = toolUse.toolUseId || `call_${Date.now()}`;
+    const toolCallId = toolUse.toolUseId || fallbackToolCallId();
     const toolName = toolUse.name || "";
     const toolInput = toolUse.input || {};
 

open-sse/translator/response/openai-responses.ts

@@ -5,6 +5,7 @@
 import { register } from "../registry.ts";
 import { FORMATS } from "../formats.ts";
 import { appendToolCallArgumentDelta } from "../../utils/toolCallArguments.ts";
+import { fallbackToolCallId } from "../helpers/toolCallHelper.ts";
 
 function normalizeToolName(value) {
   return typeof value === "string" ? value.trim() : "";
@@ -615,7 +616,7 @@ function openaiResponsesToOpenAIResponseStream(chunk, state) {
   // Function call started
   if (eventType === "response.output_item.added" && data.item?.type === "function_call") {
     const item = data.item;
-    state.currentToolCallId = item.call_id || `call_${Date.now()}`;
+    state.currentToolCallId = item.call_id || fallbackToolCallId();
     state.currentToolCallArgsBuffer = ""; // reset per-call arg buffer
     state.currentToolCallDeferred = false;
 
@@ -694,7 +695,7 @@ function openaiResponsesToOpenAIResponseStream(chunk, state) {
     const item = data.item;
     const buffered = state.currentToolCallArgsBuffer || "";
     const currentIndex = state.toolCallIndex; // capture before increment
-    const callId = item.call_id || state.currentToolCallId || `call_${Date.now()}`;
+    const callId = item.call_id || state.currentToolCallId || fallbackToolCallId();
     const toolName = normalizeToolName(item.name);
 
     if (state.currentToolCallDeferred) {

tests/unit/translator-helper-branches.test.ts

@@ -599,6 +599,26 @@ test("fixMissingToolResponses keeps OpenAI role:tool when assistant uses OpenAI
   assert.equal(fixed.messages[2].tool_call_id, "call_b");
 });
 
+test("fallbackToolCallId returns the right id shape with and without an index", () => {
+  const noIndex = toolCallHelper.fallbackToolCallId();
+  assert.match(
+    noIndex,
+    /^call_\d+$/,
+    "no-index form must be `call_<ts>` (matches kiro/openai-responses fallback shape)"
+  );
+
+  const withIndex = toolCallHelper.fallbackToolCallId(2);
+  assert.match(
+    withIndex,
+    /^call_2_\d+$/,
+    "index form must be `call_<i>_<ts>` (matches indexed fallback shape)"
+  );
+
+  // index 0 is falsy but defined — must still produce the indexed form, not the no-index form.
+  const zeroIndex = toolCallHelper.fallbackToolCallId(0);
+  assert.match(zeroIndex, /^call_0_\d+$/, "index 0 must use the indexed form, not the bare form");
+});
+
 test("translateRequest replays cached reasoning-only messages when interleaved field is reasoning_content", () => {
   clearReasoningCacheAll();
   clearModelsDevCapabilities();