fix(kiro): use neutral placeholder for tool-result-only user turns

Replace the literal 'continue' placeholder on tool-result-only user turns with 'Tool results provided.' to prevent models from treating it as a new user instruction.

open-sse/translator/concerns/kiroConversation.js

@@ -5,6 +5,20 @@ import {
 } from "../../config/kiroConstants.js";
 
 const TOOL_ID_PATTERN = /^[a-zA-Z0-9_-]+$/;
+
+/**
+ * Kiro rejects user turns with empty `content`, so a turn that only carries
+ * tool results needs placeholder text. It must not read like a user
+ * instruction: with "continue", models answer the word itself ("Nothing in
+ * progress to continue") and drop the task they were in the middle of.
+ */
+export const KIRO_TOOL_RESULTS_PLACEHOLDER = "Tool results provided.";
+export const KIRO_EMPTY_USER_PLACEHOLDER = "continue";
+
+/** Placeholder content for a user turn with no text of its own. */
+export function kiroEmptyUserContent(hasToolResults) {
+  return hasToolResults ? KIRO_TOOL_RESULTS_PLACEHOLDER : KIRO_EMPTY_USER_PLACEHOLDER;
+}
 const TOOL_NAME_PATTERN = /[^a-zA-Z0-9_-]/g;
 
 function clone(value) {
@@ -174,7 +188,8 @@ function normalizeTurns(history, currentMessage, modelId) {
 
   for (const turn of turns) {
     if (turn.userInputMessage) {
-      turn.userInputMessage.content = text(turn.userInputMessage.content).trim() || "continue";
+      turn.userInputMessage.content = text(turn.userInputMessage.content).trim()
+        || kiroEmptyUserContent(turn.userInputMessage.userInputMessageContext?.toolResults?.length > 0);
       turn.userInputMessage.modelId ||= modelId;
       if (turn.userInputMessage.userInputMessageContext?.tools) {
         delete turn.userInputMessage.userInputMessageContext.tools;

open-sse/translator/request/claude-to-kiro.js

@@ -34,6 +34,7 @@ import { ROLE, CLAUDE_BLOCK } from "../schema/index.js";
 import {
   canonicalizeKiroConversation,
   normalizeKiroToolSpecs,
+  kiroEmptyUserContent,
 } from "../concerns/kiroConversation.js";
 
 /**
@@ -53,7 +54,8 @@ function convertClaudeMessagesToKiro(messages, model) {
 
   const flushPending = () => {
     if (currentRole === ROLE.USER) {
-      const content = pendingUserContent.join("\n\n").trim() || "continue";
+      const content = pendingUserContent.join("\n\n").trim()
+        || kiroEmptyUserContent(pendingToolResults.length > 0);
       const userMsg = { userInputMessage: { content, modelId: model } };
 
       if (pendingImages.length > 0) {

open-sse/translator/request/openai-to-kiro.js

@@ -23,6 +23,7 @@ import { ROLE, OPENAI_BLOCK, CLAUDE_BLOCK } from "../schema/index.js";
 import {
   canonicalizeKiroConversation,
   normalizeKiroToolSpecs,
+  kiroEmptyUserContent,
 } from "../concerns/kiroConversation.js";
 
 /**
@@ -51,7 +52,8 @@ function convertMessages(messages, model) {
 
   const flushPending = () => {
     if (currentRole === "user") {
-      const content = pendingUserContent.join("\n\n").trim() || "continue";
+      const content = pendingUserContent.join("\n\n").trim()
+        || kiroEmptyUserContent(pendingToolResults.length > 0);
       const userMsg = {
         userInputMessage: {
           content: content,

tests/translator/__snapshots__/golden-request.test.js.snap

@@ -239,7 +239,7 @@ exports[`GOLDEN request: OpenAI → Kiro > full body (image base64 + tool_result
       "userInputMessage": {
         "content": "[Context: Current time is <TS>
 
-continue",
+Tool results provided.",
         "modelId": "claude-sonnet-4.5",
         "origin": "AI_EDITOR",
         "userInputMessageContext": {
@@ -281,7 +281,11 @@ continue",
     "history": [
       {
         "userInputMessage": {
-          "content": "You are helpful.
+          "content": "[Context: Current time is <TS>
+
+<instructions>
+You are helpful.
+</instructions>
 
 What's in this image?",
           "images": [

tests/unit/kiro-tool-result-placeholder.test.js

@@ -0,0 +1,115 @@
+import { describe, it, expect } from "vitest";
+import { openaiToKiroRequest } from "../../open-sse/translator/request/openai-to-kiro.js";
+import { claudeToKiroRequest } from "../../open-sse/translator/request/claude-to-kiro.js";
+import {
+  canonicalizeKiroConversation,
+  KIRO_TOOL_RESULTS_PLACEHOLDER,
+  KIRO_EMPTY_USER_PLACEHOLDER,
+} from "../../open-sse/translator/concerns/kiroConversation.js";
+
+const TOOLS_OPENAI = [{
+  type: "function",
+  function: {
+    name: "get_weather",
+    description: "Get weather",
+    parameters: { type: "object", properties: { city: { type: "string" } }, required: ["city"] },
+  },
+}];
+
+const TOOLS_CLAUDE = [{
+  name: "get_weather",
+  description: "Get weather",
+  input_schema: { type: "object", properties: { city: { type: "string" } }, required: ["city"] },
+}];
+
+function allUserContents(payload) {
+  const state = payload.conversationState;
+  return [
+    ...state.history.filter((t) => t.userInputMessage).map((t) => t.userInputMessage.content),
+    state.currentMessage.userInputMessage.content,
+  ];
+}
+
+describe("Kiro tool-result-only turns", () => {
+  it("OpenAI → Kiro: tool message gets a neutral placeholder, not \"continue\"", () => {
+    const payload = openaiToKiroRequest("claude-sonnet-4.6", {
+      tools: TOOLS_OPENAI,
+      messages: [
+        { role: "user", content: "The secret word is PINEAPPLE. Weather in Jakarta?" },
+        { role: "assistant", content: null, tool_calls: [{ id: "call_1", type: "function", function: { name: "get_weather", arguments: "{\"city\":\"Jakarta\"}" } }] },
+        { role: "tool", tool_call_id: "call_1", content: "32C, humid" },
+      ],
+    }, true, {});
+
+    const current = payload.conversationState.currentMessage.userInputMessage;
+    expect(current.content).toContain(KIRO_TOOL_RESULTS_PLACEHOLDER);
+    expect(current.content).not.toMatch(/\bcontinue\b/);
+    expect(current.userInputMessageContext.toolResults).toHaveLength(1);
+    expect(allUserContents(payload).join("\n")).toContain("PINEAPPLE");
+  });
+
+  it("Claude → Kiro: tool_result-only user message gets a neutral placeholder", () => {
+    const payload = claudeToKiroRequest("claude-sonnet-4.6", {
+      tools: TOOLS_CLAUDE,
+      messages: [
+        { role: "user", content: "The secret word is PINEAPPLE. Weather in Jakarta?" },
+        { role: "assistant", content: [{ type: "tool_use", id: "toolu_1", name: "get_weather", input: { city: "Jakarta" } }] },
+        { role: "user", content: [{ type: "tool_result", tool_use_id: "toolu_1", content: "32C, humid" }] },
+      ],
+    }, true, {});
+
+    const current = payload.conversationState.currentMessage.userInputMessage;
+    expect(current.content).toContain(KIRO_TOOL_RESULTS_PLACEHOLDER);
+    expect(current.content).not.toMatch(/\bcontinue\b/);
+    expect(current.userInputMessageContext.toolResults).toHaveLength(1);
+  });
+
+  it("keeps real user text when a turn has both text and tool results", () => {
+    const payload = claudeToKiroRequest("claude-sonnet-4.6", {
+      tools: TOOLS_CLAUDE,
+      messages: [
+        { role: "user", content: "Weather in Jakarta?" },
+        { role: "assistant", content: [{ type: "tool_use", id: "toolu_1", name: "get_weather", input: { city: "Jakarta" } }] },
+        { role: "user", content: [
+          { type: "tool_result", tool_use_id: "toolu_1", content: "32C" },
+          { type: "text", text: "Now answer in one word." },
+        ] },
+      ],
+    }, true, {});
+
+    const current = payload.conversationState.currentMessage.userInputMessage;
+    expect(current.content).toContain("Now answer in one word.");
+    expect(current.content).not.toContain(KIRO_TOOL_RESULTS_PLACEHOLDER);
+  });
+
+  it("canonicalize: history turn with tool results and no text uses the placeholder", () => {
+    const result = canonicalizeKiroConversation({
+      history: [
+        { userInputMessage: { content: "Weather in Jakarta?", modelId: "m" } },
+        { assistantResponseMessage: { content: "", toolUses: [{ toolUseId: "t1", name: "get_weather", input: { city: "Jakarta" } }] } },
+        { userInputMessage: { content: "", modelId: "m", userInputMessageContext: { toolResults: [{ toolUseId: "t1", status: "success", content: [{ text: "32C" }] }] } } },
+        { assistantResponseMessage: { content: "It is 32C." } },
+      ],
+      currentMessage: { userInputMessage: { content: "Hot or cold?", modelId: "m" } },
+      modelId: "m",
+      toolSpecs: [{ toolSpecification: { name: "get_weather", description: "Get weather", inputSchema: { json: { type: "object", properties: {} } } } }],
+      nameMap: new Map([["get_weather", "get_weather"]]),
+    });
+
+    expect(result.valid).toBe(true);
+    expect(result.history[2].userInputMessage.content).toBe(KIRO_TOOL_RESULTS_PLACEHOLDER);
+  });
+
+  it("canonicalize: an empty turn without tool results still falls back to \"continue\"", () => {
+    const result = canonicalizeKiroConversation({
+      history: [{ assistantResponseMessage: { content: "Hello" } }],
+      currentMessage: { userInputMessage: { content: "", modelId: "m" } },
+      modelId: "m",
+      toolSpecs: [],
+      nameMap: new Map(),
+    });
+
+    expect(result.history[0].userInputMessage.content).toBe(KIRO_EMPTY_USER_PLACEHOLDER);
+    expect(result.currentMessage.userInputMessage.content).toBe(KIRO_EMPTY_USER_PLACEHOLDER);
+  });
+});