Agents: recover malformed Anthropic-compatible tool call args (#42835)

* Agents: recover malformed anthropic tool call args

* Agents: add malformed tool call regression test

* Changelog: note Kimi tool call arg recovery

* Agents: repair toolcall end message snapshots

* Agents: narrow Kimi tool call arg repair

CHANGELOG.md

@@ -23,6 +23,7 @@ Docs: https://docs.openclaw.ai
 - iMessage/self-chat echo dedupe: drop reflected duplicate copies only when a matching `is_from_me` event was just seen for the same chat, text, and `created_at`, preventing self-chat loops without broad text-only suppression. Related to #32166. (#38440) Thanks @vincentkoc.
 - Mattermost/block streaming: fix duplicate message delivery (one threaded, one top-level) when block streaming is active by excluding `replyToId` from the block reply dedup key and adding an explicit `threading` dock to the Mattermost plugin. (#41362) Thanks @mathiasnagler and @vincentkoc.
 - BlueBubbles/self-chat echo dedupe: drop reflected duplicate webhook copies only when a matching `fromMe` event was just seen for the same chat, body, and timestamp, preventing self-chat loops without broad webhook suppression. Related to #32166. (#38442) Thanks @vincentkoc.
+- Models/Kimi Coding: send `anthropic-messages` tools in native Anthropic format again so `kimi-coding` stops degrading tool calls into XML/plain-text pseudo invocations instead of real `tool_use` blocks. (#38669, #39907, #40552) Thanks @opriz.
 
 ## 2026.3.11
 

src/agents/pi-embedded-runner/run/attempt.test.ts

@@ -13,6 +13,7 @@ import {
   shouldInjectOllamaCompatNumCtx,
   decodeHtmlEntitiesInObject,
   wrapOllamaCompatNumCtx,
+  wrapStreamFnRepairMalformedToolCallArguments,
   wrapStreamFnTrimToolCallNames,
 } from "./attempt.js";
 
@@ -430,6 +431,137 @@ describe("wrapStreamFnTrimToolCallNames", () => {
   });
 });
 
+describe("wrapStreamFnRepairMalformedToolCallArguments", () => {
+  function createFakeStream(params: { events: unknown[]; resultMessage: unknown }): {
+    result: () => Promise<unknown>;
+    [Symbol.asyncIterator]: () => AsyncIterator<unknown>;
+  } {
+    return {
+      async result() {
+        return params.resultMessage;
+      },
+      [Symbol.asyncIterator]() {
+        return (async function* () {
+          for (const event of params.events) {
+            yield event;
+          }
+        })();
+      },
+    };
+  }
+
+  async function invokeWrappedStream(baseFn: (...args: never[]) => unknown) {
+    const wrappedFn = wrapStreamFnRepairMalformedToolCallArguments(baseFn as never);
+    return await wrappedFn({} as never, {} as never, {} as never);
+  }
+
+  it("repairs anthropic-compatible tool arguments when trailing junk follows valid JSON", async () => {
+    const partialToolCall = { type: "toolCall", name: "read", arguments: {} };
+    const streamedToolCall = { type: "toolCall", name: "read", arguments: {} };
+    const endMessageToolCall = { type: "toolCall", name: "read", arguments: {} };
+    const finalToolCall = { type: "toolCall", name: "read", arguments: {} };
+    const partialMessage = { role: "assistant", content: [partialToolCall] };
+    const endMessage = { role: "assistant", content: [endMessageToolCall] };
+    const finalMessage = { role: "assistant", content: [finalToolCall] };
+    const baseFn = vi.fn(() =>
+      createFakeStream({
+        events: [
+          {
+            type: "toolcall_delta",
+            contentIndex: 0,
+            delta: '{"path":"/tmp/report.txt"}',
+            partial: partialMessage,
+          },
+          {
+            type: "toolcall_delta",
+            contentIndex: 0,
+            delta: "xx",
+            partial: partialMessage,
+          },
+          {
+            type: "toolcall_end",
+            contentIndex: 0,
+            toolCall: streamedToolCall,
+            partial: partialMessage,
+            message: endMessage,
+          },
+        ],
+        resultMessage: finalMessage,
+      }),
+    );
+
+    const stream = await invokeWrappedStream(baseFn);
+    for await (const _item of stream) {
+      // drain
+    }
+    const result = await stream.result();
+
+    expect(partialToolCall.arguments).toEqual({ path: "/tmp/report.txt" });
+    expect(streamedToolCall.arguments).toEqual({ path: "/tmp/report.txt" });
+    expect(endMessageToolCall.arguments).toEqual({ path: "/tmp/report.txt" });
+    expect(finalToolCall.arguments).toEqual({ path: "/tmp/report.txt" });
+    expect(result).toBe(finalMessage);
+  });
+
+  it("keeps incomplete partial JSON unchanged until a complete object exists", async () => {
+    const partialToolCall = { type: "toolCall", name: "read", arguments: {} };
+    const partialMessage = { role: "assistant", content: [partialToolCall] };
+    const baseFn = vi.fn(() =>
+      createFakeStream({
+        events: [
+          {
+            type: "toolcall_delta",
+            contentIndex: 0,
+            delta: '{"path":"/tmp',
+            partial: partialMessage,
+          },
+        ],
+        resultMessage: { role: "assistant", content: [partialToolCall] },
+      }),
+    );
+
+    const stream = await invokeWrappedStream(baseFn);
+    for await (const _item of stream) {
+      // drain
+    }
+
+    expect(partialToolCall.arguments).toEqual({});
+  });
+
+  it("does not repair tool arguments when trailing junk exceeds the Kimi-specific allowance", async () => {
+    const partialToolCall = { type: "toolCall", name: "read", arguments: {} };
+    const streamedToolCall = { type: "toolCall", name: "read", arguments: {} };
+    const partialMessage = { role: "assistant", content: [partialToolCall] };
+    const baseFn = vi.fn(() =>
+      createFakeStream({
+        events: [
+          {
+            type: "toolcall_delta",
+            contentIndex: 0,
+            delta: '{"path":"/tmp/report.txt"}oops',
+            partial: partialMessage,
+          },
+          {
+            type: "toolcall_end",
+            contentIndex: 0,
+            toolCall: streamedToolCall,
+            partial: partialMessage,
+          },
+        ],
+        resultMessage: { role: "assistant", content: [partialToolCall] },
+      }),
+    );
+
+    const stream = await invokeWrappedStream(baseFn);
+    for await (const _item of stream) {
+      // drain
+    }
+
+    expect(partialToolCall.arguments).toEqual({});
+    expect(streamedToolCall.arguments).toEqual({});
+  });
+});
+
 describe("isOllamaCompatProvider", () => {
   it("detects native ollama provider id", () => {
     expect(

src/agents/pi-embedded-runner/run/attempt.ts

@@ -436,6 +436,258 @@ export function wrapStreamFnTrimToolCallNames(
   };
 }
 
+function extractBalancedJsonPrefix(raw: string): string | null {
+  let start = 0;
+  while (start < raw.length && /\s/.test(raw[start] ?? "")) {
+    start += 1;
+  }
+  const startChar = raw[start];
+  if (startChar !== "{" && startChar !== "[") {
+    return null;
+  }
+
+  let depth = 0;
+  let inString = false;
+  let escaped = false;
+  for (let i = start; i < raw.length; i += 1) {
+    const char = raw[i];
+    if (char === undefined) {
+      break;
+    }
+    if (inString) {
+      if (escaped) {
+        escaped = false;
+      } else if (char === "\\") {
+        escaped = true;
+      } else if (char === '"') {
+        inString = false;
+      }
+      continue;
+    }
+    if (char === '"') {
+      inString = true;
+      continue;
+    }
+    if (char === "{" || char === "[") {
+      depth += 1;
+      continue;
+    }
+    if (char === "}" || char === "]") {
+      depth -= 1;
+      if (depth === 0) {
+        return raw.slice(start, i + 1);
+      }
+    }
+  }
+  return null;
+}
+
+const MAX_TOOLCALL_REPAIR_BUFFER_CHARS = 64_000;
+const MAX_TOOLCALL_REPAIR_TRAILING_CHARS = 3;
+const TOOLCALL_REPAIR_ALLOWED_TRAILING_RE = /^[^\s{}[\]":,\\]{1,3}$/;
+
+function shouldAttemptMalformedToolCallRepair(partialJson: string, delta: string): boolean {
+  if (/[}\]]/.test(delta)) {
+    return true;
+  }
+  const trimmedDelta = delta.trim();
+  return (
+    trimmedDelta.length > 0 &&
+    trimmedDelta.length <= MAX_TOOLCALL_REPAIR_TRAILING_CHARS &&
+    /[}\]]/.test(partialJson)
+  );
+}
+
+type ToolCallArgumentRepair = {
+  args: Record<string, unknown>;
+  trailingSuffix: string;
+};
+
+function tryParseMalformedToolCallArguments(raw: string): ToolCallArgumentRepair | undefined {
+  if (!raw.trim()) {
+    return undefined;
+  }
+  try {
+    JSON.parse(raw);
+    return undefined;
+  } catch {
+    const jsonPrefix = extractBalancedJsonPrefix(raw);
+    if (!jsonPrefix) {
+      return undefined;
+    }
+    const suffix = raw.slice(raw.indexOf(jsonPrefix) + jsonPrefix.length).trim();
+    if (
+      suffix.length === 0 ||
+      suffix.length > MAX_TOOLCALL_REPAIR_TRAILING_CHARS ||
+      !TOOLCALL_REPAIR_ALLOWED_TRAILING_RE.test(suffix)
+    ) {
+      return undefined;
+    }
+    try {
+      const parsed = JSON.parse(jsonPrefix) as unknown;
+      return parsed && typeof parsed === "object" && !Array.isArray(parsed)
+        ? { args: parsed as Record<string, unknown>, trailingSuffix: suffix }
+        : undefined;
+    } catch {
+      return undefined;
+    }
+  }
+}
+
+function repairToolCallArgumentsInMessage(
+  message: unknown,
+  contentIndex: number,
+  repairedArgs: Record<string, unknown>,
+): void {
+  if (!message || typeof message !== "object") {
+    return;
+  }
+  const content = (message as { content?: unknown }).content;
+  if (!Array.isArray(content)) {
+    return;
+  }
+  const block = content[contentIndex];
+  if (!block || typeof block !== "object") {
+    return;
+  }
+  const typedBlock = block as { type?: unknown; arguments?: unknown };
+  if (!isToolCallBlockType(typedBlock.type)) {
+    return;
+  }
+  typedBlock.arguments = repairedArgs;
+}
+
+function repairMalformedToolCallArgumentsInMessage(
+  message: unknown,
+  repairedArgsByIndex: Map<number, Record<string, unknown>>,
+): void {
+  if (!message || typeof message !== "object") {
+    return;
+  }
+  const content = (message as { content?: unknown }).content;
+  if (!Array.isArray(content)) {
+    return;
+  }
+  for (const [index, repairedArgs] of repairedArgsByIndex.entries()) {
+    repairToolCallArgumentsInMessage(message, index, repairedArgs);
+  }
+}
+
+function wrapStreamRepairMalformedToolCallArguments(
+  stream: ReturnType<typeof streamSimple>,
+): ReturnType<typeof streamSimple> {
+  const partialJsonByIndex = new Map<number, string>();
+  const repairedArgsByIndex = new Map<number, Record<string, unknown>>();
+  const disabledIndices = new Set<number>();
+  const loggedRepairIndices = new Set<number>();
+  const originalResult = stream.result.bind(stream);
+  stream.result = async () => {
+    const message = await originalResult();
+    repairMalformedToolCallArgumentsInMessage(message, repairedArgsByIndex);
+    partialJsonByIndex.clear();
+    repairedArgsByIndex.clear();
+    disabledIndices.clear();
+    loggedRepairIndices.clear();
+    return message;
+  };
+
+  const originalAsyncIterator = stream[Symbol.asyncIterator].bind(stream);
+  (stream as { [Symbol.asyncIterator]: typeof originalAsyncIterator })[Symbol.asyncIterator] =
+    function () {
+      const iterator = originalAsyncIterator();
+      return {
+        async next() {
+          const result = await iterator.next();
+          if (!result.done && result.value && typeof result.value === "object") {
+            const event = result.value as {
+              type?: unknown;
+              contentIndex?: unknown;
+              delta?: unknown;
+              partial?: unknown;
+              message?: unknown;
+              toolCall?: unknown;
+            };
+            if (
+              typeof event.contentIndex === "number" &&
+              Number.isInteger(event.contentIndex) &&
+              event.type === "toolcall_delta" &&
+              typeof event.delta === "string"
+            ) {
+              if (disabledIndices.has(event.contentIndex)) {
+                return result;
+              }
+              const nextPartialJson =
+                (partialJsonByIndex.get(event.contentIndex) ?? "") + event.delta;
+              if (nextPartialJson.length > MAX_TOOLCALL_REPAIR_BUFFER_CHARS) {
+                partialJsonByIndex.delete(event.contentIndex);
+                repairedArgsByIndex.delete(event.contentIndex);
+                disabledIndices.add(event.contentIndex);
+                return result;
+              }
+              partialJsonByIndex.set(event.contentIndex, nextPartialJson);
+              if (shouldAttemptMalformedToolCallRepair(nextPartialJson, event.delta)) {
+                const repair = tryParseMalformedToolCallArguments(nextPartialJson);
+                if (repair) {
+                  repairedArgsByIndex.set(event.contentIndex, repair.args);
+                  repairToolCallArgumentsInMessage(event.partial, event.contentIndex, repair.args);
+                  repairToolCallArgumentsInMessage(event.message, event.contentIndex, repair.args);
+                  if (!loggedRepairIndices.has(event.contentIndex)) {
+                    loggedRepairIndices.add(event.contentIndex);
+                    log.warn(
+                      `repairing kimi-coding tool call arguments after ${repair.trailingSuffix.length} trailing chars`,
+                    );
+                  }
+                }
+              }
+            }
+            if (
+              typeof event.contentIndex === "number" &&
+              Number.isInteger(event.contentIndex) &&
+              event.type === "toolcall_end"
+            ) {
+              const repairedArgs = repairedArgsByIndex.get(event.contentIndex);
+              if (repairedArgs) {
+                if (event.toolCall && typeof event.toolCall === "object") {
+                  (event.toolCall as { arguments?: unknown }).arguments = repairedArgs;
+                }
+                repairToolCallArgumentsInMessage(event.partial, event.contentIndex, repairedArgs);
+                repairToolCallArgumentsInMessage(event.message, event.contentIndex, repairedArgs);
+              }
+              partialJsonByIndex.delete(event.contentIndex);
+              disabledIndices.delete(event.contentIndex);
+              loggedRepairIndices.delete(event.contentIndex);
+            }
+          }
+          return result;
+        },
+        async return(value?: unknown) {
+          return iterator.return?.(value) ?? { done: true as const, value: undefined };
+        },
+        async throw(error?: unknown) {
+          return iterator.throw?.(error) ?? { done: true as const, value: undefined };
+        },
+      };
+    };
+
+  return stream;
+}
+
+export function wrapStreamFnRepairMalformedToolCallArguments(baseFn: StreamFn): StreamFn {
+  return (model, context, options) => {
+    const maybeStream = baseFn(model, context, options);
+    if (maybeStream && typeof maybeStream === "object" && "then" in maybeStream) {
+      return Promise.resolve(maybeStream).then((stream) =>
+        wrapStreamRepairMalformedToolCallArguments(stream),
+      );
+    }
+    return wrapStreamRepairMalformedToolCallArguments(maybeStream);
+  };
+}
+
+function shouldRepairMalformedAnthropicToolCallArguments(provider?: string): boolean {
+  return normalizeProviderId(provider ?? "") === "kimi-coding";
+}
+
 // ---------------------------------------------------------------------------
 // xAI / Grok: decode HTML entities in tool call arguments
 // ---------------------------------------------------------------------------
@@ -1379,6 +1631,15 @@ export async function runEmbeddedAttempt(
         allowedToolNames,
       );
 
+      if (
+        params.model.api === "anthropic-messages" &&
+        shouldRepairMalformedAnthropicToolCallArguments(params.provider)
+      ) {
+        activeSession.agent.streamFn = wrapStreamFnRepairMalformedToolCallArguments(
+          activeSession.agent.streamFn,
+        );
+      }
+
       if (isXaiProvider(params.provider, params.modelId)) {
         activeSession.agent.streamFn = wrapStreamFnDecodeXaiToolCallArguments(
           activeSession.agent.streamFn,