diff --git a/.changeset/tool-call-id-normalization.md b/.changeset/tool-call-id-normalization.md
new file mode 100644
index 0000000000..1be7a37374
--- /dev/null
+++ b/.changeset/tool-call-id-normalization.md
@@ -0,0 +1,6 @@
+---
+"@moonshot-ai/kosong": patch
+"@moonshot-ai/kimi-code": patch
+---
+
+Fix cross-provider tool call ID normalization when replaying tool history.
diff --git a/packages/kosong/src/providers/anthropic.ts b/packages/kosong/src/providers/anthropic.ts
index 06e5b6c912..b6adb13178 100644
--- a/packages/kosong/src/providers/anthropic.ts
+++ b/packages/kosong/src/providers/anthropic.ts
@@ -44,6 +44,11 @@ import {
   requireProviderApiKey,
   resolveAuthBackedClient,
 } from './request-auth';
+import {
+  normalizeToolCallIdsForProvider,
+  sanitizeToolCallId,
+  type ToolCallIdPolicy,
+} from './tool-call-id';
 
 /**
  * Normalize an Anthropic `stop_reason` string to the unified
@@ -109,6 +114,10 @@ const INTERLEAVED_THINKING_BETA = 'interleaved-thinking-2025-05-14';
 const FAMILY_VERSION_RE = /(?:opus|sonnet|haiku)[.-](\d+)[.-](\d{1,2})(?!\d)/;
 const OPUS_VERSION_RE = /opus[.-](\d+)[.-](\d{1,2})(?!\d)/;
 const ADAPTIVE_MIN_VERSION = { major: 4, minor: 6 } as const;
+const ANTHROPIC_TOOL_CALL_ID_POLICY: ToolCallIdPolicy = {
+  normalize: (id) => sanitizeToolCallId(id, 64),
+  maxLength: 64,
+};
 
 /**
  * Per-version default output ceilings sourced from Anthropic's Messages
@@ -903,7 +912,11 @@ export class AnthropicChatProvider implements ChatProvider {
     // Convert messages, merging consecutive tool-result-only user messages
     // into a single user message (Anthropic parallel-tool-use spec).
     const messages: MessageParam[] = [];
-    for (const msg of history) {
+    const normalizedHistory = normalizeToolCallIdsForProvider(
+      history,
+      ANTHROPIC_TOOL_CALL_ID_POLICY,
+    );
+    for (const msg of normalizedHistory) {
       const converted = convertMessage(msg);
       const last = messages.at(-1);
       if (last !== undefined && isToolResultOnly(last) && isToolResultOnly(converted)) {
diff --git a/packages/kosong/src/providers/kimi.ts b/packages/kosong/src/providers/kimi.ts
index 77a7239f60..ef53eca7c1 100644
--- a/packages/kosong/src/providers/kimi.ts
+++ b/packages/kosong/src/providers/kimi.ts
@@ -35,6 +35,11 @@ import {
   requireProviderApiKey,
   resolveAuthBackedClient,
 } from './request-auth';
+import {
+  normalizeToolCallIdsForProvider,
+  sanitizeToolCallId,
+  type ToolCallIdPolicy,
+} from './tool-call-id';
 export interface KimiOptions {
   apiKey?: string | undefined;
   baseUrl?: string | undefined;
@@ -77,6 +82,10 @@ export interface ExtraBody {
   thinking?: ThinkingConfig;
   [key: string]: unknown;
 }
+const KIMI_TOOL_CALL_ID_POLICY: ToolCallIdPolicy = {
+  normalize: (id) => sanitizeToolCallId(id, 64),
+  maxLength: 64,
+};
 interface OpenAIMessage {
   role: string;
   content?: string | OpenAIContentPart[] | undefined;
@@ -426,7 +435,8 @@ export class KimiChatProvider implements ChatProvider {
     if (systemPrompt) {
       messages.push({ role: 'system', content: systemPrompt });
     }
-    for (const msg of history) {
+    const normalizedHistory = normalizeToolCallIdsForProvider(history, KIMI_TOOL_CALL_ID_POLICY);
+    for (const msg of normalizedHistory) {
       messages.push(convertMessage(msg));
     }
 
diff --git a/packages/kosong/src/providers/openai-legacy.ts b/packages/kosong/src/providers/openai-legacy.ts
index 7254dae79c..e050e9ede5 100644
--- a/packages/kosong/src/providers/openai-legacy.ts
+++ b/packages/kosong/src/providers/openai-legacy.ts
@@ -35,12 +35,21 @@ import {
   requireProviderApiKey,
   resolveAuthBackedClient,
 } from './request-auth';
+import {
+  normalizeToolCallIdsForProvider,
+  sanitizeToolCallId,
+  type ToolCallIdPolicy,
+} from './tool-call-id';
 
 // Inbound: scan in priority order; first string value wins. Outbound: the first
 // entry doubles as the default field we serialize ThinkPart back into. Both
 // arms can be overridden by an explicit `reasoningKey` on the provider config.
 const KNOWN_REASONING_KEYS = ['reasoning_content', 'reasoning_details', 'reasoning'] as const;
 const DEFAULT_OUTBOUND_REASONING_KEY = KNOWN_REASONING_KEYS[0];
+const OPENAI_CHAT_TOOL_CALL_ID_POLICY: ToolCallIdPolicy = {
+  normalize: (id) => sanitizeToolCallId(id, 64),
+  maxLength: 64,
+};
 
 function extractReasoningContent(
   source: unknown,
@@ -397,7 +406,11 @@ export class OpenAILegacyChatProvider implements ChatProvider {
     if (systemPrompt) {
       messages.push({ role: 'system', content: systemPrompt });
     }
-    for (const msg of history) {
+    const normalizedHistory = normalizeToolCallIdsForProvider(
+      history,
+      OPENAI_CHAT_TOOL_CALL_ID_POLICY,
+    );
+    for (const msg of normalizedHistory) {
       messages.push(convertMessage(msg, this._reasoningKey, this._toolMessageConversion));
     }
 
diff --git a/packages/kosong/src/providers/openai-responses.ts b/packages/kosong/src/providers/openai-responses.ts
index 336da282c1..59c0c852da 100644
--- a/packages/kosong/src/providers/openai-responses.ts
+++ b/packages/kosong/src/providers/openai-responses.ts
@@ -29,6 +29,11 @@ import {
   requireProviderApiKey,
   resolveAuthBackedClient,
 } from './request-auth';
+import {
+  normalizeToolCallIdsForProvider,
+  sanitizeOpenAIResponsesCallId,
+  type ToolCallIdPolicy,
+} from './tool-call-id';
 
 /**
  * Normalize the Responses API status / incomplete_details into the unified
@@ -68,6 +73,10 @@ function normalizeResponsesFinishReason(
 }
 
 type RawObject = Record<string, unknown>;
+const OPENAI_RESPONSES_TOOL_CALL_ID_POLICY: ToolCallIdPolicy = {
+  normalize: (id) => sanitizeOpenAIResponsesCallId(id, 64),
+  maxLength: 64,
+};
 
 type ResponseOutputItemView =
   | {
@@ -904,7 +913,11 @@ export class OpenAIResponsesChatProvider implements ChatProvider {
       input.push(sysItem);
     }
 
-    for (const msg of history) {
+    const normalizedHistory = normalizeToolCallIdsForProvider(
+      history,
+      OPENAI_RESPONSES_TOOL_CALL_ID_POLICY,
+    );
+    for (const msg of normalizedHistory) {
       input.push(...convertMessage(msg, this._model, this._toolMessageConversion));
     }
 
diff --git a/packages/kosong/src/providers/tool-call-id.ts b/packages/kosong/src/providers/tool-call-id.ts
new file mode 100644
index 0000000000..fd70267182
--- /dev/null
+++ b/packages/kosong/src/providers/tool-call-id.ts
@@ -0,0 +1,132 @@
+import type { Message, ToolCall } from '#/message';
+
+export interface ToolCallIdPolicy {
+  normalize: (id: string) => string;
+  maxLength?: number;
+}
+
+const EMPTY_TOOL_CALL_ID = 'tool_call';
+const TOOL_CALL_ID_SAFE_CHARS = /[^a-zA-Z0-9_-]/g;
+
+export function sanitizeToolCallId(id: string, maxLength?: number): string {
+  const sanitized = id.replace(TOOL_CALL_ID_SAFE_CHARS, '_');
+  return maxLength === undefined ? sanitized : sanitized.slice(0, maxLength);
+}
+
+export function sanitizeOpenAIResponsesCallId(id: string, maxLength?: number): string {
+  const [callId] = id.split('|', 1);
+  return sanitizeToolCallId(callId ?? id, maxLength);
+}
+
+export function normalizeToolCallIdsForProvider(
+  messages: Message[],
+  policy: ToolCallIdPolicy,
+): Message[] {
+  const rawIds = collectToolCallIds(messages);
+  if (rawIds.length === 0) return messages;
+
+  const mappedIds = buildToolCallIdMap(rawIds, policy);
+  let changed = false;
+  const normalizedMessages = messages.map((message) => {
+    let messageChanged = false;
+    let toolCalls = message.toolCalls;
+
+    if (message.toolCalls.length > 0) {
+      toolCalls = message.toolCalls.map((toolCall) => {
+        const mappedId = mappedIds.get(toolCall.id);
+        if (mappedId === undefined || mappedId === toolCall.id) return toolCall;
+        messageChanged = true;
+        return { ...toolCall, id: mappedId } satisfies ToolCall;
+      });
+    }
+
+    const toolCallId =
+      message.toolCallId === undefined ? undefined : mappedIds.get(message.toolCallId);
+    const mappedToolCallId = toolCallId ?? message.toolCallId;
+    if (mappedToolCallId !== message.toolCallId) {
+      messageChanged = true;
+    }
+
+    if (!messageChanged) return message;
+    changed = true;
+    return { ...message, toolCalls, toolCallId: mappedToolCallId };
+  });
+
+  return changed ? normalizedMessages : messages;
+}
+
+function collectToolCallIds(messages: Message[]): string[] {
+  const ids: string[] = [];
+  const seen = new Set<string>();
+  const append = (id: string): void => {
+    if (seen.has(id)) return;
+    seen.add(id);
+    ids.push(id);
+  };
+
+  for (const message of messages) {
+    for (const toolCall of message.toolCalls) {
+      append(toolCall.id);
+    }
+    if (message.toolCallId !== undefined) {
+      append(message.toolCallId);
+    }
+  }
+
+  return ids;
+}
+
+function buildToolCallIdMap(
+  rawIds: string[],
+  policy: ToolCallIdPolicy,
+): Map<string, string> {
+  const mappedIds = new Map<string, string>();
+  const usedIds = new Set<string>();
+
+  for (const rawId of rawIds) {
+    const normalized = policy.normalize(rawId);
+    if (normalized === rawId && normalized.length > 0) {
+      mappedIds.set(rawId, normalized);
+      usedIds.add(normalized);
+    }
+  }
+
+  for (const rawId of rawIds) {
+    if (mappedIds.has(rawId)) continue;
+    const normalized = policy.normalize(rawId);
+    const unique = makeUniqueToolCallId(normalized, usedIds, policy.maxLength);
+    mappedIds.set(rawId, unique);
+    usedIds.add(unique);
+  }
+
+  return mappedIds;
+}
+
+function makeUniqueToolCallId(
+  normalized: string,
+  usedIds: Set<string>,
+  maxLength: number | undefined,
+): string {
+  const base = normalized.length > 0 ? normalized : EMPTY_TOOL_CALL_ID;
+  const candidate = truncateToolCallId(base, maxLength, '');
+  if (!usedIds.has(candidate)) return candidate;
+
+  for (let i = 2; ; i++) {
+    const suffix = `_${i}`;
+    const suffixed = truncateToolCallId(base, maxLength, suffix);
+    if (!usedIds.has(suffixed)) return suffixed;
+  }
+}
+
+function truncateToolCallId(
+  base: string,
+  maxLength: number | undefined,
+  suffix: string,
+): string {
+  if (maxLength === undefined) return `${base}${suffix}`;
+  const baseLength = maxLength - suffix.length;
+  if (baseLength <= 0) {
+    throw new Error(`Tool call id maxLength ${maxLength} is too small for suffix ${suffix}.`);
+  }
+  return `${base.slice(0, baseLength)}${suffix}`;
+}
diff --git a/packages/kosong/test/anthropic.test.ts b/packages/kosong/test/anthropic.test.ts
index 5f40f9e638..0789204a49 100644
--- a/packages/kosong/test/anthropic.test.ts
+++ b/packages/kosong/test/anthropic.test.ts
@@ -321,6 +321,85 @@ describe('AnthropicChatProvider', () => {
       ]);
     });
 
+    it('normalizes invalid historical tool call ids and matching tool results', async () => {
+      const provider = createProvider();
+      const history: Message[] = [
+        { role: 'user', content: [{ type: 'text', text: 'Run tools' }], toolCalls: [] },
+        {
+          role: 'assistant',
+          content: [],
+          toolCalls: [
+            {
+              type: 'function',
+              id: 'Write:6',
+              name: 'Write',
+              arguments: '{"path":"/tmp/b","content":"ok"}',
+            },
+            {
+              type: 'function',
+              id: 'Write_6',
+              name: 'Write',
+              arguments: '{"path":"/tmp/a","content":"ok"}',
+            },
+          ],
+        },
+        {
+          role: 'tool',
+          content: [{ type: 'text', text: 'wrote b' }],
+          toolCallId: 'Write:6',
+          toolCalls: [],
+        },
+        {
+          role: 'tool',
+          content: [{ type: 'text', text: 'wrote a' }],
+          toolCallId: 'Write_6',
+          toolCalls: [],
+        },
+      ];
+
+      const body = await captureRequestBody(provider, '', [], history);
+
+      expect(body['messages']).toEqual([
+        {
+          role: 'user',
+          content: [{ type: 'text', text: 'Run tools' }],
+        },
+        {
+          role: 'assistant',
+          content: [
+            {
+              type: 'tool_use',
+              id: 'Write_6_2',
+              name: 'Write',
+              input: { path: '/tmp/b', content: 'ok' },
+            },
+            {
+              type: 'tool_use',
+              id: 'Write_6',
+              name: 'Write',
+              input: { path: '/tmp/a', content: 'ok' },
+            },
+          ],
+        },
+        {
+          role: 'user',
+          content: [
+            {
+              type: 'tool_result',
+              tool_use_id: 'Write_6_2',
+              content: [{ type: 'text', text: 'wrote b' }],
+            },
+            {
+              type: 'tool_result',
+              tool_use_id: 'Write_6',
+              content: [{ type: 'text', text: 'wrote a' }],
+              cache_control: { type: 'ephemeral' },
+            },
+          ],
+        },
+      ]);
+    });
+
     it('tool call with image result wraps image source inside tool_result', async () => {
       const provider = createProvider();
       const toolCall: ToolCall = {
diff --git a/packages/kosong/test/kimi.test.ts b/packages/kosong/test/kimi.test.ts
index f72aff7d38..f309b2030e 100644
--- a/packages/kosong/test/kimi.test.ts
+++ b/packages/kosong/test/kimi.test.ts
@@ -358,6 +358,48 @@ describe('KimiChatProvider', () => {
       ]);
     });
 
+    it('normalizes invalid historical tool call ids and matching tool results', async () => {
+      const provider = createProvider();
+      const history: Message[] = [
+        { role: 'user', content: [{ type: 'text', text: 'Read a file' }], toolCalls: [] },
+        {
+          role: 'assistant',
+          content: [],
+          toolCalls: [
+            {
+              type: 'function',
+              id: 'Read:9',
+              name: 'Read',
+              arguments: '{"path":"/tmp/file"}',
+            },
+          ],
+        },
+        {
+          role: 'tool',
+          content: [{ type: 'text', text: 'content' }],
+          toolCallId: 'Read:9',
+          toolCalls: [],
+        },
+      ];
+
+      const body = await captureRequestBody(provider, '', [], history);
+
+      expect(body['messages']).toEqual([
+        { role: 'user', content: 'Read a file' },
+        {
+          role: 'assistant',
+          tool_calls: [
+            {
+              type: 'function',
+              id: 'Read_9',
+              function: { name: 'Read', arguments: '{"path":"/tmp/file"}' },
+            },
+          ],
+        },
+        { role: 'tool', content: 'content', tool_call_id: 'Read_9' },
+      ]);
+    });
+
     it('tool call with image result', async () => {
       const provider = createProvider();
       const toolCall: ToolCall = {
diff --git a/packages/kosong/test/openai-legacy.test.ts b/packages/kosong/test/openai-legacy.test.ts
index f01c6aadc2..d51f8d8a6c 100644
--- a/packages/kosong/test/openai-legacy.test.ts
+++ b/packages/kosong/test/openai-legacy.test.ts
@@ -245,6 +245,48 @@ describe('OpenAILegacyChatProvider', () => {
       ]);
     });
 
+    it('normalizes invalid historical tool call ids and matching tool results', async () => {
+      const provider = createProvider();
+      const history: Message[] = [
+        { role: 'user', content: [{ type: 'text', text: 'Run bash' }], toolCalls: [] },
+        {
+          role: 'assistant',
+          content: [],
+          toolCalls: [
+            {
+              type: 'function',
+              id: 'Bash:7',
+              name: 'Bash',
+              arguments: '{"command":"pwd"}',
+            },
+          ],
+        },
+        {
+          role: 'tool',
+          content: [{ type: 'text', text: '/tmp' }],
+          toolCallId: 'Bash:7',
+          toolCalls: [],
+        },
+      ];
+
+      const body = await captureRequestBody(provider, '', [], history);
+
+      expect(body['messages']).toEqual([
+        { role: 'user', content: 'Run bash' },
+        {
+          role: 'assistant',
+          tool_calls: [
+            {
+              type: 'function',
+              id: 'Bash_7',
+              function: { name: 'Bash', arguments: '{"command":"pwd"}' },
+            },
+          ],
+        },
+        { role: 'tool', content: '/tmp', tool_call_id: 'Bash_7' },
+      ]);
+    });
+
     it('tool call with image result flattens to text to satisfy API constraints', async () => {
       // OpenAI Chat Completions `tool` messages only accept text content.
       // Even when toolMessageConversion is unset, a tool result containing
diff --git a/packages/kosong/test/openai-responses.test.ts b/packages/kosong/test/openai-responses.test.ts
index e3b69d075b..572527cba4 100644
--- a/packages/kosong/test/openai-responses.test.ts
+++ b/packages/kosong/test/openai-responses.test.ts
@@ -604,6 +604,46 @@ describe('OpenAIResponsesChatProvider', () => {
       });
     });
 
+    it('normalizes invalid historical tool call ids and matching function outputs', async () => {
+      const provider = createProvider();
+      const history: Message[] = [
+        { role: 'user', content: [{ type: 'text', text: 'Run bash' }], toolCalls: [] },
+        {
+          role: 'assistant',
+          content: [],
+          toolCalls: [
+            {
+              type: 'function',
+              id: 'Bash:21',
+              name: 'Bash',
+              arguments: '{"command":"pwd"}',
+            },
+          ],
+        },
+        {
+          role: 'tool',
+          content: [{ type: 'text', text: '/tmp' }],
+          toolCallId: 'Bash:21',
+          toolCalls: [],
+        },
+      ];
+
+      const body = await captureRequestBody(provider, '', [], history);
+      const input = body['input'] as unknown[];
+
+      expect(input[1]).toEqual({
+        arguments: '{"command":"pwd"}',
+        call_id: 'Bash_21',
+        name: 'Bash',
+        type: 'function_call',
+      });
+      expect(input[2]).toEqual({
+        call_id: 'Bash_21',
+        output: [{ type: 'input_text', text: '/tmp' }],
+        type: 'function_call_output',
+      });
+    });
+
     it('assistant with reasoning (ThinkPart with encrypted)', async () => {
       const provider = createProvider();
       const history: Message[] = [