From d158f2cd39e667f9be0cf117d12aa03e8428354f Mon Sep 17 00:00:00 2001
From: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>
Date: Fri, 21 Aug 2026 00:54:31 -0500
Subject: [PATCH] fix(ai): scrub Anthropic tool call IDs (#43796)

---
 .../ai/src/protocols/anthropic-messages.ts    | 10 ++++---
 .../test/provider/anthropic-messages.test.ts  | 27 +++++++++++++++++--
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/packages/ai/src/protocols/anthropic-messages.ts b/packages/ai/src/protocols/anthropic-messages.ts
index 14c6bc1b16..ed5087f516 100644
--- a/packages/ai/src/protocols/anthropic-messages.ts
+++ b/packages/ai/src/protocols/anthropic-messages.ts
@@ -374,16 +374,18 @@ const lowerToolChoice = (toolChoice: NonNullable<LLMRequest["toolChoice"]>) =>
     tool: (name) => ({ type: "tool" as const, name }),
   })
 
+const scrubToolCallID = (id: string) => id.replace(/[^a-zA-Z0-9_-]/g, "_")
+
 const lowerToolCall = (part: ToolCallPart): AnthropicToolUseBlock => ({
   type: "tool_use",
-  id: part.id,
+  id: scrubToolCallID(part.id),
   name: part.name,
   input: part.input,
 })
 
 const lowerServerToolCall = (part: ToolCallPart): AnthropicServerToolUseBlock => ({
   type: "server_tool_use",
-  id: part.id,
+  id: scrubToolCallID(part.id),
   name: part.name,
   input: part.input,
 })
@@ -405,7 +407,7 @@ const lowerServerToolResult = Effect.fn("AnthropicMessages.lowerServerToolResult
   // Prefer the provider-owned replay payload; fall back to the result value for
   // histories constructed directly from provider events.
   const payload = part.providerMetadata?.anthropic?.["result"] ?? part.result.value
-  return { type: wireType, tool_use_id: part.id, content: payload } satisfies AnthropicServerToolResultBlock
+  return { type: wireType, tool_use_id: scrubToolCallID(part.id), content: payload } satisfies AnthropicServerToolResultBlock
 })
 
 const lowerMedia = Effect.fn("AnthropicMessages.lowerMedia")(function* (part: MediaPart) {
@@ -587,7 +589,7 @@ const lowerMessages = Effect.fn("AnthropicMessages.lowerMessages")(function* (
         return yield* ProviderShared.unsupportedContent("Anthropic Messages", "tool", ["tool-result"])
       content.push({
         type: "tool_result",
-        tool_use_id: part.id,
+        tool_use_id: scrubToolCallID(part.id),
         content: yield* lowerToolResultContent(part),
         is_error: part.result.type === "error" ? true : undefined,
         cache_control: cacheControl(breakpoints, part.cache),
diff --git a/packages/ai/test/provider/anthropic-messages.test.ts b/packages/ai/test/provider/anthropic-messages.test.ts
index 9a03840225..a2447aea90 100644
--- a/packages/ai/test/provider/anthropic-messages.test.ts
+++ b/packages/ai/test/provider/anthropic-messages.test.ts
@@ -327,6 +327,29 @@ describe("Anthropic Messages route", () => {
     }),
   )
 
+  it.effect("scrubs outbound tool call IDs without truncating them", () =>
+    Effect.gen(function* () {
+      const id = `functions.lookup:1|${"x".repeat(64)}`
+      const scrubbed = `functions_lookup_1_${"x".repeat(64)}`
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model,
+          messages: [
+            Message.assistant([ToolCallPart.make({ id, name: "lookup", input: {} })]),
+            Message.tool({ id, name: "lookup", result: "done" }),
+          ],
+          cache: "none",
+        }),
+      )
+
+      expect(prepared.body.messages).toMatchObject([
+        { role: "assistant", content: [{ type: "tool_use", id: scrubbed, name: "lookup", input: {} }] },
+        { role: "user", content: [{ type: "tool_result", tool_use_id: scrubbed }] },
+      ])
+      expect(scrubbed.length).toBeGreaterThan(64)
+    }),
+  )
+
   it.effect("batches parallel tool results into one Anthropic user message", () =>
     Effect.gen(function* () {
       const prepared = yield* compileRequest(
@@ -1393,14 +1416,14 @@ describe("Anthropic Messages route", () => {
             Message.assistant([
               {
                 type: "tool-call",
-                id: "srvtoolu_abc",
+                id: "srvtoolu.abc",
                 name: "web_search",
                 input: { query: "effect 4" },
                 providerExecuted: true,
               },
               {
                 type: "tool-result",
-                id: "srvtoolu_abc",
+                id: "srvtoolu.abc",
                 name: "web_search",
                 result: { type: "json", value: [{ url: "https://example.com" }] },
                 providerExecuted: true,