fix: replay thought signatures only to their issuer

deno.json

@@ -1,6 +1,6 @@
 {
   "name": "@alphaxiv/agents",
-  "version": "0.7.2",
+  "version": "0.7.3",
   "license": "MIT",
   "fmt": {
     "lineWidth": 120

src/adapters/google_genai/adapter.ts

@@ -32,6 +32,7 @@ export function googleGenerateContentAPIModel<zO, zI>(
   const client = new GoogleGenAI(options?.googleGenAIOptions ?? {});
   const baseUrl = options.googleGenAIOptions?.httpOptions?.baseUrl ?? "https://generativelanguage.googleapis.com";
   const thinkingConfig = options.thinkingConfig;
+  const provider = options.provider ?? "GoogleGenerateContentAPI";
 
   async function ensureFileUploaded(url: string, mimeType: string, abortSignal: AbortSignal): Promise<string> {
     // Create a safe filename by hashing the URL
@@ -102,7 +103,7 @@ export function googleGenerateContentAPIModel<zO, zI>(
   }
 
   return {
-    provider: options.provider ?? "GoogleGenerateContentAPI",
+    provider,
     model: options.model,
     stream: async function* stream<zO, zI>({
       history,
@@ -113,6 +114,7 @@ export function googleGenerateContentAPIModel<zO, zI>(
     }: AdapterStreamOptions<zO, zI>): AdapterStreamIterator {
       const normalizedTools = normalizeGoogleTools(tools);
       const googleHistory = await getGoogleGenerateContentAPIHistory({
+        provider,
         history,
         toolMap: normalizedTools,
         signal,
@@ -170,7 +172,7 @@ export function googleGenerateContentAPIModel<zO, zI>(
             const tool = normalizedTools.find((tool) => tool.google.name === func.name);
 
             if (part.thoughtSignature) {
-              rememberGoogleThoughtSignature(funcId, part.thoughtSignature);
+              rememberGoogleThoughtSignature(provider, funcId, part.thoughtSignature);
             }
 
             const index = advanceIndex(funcId);

src/adapters/google_genai/history.ts

@@ -7,7 +7,11 @@ import type { GoogleToolMap } from "./tools.ts";
 
 type EnsureFileUploaded = (url: string, mimeType: string, abortSignal: AbortSignal) => Promise<string>;
 
-const signatureMap = new Map<string, string>();
+// A signature is only valid on the endpoint that issued it, so a replay elsewhere sends the placeholder instead.
+const signatureMap = new Map<string, { provider: string; signature: string }>();
+
+// Magic word comes from https://ai.google.dev/gemini-api/docs/gemini-3?thinking=high#migrating_from_other_models
+const PLACEHOLDER_THOUGHT_SIGNATURE = "context_engineering_is_the_way_to_go";
 
 /**
  * Google requires functionCall.args to be an object-like Struct, so replayed
@@ -31,11 +35,12 @@ function getGoogleFileBaseUrl(url: string) {
   return new URL("v1beta/files/", url.endsWith("/") ? url : `${url}/`).toString();
 }
 
-export function rememberGoogleThoughtSignature(toolUseId: string, signature: string) {
-  signatureMap.set(toolUseId, signature);
+export function rememberGoogleThoughtSignature(provider: string, toolUseId: string, signature: string) {
+  signatureMap.set(toolUseId, { provider, signature });
 }
 
 export async function getGoogleGenerateContentAPIHistory(options: {
+  provider: string;
   history: ChatItem[];
   toolMap: GoogleToolMap[];
   signal: AbortSignal;
@@ -58,8 +63,10 @@ export async function getGoogleGenerateContentAPIHistory(options: {
         break;
       case "tool_use": {
         const tool = options.toolMap.find((tool) => tool.original.name === item.kind);
-        // Magic word comes from https://ai.google.dev/gemini-api/docs/gemini-3?thinking=high#migrating_from_other_models
-        const thoughtSignature = signatureMap.get(item.tool_use_id) ?? "context_engineering_is_the_way_to_go";
+        const remembered = signatureMap.get(item.tool_use_id);
+        const thoughtSignature = remembered?.provider === options.provider
+          ? remembered.signature
+          : PLACEHOLDER_THOUGHT_SIGNATURE;
 
         googleHistory.push({
           role: "model",

tests/adapters/gemini.test.ts

@@ -3,7 +3,10 @@ import { assertEquals } from "@std/assert";
 import { encodeBase64 } from "@std/encoding";
 import { geminiModel } from "../../src/adapters/gemini/adapter.ts";
 import { getThinkingConfig, googleGenerateContentAPIModel } from "../../src/adapters/google_genai/adapter.ts";
-import { getGoogleGenerateContentAPIHistory } from "../../src/adapters/google_genai/history.ts";
+import {
+  getGoogleGenerateContentAPIHistory,
+  rememberGoogleThoughtSignature,
+} from "../../src/adapters/google_genai/history.ts";
 import {
   createToolFixtures,
   INTEGRATION_TIMEOUT_MS,
@@ -407,6 +410,7 @@ Deno.test({
 
 Deno.test("GeminiAdapter replays tool calls and results without current tool definitions", async () => {
   const history = await getGoogleGenerateContentAPIHistory({
+    provider: "Gemini",
     history: [
       { type: "tool_use", tool_use_id: "call_1", kind: "Load Project Snapshot", content: undefined },
       { type: "tool_result_text", tool_use_id: "call_1", content: "ready" },
@@ -440,8 +444,30 @@ Deno.test("GeminiAdapter replays tool calls and results without current tool def
   ]);
 });
 
+Deno.test("GeminiAdapter replays a thought signature only to the endpoint that issued it", async () => {
+  rememberGoogleThoughtSignature("Vertex AI", "call_1", "vertex-signature");
+  const history = [{ type: "tool_use" as const, tool_use_id: "call_1", kind: "Search Papers", content: undefined }];
+
+  const vertex = await getGoogleGenerateContentAPIHistory({
+    provider: "Vertex AI",
+    history,
+    toolMap: [],
+    signal: AbortSignal.abort(),
+  });
+  assertEquals(vertex[0].parts?.[0].thoughtSignature, "vertex-signature");
+
+  const gemini = await getGoogleGenerateContentAPIHistory({
+    provider: "Gemini",
+    history,
+    toolMap: [],
+    signal: AbortSignal.abort(),
+  });
+  assertEquals(gemini[0].parts?.[0].thoughtSignature, "context_engineering_is_the_way_to_go");
+});
+
 Deno.test("GeminiAdapter drops a tool result whose call is missing from the history", async () => {
   const history = await getGoogleGenerateContentAPIHistory({
+    provider: "Gemini",
     history: [
       { type: "tool_result_text", tool_use_id: "call_1", content: "orphaned result" },
       { type: "input_text", content: "what did you find?" },
@@ -455,6 +481,7 @@ Deno.test("GeminiAdapter drops a tool result whose call is missing from the hist
 
 Deno.test("GeminiAdapter wraps primitive tool arguments when replaying without current tool definitions", async () => {
   const history = await getGoogleGenerateContentAPIHistory({
+    provider: "Gemini",
     history: [
       {
         type: "tool_use",
@@ -484,6 +511,7 @@ Deno.test("GeminiAdapter wraps primitive tool arguments when replaying without c
 
 Deno.test("GeminiAdapter replays mixed tool history for a tool-less handoff", async () => {
   const history = await getGoogleGenerateContentAPIHistory({
+    provider: "Gemini",
     history: [
       {
         type: "tool_use",
@@ -605,6 +633,7 @@ Deno.test("GeminiAdapter inlines file history instead of using the Files API", a
   const server = Deno.serve({ port: 0, onListen: () => {} }, () => new Response(bytes));
   try {
     const history = await getGoogleGenerateContentAPIHistory({
+      provider: "Gemini",
       history: [{
         type: "input_file",
         kind: "application/pdf",