From f26c0ef7b347bba0d166b8a404f89e2053ebc9d6 Mon Sep 17 00:00:00 2001
From: Arjun Natarajan <arjun@langchain.dev>
Date: Tue, 10 Jun 2025 15:35:27 -0400
Subject: [PATCH] feat: pagination and tracing

---
 libs/langgraph-api/src/api/assistants.mts  | 15 ++++++++----
 libs/langgraph-api/src/api/meta.mts        | 27 +++++++++++++++++++++-
 libs/langgraph-api/src/http/middleware.mts | 27 +++++++++++++---------
 libs/langgraph-api/src/storage/ops.mts     | 13 +++++++++--
 4 files changed, 63 insertions(+), 19 deletions(-)

diff --git a/libs/langgraph-api/src/api/assistants.mts b/libs/langgraph-api/src/api/assistants.mts
index 62fecc4..c061be3 100644
--- a/libs/langgraph-api/src/api/assistants.mts
+++ b/libs/langgraph-api/src/api/assistants.mts
@@ -1,19 +1,19 @@
-import { Hono } from "hono";
 import { zValidator } from "@hono/zod-validator";
+import { Hono } from "hono";
 
 import { v4 as uuid } from "uuid";
 import { z } from "zod";
 
 import {
   getAssistantId,
-  getGraph,
   getCachedStaticGraphSchema,
+  getGraph,
 } from "../graph/load.mjs";
 import { getRuntimeGraphSchema } from "../graph/parser/index.mjs";
 
-import { Assistants } from "../storage/ops.mjs";
-import * as schemas from "../schemas.mjs";
 import { HTTPException } from "hono/http-exception";
+import * as schemas from "../schemas.mjs";
+import { Assistants } from "../storage/ops.mjs";
 const api = new Hono();
 
 const RunnableConfigSchema = z.object({
@@ -71,6 +71,7 @@ api.post(
     const payload = c.req.valid("json");
     const result: unknown[] = [];
 
+    let total = 0;
     for await (const item of Assistants.search(
       {
         graph_id: payload.graph_id,
@@ -80,9 +81,13 @@ api.post(
       },
       c.var.auth,
     )) {
-      result.push(item);
+      result.push(item.assistant);
+      if (total === 0) {
+        total = item.total;
+      }
     }
 
+    c.res.headers.set("X-Pagination-Total", total.toString());
     return c.json(result);
   },
 );
diff --git a/libs/langgraph-api/src/api/meta.mts b/libs/langgraph-api/src/api/meta.mts
index 7921ab1..600f93b 100644
--- a/libs/langgraph-api/src/api/meta.mts
+++ b/libs/langgraph-api/src/api/meta.mts
@@ -2,7 +2,32 @@ import { Hono } from "hono";
 
 const api = new Hono();
 
-api.get("/info", (c) => c.json({ flags: { assistants: true, crons: false } }));
+// read env variable
+const env = process.env;
+
+api.get("/info", (c) => {
+  const langsmithApiKey = env["LANGSMITH_API_KEY"] || env["LANGCHAIN_API_KEY"];
+
+  const langsmithTracing = (() => {
+    if (langsmithApiKey) {
+      // Check if any tracing variable is explicitly set to "false"
+      const tracingVars = [
+        env["LANGCHAIN_TRACING_V2"],
+        env["LANGCHAIN_TRACING"],
+        env["LANGSMITH_TRACING_V2"],
+        env["LANGSMITH_TRACING"],
+      ];
+
+      // Return true unless explicitly disabled
+      return !tracingVars.some((val) => val === "false" || val === "False");
+    }
+    return undefined;
+  })();
+  return c.json({
+    flags: { assistants: true, crons: false, langsmith: langsmithTracing },
+    env,
+  });
+});
 
 api.get("/ok", (c) => c.json({ ok: true }));
 
diff --git a/libs/langgraph-api/src/http/middleware.mts b/libs/langgraph-api/src/http/middleware.mts
index 8d9f731..135ae98 100644
--- a/libs/langgraph-api/src/http/middleware.mts
+++ b/libs/langgraph-api/src/http/middleware.mts
@@ -17,7 +17,7 @@ export const cors = (
   if (cors == null) {
     return honoCors({
       origin: "*",
-      exposeHeaders: ["content-location"],
+      exposeHeaders: ["content-location", "x-pagination-total"],
     });
   }
 
@@ -33,16 +33,21 @@ export const cors = (
       }
     : (cors.allow_origins ?? []);
 
-  if (
-    !!cors.expose_headers?.length &&
-    cors.expose_headers.some(
-      (i) => i.toLocaleLowerCase() === "content-location",
-    )
-  ) {
-    console.warn(
-      "Adding missing `Content-Location` header in `cors.expose_headers`.",
-    );
-    cors.expose_headers.push("content-location");
+  if (cors.expose_headers?.length) {
+    const headersSet = new Set(cors.expose_headers.map((h) => h.toLowerCase()));
+
+    if (!headersSet.has("content-location")) {
+      console.warn(
+        "Adding missing `Content-Location` header in `cors.expose_headers`.",
+      );
+      cors.expose_headers.push("content-location");
+    }
+    if (!headersSet.has("x-pagination-total")) {
+      console.warn(
+        "Adding missing `X-Pagination-Total` header in `cors.expose_headers`.",
+      );
+      cors.expose_headers.push("x-pagination-total");
+    }
   }
 
   // TODO: handle `cors.allow_credentials`
diff --git a/libs/langgraph-api/src/storage/ops.mts b/libs/langgraph-api/src/storage/ops.mts
index 817a13a..0696928 100644
--- a/libs/langgraph-api/src/storage/ops.mts
+++ b/libs/langgraph-api/src/storage/ops.mts
@@ -323,7 +323,7 @@ export class Assistants {
       offset: number;
     },
     auth: AuthContext | undefined,
-  ) {
+  ): AsyncGenerator<{ assistant: Assistant; total: number }> {
     const [filters] = await handleAuthEvent(auth, "assistants:search", {
       graph_id: options.graph_id,
       metadata: options.metadata,
@@ -360,11 +360,20 @@ export class Assistants {
           return bCreatedAt - aCreatedAt;
         });
 
+      // Calculate total count before pagination
+      const total = filtered.length;
+
       for (const assistant of filtered.slice(
         options.offset,
         options.offset + options.limit,
       )) {
-        yield { ...assistant, name: assistant.name ?? assistant.graph_id };
+        yield {
+          assistant: {
+            ...assistant,
+            name: assistant.name ?? assistant.graph_id,
+          },
+          total,
+        };
       }
     });
   }