diff --git a/packages/app/src/utils/session-export.test.ts b/packages/app/src/utils/session-export.test.ts
index ff18a16b7fa3..23d34c8de94d 100644
--- a/packages/app/src/utils/session-export.test.ts
+++ b/packages/app/src/utils/session-export.test.ts
@@ -16,6 +16,13 @@ describe("sessionExportFilename", () => {
   test("falls back to id when title and slug are empty", () => {
     expect(sessionExportFilename({ id: "ses_123" })).toBe("ses_123.json")
   })
+
+  test("limits filename length while preserving the extension", () => {
+    const filename = sessionExportFilename({ id: "ses_123", title: "x".repeat(300) })
+
+    expect(filename).toBe(`${"x".repeat(250)}.json`)
+    expect(new TextEncoder().encode(filename)).toHaveLength(255)
+  })
 })
 
 describe("fetchSessionExport", () => {
diff --git a/packages/app/src/utils/session-export.ts b/packages/app/src/utils/session-export.ts
index 6eb9f9ab6a7c..bf8b3d35d0c3 100644
--- a/packages/app/src/utils/session-export.ts
+++ b/packages/app/src/utils/session-export.ts
@@ -16,6 +16,8 @@ export type SessionExportClient = {
   }
 }
 
+const MAX_EXPORT_BASENAME_LENGTH = 250
+
 export async function fetchSessionExport(input: {
   sessionID: string
   client: SessionExportClient
@@ -43,6 +45,7 @@ export function sessionExportFilename(session: { id: string; title?: string; slu
   const clean = name
     .toLowerCase()
     .replace(/[^a-z0-9_-]+/gi, "-")
+    .slice(0, MAX_EXPORT_BASENAME_LENGTH)
     .replace(/^-+|-+$/g, "")
   return `${clean || session.id}.json`
 }