fix(cli): don't send dynamic IR bodies in registerApiDefinition request

packages/cli/cli/changes/unreleased/fix-register-api-definition-payload-too-large.yml

@@ -0,0 +1,6 @@
+- summary: |
+    Fix `PAYLOAD_TOO_LARGE` failures when publishing docs for large APIs with dynamic snippets. The
+    dynamic IRs were being sent inline in the `registerApiDefinition` request once per SDK language,
+    even though the registry only needs the language names to issue upload URLs (the IRs are uploaded
+    to S3 separately).
+  type: fix

packages/cli/generation/remote-generation/remote-workspace-runner/src/__test__/toRegisterDynamicIRsInput.test.ts

@@ -0,0 +1,25 @@
+import { describe, expect, it } from "vitest";
+import { toRegisterDynamicIRsInput } from "../toRegisterDynamicIRsInput.js";
+
+describe("toRegisterDynamicIRsInput", () => {
+    it("returns undefined when there are no dynamic IRs", () => {
+        expect(toRegisterDynamicIRsInput(undefined)).toBeUndefined();
+    });
+
+    it("preserves the language keys", () => {
+        const result = toRegisterDynamicIRsInput({
+            python: { dynamicIR: { types: {} } },
+            typescript: { dynamicIR: { types: {} } }
+        });
+
+        expect(Object.keys(result ?? {}).sort()).toEqual(["python", "typescript"]);
+    });
+
+    it("strips the IR bodies so they are not sent in the registration request", () => {
+        const dynamicIR = { types: { User: { name: "User" } } };
+        const result = toRegisterDynamicIRsInput({ python: { dynamicIR }, go: { dynamicIR } });
+
+        expect(result).toEqual({ python: {}, go: {} });
+        expect(JSON.stringify(result)).not.toContain("User");
+    });
+});

packages/cli/generation/remote-generation/remote-workspace-runner/src/publishDocs.ts

@@ -69,6 +69,7 @@ import { normalizeRepoUrlToHttps } from "./normalizeRepoUrl.js";
 import { publishDocsViaLedger } from "./publishDocsLedger.js";
 import { publishDocsViaLedgerPreview } from "./publishDocsLedgerPreview.js";
 import { retryWithBackoff } from "./retryWithBackoff.js";
+import { toRegisterDynamicIRsInput } from "./toRegisterDynamicIRsInput.js";
 import { asyncPool } from "./utils/asyncPool.js";
 
 const MEASURE_IMAGE_BATCH_SIZE = 10;
@@ -487,7 +488,7 @@ export async function publishDocs({
                             orgId: CjsFdrSdk.OrgId(organization),
                             apiId: CjsFdrSdk.ApiId(effectiveApiName),
                             definition: apiDefinition,
-                            dynamicIRs: dynamicIRsByLanguage
+                            dynamicIRs: toRegisterDynamicIRsInput(dynamicIRsByLanguage)
                         }),
                     maxRetries: REGISTER_MAX_RETRIES,
                     baseDelayMs: REGISTER_BASE_DELAY_MS,

packages/cli/generation/remote-generation/remote-workspace-runner/src/toRegisterDynamicIRsInput.ts

@@ -0,0 +1,18 @@
+import type { APIV1Write } from "@fern-api/fdr-sdk";
+
+type DynamicIr = APIV1Write.DynamicIr;
+
+/**
+ * FDR only reads the language keys of `dynamicIRs` when registering an API definition — it mints one
+ * presigned upload URL per language, and the IRs themselves are uploaded directly to S3 afterwards.
+ * Sending the IR bodies inline duplicates the entire IR once per language in the registration request
+ * body, which can exceed the server's request size limit for large APIs.
+ */
+export function toRegisterDynamicIRsInput(
+    dynamicIRsByLanguage: Record<string, DynamicIr> | undefined
+): Record<string, DynamicIr> | undefined {
+    if (dynamicIRsByLanguage == null) {
+        return undefined;
+    }
+    return Object.fromEntries(Object.keys(dynamicIRsByLanguage).map((language) => [language, {}]));
+}