diff --git a/src/lib/components/event/event-card.svelte b/src/lib/components/event/event-card.svelte
index e33cc5954b..57108304d4 100644
--- a/src/lib/components/event/event-card.svelte
+++ b/src/lib/components/event/event-card.svelte
@@ -182,9 +182,27 @@
       {format(key)}
     </p>
     {#if value?.payloads}
-      <PayloadCodeBlock {value} maxHeight={384} />
+      <PayloadCodeBlock
+        filenameData={{
+          workflowId: workflow,
+          runId: run,
+          eventId: event.id,
+          type: key,
+        }}
+        {value}
+        maxHeight={384}
+      />
     {:else}
-      <PayloadCodeBlock value={codeBlockValue} maxHeight={384} />
+      <PayloadCodeBlock
+        filenameData={{
+          workflowId: workflow,
+          runId: run,
+          eventId: event.id,
+          type: key,
+        }}
+        value={codeBlockValue}
+        maxHeight={384}
+      />
     {/if}
   </div>
   {#if stackTrace}
diff --git a/src/lib/components/payload/payload-code-block.svelte b/src/lib/components/payload/payload-code-block.svelte
index 65b8a17ca4..cb5f0133ae 100644
--- a/src/lib/components/payload/payload-code-block.svelte
+++ b/src/lib/components/payload/payload-code-block.svelte
@@ -1,34 +1,142 @@
 <script lang="ts">
+  import Button from '$lib/holocene/button.svelte';
   import CodeBlock from '$lib/holocene/code-block.svelte';
+  import Icon from '$lib/holocene/icon/icon.svelte';
+  import Link from '$lib/holocene/link.svelte';
+  import Tooltip from '$lib/holocene/tooltip.svelte';
   import { translate } from '$lib/i18n/translate';
-  import type {
-    PayloadContainingObject,
-    PotentiallyDecodable,
+  import { downloadExternalPayloadWithCodec } from '$lib/services/data-encoder';
+  import { codecEndpoint } from '$lib/stores/data-encoder-config';
+  import type { Payload, Payloads } from '$lib/types';
+  import {
+    isExternallyStoredRawPayload,
+    parseRawPayloadToJSON,
+    type PayloadContainingObject,
   } from '$lib/utilities/decode-payload';
+  import { formatBytes } from '$lib/utilities/format-bytes';
+  import { isNetworkError } from '$lib/utilities/is-network-error';
+  import { stringifyWithBigInt } from '$lib/utilities/parse-with-big-int';
 
   import PayloadDecoder from './payload-decoder.svelte';
 
+  type FilenameData = {
+    workflowId: string | undefined;
+    runId: string | undefined;
+    type: 'input' | 'result' | undefined;
+    eventId?: string | undefined;
+  };
+
   interface Props {
-    value: PotentiallyDecodable | PayloadContainingObject;
+    value: Payload | Payloads | PayloadContainingObject;
     maxHeight?: number;
     testId?: string;
+    filenameData?: FilenameData;
   }
 
-  let { value, maxHeight, testId }: Props = $props();
+  let { value, maxHeight, testId, filenameData = undefined }: Props = $props();
+
+  let downloadError: string | undefined = $state(undefined);
+  let downloadLoading: boolean = $state(false);
+
+  const fileName = $derived.by(() => {
+    if (!filenameData) {
+      return 'payload.json';
+    }
+
+    const base = `payload-wf-${filenameData.workflowId}-run-${filenameData.runId}`;
+
+    if (filenameData.eventId) {
+      return `${base}-event-${filenameData.eventId}-${filenameData.type}.json`;
+    }
+
+    return `${base}-${filenameData.type}.json`;
+  });
+
+  const downloadExternalPayload = async (payload: Payload) => {
+    downloadLoading = true;
+    let data: Payloads | undefined = undefined;
+    try {
+      data = await downloadExternalPayloadWithCodec(payload);
+      const parsed = parseRawPayloadToJSON(data.payloads[0]);
+      const content = stringifyWithBigInt(parsed, undefined, 2);
+      const a = document.createElement('a');
+      const file = new Blob([content], { type: 'json/plain' });
+      a.href = URL.createObjectURL(file);
+      a.download = fileName;
+      a.click();
+    } catch (error) {
+      if (isNetworkError(error) && error.statusCode === 404) {
+        downloadError =
+          "Unable to download payload file. Your codec server is connected, but it isn't configured to download from external storage.";
+      } else {
+        downloadError = 'Unable to download payload file.';
+      }
+    } finally {
+      downloadLoading = false;
+    }
+  };
 </script>
 
 <PayloadDecoder {value}>
-  {#snippet children(decodedValue)}
+  {#snippet children(results)}
     <div class="space-y-2">
-      {#each decodedValue as data (data)}
-        <CodeBlock
-          content={data}
-          {maxHeight}
-          copyIconTitle={translate('common.copy-icon-title')}
-          copySuccessIconTitle={translate('common.copy-success-icon-title')}
-          {testId}
-          language="json"
-        />
+      {#each results as result (result.decodedValue)}
+        {#if isExternallyStoredRawPayload(result.decodedValue)}
+          <CodeBlock
+            content={stringifyWithBigInt(result.decodedValue.data)}
+            {maxHeight}
+            copyIconTitle={translate('common.copy-icon-title')}
+            copySuccessIconTitle={translate('common.copy-success-icon-title')}
+            {testId}
+            language="json"
+          >
+            {#snippet headerActions()}
+              <Tooltip
+                width={192}
+                top
+                hide={!!$codecEndpoint}
+                text="Add a codec server with a /download endpoint to download this payload."
+              >
+                <Button
+                  size="sm"
+                  variant="ghost"
+                  leadingIcon="download"
+                  disabled={!$codecEndpoint}
+                  loading={downloadLoading}
+                  on:click={() => downloadExternalPayload(result.originalValue)}
+                >
+                  {formatBytes(
+                    result.decodedValue.externalPayloads?.[0].sizeBytes,
+                  )}
+                </Button>
+              </Tooltip>
+            {/snippet}
+          </CodeBlock>
+          {#if downloadError}
+            <div class="flex items-start gap-2 text-danger">
+              <Icon width={16} height={16} name="exclamation-octagon" />
+              <p class="leading-4">{downloadError}</p>
+            </div>
+          {/if}
+          <p>
+            Payload downloads require a codec server with a <span
+              class="rounded-sm bg-code-block px-1 font-mono">/download</span
+            >
+            endpoint. <Link href="https://docs.temporal.io/codec-server" newTab
+              >How to set up a codec server
+            </Link>
+            <Icon class="inline" name="external-link" />
+          </p>
+        {:else}
+          <CodeBlock
+            content={stringifyWithBigInt(result.decodedValue.data)}
+            {maxHeight}
+            copyIconTitle={translate('common.copy-icon-title')}
+            copySuccessIconTitle={translate('common.copy-success-icon-title')}
+            {testId}
+            language="json"
+          />
+        {/if}
       {/each}
     </div>
   {/snippet}
diff --git a/src/lib/components/payload/payload-decoder.svelte b/src/lib/components/payload/payload-decoder.svelte
index 7a4382249a..68af83c37a 100644
--- a/src/lib/components/payload/payload-decoder.svelte
+++ b/src/lib/components/payload/payload-decoder.svelte
@@ -1,52 +1,102 @@
+<script lang="ts" module>
+  export type DecodedPayloadResult = {
+    decodedValue: ParsedPayload | PayloadContainingObject;
+    originalValue: Payload | PayloadContainingObject;
+  }[];
+</script>
+
 <script lang="ts">
   import { type Snippet } from 'svelte';
 
+  import type { Payload, Payloads } from '$lib/types';
   import {
     decodeEventAttributes,
     decodePayloadAndParseDataToJSON,
     decodePayloadsAndParseDataToJSON,
     isRawPayload,
     isRawPayloads,
+    type ParsedPayload,
     type PayloadContainingObject,
-    type PotentiallyDecodable,
   } from '$lib/utilities/decode-payload';
-  import { stringifyWithBigInt } from '$lib/utilities/parse-with-big-int';
 
-  export const decodePayloadValue = async (
-    value: PotentiallyDecodable | PayloadContainingObject,
-  ): Promise<string[]> => {
+  type T = $$Generic<PayloadContainingObject>;
+
+  const decodePayloadValue = async (
+    value: Payload,
+  ): Promise<DecodedPayloadResult> => {
+    const decodedPayload = await decodePayloadAndParseDataToJSON(value, false);
+    const result = [
+      {
+        decodedValue: decodedPayload,
+        originalValue: value,
+      },
+    ];
+
+    onDecode?.(result);
+    return result;
+  };
+
+  const decodePayloadsValue = async (
+    value: Payloads,
+  ): Promise<DecodedPayloadResult> => {
+    const decodedPayloads = await decodePayloadsAndParseDataToJSON(
+      value,
+      false,
+    );
+    const result = decodedPayloads.map((decodedPayload, idx) => {
+      return {
+        decodedValue: decodedPayload,
+        originalValue: value.payloads[idx],
+      };
+    });
+
+    onDecode?.(result);
+    return result;
+  };
+
+  const decodePayloadContainingObjectValue = async <
+    T extends PayloadContainingObject,
+  >(
+    value: T,
+  ): Promise<DecodedPayloadResult> => {
+    const decodedValue = await decodeEventAttributes(value);
+    const result = [
+      {
+        decodedValue,
+        originalValue: value,
+      },
+    ];
+
+    onDecode?.(result);
+    return result;
+  };
+
+  const decodeValue = (
+    value: Payload | Payloads | T,
+  ): Promise<DecodedPayloadResult> => {
     if (isRawPayload(value)) {
-      const decodedPayloadData = await decodePayloadAndParseDataToJSON(value);
-      const stringified = stringifyWithBigInt(decodedPayloadData);
-      onDecode?.([stringified]);
-      return [stringified];
-    } else if (isRawPayloads(value)) {
-      const parsedPayloadsData = await decodePayloadsAndParseDataToJSON(value);
-      const stringified = parsedPayloadsData.map((data) =>
-        stringifyWithBigInt(data),
-      );
-      onDecode?.(stringified);
-      return stringified;
-    } else {
-      const decoded = await decodeEventAttributes(value);
-      const stringified = stringifyWithBigInt(decoded);
-      onDecode?.([stringified]);
-      return [stringified];
+      return decodePayloadValue(value);
     }
+
+    if (isRawPayloads(value)) {
+      return decodePayloadsValue(value);
+    }
+
+    return decodePayloadContainingObjectValue(value);
   };
 
-  interface Props {
-    value: PotentiallyDecodable | PayloadContainingObject;
-    onDecode?: (decodedPayloads: string[]) => void;
-    children: Snippet<[decodedPayloads: string[]]>;
-    loading?: Snippet;
-  }
+  type Props = {
+    value: Payload | Payloads | T;
+    children: Snippet<[DecodedPayloadResult]>;
+    onDecode?: (result: DecodedPayloadResult) => void;
+    loading?: Snippet<[]>;
+  };
 
-  let { value, onDecode, children, loading }: Props = $props();
+  let { value, children, onDecode, loading }: Props = $props();
 </script>
 
-{#await decodePayloadValue(value)}
+{#await decodeValue(value)}
   {@render loading?.()}
-{:then decodedValue}
-  {@render children(decodedValue)}
+{:then decodeResult}
+  {@render children(decodeResult)}
 {/await}
diff --git a/src/lib/components/payload/payload-inline.svelte b/src/lib/components/payload/payload-inline.svelte
index 19a220f6b0..7b769b6def 100644
--- a/src/lib/components/payload/payload-inline.svelte
+++ b/src/lib/components/payload/payload-inline.svelte
@@ -1,5 +1,6 @@
 <script lang="ts">
   import type { PotentiallyDecodable } from '$lib/utilities/decode-payload';
+  import { stringifyWithBigInt } from '$lib/utilities/parse-with-big-int';
 
   import PayloadDecoder from './payload-decoder.svelte';
 
@@ -13,15 +14,13 @@
 </script>
 
 <PayloadDecoder {value}>
-  {#snippet children(decodedValue)}
+  {#snippet children(result)}
+    {@const stringifiedData = stringifyWithBigInt(result[0].decodedValue.data)}
     <div
       class="overflow-hidden border border-subtle bg-code-block px-1 py-0.5 font-mono text-xs text-primary {className}"
     >
       <code>
-        <pre class="truncate">{(decodedValue[0] ?? '').slice(
-            0,
-            truncateAt,
-          )}</pre>
+        <pre class="truncate">{stringifiedData.slice(0, truncateAt)}</pre>
       </code>
     </div>
   {/snippet}
diff --git a/src/lib/components/schedule/schedule-form/schedule-input-payload.svelte b/src/lib/components/schedule/schedule-form/schedule-input-payload.svelte
index cbda4c872c..a44c4b1caa 100644
--- a/src/lib/components/schedule/schedule-form/schedule-input-payload.svelte
+++ b/src/lib/components/schedule/schedule-form/schedule-input-payload.svelte
@@ -1,7 +1,9 @@
 <script lang="ts">
   import type { Writable } from 'svelte/store';
 
-  import PayloadDecoder from '$lib/components/payload/payload-decoder.svelte';
+  import PayloadDecoder, {
+    type DecodedPayloadResult,
+  } from '$lib/components/payload/payload-decoder.svelte';
   import PayloadInputWithEncoding from '$lib/components/payload-input-with-encoding.svelte';
   import Button from '$lib/holocene/button.svelte';
   import { translate } from '$lib/i18n/translate';
@@ -35,8 +37,9 @@
   let initialMessageType = $state('');
   let loading = $state(true);
 
-  const setInitialInput = (decodedValue: string[]): void => {
-    initialInput = decodedValue[0];
+  const setInitialInput = (result: DecodedPayloadResult): void => {
+    initialInput = result[0].decodedValue.data;
+
     input = initialInput;
     let currentEncoding: PayloadInputEncoding = 'json/plain';
     let currentMessageType = '';
diff --git a/src/lib/components/workflow/input-and-results-payload.svelte b/src/lib/components/workflow/input-and-results-payload.svelte
deleted file mode 100644
index 9e341f24c4..0000000000
--- a/src/lib/components/workflow/input-and-results-payload.svelte
+++ /dev/null
@@ -1,43 +0,0 @@
-<script lang="ts">
-  import type { Snippet } from 'svelte';
-
-  import PayloadCodeBlock from '$lib/components/payload/payload-code-block.svelte';
-  import CodeBlock from '$lib/holocene/code-block.svelte';
-  import type { Payloads } from '$lib/types';
-  import type { CompletionEventAttributes } from '$lib/utilities/get-started-completed-and-task-failed-events';
-
-  type Props = {
-    title: string;
-    titleSnippet?: Snippet;
-    content: Payloads | CompletionEventAttributes;
-    isPending?: boolean;
-  };
-  let {
-    title,
-    titleSnippet = defaultTitleSnippet,
-    content,
-    isPending = false,
-  }: Props = $props();
-
-  const MAX_HEIGHT = 300;
-</script>
-
-{#snippet defaultTitleSnippet()}
-  <h3 class="flex items-center gap-2 text-xs text-secondary">
-    {title}
-  </h3>
-{/snippet}
-
-<div class="flex w-full grow flex-col gap-2">
-  {@render titleSnippet()}
-  {#if content}
-    <PayloadCodeBlock maxHeight={MAX_HEIGHT} value={content} />
-  {:else}
-    <CodeBlock
-      content={isPending ? 'Results will appear upon completion.' : 'null'}
-      language="text"
-      copyable={false}
-      maxHeight={MAX_HEIGHT}
-    />
-  {/if}
-</div>
diff --git a/src/lib/components/workflow/input-and-results.svelte b/src/lib/components/workflow/input-and-results.svelte
index 7391c4f345..59f74054d3 100644
--- a/src/lib/components/workflow/input-and-results.svelte
+++ b/src/lib/components/workflow/input-and-results.svelte
@@ -1,26 +1,62 @@
 <script lang="ts">
+  import PayloadCodeBlock from '$lib/components/payload/payload-code-block.svelte';
+  import CodeBlock from '$lib/holocene/code-block.svelte';
   import { translate } from '$lib/i18n/translate';
   import { fullEventHistory } from '$lib/stores/events';
   import { workflowRun } from '$lib/stores/workflow-run';
   import { getWorkflowStartedCompletedAndTaskFailedEvents } from '$lib/utilities/get-started-completed-and-task-failed-events';
 
-  import InputAndResultsPayload from './input-and-results-payload.svelte';
+  const workflowEvents = $derived(
+    getWorkflowStartedCompletedAndTaskFailedEvents($fullEventHistory),
+  );
+  const isPending = $derived(
+    $workflowRun.workflow.isRunning || $workflowRun.workflow.isPaused,
+  );
+  const payloadDownloadFilenameData = $derived({
+    workflowId: $workflowRun.workflow.id,
+    runId: $workflowRun.workflow.runId,
+  });
 
-  $: workflowEvents =
-    getWorkflowStartedCompletedAndTaskFailedEvents($fullEventHistory);
-  $: isPending =
-    $workflowRun.workflow.isRunning || $workflowRun.workflow.isPaused;
+  const MAX_HEIGHT = 300;
 </script>
 
 <div class="flex flex-col gap-4 lg:flex-row" data-testid="input-and-result">
-  <InputAndResultsPayload
-    title={translate('workflows.input')}
-    content={workflowEvents.input}
-    {isPending}
-  />
-  <InputAndResultsPayload
-    title={translate('workflows.result')}
-    content={workflowEvents.results}
-    {isPending}
-  />
+  <div class="flex w-full grow flex-col gap-2">
+    <h3 class="flex items-center gap-2 text-xs text-secondary">
+      {translate('workflows.input')}
+    </h3>
+    {#if workflowEvents.input}
+      <PayloadCodeBlock
+        filenameData={{ ...payloadDownloadFilenameData, type: 'input' }}
+        maxHeight={300}
+        value={workflowEvents.input}
+      />
+    {:else}
+      <CodeBlock
+        content={isPending ? 'Results will appear upon completion.' : 'null'}
+        language="text"
+        copyable={false}
+        maxHeight={MAX_HEIGHT}
+      />
+    {/if}
+  </div>
+  <div class="flex w-full grow flex-col gap-2">
+    <h3 class="flex items-center gap-2 text-xs text-secondary">
+      {translate('workflows.results')}
+    </h3>
+    {#if workflowEvents.results}
+      <PayloadCodeBlock
+        filenameData={{ ...payloadDownloadFilenameData, type: 'result' }}
+        maxHeight={300}
+        value={workflowEvents.results}
+      />
+    {:else}
+      <CodeBlock
+        content={isPending ? 'Results will appear upon completion.' : 'null'}
+        language="text"
+        copyable={false}
+        maxHeight={MAX_HEIGHT}
+      />
+    {/if}
+  </div>
 </div>
diff --git a/src/lib/holocene/button.svelte b/src/lib/holocene/button.svelte
index dcbce6f925..efa7c8148c 100644
--- a/src/lib/holocene/button.svelte
+++ b/src/lib/holocene/button.svelte
@@ -194,14 +194,14 @@
     )}
     {...$$restProps}
   >
-    {#if leadingIcon}
-      <span>
-        <Icon name={leadingIcon} />
+    {#if (leadingIcon || loading) && !trailingIcon}
+      <span class:animate-spin={loading}>
+        <Icon name={loading ? 'spinner' : leadingIcon} />
       </span>
     {/if}
     <slot />
 
-    {#if trailingIcon || loading}
+    {#if (trailingIcon || loading) && !leadingIcon}
       <span class:animate-spin={loading}>
         <Icon name={loading ? 'spinner' : trailingIcon} />
       </span>
diff --git a/src/lib/holocene/code-block.svelte b/src/lib/holocene/code-block.svelte
index 1cce013ce3..a31b8a287a 100644
--- a/src/lib/holocene/code-block.svelte
+++ b/src/lib/holocene/code-block.svelte
@@ -295,7 +295,9 @@
     ></div>
 
     {#snippet actions()}
-      {#if copyable && !hasHeader}
+      {#if headerActions}
+        {@render headerActions()}
+      {:else if copyable && !hasHeader}
         <CopyButton
           {copyIconTitle}
           {copySuccessIconTitle}
diff --git a/src/lib/i18n/locales/en/common.ts b/src/lib/i18n/locales/en/common.ts
index 6a8dc29988..6e32db8744 100644
--- a/src/lib/i18n/locales/en/common.ts
+++ b/src/lib/i18n/locales/en/common.ts
@@ -169,6 +169,7 @@ export const Strings = {
   'not-equal-to': 'Not equal to',
   'encode-failed': 'Data encoding failed',
   'decode-failed': 'Data decoding failed',
+  'download-failed': 'Download failed',
   'job-id': 'Job ID',
   'auto-refresh': 'Auto refresh',
   'auto-refresh-tooltip': '{{ interval }} second page refresh',
diff --git a/src/lib/services/data-encoder.ts b/src/lib/services/data-encoder.ts
index 279dbf2ebb..0c3989bc50 100644
--- a/src/lib/services/data-encoder.ts
+++ b/src/lib/services/data-encoder.ts
@@ -5,7 +5,7 @@ import {
   setLastDataEncoderFailure,
   setLastDataEncoderSuccess,
 } from '$lib/stores/data-encoder-config';
-import type { Payloads } from '$lib/types';
+import type { Payload, Payloads } from '$lib/types';
 import type { NetworkError } from '$lib/types/global';
 import { getAccessToken, getIdToken } from '$lib/utilities/core-provider';
 import {
@@ -18,11 +18,15 @@ import { stringifyWithBigInt } from '$lib/utilities/parse-with-big-int';
 
 export type PotentialPayloads = { payloads: unknown[] };
 
+export const NO_CODEC_SERVER_CONFIGURED_ERROR = new Error(
+  'No codec server configured',
+);
+
 export async function codeServerRequest({
   type,
   payloads,
 }: {
-  type: 'decode' | 'encode';
+  type: 'decode' | 'encode' | 'download';
   payloads: PotentialPayloads;
 }): Promise<Payloads> {
   const settings = page.data.settings;
@@ -31,7 +35,7 @@ export async function codeServerRequest({
 
   if (!endpoint) {
     if (type === 'decode') return payloads;
-    throw new Error('No codec endpoint configured');
+    throw NO_CODEC_SERVER_CONFIGURED_ERROR;
   }
 
   const passAccessToken = getCodecPassAccessToken(settings);
@@ -71,10 +75,10 @@ export async function codeServerRequest({
         body: stringifyWithBigInt(payloads),
       };
 
-  const decoderResponse: Promise<PotentialPayloads> = fetch(
-    endpoint + `/${type}`,
-    requestOptions,
-  )
+  const url = new URL(type, endpoint);
+  url.searchParams.set('preserveStorageRefs', 'true');
+
+  const decoderResponse: Promise<PotentialPayloads> = fetch(url, requestOptions)
     .then((response) => {
       if (response.ok === false) {
         throw {
@@ -93,7 +97,9 @@ export async function codeServerRequest({
       return response;
     })
     .catch((err: unknown) => {
-      setLastDataEncoderFailure(err);
+      if (type !== 'download') {
+        setLastDataEncoderFailure(err);
+      }
       if (type === 'decode') {
         return payloads;
       } else {
@@ -119,3 +125,12 @@ export async function encodePayloadsWithCodec({
 }): Promise<Payloads> {
   return codeServerRequest({ type: 'encode', payloads });
 }
+
+export async function downloadExternalPayloadWithCodec(
+  payload: Payload,
+): Promise<Payloads> {
+  return codeServerRequest({
+    type: 'download',
+    payloads: { payloads: [payload] },
+  });
+}
diff --git a/src/lib/utilities/decode-payload.ts b/src/lib/utilities/decode-payload.ts
index a6f0547b00..610574bc92 100644
--- a/src/lib/utilities/decode-payload.ts
+++ b/src/lib/utilities/decode-payload.ts
@@ -33,6 +33,10 @@ export type ParsedPayload = {
   metadata: ParsedMetadata;
 };
 
+export type ParsedExternalPayload = ParsedPayload & {
+  externalPayloads: { sizeBytes: number }[];
+};
+
 /**
  * Decoding TL;DR
  * Decoding includes either 1 or 2 phases - "parse" and "decode"
@@ -113,6 +117,7 @@ export function parseRawPayloadToJSON(
     return {
       metadata,
       data,
+      externalPayloads: payload.externalPayloads ?? [],
     };
   } catch (_e) {
     console.warn('Could not parse payload: ', _e);
@@ -237,8 +242,23 @@ const keyIs = (key: string, ...validKeys: string[]) => {
 export const isRawPayload = (payload: unknown): payload is Payload => {
   if (!isObject(payload)) return false;
   const keys = Object.keys(payload);
+  return keys.length >= 2 && keys.includes('metadata') && keys.includes('data');
+};
+
+export const isParsedPayload = (payload: unknown): payload is ParsedPayload => {
+  if (!isObject(payload)) return false;
+  const keys = Object.keys(payload);
+  return keys.length >= 2 && keys.includes('metadata') && keys.includes('data');
+};
+
+export const isExternallyStoredRawPayload = (
+  payload: unknown,
+): payload is ParsedExternalPayload => {
   return (
-    keys.length === 2 && keys.includes('metadata') && keys.includes('data')
+    isParsedPayload(payload) &&
+    has(payload.metadata, 'messageType') &&
+    payload.metadata.messageType ===
+      'temporal.api.sdk.v1.ExternalStorageReference'
   );
 };
 
@@ -275,17 +295,27 @@ export async function decodePayloadAndParseDataToJSON(
   return parseRawPayloadToJSON(decoded[0], returnDataOnly);
 }
 
-export const decodePayloadsAndParseDataToJSON = async (
+export async function decodePayloadsAndParseDataToJSON(
+  payload: Payloads,
+): Promise<unknown[]>;
+export async function decodePayloadsAndParseDataToJSON(
+  payload: Payloads,
+  returnDataOnly: false,
+): Promise<ParsedPayload[]>;
+export async function decodePayloadsAndParseDataToJSON(
   payloads: Payloads | null | undefined,
-): Promise<unknown[]> => {
+  returnDataOnly: boolean = true,
+): Promise<unknown[]> {
   const decoded = await decodePayloadsWithRemoteCodec(payloads?.payloads);
 
   if (!decoded || !decoded[0]) {
     return [null];
   }
 
-  return decoded.map((payload) => parseRawPayloadToJSON(payload));
-};
+  return decoded.map((payload) =>
+    parseRawPayloadToJSON(payload, returnDataOnly),
+  );
+}
 
 /**
  * Phase 2 internal implementation shared by {@link decodeEventAttributes} and
diff --git a/temporal/codec-server.ts b/temporal/codec-server.ts
index 9800f6fd4d..02537dcebc 100644
--- a/temporal/codec-server.ts
+++ b/temporal/codec-server.ts
@@ -94,6 +94,10 @@ export async function createCodecServer(
     }
   });
 
+  app.post('/download', async (req, res) => {
+    res.status(404).end('Not found');
+  });
+
   const start = () =>
     new Promise<Server>((resolve, reject) => {
       server = app.listen(port, () => {