improvement(buffer): explicit mediaType override; error instead of guessing on ambiguous media

Author: waleedlatif1

apps/docs/content/docs/en/integrations/buffer.mdx

@@ -34,6 +34,7 @@ Create a post in Buffer for a channel — add it to the queue, share it immediat
 | `dueAt` | string | No | Publish time as an ISO 8601 timestamp \(required when mode is customScheduled\) |
 | `saveToDraft` | boolean | No | Save the post as a draft instead of scheduling it |
 | `media` | file | No | Image or video to attach — an uploaded file, a file reference from a previous block, or a publicly accessible URL |
+| `mediaType` | string | No | Force the attachment type when it cannot be detected from the file or URL: image or video \(default auto\) |
 | `mediaAltText` | string | No | Alt text for an attached image |
 
 #### Output
@@ -83,6 +84,7 @@ Edit an existing Buffer post — update its text, schedule, or media. Attaching
 | `dueAt` | string | No | Publish time as an ISO 8601 timestamp \(required when mode is customScheduled\) |
 | `saveToDraft` | boolean | No | Save the post as a draft instead of scheduling it |
 | `media` | file | No | Image or video to attach — an uploaded file, a file reference from a previous block, or a publicly accessible URL. Replaces existing attachments |
+| `mediaType` | string | No | Force the attachment type when it cannot be detected from the file or URL: image or video \(default auto\) |
 | `mediaAltText` | string | No | Alt text for an attached image |
 
 #### Output

apps/sim/app/api/tools/buffer/server-utils.ts

@@ -53,6 +53,7 @@ const EDIT_POST_MUTATION = `
 
 interface ResolveMediaAssetOptions {
   media: RawFileInput | string
+  mediaType?: 'auto' | 'image' | 'video' | null
   mediaAltText?: string | null
   userId: string
   requestId: string
@@ -79,15 +80,16 @@ function mediaKindFromExtension(pathOrName: string): 'image' | 'video' | null {
  * Determines whether media should be attached as a video or image asset.
  * Prefers the file's MIME type, then the path/URL extension, and for
  * extensionless URLs falls back to a DNS-pinned HEAD probe of the resolved
- * URL's Content-Type. Defaults to image when nothing is conclusive.
+ * URL's Content-Type. Returns null when nothing is conclusive so the caller
+ * can ask for an explicit media type instead of guessing.
  */
 async function resolveMediaKind(
   mimeType: string | undefined,
   pathOrName: string,
   fileUrl: string,
   requestId: string,
   logger: Logger
-): Promise<'image' | 'video'> {
+): Promise<'image' | 'video' | null> {
   if (mimeType?.startsWith('video/')) return 'video'
   if (mimeType?.startsWith('image/')) return 'image'
 
@@ -106,11 +108,11 @@ async function resolveMediaKind(
       if (contentType.startsWith('image/')) return 'image'
     }
   } catch (error) {
-    logger.warn(`[${requestId}] Media content-type probe failed, defaulting to image`, {
+    logger.warn(`[${requestId}] Media content-type probe was inconclusive`, {
       error: getErrorMessage(error, 'probe failed'),
     })
   }
-  return 'image'
+  return null
 }
 
 /**
@@ -122,7 +124,7 @@ async function resolveMediaKind(
 export async function resolveMediaAsset(
   options: ResolveMediaAssetOptions
 ): Promise<ResolvedMediaAsset> {
-  const { media, mediaAltText, userId, requestId, logger } = options
+  const { media, mediaType, mediaAltText, userId, requestId, logger } = options
 
   const isFileInput = typeof media === 'object'
   const resolution = await resolveFileInputToUrl({
@@ -143,7 +145,22 @@ export async function resolveMediaAsset(
 
   const mimeType = isFileInput ? media.type : undefined
   const pathOrName = isFileInput ? media.name || '' : media
-  const kind = await resolveMediaKind(mimeType, pathOrName, resolution.fileUrl, requestId, logger)
+  const kind =
+    mediaType === 'image' || mediaType === 'video'
+      ? mediaType
+      : await resolveMediaKind(mimeType, pathOrName, resolution.fileUrl, requestId, logger)
+  if (!kind) {
+    return {
+      errorResponse: NextResponse.json(
+        {
+          success: false,
+          error:
+            'Could not determine whether the media is an image or a video. Set mediaType to "image" or "video".',
+        },
+        { status: 400 }
+      ),
+    }
+  }
   if (kind === 'video') {
     return { asset: { video: { url: resolution.fileUrl } } }
   }
@@ -210,6 +227,7 @@ interface ForwardPostMutationOptions {
   dueAt?: string | null
   saveToDraft?: boolean | null
   media?: RawFileInput | string | null
+  mediaType?: 'auto' | 'image' | 'video' | null
   mediaAltText?: string | null
   userId: string
   requestId: string
@@ -224,7 +242,8 @@ interface ForwardPostMutationOptions {
 export async function forwardPostMutation(
   options: ForwardPostMutationOptions
 ): Promise<NextResponse> {
-  const { apiKey, postId, channelId, media, mediaAltText, userId, requestId, logger } = options
+  const { apiKey, postId, channelId, media, mediaType, mediaAltText, userId, requestId, logger } =
+    options
 
   const input: Record<string, unknown> = {
     mode: options.mode,
@@ -243,6 +262,7 @@ export async function forwardPostMutation(
   if (media) {
     const { asset, errorResponse } = await resolveMediaAsset({
       media,
+      mediaType,
       mediaAltText,
       userId,
       requestId,

apps/sim/blocks/blocks/buffer.ts

@@ -140,6 +140,19 @@ export const BufferBlock: BlockConfig<BufferPostResponse> = {
       mode: 'advanced',
       condition: { field: 'operation', value: POST_EDIT_OPS },
     },
+    {
+      id: 'mediaType',
+      title: 'Media Type',
+      type: 'dropdown',
+      options: [
+        { label: 'Auto-detect', id: 'auto' },
+        { label: 'Image', id: 'image' },
+        { label: 'Video', id: 'video' },
+      ],
+      value: () => 'auto',
+      mode: 'advanced',
+      condition: { field: 'operation', value: POST_EDIT_OPS },
+    },
     {
       id: 'mediaAltText',
       title: 'Media Alt Text',
@@ -321,6 +334,10 @@ export const BufferBlock: BlockConfig<BufferPostResponse> = {
     dueAt: { type: 'string', description: 'Publish time (ISO 8601)' },
     saveToDraft: { type: 'boolean', description: 'Save the post as a draft' },
     media: { type: 'string', description: 'Image or video attachment (file or public URL)' },
+    mediaType: {
+      type: 'string',
+      description: 'Attachment type override: auto, image, or video',
+    },
     mediaAltText: { type: 'string', description: 'Alt text for an attached image' },
     channelIds: { type: 'string', description: 'Comma-separated channel IDs filter' },
     status: { type: 'string', description: 'Comma-separated post status filter' },

apps/sim/lib/api/contracts/tools/buffer.ts

@@ -62,6 +62,7 @@ const postSharedFields = {
     .nullable(),
   saveToDraft: z.boolean().optional().nullable(),
   media: FileInputSchema.optional().nullable(),
+  mediaType: z.enum(['auto', 'image', 'video']).default('auto'),
   mediaAltText: z.string().max(1000, 'mediaAltText is too long').optional().nullable(),
 }
 

apps/sim/tools/buffer/create_post.ts

@@ -64,6 +64,13 @@ export const bufferCreatePostTool: ToolConfig<BufferCreatePostParams, BufferPost
       description:
         'Image or video to attach — an uploaded file, a file reference from a previous block, or a publicly accessible URL',
     },
+    mediaType: {
+      type: 'string',
+      required: false,
+      visibility: 'user-or-llm',
+      description:
+        'Force the attachment type when it cannot be detected from the file or URL: image or video (default auto)',
+    },
     mediaAltText: {
       type: 'string',
       required: false,
@@ -85,6 +92,7 @@ export const bufferCreatePostTool: ToolConfig<BufferCreatePostParams, BufferPost
       dueAt: params.dueAt,
       saveToDraft: params.saveToDraft,
       media: params.media,
+      mediaType: params.mediaType,
       mediaAltText: params.mediaAltText,
     }),
   },

apps/sim/tools/buffer/edit_post.ts

@@ -64,6 +64,13 @@ export const bufferEditPostTool: ToolConfig<BufferEditPostParams, BufferPostResp
       description:
         'Image or video to attach — an uploaded file, a file reference from a previous block, or a publicly accessible URL. Replaces existing attachments',
     },
+    mediaType: {
+      type: 'string',
+      required: false,
+      visibility: 'user-or-llm',
+      description:
+        'Force the attachment type when it cannot be detected from the file or URL: image or video (default auto)',
+    },
     mediaAltText: {
       type: 'string',
       required: false,
@@ -85,6 +92,7 @@ export const bufferEditPostTool: ToolConfig<BufferEditPostParams, BufferPostResp
       dueAt: params.dueAt,
       saveToDraft: params.saveToDraft,
       media: params.media,
+      mediaType: params.mediaType,
       mediaAltText: params.mediaAltText,
     }),
   },

apps/sim/tools/buffer/types.ts

@@ -389,6 +389,7 @@ export interface BufferCreatePostParams extends BufferBaseParams {
   dueAt?: string
   saveToDraft?: boolean
   media?: unknown
+  mediaType?: 'auto' | 'image' | 'video'
   mediaAltText?: string
 }
 
@@ -400,6 +401,7 @@ export interface BufferEditPostParams extends BufferBaseParams {
   dueAt?: string
   saveToDraft?: boolean
   media?: unknown
+  mediaType?: 'auto' | 'image' | 'video'
   mediaAltText?: string
 }