fix(files): tighten streaming preview invariant and component consistency

- Apply structural invariant to PDF streaming path: never surface errors
  while streamingContent is defined; only log at info level
- Remove redundant setRenderError(null) from DOCX streaming effect — the
  gate at the display layer already suppresses errors during streaming
- Wrap PptxPreview in memo for consistency with DocxPreview
- Add key={file.id} to PptxPreview mount site (was missing, DocxPreview
  had it) so the component resets when the viewed file changes
- Fix --text-body → --text-primary across PreviewError, UnsupportedPreview,
  and MermaidDiagram error label; --text-body is not a valid EMCN token

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/docx-preview.tsx

@@ -89,7 +89,6 @@ export const DocxPreview = memo(function DocxPreview({
 
       try {
         setRendering(true)
-        setRenderError(null)
 
         const response = await fetch(`/api/workspaces/${workspaceId}/docx/preview`, {
           method: 'POST',

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/file-viewer.tsx

@@ -18,12 +18,7 @@ import { ImagePreview } from './image-preview'
 import type { PdfDocumentSource } from './pdf-viewer'
 import { PptxPreview } from './pptx-preview'
 import { resolvePreviewType } from './preview-panel'
-import {
-  PDF_PAGE_SKELETON,
-  PreviewError,
-  resolvePreviewError,
-  shouldSuppressStreamingDocumentError,
-} from './preview-shared'
+import { PDF_PAGE_SKELETON, PreviewError, resolvePreviewError } from './preview-shared'
 import { TextEditor } from './text-editor'
 import { XlsxPreview } from './xlsx-preview'
 
@@ -128,7 +123,14 @@ export function FileViewer({
   }
 
   if (category === 'pptx-previewable') {
-    return <PptxPreview file={file} workspaceId={workspaceId} streamingContent={streamingContent} />
+    return (
+      <PptxPreview
+        key={file.id}
+        file={file}
+        workspaceId={workspaceId}
+        streamingContent={streamingContent}
+      />
+    )
   }
 
   if (category === 'xlsx-previewable') {
@@ -196,12 +198,7 @@ const IframePreview = memo(function IframePreview({
       } catch (err) {
         if (!cancelled && !(err instanceof DOMException && err.name === 'AbortError')) {
           const msg = toError(err).message || 'Failed to render PDF'
-          if (streamingBufferRef.current || shouldSuppressStreamingDocumentError(msg)) {
-            logger.info('Suppressing transient PDF streaming preview error', { error: msg })
-          } else {
-            logger.error('PDF render failed', { error: msg })
-            setRenderError(msg)
-          }
+          logger.info('Transient PDF streaming preview error (suppressed)', { error: msg })
         }
       } finally {
         if (!cancelled) setRendering(false)
@@ -228,7 +225,8 @@ const IframePreview = memo(function IframePreview({
     [streamingBuffer]
   )
 
-  if (renderError) return <PreviewError label='PDF' error={renderError} />
+  if (streamingContent === undefined && renderError)
+    return <PreviewError label='PDF' error={renderError} />
 
   if (streamingContent !== undefined) {
     if (!streamingSource) {
@@ -361,7 +359,7 @@ const UnsupportedPreview = memo(function UnsupportedPreview({
 
   return (
     <div className='flex flex-1 flex-col items-center justify-center gap-[8px]'>
-      <p className='font-medium text-[14px] text-[var(--text-body)]'>
+      <p className='font-medium text-[14px] text-[var(--text-primary)]'>
         Preview not available{ext ? ` for .${ext} files` : ' for this file'}
       </p>
       <p className='text-[13px] text-[var(--text-muted)]'>

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/pptx-preview.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import { useEffect, useState } from 'react'
+import { memo, useEffect, useState } from 'react'
 import { createLogger } from '@sim/logger'
 import { toError } from '@sim/utils/errors'
 import { Skeleton } from '@/components/emcn'
@@ -123,7 +123,7 @@ async function getPptxRenderSize(
   }
 }
 
-export function PptxPreview({
+export const PptxPreview = memo(function PptxPreview({
   file,
   workspaceId,
   streamingContent,
@@ -269,4 +269,4 @@ export function PptxPreview({
       </div>
     </div>
   )
-}
+})

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/preview-panel.tsx

@@ -291,7 +291,7 @@ const MermaidDiagram = memo(function MermaidDiagram({ definition }: { definition
   if (error) {
     return (
       <div className='my-4 rounded-lg border border-[var(--border)] p-4 text-[13px] text-[var(--text-muted)]'>
-        <span className='font-medium text-[var(--text-body)]'>Diagram error: </span>
+        <span className='font-medium text-[var(--text-primary)]'>Diagram error: </span>
         {error}
       </div>
     )

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/preview-shared.tsx

@@ -5,7 +5,9 @@ import { Skeleton } from '@/components/emcn'
 export function PreviewError({ label, error }: { label: string; error: string }) {
   return (
     <div className='flex flex-1 flex-col items-center justify-center gap-[8px]'>
-      <p className='font-medium text-[14px] text-[var(--text-body)]'>Failed to preview {label}</p>
+      <p className='font-medium text-[14px] text-[var(--text-primary)]'>
+        Failed to preview {label}
+      </p>
       <p className='text-[13px] text-[var(--text-muted)]'>{error}</p>
     </div>
   )