chore(files): polish style extraction — type narrowing + empty-styles guard

Explicit 'docx' | 'pptx' type annotation after the extension guard in
both route.ts and workspace-vfs.ts so TypeScript sees the narrowed type
rather than string. Only set summary.styles when the parsed array is
non-empty so the JSON response doesn't include "styles": []. Remove
redundant inline WHAT-comments from parseColorSlot.

Author: waleedlatif1

apps/sim/app/api/workspaces/[id]/files/[fileId]/style/route.ts

@@ -37,13 +37,14 @@ export const GET = withRouteHandler(
       return NextResponse.json({ error: 'File not found' }, { status: 404 })
     }
 
-    const ext = fileRecord.name.split('.').pop()?.toLowerCase()
-    if (ext !== 'docx' && ext !== 'pptx') {
+    const rawExt = fileRecord.name.split('.').pop()?.toLowerCase()
+    if (rawExt !== 'docx' && rawExt !== 'pptx') {
       return NextResponse.json(
         { error: 'Style extraction only supports .docx and .pptx files' },
         { status: 422 }
       )
     }
+    const ext: 'docx' | 'pptx' = rawExt
 
     let buffer: Buffer
     try {

apps/sim/lib/copilot/vfs/document-style.ts

@@ -55,6 +55,7 @@ function between(xml: string, open: string, close: string): string {
 function parseColorSlot(xml: string, slot: string): string {
   const inner = between(xml, `<a:${slot}>`, `</a:${slot}>`)
   if (!inner) return ''
+  // srgbClr uses val=; sysClr has val="windowText" but lastClr holds the fallback hex
   const srgb = attr(inner, 'val')
   if (srgb && inner.includes('<a:srgbClr')) return srgb.toUpperCase()
   const lastClr = attr(inner, 'lastClr')
@@ -138,7 +139,6 @@ export async function extractDocumentStyle(
   buffer: Buffer,
   ext: 'docx' | 'pptx'
 ): Promise<DocumentStyleSummary | null> {
-  // Verify ZIP magic bytes
   if (buffer.length < 4) return null
   for (let i = 0; i < 4; i++) {
     if (buffer[i] !== ZIP_MAGIC[i]) return null
@@ -152,14 +152,14 @@ export async function extractDocumentStyle(
     const themeFile = zip.file(themePath)
     if (!themeFile) return null
 
-    const themeXml = await themeFile.async('string')
-    const theme = parseThemeXml(themeXml)
+    const theme = parseThemeXml(await themeFile.async('string'))
     const summary: DocumentStyleSummary = { format: ext, theme }
 
     if (ext === 'docx') {
       const stylesFile = zip.file('word/styles.xml')
       if (stylesFile) {
-        summary.styles = parseDocxStyles(await stylesFile.async('string'))
+        const styles = parseDocxStyles(await stylesFile.async('string'))
+        if (styles && styles.length > 0) summary.styles = styles
       }
     }
 

apps/sim/lib/copilot/vfs/workspace-vfs.ts

@@ -462,8 +462,9 @@ export class WorkspaceVFS {
       try {
         const record = await getWorkspaceFile(this._workspaceId, fileId)
         if (!record) return null
-        const ext = record.name.split('.').pop()?.toLowerCase()
-        if (ext !== 'docx' && ext !== 'pptx') return null
+        const rawExt = record.name.split('.').pop()?.toLowerCase()
+        if (rawExt !== 'docx' && rawExt !== 'pptx') return null
+        const ext: 'docx' | 'pptx' = rawExt
         const buffer = await downloadWorkspaceFile(record)
         const summary = await extractDocumentStyle(buffer, ext)
         if (!summary) return null