Stop shipping html-ppt README preview payloads

Constraint: README preview media and pre-rendered verification screenshots are nonessential for installed skills.
Rejected: WebP recompression | GIF conversion increased size and static compression leaves unnecessary package payload.
Confidence: high
Scope-risk: moderate
Directive: Use external source pruning fields instead of hand-editing generated plugin assets.
Tested: python scripts/validate_marketplace.py; validate_plugin.py plugins/codex/plugins/html-ppt; uv run python -m pytest backend/tests/test_skill_market_publish.py backend/tests/test_skill_market_scheduler.py -q; node web/tests/skills-market-ui.test.mjs; git diff --check
Not-tested: PowerShell execution because pwsh/powershell is not installed locally.

scripts/sync_external_plugins.ps1

@@ -89,6 +89,132 @@ function Copy-DirectoryFiltered {
   }
 }
 
+function Assert-RelativePathValue {
+  param([string]$Path)
+  $trimmed = $Path.Trim()
+  if ([string]::IsNullOrWhiteSpace($Path) -or $trimmed -eq "." -or [System.IO.Path]::IsPathRooted($Path)) {
+    throw "Invalid external source exclude path: $Path"
+  }
+  $parts = $trimmed -split '[\\/]'
+  if ($parts -contains "..") {
+    throw "Invalid external source exclude path: $Path"
+  }
+}
+
+function Remove-ConfiguredExcludes {
+  param(
+    [string]$Root,
+    [object]$ExcludePaths,
+    [string]$Within
+  )
+  if ($null -eq $ExcludePaths) {
+    return
+  }
+  foreach ($exclude in @($ExcludePaths)) {
+    $relative = [string]$exclude
+    Assert-RelativePathValue -Path $relative
+    Remove-PathIfExists -Path (Join-Path $Root $relative) -Within $Within
+  }
+}
+
+function Get-MarkdownImageTarget {
+  param([string]$Line)
+  $match = [regex]::Match($Line, '^\s*!\[[^\]]*\]\(([^)\s]+)(?:\s+"[^"]*")?\)\s*$')
+  if (-not $match.Success) {
+    return $null
+  }
+  return $match.Groups[1].Value.Trim().Trim("<", ">").Replace("\", "/").TrimStart([char[]]@(".", "/"))
+}
+
+function Remove-ReadmeImageReferences {
+  param(
+    [string]$Root,
+    [object]$ImagePathPrefixes
+  )
+  if ($null -eq $ImagePathPrefixes) {
+    return
+  }
+  $prefixes = @(
+    foreach ($prefix in @($ImagePathPrefixes)) {
+      $normalized = ([string]$prefix).Trim().Replace("\", "/").Trim("/")
+      if ($normalized) {
+        $normalized
+      }
+    }
+  )
+  if ($prefixes.Count -eq 0) {
+    return
+  }
+  foreach ($readme in Get-ChildItem -LiteralPath $Root -Recurse -Filter "README*.md" | Where-Object { -not $_.PSIsContainer }) {
+    $lines = @([System.IO.File]::ReadAllLines($readme.FullName, [System.Text.Encoding]::UTF8))
+    $updated = New-Object System.Collections.Generic.List[string]
+    $changed = $false
+    foreach ($line in $lines) {
+      $target = Get-MarkdownImageTarget -Line $line
+      $strip = $false
+      if ($target) {
+        foreach ($prefix in $prefixes) {
+          if ($target -eq $prefix -or $target.StartsWith("$prefix/")) {
+            $strip = $true
+            break
+          }
+        }
+      }
+      if ($strip) {
+        $changed = $true
+      } else {
+        $updated.Add($line)
+      }
+    }
+    if ($changed) {
+      Write-Utf8NoBomText -Path $readme.FullName -Text (($updated -join "`n").TrimEnd() + "`n")
+    }
+  }
+}
+
+function Remove-ReadmeLines {
+  param(
+    [string]$Root,
+    [object]$LineExcludes
+  )
+  if ($null -eq $LineExcludes) {
+    return
+  }
+  $needles = @(
+    foreach ($lineExclude in @($LineExcludes)) {
+      $needle = [string]$lineExclude
+      if ($needle) {
+        $needle
+      }
+    }
+  )
+  if ($needles.Count -eq 0) {
+    return
+  }
+  foreach ($readme in Get-ChildItem -LiteralPath $Root -Recurse -Filter "README*.md" | Where-Object { -not $_.PSIsContainer }) {
+    $lines = @([System.IO.File]::ReadAllLines($readme.FullName, [System.Text.Encoding]::UTF8))
+    $updated = New-Object System.Collections.Generic.List[string]
+    $changed = $false
+    foreach ($line in $lines) {
+      $strip = $false
+      foreach ($needle in $needles) {
+        if ($line.Contains($needle)) {
+          $strip = $true
+          break
+        }
+      }
+      if ($strip) {
+        $changed = $true
+      } else {
+        $updated.Add($line)
+      }
+    }
+    if ($changed) {
+      Write-Utf8NoBomText -Path $readme.FullName -Text (($updated -join "`n").TrimEnd() + "`n")
+    }
+  }
+}
+
 function Read-JsonFile {
   param([string]$Path)
   $resolvedPath = (Resolve-Path -LiteralPath $Path).Path
@@ -350,6 +476,9 @@ function Sync-CodexPlugin {
     $dst = Join-Path $pluginDir $include
     Copy-PathIfExists -Source $src -Destination $dst -Within $RepoRoot
   }
+  Remove-ConfiguredExcludes -Root $pluginDir -ExcludePaths $Source.excludePaths -Within $RepoRoot
+  Remove-ReadmeImageReferences -Root $pluginDir -ImagePathPrefixes $Source.readmeImageExcludes
+  Remove-ReadmeLines -Root $pluginDir -LineExcludes $Source.readmeLineExcludes
   Apply-LocalOverrides -PluginDir $pluginDir -Source $Source
   Write-Provenance -PluginDir $pluginDir -Source $Source -Commit $Commit -SyncedAt $SyncedAt -SourcePath $relativeSourcePath
 }
@@ -407,6 +536,9 @@ function Sync-ClaudeSkill {
   foreach ($rootFile in $includeRootFiles) {
     Copy-PathIfExists -Source (Join-Path $ClonePath $rootFile) -Destination (Join-Path $pluginDir $rootFile) -Within $RepoRoot
   }
+  Remove-ConfiguredExcludes -Root $skillDest -ExcludePaths $Source.excludePaths -Within $RepoRoot
+  Remove-ReadmeImageReferences -Root $pluginDir -ImagePathPrefixes $Source.readmeImageExcludes
+  Remove-ReadmeLines -Root $pluginDir -LineExcludes $Source.readmeLineExcludes
 
   $description = $metadata.description
   if (-not $description) {