Fix complex website preview loading and broken asset resolution

[SirajChokshi]

Summary

• Merge latest origin/main into this branch and resolve src/utils/lang/html.ts conflicts by combining both intents safely.
• Keep the DOMParser-based rewrite/deferred-script pipeline from this branch.
• Integrate main’s runtime fetch-resolver support by injecting the resolver script into processed HTML before deferred script handling.
• Add tests/html.test.ts from main, adapted to synthetic fixture URLs and to assert merged behavior (resolver injection + rewrite semantics).

Conflict classification and resolution

• Simple conflict (resolved): top-level additions in html.ts were non-overlapping (PREVIEW_SCRIPT_* constants vs getFetchResolverScript() helper), so both were kept.
• Complicated conflict (resolved with intent merge): processHTML() had conflicting implementations (DOMParser pipeline vs regex/string replacement). Resolved by preserving DOMParser architecture and integrating resolver injection as an additive step.

Testing

• npm run test -- tests/html.test.ts tests/preview.test.ts tests/image-fallback.test.ts tests/proxy.test.ts
• npm run lint
• npm run check

Walkthrough

  

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Project	Deployment	Actions	Updated (UTC)
static-preview	Ready	Preview, Comment	Apr 7, 2026 6:43am

[cursor]

Cursor Bugbot has reviewed your changes and found 3 potential issues.

Autofix Details

Bugbot Autofix prepared fixes for all 3 issues found in the latest run.

• ✅ Fixed: External script append doesn't wait for load
  • Replaced the async function with a Promise-based implementation using onload/onerror handlers so the await in loadPageElements actually waits for each external script to load before proceeding.
• ✅ Fixed: Duplicate getRepositoryRoot with divergent behavior
  • Removed the duplicate local function from image-fallback.ts and imported the canonical exported version from lang/html.ts, consolidating the logic in one place.
• ✅ Fixed: Property currentPageUrl is assigned but never read
  • Removed the unused currentPageUrl property declaration and its assignment in loadHTML since no code ever reads it.

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@cursor push 50aaad52cc

Preview (50aaad52cc)

diff --git a/src/utils/image-fallback.ts b/src/utils/image-fallback.ts
--- a/src/utils/image-fallback.ts
+++ b/src/utils/image-fallback.ts
@@ -1,29 +1,7 @@
 import { resourceType } from '../types/resources'
+import { getRepositoryRoot } from './lang/html'
 import { getResourceType, isValidURL, processUrl } from './url'
 
-function getRepositoryRoot(rawHtmlUrl: URL): string | undefined {
-  const segments = rawHtmlUrl.pathname.split('/').filter(Boolean)
-
-  if (
-    rawHtmlUrl.hostname === 'raw.githubusercontent.com' &&
-    segments.length >= 3
-  ) {
-    const [owner, repo, branch] = segments
-    return `https://${rawHtmlUrl.hostname}/${owner}/${repo}/${branch}/`
-  }
-
-  const rawMarker = segments.findIndex(
-    (segment, idx) => segment === '-' && segments[idx + 1] === 'raw',
-  )
-  if (rawHtmlUrl.hostname === 'gitlab.com' && rawMarker >= 2) {
-    return `https://${rawHtmlUrl.hostname}/${segments
-      .slice(0, rawMarker + 3)
-      .join('/')}/`
-  }
-
-  return undefined
-}
-
 export function sanitizeRelativePath(
   pathParam: string | undefined,
 ): string | undefined {

diff --git a/src/utils/lang/html.ts b/src/utils/lang/html.ts
--- a/src/utils/lang/html.ts
+++ b/src/utils/lang/html.ts
@@ -126,7 +126,7 @@
   return `/${normalized.join('/')}`
 }
 
-function getRepositoryRoot(url: URL): string {
+export function getRepositoryRoot(url: URL): string {
   const pathname = normalizePathname(url.pathname)
   const segments = pathname.split('/').filter(Boolean)
 

diff --git a/src/utils/preview.ts b/src/utils/preview.ts
--- a/src/utils/preview.ts
+++ b/src/utils/preview.ts
@@ -19,7 +19,6 @@
 
   // Session
   resources: Record<string, string> = {}
-  currentPageUrl: URL | undefined
 
   // TODO - might be worth memoizing against the URL for the session
   pageData: Partial<HTMLPageData> = {}
@@ -93,7 +92,6 @@
     }
 
     const { processedHTML, title } = processHTML(data, url)
-    this.currentPageUrl = new URL(url)
 
     this.pageData.title = title ?? url
 
@@ -262,18 +260,22 @@
     this.iframeDocument.document.head.appendChild(tag)
   }
 
-  private async appendExternalScriptToHead(
+  private appendExternalScriptToHead(
     src: string,
     type?: 'module',
   ): Promise<void> {
-    const tag = this.iframeDocument.document.createElement('script')
+    return new Promise<void>((resolve, reject) => {
+      const tag = this.iframeDocument.document.createElement('script')
 
-    if (type) {
-      tag.type = type
-    }
+      if (type) {
+        tag.type = type
+      }
 
-    tag.src = src
-    this.iframeDocument.document.head.appendChild(tag)
+      tag.onload = () => resolve()
+      tag.onerror = () => reject(new Error(`Failed to load script: ${src}`))
+      tag.src = src
+      this.iframeDocument.document.head.appendChild(tag)
+    })
   }
 
   /**

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

Autofix Details

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: External script failure crashes entire preview rendering
  • Wrapped the await this.appendExternalScriptToHead(source, type) call in a try/catch block that logs a warning and continues, matching the error handling already present in the proxied script branch.

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@cursor push afdea6ba15

Preview (afdea6ba15)

diff --git a/src/utils/preview.ts b/src/utils/preview.ts
--- a/src/utils/preview.ts
+++ b/src/utils/preview.ts
@@ -195,7 +195,11 @@
           continue
         }
 
-        await this.appendExternalScriptToHead(source, type)
+        try {
+          await this.appendExternalScriptToHead(source, type)
+        } catch (err) {
+          logger.warn(`Skipping external script after failed load: ${err}`)
+        }
         continue
       }

_{You can send follow-ups to the cloud agent here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

Autofix Details

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Non-JavaScript script types lost during deferred execution
  • Changed loadPageElements to preserve all original script types (not just 'module') when re-injecting deferred scripts, while filtering out the internal placeholder type to avoid leaking it.

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@cursor push 37735f7efe

Preview (37735f7efe)

diff --git a/src/utils/preview.ts b/src/utils/preview.ts
--- a/src/utils/preview.ts
+++ b/src/utils/preview.ts
@@ -174,12 +174,17 @@
     for (const script of [...$script]) {
       const source =
         script.getAttribute(PREVIEW_SCRIPT_SRC_ATTRIBUTE) ?? script.src ?? ''
+      const savedType = script
+        .getAttribute(PREVIEW_SCRIPT_TYPE_ATTRIBUTE)
+        ?.toLowerCase()
+        .trim()
+      const fallbackType = script.getAttribute('type')?.toLowerCase().trim()
       const scriptType =
-        script
-          .getAttribute(PREVIEW_SCRIPT_TYPE_ATTRIBUTE)
-          ?.toLowerCase()
-          .trim() ?? script.getAttribute('type')?.toLowerCase().trim()
-      const type = scriptType === 'module' ? ('module' as const) : undefined
+        savedType ??
+        (fallbackType !== PREVIEW_SCRIPT_PLACEHOLDER_TYPE
+          ? fallbackType
+          : undefined)
+      const type = scriptType || undefined
       const inlinePayload = script.textContent ?? ''
 
       script.remove()
@@ -249,7 +254,7 @@
   /**
    * Inline JS into the preview head.
    */
-  private appendScriptToHead(data: string, type?: 'module'): void {
+  private appendScriptToHead(data: string, type?: string): void {
     if (!data) {
       return
     }
@@ -266,7 +271,7 @@
 
   private appendExternalScriptToHead(
     src: string,
-    type?: 'module',
+    type?: string,
   ): Promise<void> {
     return new Promise<void>((resolve, reject) => {
       const tag = this.iframeDocument.document.createElement('script')

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

Autofix Details

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Click handler resolves URLs against wrong base
  • Replaced manual URL resolution via new URL(href, iframeDocument.location.href) with $anchor.href (the IDL property), which automatically resolves against the document's <base> tag instead of the iframe's about:blank location.

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@cursor push b9c7a51fbd

Preview (b9c7a51fbd)

diff --git a/src/utils/preview.ts b/src/utils/preview.ts
--- a/src/utils/preview.ts
+++ b/src/utils/preview.ts
@@ -115,22 +115,17 @@
           return
         }
 
-        let resolvedUrl: URL
-        try {
-          resolvedUrl = new URL(href, this.iframeDocument.location.href)
-        } catch {
-          return
-        }
+        const resolvedUrl = $anchor.href
 
         // Keep external links inside the iframe navigation flow.
-        if (!this.isProxySupportedUrl(resolvedUrl.toString())) {
+        if (!this.isProxySupportedUrl(resolvedUrl)) {
           return
         }
 
         e.preventDefault()
 
         // use Svelte navigation to trigger a re-render from the top of the UI
-        goto(`/${encodeURIComponent(resolvedUrl.toString())}`)
+        goto(`/${encodeURIComponent(resolvedUrl)}`)
       })
     })
   }

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Selectors include [content] but never process it
  • Removed [content] from the querySelectorAll selectors in all three functions since content attributes were never processed by the iteration arrays, making the selector dead code that unnecessarily matched elements like <meta> tags.

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@cursor push eb86479dd9

Preview (eb86479dd9)

diff --git a/src/utils/lang/html.ts b/src/utils/lang/html.ts
--- a/src/utils/lang/html.ts
+++ b/src/utils/lang/html.ts
@@ -88,7 +88,7 @@
 
 function rewriteRootRelativeAttributes(doc: Document) {
   const rootRelativeAttributes = ['src', 'href'] as const
-  const $assets = doc.querySelectorAll<HTMLElement>('[src], [href], [content]')
+  const $assets = doc.querySelectorAll<HTMLElement>('[src], [href]')
 
   for (const $asset of $assets) {
     for (const attr of rootRelativeAttributes) {
@@ -124,7 +124,7 @@
 
 function rewriteRelativeResourceAttributes(doc: Document, pageUrl: URL) {
   const urlAttributes = ['src', 'href'] as const
-  const $assets = doc.querySelectorAll<HTMLElement>('[src], [href], [content]')
+  const $assets = doc.querySelectorAll<HTMLElement>('[src], [href]')
 
   for (const $asset of $assets) {
     const tagName = $asset.tagName.toLowerCase()
@@ -210,7 +210,7 @@
   const repositoryRoot = getRepositoryRoot(rawPageUrl)
 
   const rootRelativeAttributes = ['src', 'href'] as const
-  const $assets = doc.querySelectorAll<HTMLElement>('[src], [href], [content]')
+  const $assets = doc.querySelectorAll<HTMLElement>('[src], [href]')
 
   for (const $asset of $assets) {
     const tagName = $asset.tagName.toLowerCase()

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^{Reviewed by Cursor Bugbot for commit f1c95a7. Configure here.}