fix(presentation): pass absolute URLs through getPreviewThumbnail

[clayrisser]

Problem

packages/presentation has three functions that turn a blob ref into a URL, and they disagree about what to do when the ref is already an absolute URL.

getFileUrl (file.ts:55) passes it through:

if (file.includes('://')) {
  return file
}

blobToSrcSet (preview.ts:52) also recognises it, and returns '' — correctly, because there is no srcset to build for an external URL.

getPreviewThumbnail (preview.ts:92) has no guard at all:

export function getPreviewThumbnail (file: string, width: number, height: number, dpr?: number): string {
  return getImagePreviewUrl(
    encodeURIComponent(getCurrentWorkspaceUuid()),
    encodeURIComponent(file),
    …

So an absolute URL is percent-encoded and pasted into the preview service's path, producing something like:

https://preview.example.com/image/fit=cover,width=100,height=200,dpr=2/<ws>/https%3A%2F%2Fcdn.example.com%2Fcover.png

which is not a thumbnail of anything.

Fix

Add the passthrough, matching getFileUrl — a thumbnail needs a usable src, so passthrough rather than blobToSrcSet's empty string is the right analogue:

 export function getPreviewThumbnail (file: string, width: number, height: number, dpr?: number): string {
+  // Absolute URLs pass through unchanged, same as getFileUrl (blobToSrcSet
+  // guards on '://' too but returns '' — a thumbnail src wants the passthrough)
+  if (file.includes('://')) {
+    return file
+  }
+
   return getImagePreviewUrl(

Verification

Five cases in packages/presentation/src/___tests___/preview.test.ts, alongside the four suites already in that directory:

• a plain blob id is routed through the preview service
• a blob id needing percent-encoding is still encoded (so the guard does not change the normal path)
• an absolute URL passes through byte-for-byte
• an absolute URL with a query string passes through byte-for-byte
• getPreviewThumbnail agrees with getSrcSet about what counts as an absolute ref

The last one is the point of the change rather than a restatement of it: the three functions disagreeing is the actual defect, and that case pins them together. Three of the five fail with the guard removed.

⚠️ These tests will not run in CI as things stand. packages/presentation has jest.config.js, the jest devDependencies, and four existing suites, but no test / _phase:test script — and rush's phases are declared ignoreMissingScript: true, so the whole package is skipped silently. I have opened that separately as a one-line-per-package build change. Either land that first, or fold those two lines into this PR — happy either way, just say which you prefer.

Verified against develop @ 1be6047c8: getFileUrl's guard at file.ts:55 and blobToSrcSet's at preview.ts:52 are both still there, getPreviewThumbnail at :92 still has none.

Note on scope

This was originally prepared together with three unrelated error-handling fixes on the same read path (a TextViewer fetch with no try/catch, an ImageViewer <img> with no on:error, and an embed nodeview promise with no .catch). I have split those into a separate PR, since they are a different concern and mixing them would make both harder to review.