[PER-10778] Video stuck in processing

[aasandei-vsp]

Manual test cases — video stuck on "This video is processing"

Setup: Sign in as the owner of an archive and open a private folder holding
at least 12 items, of which at least 3 are videos that play normally today.
You need: one folder with more than 12 children so the viewer's prefetch window
matters, one video near the end of that folder's list, one record with a
distinctive name and size sitting directly next to a video, and one subfolder.

The visible change: a video that opens before its files have arrived no longer
sits on This video is processing. Please check back later. until you leave the
viewer — it starts playing on its own. Nothing about the placeholder's wording or
appearance changed.

---

Playing a video ⭐

Scenario — opening a video directly

1. Click a video in the file list.
   • EXPECTED: The full-screen viewer opens, a spinner shows briefly, and the
     video appears with working controls. No processing message at any point.
2. Press Back, then click the same video again.
   • EXPECTED: It plays again, with no processing message.

Scenario — arrowing onto a video

This is the case that was broken before: arrowing set the record and drew the player
in the same breath, so a video reached this way could show the placeholder and never
recover.

1. Open the record immediately before a video, then press the right arrow key
   (or click the › control) once.
   • EXPECTED: The viewer moves to the video and it plays. If a processing
     message appears at all it is momentary and clears on its own — you should
     not have to press Back to make it go away.
2. Arrow past the video and back onto it several times in quick succession.
   • EXPECTED: It plays every time.

---

The placeholder still appears when it should

Scenario — a record whose file really is not there yet

1. Upload a large video (500MB or more) and, as soon as it appears in the list,
   open it.
   • EXPECTED: Either it plays, or it shows This video is processing. and
     Please check back later. — and if it shows that, leave the viewer open.
2. Wait for processing to finish, without closing the viewer or reloading.
   • EXPECTED: The message disappears on its own and the video appears. This
     is the fix — previously it stayed until the viewer was closed and reopened.

---

Record details are the right record's ⭐

Scenario — arrowing between neighbours

1. Open the record sitting next to a video and note its Name, Size, Date
   and Type.
2. Arrow onto the video, then arrow straight back.
   • EXPECTED: The panel shows the first record's own values again — not the
     video's, and not a blank Size.
3. Arrow forward and back across five or six records in a row.
   • EXPECTED: Each record's panel matches the item named at the top of it.
     Size is never blank for a record that has a file.

Scenario — multi-select

1. In the file list, select six or more items including at least one subfolder and
   one video.
   • EXPECTED: The sidebar shows a count and the shared actions, with no error.
2. Click a single item to narrow the selection back to one.
   • EXPECTED: The sidebar shows that item's own name, size and date.

---

Folders still load their own contents

Scenario — opening and leaving a subfolder

1. Open a subfolder from the file list.
   • EXPECTED: Its own name is in the breadcrumb and its own children are
     listed — not the parent's.
2. Press browser Back, then open a different subfolder.
   • EXPECTED: The second folder shows its own children.

---

Download and tags

Scenario — downloading straight from the list

1. Select a record you have not opened this session and download it.
   • EXPECTED: The file that downloads is that record's, with its own filename.

Scenario — the tag editor

1. Open Keywords on a record, add a keyword and save.
   • EXPECTED: The keyword appears on that record and not on its neighbours.

---

Regression list

Cheap sanity checks; these were traced as unchanged by this PR.

1. Images, PDFs and audio open and display in the full-screen viewer.
2. Thumbnails in the file list appear for newly uploaded items without a reload.
3. Sorting and renaming in the file list behave as before.
4. The share-preview route opens a shared folder and its records.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 54.02%. Comparing base (57f1dd3) to head (a112eb8).

Additional details and impacted files

@@                                    Coverage Diff                                     @@
##           PER-10680-migrate-navigate-lean-refresh-current-folder    #1179      +/-   ##
==========================================================================================
+ Coverage                                                   53.85%   54.02%   +0.17%     
==========================================================================================
  Files                                                         364      364              
  Lines                                                       12765    12786      +21     
  Branches                                                     2327     2332       +5     
==========================================================================================
+ Hits                                                         6874     6908      +34     
+ Misses                                                       5650     5638      -12     
+ Partials                                                      241      240       -1     

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