What they did
Sarkar, working in the Claude desktop app, clicked the path of a memory note Claude had just saved and got told the file was outside the session's folders. Instead of filing a bug report, Sarkar opened a new session and had Claude build a mod for the app (the desktop app runs Claude Code underneath and accepts plugins). The first cut was a /view-file slash command that read a path from disk and showed it in a pane with no folder check. The mod then grew: a bar above the prompt that tracks every file Claude reads, edits or writes in the session, a filterable list labelled by action, rendered Markdown with a frontmatter card and clickable [[wiki links]] between memory notes, a Back button, a raw source view, and a tool Claude itself can call to open a file in the pane.
How it went
The original problem was gone about twenty minutes in. By the evening the mod had tests, screenshots, a README and an MIT licence, at roughly 500 lines, most of it rendering. Snags along the way: the pane only draws about 100,000 characters so big files get cut with a note, pasted paths arrive with quotes, tildes or Windows backslashes, and opening a deleted file first showed a raw system error, fixed in version 0.2.2 with a plain message. It is published as file-viewer.
Worth knowing
The write-up does not spell out which parts Claude wrote and which Sarkar wrote, and it gives no cost or token figures. The mod is installed through the Plugins menu next to the prompt box or with claude plugin install, so it only helps people who use the desktop app or Claude Code.