Desktop app: file cards and file-preview panel can't reliably show an existing file
Summary
Two related, recurring faults in the Claude desktop app's file-delivery paths:
- File cards sent into chat do nothing useful when clicked — no working preview, no open, no download.
- The file-preview panel reports "Couldn't find this file" for a path that demonstrably exists — its own "Show in Explorer" button then finds it immediately.
Environment
Windows 11. Recurred across an app update: 1.40609.1.0 (3 Sept 2026) → 1.46388.4.0 (8 Sept 2026). Not a one-build regression.
Evidence
3 Sept and again 8 Sept: a file referenced by Claude Code (confirmed present via ls, correct size, tracked in git) triggered "Couldn't find this file" in the panel. "Show in Explorer" on that same error screen located it immediately — proving the panel's own fallback disagrees with its main lookup.
Impact
Real, repeated time lost with no in-app recovery beyond "Show in Explorer," which is itself only offered after the false error, not from the file-card path.
Suggested fix
Make "Show in Explorer" use the same path-resolution code as the primary preview load, so the two can't disagree about whether a file exists. Add a working open/preview action to file cards, or make clearly non-interactive if intentional.