[Bug]: desktop thread file links do nothing instead of opening the file panel #6360

Before submitting

• I searched existing issues and did not find an exact duplicate.
• I reproduced the problem with a file that exists at its canonical path.
• I included enough detail to investigate the problem.

Summary

On macOS, clicking a valid local-file link rendered in a thread silently does nothing. T3 Code recognizes the link as an internal t3code://app/... URL, but it does not open the file side panel or report an error. This reproduces with a confirmed existing file and with both mouse and keyboard activation.

Area

apps/desktop

Steps to reproduce

1. Open a thread in the macOS desktop app.

2. Have the agent include a Markdown link to an existing local file, for example:

   [Example note.md](</path/to/vault/Example note.md>)

3. Confirm that the rendered link resolves to an internal URL resembling:

   t3code://app/path/to/vault/Example%20note.md
   

4. Click the link.

The problem can also be reproduced by focusing the link and pressing Return.

Expected behavior

T3 Code opens the referenced file in the file side panel, or displays an actionable error if the file cannot be opened.

Actual behavior

The link receives focus, but nothing else happens:

• The file side panel remains closed.
• The current thread does not change.
• No error or feedback is shown.
• Pressing Return on the focused link also does nothing.
• The desktop logs contain no corresponding file-opening failure.

Reproduction notes

I reproduced this using Computer Use against a canonical file that currently exists on disk. The accessibility tree recognized the rendered element as a real link with a valid t3code://app/... value, so this does not appear to be a coordinate-click or missing-file problem.

The incident that prompted the investigation initially involved an agent linking to an ephemeral transaction-worktree path. That particular path later became stale, which explained some confusion in the thread. However, replacing it with the valid canonical path produced the same silent failure.

Impact

Users cannot reliably open files referenced by agents from the conversation. Because failure is silent, it is difficult to distinguish among:

• a missing or stale file;
• an incorrectly generated link;
• a valid link that the desktop app failed to handle.

This can also cause agents and users to become confused about whether an artifact was actually created or synced.

Version

T3 Code Nightly 0.0.34-nightly.20260812.1072
macOS

Logs or stack traces

No relevant error was emitted when the valid file link was clicked or activated with Return.

The absence of an error appears to be part of the defect.

Related issue

Potentially related to #5839, which reports that thread Markdown links discard openURL failures on mobile.

This report covers a different surface and link type:

• macOS desktop rather than mobile
• internal t3code://app/... file links rather than unsupported external URLs

The two issues may share a missing error-handling path.