[Bug]: visualize output is shown as raw tool text instead of rendering the visualization

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/desktop

Steps to reproduce

1. In T3 Code, ask the assistant to create and show a visualization in the conversation (built-in codex skill)
2. Wait for the assistant to generate the visualization and return the visualize result.
3. Observe the assistant response.

Expected behavior

The generated visualization should render as an inline preview in the conversation, with the visualization content visible to the user.

Actual behavior

The response shows the raw visualize tool marker and JSON path instead of rendering the visualization. The observed output is:

�visualize�{"path":"/tmp/codex-studiozoek-email-audit/studiozoek-email-audit.html","mode":"wide"}�

No visualization preview is shown, so the generated HTML is not usable from the conversation.

Impact

Major degradation or frequent failure

Version or commit

latest nightly

Environment

T3 Code desktop app on macOS 26.1 arm64.

Logs or stack traces

�visualize�{"path":"/tmp/codex-studiozoek-email-audit/studiozoek-email-audit.html","mode":"wide"}�

Screenshots, recordings, or supporting files

Workaround

No workaround found in T3 Code. Opening the generated HTML file manually may work if the temporary path is still accessible.

Start in apps/desktop and trace how the built-in codex skill's visualize result is handled in the conversation. Reproduce the issue with the shown visualize marker and JSON path, then verify that the result appears as an inline visualization preview instead of raw tool text.