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

[marijnbent]

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.

[PixPMusic]

Following up now that #15968 has merged and shipped in 0.0.46-nightly.20261005.2702, introducing html_preview / html_render and inline HTML attachments across web, desktop, and mobile.

I also saw Julius's explanation for closing #11634: the direction is MCP Apps, where tools return UI resources for the client to host. That clarifies that revisiting #7220 is about more than resolving the earlier durability concerns; workspace-file capture and provider artifact protocols aren't the intended approach.

With that direction in mind, could Codex's built-in Visualize skill be adapted to publish through the new tool-based rendering path? It currently writes an HTML fragment to a local file and emits a reference with its path and optional mode: "wide", whereas T3's HTML tools accept a complete document.

Would support for wrapping those fragments with the required styles/runtime and publishing them through T3's tools be in scope? Or is the intended behavior to use T3's visual tools exclusively, with native visualize references remaining unsupported?