Browser and Chrome plugins unavailable with gpt-5.6-sol but work with gpt-5.6-terra

What version of the Codex App are you using?

ChatGPT/Codex desktop app 26.707.91948, bundled Codex CLI 0.144.5.

What subscription do you have?

ChatGPT subscription. The exact tier is not displayed in the Codex diagnostics.

What platform is your computer?

Darwin 25.5.0 arm64 arm

What issue are you seeing?

Browser and Chrome control stopped being exposed in new Codex tasks using gpt-5.6-sol.

The Browser and Chrome plugins and the node_repl MCP server were installed and enabled. The in-app Browser backend started successfully and its socket became ready, but tasks using gpt-5.6-sol reported that the browser-control or node_repl runtime was unavailable.

Local health checks passed for configuration, authentication, MCP setup, network connectivity, plugin installation, and the Browser backend. Restarting the app and reinstalling or re-enabling plugins did not help.

A controlled A/B test showed model-specific behavior:

• gpt-5.6-sol: reports that node_repl MCP is unavailable.
• gpt-5.6-terra: performs a real node_repl MCP call successfully.

The current model catalog marks gpt-5.6-sol as tool_mode=direct and gpt-5.6-terra as tool_mode=code_mode_only. Switching the default model to Terra and starting a fresh task immediately restored Browser control.

What steps can reproduce the bug?

1. Install and enable the bundled Browser or Chrome plugin.
2. Confirm that the node_repl MCP server is enabled.
3. Start a fresh Codex task using gpt-5.6-sol.
4. Ask the task to use Browser or explicitly call node_repl.
5. Observe that the tool is unavailable even though the Browser backend starts successfully.
6. Run the equivalent request in a fresh task or ephemeral CLI session using gpt-5.6-terra.
7. Observe that node_repl is exposed and Browser control works.

The last confirmed working Browser call using Sol was July 15, 2026 at 21:46 Europe/Berlin. The first task already missing the code-mode bridge was July 16 at 11:19, before any local plugin cleanup or configuration changes.

Private feedback was also submitted through /feedback without logs. Feedback thread ID: 019f6b08-b264-7e13-adc0-1d9f2dcbd49a.

What is the expected behavior?

Browser, Chrome, and Computer Use plugins should remain callable with gpt-5.6-sol. If this is an intentional model limitation, the model selector or plugin UI should communicate it clearly instead of showing the plugins as installed and healthy but unreachable.

Additional information

Changing only the default model from Sol to Terra is a reliable workaround. No secrets, logs, local paths, or private task content are included in this public report.