Allow model selection for Slack-triggered Claude Code sessions

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When starting Claude Code sessions via Slack integration, there's no way to configure which model is used. The session always runs on a default model (currently claude-opus-4-5), ignoring the "model" setting in the repository's .claude/settings.json.

Current behavior:

• .claude/settings.json includes "model": "claude-opus-4-8"
• Slack-triggered session still runs on claude-opus-4-5
• The code.claude.com environment/trigger settings don't expose a model selector

Proposed Solution

Either:

1. Honor the repo-level "model" setting from .claude/settings.json for remote/Slack-triggered sessions, OR
2. Add a model selector in the environment/trigger configuration on code.claude.com

This would allow users who have access to newer models (e.g., claude-opus-4-8) to use them in Slack-initiated workflows, just as they can in local CLI sessions.

Alternative Solutions

Currently, there is no known workaround to change the model for Slack-triggered sessions short of modifying the default at the platform level. Users may attempt to set the model in .claude/settings.json, but this setting is currently ignored for remote sessions.

Priority

High - Significant impact on productivity

Feature Category

Configuration and settings

Use Case Example

1. A user has access to claude-opus-4-8 and wants to use it for their team's Slack-triggered CI/review workflows.
2. They add "model": "claude-opus-4-8" to .claude/settings.json in their repository, following the pattern that works for local CLI sessions.
3. They trigger a Claude Code session via Slack.
4. The session runs on claude-opus-4-5 instead, ignoring the settings file.
5. With this feature, the session would either pick up the repo-level model setting or allow the user to select the model in the code.claude.com trigger/environment configuration.

Additional Context

_No response_