Cowork Hardcodes Medium Effort and Ignores User Settings for Claude Opus

Claude's Cowork feature is hardcoding medium effort level for Opus 4.6 and ignoring all user configuration settings, according to a detailed investigation by a Max plan user.

What's Happening

A user running Cowork on Windows examined the cowork_vm_node.log file and found that Cowork passes --effort medium --model claude-opus-4-6 as hardcoded CLI flags every time it spawns a session. This overrides all user settings at the application layer.

Settings Overrides That Don't Work

The user tested three methods to override these settings, all of which failed:

• Setting CLAUDE_CODE_EFFORT_LEVEL=high as a user environment variable
• Adding "effortLevel": "high" to ~/.claude/settings.json
• Changing "model": "opus" to "model": "claude-opus-4-6[1m]" in settings.json to enable the 1M context window

Logs continued to show --effort medium and --model claude-opus-4-6 without the [1m] suffix.

Why This Matters

Anthropic changed the default effort for Opus 4.6 from high to medium in v2.1.68. While Claude Code CLI allows overriding with /effort high or through settings, Cowork ignores these options. This means:

• Users are locked into medium effort regardless of their settings
• Max plan users paying $200/month cannot access the 1M context window they're paying for
• Complex tasks requiring deeper reasoning (architectural planning, multi-document synthesis) get a throttled version of Opus

Checking Your Own Logs

To verify if you're affected:

Windows:

Select-String -Pattern "Spawn:create" -Path "$env:APPDATA\Claude\logs\cowork_vm_node.log" | Select-Object -Last 5

macOS:

grep "Spawn:create" ~/Library/Logs/Claude/cowork_vm_node.log | tail -5

Look for --effort and --model in the output. If you see --effort medium and no [1m] suffix on the model, you're experiencing the same issue.

Context Window Limitation

The 1M context window is supposed to be available for Opus 4.6 on the Max plan. In Claude Code CLI, you can access it by specifying claude-opus-4-6[1m] as your model. Cowork doesn't offer this option in its UI and ignores the model string in settings.json.

Ironically, GitHub issue #33154 reported that some macOS builds were forcing [1m] by default, causing rate limit errors, indicating the plumbing for 1M context exists in Cowork but isn't exposed as a user choice.

The user suggests Cowork needs an effort selector and context window toggle in its UI, noting that Max plan users shouldn't have to reverse-engineer log files to discover they're running on nerfed settings.