[BUG] Model suffix [1m] in settings.json ignored — context window capped at 200k instead of 1M

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Description

The [1m] suffix on the model name in settings.json is being ignored. The context window is capped at 200k tokens instead of 1M, despite the setting being correctly configured. This was working ~24 hours ago.

Settings

~/.claude/settings.json:

{
  "model": "claude-opus-4-6[1m]"
}
No project-level settings override the model.

Observed behavior
Context usage panel shows:


claude-opus-4-6
82.4k / 200.0k tokens (41%)
Autocompact triggers at ~200k. Sessions compact frequently during complex work.

Expected behavior
Context window should be 1M tokens as specified by the [1m] suffix:


claude-opus-4-6
82.4k / 1000.0k tokens (8%)
Environment
Claude Code version: 2.0.65
Running in: VSCode extension
OS: macOS (Darwin 25.4.0)
Model: claude-opus-4-6[1m]
Worked correctly: ~24 hours ago (2026-05-20)
Stopped working: 2026-05-21
Reproduction
Set "model": "claude-opus-4-6[1m]" in ~/.claude/settings.json
Start a new session (tried restart + /clear)
Check context usage — shows 200k limit instead of 1M

### What Should Happen?

## Description

The `[1m]` suffix on the model name in `settings.json` is being ignored. The context window is capped at 200k tokens instead of 1M, despite the setting being correctly configured. This was working ~24 hours ago.

## Settings

`~/.claude/settings.json`:
```json
{
  "model": "claude-opus-4-6[1m]"
}
No project-level settings override the model.

Observed behavior
Context usage panel shows:


claude-opus-4-6
82.4k / 200.0k tokens (41%)
Autocompact triggers at ~200k. Sessions compact frequently during complex work.

Expected behavior
Context window should be 1M tokens as specified by the [1m] suffix:


claude-opus-4-6
82.4k / 1000.0k tokens (8%)
Environment
Claude Code version: 2.0.65
Running in: VSCode extension
OS: macOS (Darwin 25.4.0)
Model: claude-opus-4-6[1m]
Worked correctly: ~24 hours ago (2026-05-20)
Stopped working: 2026-05-21
Reproduction
Set "model": "claude-opus-4-6[1m]" in ~/.claude/settings.json
Start a new session (tried restart + /clear)
Check context usage — shows 200k limit instead of 1M

### Error Messages/Logs

```shell

Steps to Reproduce

Description

The [1m] suffix on the model name in settings.json is being ignored. The context window is capped at 200k tokens instead of 1M, despite the setting being correctly configured. This was working ~24 hours ago.

Settings

~/.claude/settings.json:

{
  "model": "claude-opus-4-6[1m]"
}
No project-level settings override the model.

Observed behavior
Context usage panel shows:


claude-opus-4-6
82.4k / 200.0k tokens (41%)
Autocompact triggers at ~200k. Sessions compact frequently during complex work.

Expected behavior
Context window should be 1M tokens as specified by the [1m] suffix:


claude-opus-4-6
82.4k / 1000.0k tokens (8%)
Environment
Claude Code version: 2.0.65
Running in: VSCode extension
OS: macOS (Darwin 25.4.0)
Model: claude-opus-4-6[1m]
Worked correctly: ~24 hours ago (2026-05-20)
Stopped working: 2026-05-21
Reproduction
Set "model": "claude-opus-4-6[1m]" in ~/.claude/settings.json
Start a new session (tried restart + /clear)
Check context usage — shows 200k limit instead of 1M

### Claude Model

None

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

_No response_

### Claude Code Version

2.0.65 

### Platform

Anthropic API

### Operating System

macOS

### Terminal/Shell

VS Code integrated terminal

### Additional Information

_No response_