Opus 4.6 (1M context) disappeared from Desktop app model dropdown — Max plan regression

Environment

• Plan: Max
• Platform: macOS (Darwin 25.3.0)
• App: Claude Desktop (latest version as of 2026-03-20)

Description

Opus 4.6 with 1M context was available and actively in use in the Claude Desktop app model dropdown for the past 3 days. After what appears to be an automatic update, the model no longer appears in the dropdown. No plan changes were made.

Steps to reproduce

1. Open Claude Desktop app on macOS
2. Click the model dropdown
3. Opus 4.6 (1M context) is no longer listed

Expected behavior

Opus 4.6 (1M context) should be available in the model dropdown for Max plan subscribers, as documented in the 1M context GA announcement.

What I've tried

• Restarting the Desktop app
• Editing ~/.claude/settings.json with "model": "opus[1m]" — this only affects Claude Code CLI, not Desktop
• Inspected ~/Library/Application Support/Claude/claude_desktop_config.json and config.json — no model override exists for Desktop; the model list is server-controlled
• Confirmed Opus 4.6 (1M) still works in Claude Code CLI on the same account

Related issues

• #34333 — Opus 4.6 with 1M context not available on Max 5x plan
• #26428 — Sonnet 1M disappeared after update on Max plan