[Bug] Unexplained Opus 4.7 model usage despite Sonnet-only configuration

Bug Description
Unexplained Opus 4.7 usage in the model usage table (Claude Desktop), although only Sonnet is configured.

Setup (Claude Code v2.1.286, Windows 11):

• Main model: "model": "sonnet" in ~/.claude/settings.json. I have never selected Opus in /model.
• CLAUDE_CODE_SUBAGENT_MODEL=sonnet and CLAUDE_CODE_SUBAGENT_MODEL_FORCE=1, so all subagents should run on Sonnet, including plugin agents that declare "model: opus".
• No override of the opus alias (no ANTHROPIC_DEFAULT_OPUS_MODEL).
• My own agents/skills/commands under ~/.cla

Observed:

• The Opus 4.7 share appears across the whole period I can view in the table (7 days up to 30 days), not just once. Every session I work in with Sonnet shows some Opus usage.
• In a recent session I used only Sonnet, and every subagent was started with an explicit model: sonnet. The table still lists Opus 4.7.
• It is Opus 4.7, not the newest Opus. I donmes from or why the "opus" alias wouldresolve to it.

Questions:

1. Which calls are counted as Opus 4.7 (background tasks, summaries, Explore agent, plan mode, something else)?
2. Can any internal/automatic call use Opus regardless of my settings?
3. Why does the alias resolve to 4.7 instead
4. Does this usage count against my limits? If this is a display or accounting bug, please correct it.

Environment Info

• Platform: win32
• Terminal: windows-terminal
• Version: 2.1.286
• Feedback ID: f2c0e849-d755-4dd2-b695-77d2cd7ca882

Errors

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