[BUG] Plan-approval dialog reports auto mode unavailable while Auto is selectable in the mode selector (VS Code 2.1.220, Opus 5 [1m])

Summary

In the same session, the plan-approval dialog and the mode selector disagree about whether auto mode is available.

The docs define the dialog's first option: "Yes, and use auto mode … When auto mode is unavailable, this option reads Yes, auto-accept edits."

Mine reads "Yes, auto-accept edits" — the unavailable variant. But Auto is listed and selectable in the VS Code mode selector in that same session, and picking it works. Only the plan-approval path treats auto mode as unavailable.

Steps to Reproduce

1. VS Code extension 2.1.220, model claude-opus-5[1m], permissions.defaultMode: "plan".
2. Open the mode selector — Auto is listed and selectable.
3. Produce a plan, let it reach ExitPlanMode.
4. First option reads "Yes, auto-accept edits", not "Yes, and use auto mode".
5. Approve with the option given, then pick Auto from the selector — it works.

Expected

The dialog should offer "Yes, and use auto mode" whenever Auto is selectable in the mode selector; both should read the same availability check. If the plan-approval path is deliberately gated tighter, it shouldn't signal that with a label meaning "unavailable for your account" — that sends people diagnosing an account or model problem they don't have.

Environment

• Extension anthropic.claude-code-2.1.220-linux-x64 (sidebar UI), CLI 2.1.220, Linux
• Model claude-opus-5[1m], claude.ai subscription
• Ruled out: tengu_auto_mode_config.enabled is "enabled"; no disableAutoMode; no managed settings; no availableModels restriction

Related

Closest predecessor is #49653 — Opus 4.7 1M, auto mode working via startup and Shift+Tab but refused at plan approval. There the option was offered and then rejected; here it isn't offered. It was closed NOT_PLANNED/stale and locked, as were #44101 and #79024, and #49947 was closed as a duplicate of it. None record a root cause, so this isn't tracked anywhere.

Not #80977 (severityByModel has no Opus 5 entry) — that is classifier calibration after auto mode starts, and its own repro enables auto mode on Opus 5. #82766 is the nearest open neighbour and the mirror image: Auto unselectable in the sidebar while the session model is fine.