[Bug] Plan-approval auto mode rejected with inconsistent gating, disables shift+tab auto

Bug Description
Title: Plan-approval "Start in auto mode" is rejected with "unavailable for your plan" on Max plan, and poisons session so shift+tab auto also breaks

Environment

• Claude Code: 2.1.112 (Windows 11)
• Account: Claude Max (verified via /status → "Login method: Claude Max account")
• Model: Opus 4.7 (1M context)

Summary
Auto mode gating is inconsistent across entry paths for the same session on the same plan. The plan-approval path rejects auto with a misleading plan-tier error, and the rejection leaves the session in a state where shift+tab can no longer select Auto either. A CLI restart is required to recover.

Steps to reproduce

1. In a session where Auto mode works normally (e.g. startup with permissions.defaultMode: "auto" succeeds, and shift+tab cycle includes Auto).
2. Invoke /plan and have the assistant produce a plan.
3. On the approval prompt, choose "Approve and start in auto mode".
4. Status line briefly displays: plan exit → default · auto mode is unavailable for your plan. Session falls back to default mode.
5. Press shift+tab and cycle through modes — Auto is no longer a candidate.
6. Restart Claude Code; Auto becomes selectable again both on startup and via shift+tab.

Expected

• Max plan users should be able to enter Auto via plan-approval. OR
• If gating applies, the error should be consistent across entry paths (startup / shift+tab / plan-approval). OR at minimum
• A rejected plan-approval auto transition should not disable Auto for subsequent shift+tab cycles in the same session.

Actual

• Plan-approval auto is rejected with a plan-tier message even though Max plan allows auto elsewhere.
• The rejection causes Auto to disappear from shift+tab cycle until CLI restart.

Notes

• Message text "unavailable for your plan" is misleading — Max does support Auto via other paths.
• No log file documents the rejection reason beyond the brief status-line text.

Environment Info

• Platform: win32
• Terminal: windows-terminal
• Version: 2.1.112
• Feedback ID: a6b77074-2ea8-48ed-938e-cffe3e8aedac

Errors

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