claude-code - 💡(How to fix) Fix [Bug] Sonnet 4.6 sessions: auto mode not available via any entry path (UI, flag, settings), while Opus 4.7 in same install works [2 comments, 2 participants]

Bug Description

In the same Claude Code install, auto mode is available on Opus 4.7 sessions but completely unreachable on Sonnet 4.6 sessions — not just missing from the Shift+Tab cycle, but also ignored when passed via --permission-mode auto or set via permissions.defaultMode: "auto" in settings.json.

Per docs (https://code.claude.com/docs/en/permission-modes) auto mode isn't formally supported on Pro/Max. However issue #49653 confirms Max accounts do receive auto mode through the startup path on Opus. This report is about the model-specific gap: the same Max path that works on Opus does not work on Sonnet.

Environment

• Claude Code: 2.1.117
• OS: macOS 26.1 (Darwin 25.1.0)
• Shell: zsh
• Plan: Max (auto mode working on Opus 4.7 sessions in this install)
• Relevant settings:

  {
    "permissions": { "defaultMode": "auto" },
    "skipAutoPermissionPrompt": true,
    "effortLevel": "xhigh"
  }

Steps to Reproduce

A. Model switch mid-session (Opus → Sonnet)

1. Start session: claude (Opus 4.7, auto mode active ✅)
2. /model sonnet → system emits ## Exited Auto Mode
3. Shift+Tab cycle: auto option is gone

B. Fresh Sonnet session via CLI flag

1. claude --model sonnet --permission-mode auto
2. Auto mode is not in Shift+Tab cycle and indicator does not show "auto mode on" (silently downgrades, same symptom as #42648's Haiku case)

C. Fresh Sonnet session via settings

1. With permissions.defaultMode: "auto" in ~/.claude/settings.json
2. claude --model sonnet
3. Auto mode does not activate on startup (whereas identical config activates it on Opus)

All three paths fail. Restart back to Opus → auto mode returns.

Expected

Either:

• A: Auto mode should work on Sonnet 4.6 in the same paths that succeed on Opus 4.7 (symmetry across supported models per #42648 which states "Sonnet 4.6, Opus 4.6+" as supported).
• B: If Sonnet is intentionally excluded on Max, surface a clear message at startup ("auto mode requires Opus on Max plan" or similar) — current silent downgrade is identical to the UX issue filed in #42648.

Actual

Silent downgrade with no indication of why. User-facing signal is only "auto is missing from Shift+Tab cycle" + one-shot ## Exited Auto Mode message on model switch.

Related

• #49653 — Shift+Tab auto disappears after plan-approval on Opus (similar end-state, different trigger)
• #42648 / #43235 — Auto mode silently unavailable on Haiku (claims Sonnet 4.6 is supported, contradicting this report)
• #46616 — Max plan auto mode gating inconsistency
• #49273 — defaultMode:"auto" not activating at session start (Max + Opus 4.7)

Additional Context

The contradiction with #42648 (which states Sonnet 4.6 is a supported model for auto mode) suggests either (a) a regression on Sonnet 4.6 in recent versions, or (b) Max-plan-specific model gating that's not documented.