Max plan: 'Auto mode is unavailable for your plan' crash mid-session (bypassPermissions + EnterPlanMode)

Description

Claude Code Desktop crashes mid-session with error "Auto mode is unavailable for your plan" followed by "Something went wrong". This happens on a Max plan ($200/month) with bypassPermissions mode enabled.

The crash has occurred in 3+ consecutive sessions today, making the tool unusable for extended work.

Environment

• Plan: Max ($200/month, 20x usage)
• Platform: Windows 11 Pro 10.0.26200
• Claude Code Desktop version: 2.1.87
• Model: Sonnet 4.6 (also observed with Opus 4.6)
• Permission mode: bypassPermissions in settings.json
• Auto accept edits: enabled

settings.json (relevant)

{
  "permissions": {
    "defaultMode": "bypassPermissions",
    "allow": ["Bash(*)", "Edit(*)", "Write(*)", "Read(*)", "Grep(*)", "Glob(*)", "Agent(*)", ...]
  }
}

Reproduction

The crash occurs when EnterPlanMode is triggered during a session with bypassPermissions enabled on a Max plan. It does not crash every time — intermittent.

Session forensics

I analyzed the JSONL conversation files of 3 crashed sessions. Key findings:

Session 1 (629420b1) — Crashed on message #2

[15:52:28] USER: "After CC-48A commit, immediately begin CC-48B in plan mode."
[15:52:36] ASST: in=70,696 tokens — responded normally
[15:52:36] ASST: Called EnterPlanMode tool
[15:52:36] USER: "Entered plan mode..." (system response)
[15:52:36] ASST: stop_reason=stop_sequence → "Auto mode is unavailable for your plan"

Crashed immediately after EnterPlanMode, on the very first substantive exchange.

Session 2 (536645e1) — Crashed after model switch

[15:19:58] USER: Started session (initial input ~70,250 tokens)
[15:46:28] USER: Switched model to Sonnet 4.6 via /model
[15:46:28] USER: "אתה איתי?" ("are you with me?")
[15:46:29] ASST: "Auto mode is unavailable for your plan"

Session 3 (4375cae7) — Crashed during conversation about the crash

[15:53:50] USER: "whats wrong" (asking about previous crash)
[15:54:06] ASST: in=71,786 — responded explaining the error
[15:59:42] ASST: in=77,586 — last response before crash

Key observations

1. The error text is returned by the model as content (stop_reason=stop_sequence), not as a UI error. The model produces "Auto mode is unavailable for your plan" as if it were a legitimate response.

1. All sessions start with ~70,000 input tokens (large CLAUDE.md + project files + system prompt + tool definitions). This is high but should not cause crashes — context window is much larger.

1. EnterPlanMode appears to be a trigger — Session 1 crashed immediately after it was called. However, in another session the same tool worked fine, so the crash is intermittent.

1. Model switching may also trigger it — Session 2 crashed after /model switch to Sonnet.

1. Not a plan limitation — The user has Max plan with 20x usage. Auto mode is not configured or requested. The defaultMode is bypassPermissions.

Expected behavior

Sessions should not crash with "Auto mode is unavailable" when the user has never configured or requested auto mode. bypassPermissions mode should work independently of auto mode availability.

Possible root cause

The EnterPlanMode tool or model-switch flow may be checking plan capabilities for "auto mode" even when the user's defaultMode is bypassPermissions. On Max plan (non-Team), this check fails and produces the error as model output rather than handling it gracefully.

Related

• Possibly related to #42449 (auto mode error persisting after mode change)