`--continue` on 2.1.90 silently drops conversation context (regression from 2.1.89)

Description

claude --continue on v2.1.90 introduces a new dialog prompt on session restore that did not exist in v2.1.89. After interacting with this dialog, the conversation context is silently dropped — no compact_boundary event is written, and no /clear event is recorded — yet the restored session contains almost none of the prior conversation.

Steps to Reproduce

1. Have a long-running session (~45K lines, ~280MB JSONL)
2. On v2.1.89: exit → claude --continue → session restores correctly ✅
3. Update to v2.1.90
4. exit → claude --continue → new dialog appears with options like "Summarize / Keep as-is / Don't ask again"
5. Select "Don't ask again"
6. Session loads with most conversation context missing

Expected Behavior

--continue should restore the session the same way it did in 2.1.89 — directly, without an intermediate dialog, and without data loss.

Actual Behavior

• A new dialog prompt appears during --continue that was not present in 2.1.89
• After the dialog, the conversation context is drastically reduced
• Inspection of the JSONL transcript shows:
• No compact_boundary event for the current date — this was not a normal compaction
• No /clear event — this was not a user-initiated clear
• The last compact_boundary in the file is from a previous date (v2.1.84), with 5,500+ lines added after it
• Messages simply vanish from the loaded context without any recorded event

Additional Context

• /resume (interactive session picker) works correctly for the same session — context is fully preserved
• The session had survived 41 normal auto-compactions across versions 2.1.69 → 2.1.72 → 2.1.84 without issue
• The "Don't ask again" option's default behavior is unclear — it's not documented what action it defaults to
• A session backup was made before the --continue attempt, confirming all messages exist in the JSONL file but are not loaded into context

Environment

• Claude Code v2.1.90 (built 2026-04-01)
• Previously working on v2.1.89
• Linux (WSL2, Ubuntu 24.04)
• Session size: ~45,000 lines, ~280MB JSONL
• Auto-compact enabled, CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=90

Impact

• Data loss: Days of conversation context (March 27 – April 2) silently dropped
• No recovery path: The context cannot be restored even though the JSONL file is intact
• Breaks existing workflow: Users relying on --continue for frictionless session restoration are affected
• Behavioral regression: The new dialog fundamentally changes the --continue contract (direct restore → interactive prompt)