--continue compacts session despite autoCompact: false setting

Description

When using --continue to resume a session, the session is being summarized/compacted despite autoCompact: false being set. Evidence includes:

1. Context usage decreases after resume (~40% used → ~25% used)
2. Claude (LLM) responds with "I have context from the previous session..." indicating it received a summary, not the full conversation history

Previous Behavior (expected)

• /exit + claude --continue = exact same state
• Same context usage, full conversation history loaded
• Claude continues seamlessly mid-conversation without mentioning "previous session"

Current Behavior (2.1.23)

• /exit + claude --continue = reduced context usage
• Claude treats this as a new session with injected context summary
• Claude explicitly mentions having "context from the previous session"

Steps to Reproduce

1. Set autoCompact: false in settings
2. Work in a session until ~40% context is used
3. Exit with /exit
4. Resume with claude --continue
5. Observe: context reduced to ~25%, Claude mentions "previous session"

Environment

• Claude Code version: 2.1.23
• Platform: Linux (WSL2)
• Setting: autoCompact: false

Impact

Users who disable auto-compact to preserve full conversation history lose that history on every exit/continue cycle. This breaks workflows that depend on exact session state preservation.

Related Issues

• #18264
• #18152
• #15837