Claude Code session draft lost when app updates — input not persisted across Claude Code version upgrades

Description

When Claude Code updates (e.g., from 2.1.63 → 2.1.64), any unsent message being composed in the Claude Code input field is permanently lost. The Claude Code session's draft auto-save mechanism writes to Local Storage approximately every 5 seconds, but the update process terminates the Claude Code process without triggering a final save. After the update, Claude Code does not restore the draft from the last auto-save snapshot either — the session appears empty.

This is a Claude Code data loss bug: the user's in-progress Claude Code input (which can be substantial — multi-paragraph prompts) is silently discarded during version upgrades.

Steps to reproduce

1. Open a Claude Code session (via Desktop app or terminal)
2. Begin typing a long message in the Claude Code input field (spend 30+ seconds typing)
3. A Claude Code update becomes available (e.g., 2.1.63 → 2.1.64)
4. The update proceeds (either auto-update or user-initiated)
5. After update completes, reopen the Claude Code session

Expected behavior

The Claude Code draft should be preserved across version upgrades, either by:

• Claude Code flushing the current draft to persistent storage before the update kills the process
• Claude Code restoring the draft from the last auto-save snapshot after restarting post-update

Actual behavior

• The Claude Code session appears empty after the update — the draft is gone
• The auto-saved data is technically still present in LevelDB SSTable files (.ldb) but is logically deleted and not recovered by Claude Code
• Content typed between the last auto-save (~5 sec interval) and the update is permanently lost

Root cause analysis

Claude Code's draft auto-save writes to Chromium Local Storage (LevelDB) every ~5 seconds. During a version upgrade:

1. The update process kills the Claude Code process (UtilityProcess terminated) without signaling a graceful shutdown
2. The last auto-save may be up to 5 seconds stale
3. After restart, Claude Code does not check for orphaned auto-save entries from the previous version
4. The LevelDB entries are logically deleted during post-update cleanup

Technical evidence (forensic recovery from LevelDB)

I manually parsed the LevelDB SSTable files to recover the lost draft:

• Found 72 progressive auto-save snapshots across multiple .ldb files (Snappy-compressed SSTable data blocks)
• Snapshots span ~33 minutes of typing, one every ~5 seconds
• Final recovered snapshot: 4,297 characters (message was cut off mid-word — last ~30 seconds of typing lost)
• Auto-save entries stored as JSON: {"value":"<draft>","tabId":"<id>","timestamp":<epoch_ms>}
• After the update, these entries were logically deleted (physically present in .ldb files but absent from live DB reads)

Suggested fix

1. Pre-update flush: Before killing the Claude Code process for an update, signal it to flush the current input draft to persistent storage
2. Post-update recovery: On startup after a version upgrade, check for orphaned auto-save drafts from the previous session and offer to restore them
3. Increase auto-save frequency: Consider reducing the ~5 second auto-save interval for the input field, or flush on every keystroke pause (debounced)

Environment

• macOS (arm64)
• Claude Code updated from 2.1.63 → 2.1.64
• March 2026