2.1.27: 100% CPU infinite loop on --continue / --resume / session listing

Description

Claude Code 2.1.27 enters an infinite loop with 100% CPU and rapidly growing memory (11+ GB) when loading or listing sessions. Fresh starts (claude with no flags) work fine. The issue is specific to any operation that scans or loads existing session files:

• claude --continue
• claude --resume
• /resume from within a running session

Reproduction

1. Have a project directory with session history (100+ sessions in ~/.claude/projects/)
2. Run claude --continue or claude --resume
3. Process immediately spikes to 100% CPU and memory grows unbounded
4. Must be force-killed (kill -9)

Environment

• macOS 26.2 (Sequoia), Apple Silicon (M4 Pro)
• Claude Code 2.1.27 — broken
• Claude Code 2.1.25 — works fine with the same session files
• Node versions tested: v25.5.0 and v22.22.0 (same behavior on both)
• ~130 session files in the affected project directory (~160MB total)

Key observations

• claude --version and claude --print "test" work fine on 2.1.27 (no session scanning)
• Fresh claude (no --continue/--resume) launches normally on 2.1.27
• Downgrading to 2.1.25 immediately fixes the issue — --continue and --resume work with the exact same session files
• Not caused by MCP servers, plugins, statusLine config, or project-specific settings (all tested independently)
• Auto-updater aggressively overwrites the symlink back to 2.1.27 on each launch, making it difficult to stay pinned to 2.1.25

Workaround

# Delete 2.1.27 and pin to 2.1.25
rm ~/.local/share/claude/versions/2.1.27
ln -sf ~/.local/share/claude/versions/2.1.25 ~/.local/bin/claude

Note: The auto-updater will eventually re-download a newer version, so this needs to be repeated if a fixed version hasn't been released.