[BUG] Agent spawn fails on macOS Sequoia: com.apple.provenance on team config files blocks reads

Summary

Agent spawning fails with Team config file unreadable (lock acquired, read failed) on macOS Sequoia (Darwin 25.5.0). The root cause is the com.apple.provenance extended attribute on team config files under ~/.claude/teams/.

Reproduction

1. macOS Sequoia (Darwin 25.5.0), Apple Silicon
2. Claude Code 2.1.220
3. Spawn any agent via the Agent tool
4. Error: Team config file unreadable (lock acquired, read failed)

Root Cause

• ~/.claude/ directory was created by Claude Code, which stamps it with com.apple.provenance
• macOS Sequoia propagates this xattr to ALL files/dirs created inside, regardless of which process creates them
• Even files created by the user's own shell inherit the provenance from the parent directory
• xattr -cr ~/.claude/teams/ does not remove it — the attribute is kernel-level immutable on Sequoia
• The team config reader fails when encountering this xattr despite the file having correct permissions (644) and valid content

What We Tried

1. xattr -cr ~/.claude/teams/ from external terminal — attribute persists
2. xattr -d com.apple.provenance on individual files — attribute persists
3. Deleting and recreating files from user's terminal — new files inherit provenance from parent dir
4. Deleting and recreating the entire directory from user's terminal — still inherits from ~/.claude/

Impact

All agent spawning is broken. No workaround found. Affects any macOS Sequoia user.

Expected Behavior

The team config file reader should handle files with com.apple.provenance xattr, since Claude Code itself creates the ~/.claude/ directory that causes the attribute to propagate.

Environment

• macOS: Darwin 25.5.0 (Sequoia)
• Claude Code: 2.1.220
• Arch: arm64 (Apple Silicon)