Explicit Identity

Explicit Identity Across Boundaries

Never rely on "latest" or "current" when crossing process or async boundaries.

Pattern

Pass explicit identifiers through the entire pipeline. "Most recent" is a race condition.

DO

• Pass --session-id $ID when spawning processes
• Store IDs in state files for later correlation
• Use full UUIDs, not partial matches
• Keep different ID types separate (don't collapse concepts)

DON'T

• Query for "most recent session" at execution time
• Assume the current context will still be current after await/spawn
• Collapse different ID types:
  • session_id = Claude Code session (human-facing)
  • root_span_id = Braintrust trace (query key)
  • turn_span_id = Braintrust turn within session