Atomic admission

The store-side decision that combines policy, claim, and lease.

Admission is the defining operation in headgate. A worker provides its queue set and free capacity. The store evaluates every configured policy using store-owned time, then writes the claim and lease in the same atomic operation.

Non-negotiable properties

• Policy-rejected jobs remain visible and unlocked.
• The lease is written by the same statement or Lua script that claims the job.
• Store time controls refill, scheduling, and lease expiry.
• Candidate selection draws per partition so one flooding tenant cannot hide quiet ones.
• Fairness is work-conserving: spare capacity never idles to punish a noisy tenant.
• Rate-limited work is requeued without consuming an attempt.

PostgreSQL uses one admission query, MySQL uses its matching atomic transaction path, and Redis uses one Lua script. Their behavior is compared by cross-language conformance.

Admission units

Claims are returned in groups called admission units. Units normally contain one job today, but the shape reserves correct accounting for future store-side aggregation without reopening the hardest boundary in the system.