Core: exempt destinations should bypass consent queue and event buffer

[tyssejc]

Problem

"Necessary" and "exempt" currently behave identically in the consent engine — both short-circuit isAllowed() to true. But they serve different purposes and should have different dispatch behavior.

"Exempt" destinations (error monitoring, observability) are operational — they need events immediately, not after a 2s buffer timer or consent queue drain. Current behavior adds unnecessary latency for Sentry errors and first-party analytics.

Proposed Behavioral Divergence

Aspect	necessary	exempt
Consent UI	Visible	Hidden
Consent queue	Participates	Bypasses
Event buffer	Participates	Bypasses — dispatch immediately
sentTo tracking	Included	Excluded (always receives, even on replay)

Implementation

In collector.ts, when track() is called:

1. Before buffering, check if any destinations are exempt
2. Dispatch to exempt destinations immediately (skip buffer)
3. Buffer the event for consent-gated destinations as normal

This means exempt destinations get events with near-zero latency while consent-gated destinations still respect the queue and buffer.

Edge cases

• Exempt destinations still go through transform() and send() — no shortcutting the destination interface
• Events dispatched to exempt destinations should still emit destination:send for debug panel visibility
• sentTo should NOT include exempt destinations, so they also receive the event on consent queue replay (they're observability sinks — seeing the event twice with different consent context is valuable)

Files

• packages/core/src/collector.ts — split dispatch path in track() and dispatchToDestinations()
• packages/core/src/collector.test.ts — new tests for immediate exempt dispatch

Context

See standard: agent-os/standards/core/necessary-vs-exempt.md (behavioral divergence section)