Cross-domain confidence calibration + per-domain recency half-life

[tomas-samek]

Summary

Confidence thresholds and recency half-life are currently global constants. Different domains (code, prose, math, timely facts) need different calibration.

What to do

• Promote thresholds and half-life from constants to a per-domain config (keyed by layer.domain).
• Ship defaults that match current behavior so no regression for untagged memories.
• Add a small calibration harness that given a scenario set per domain, suggests threshold adjustments.

Acceptance

• A memory in a code:* layer and a memory in a news:* layer can have different recency decay.
• Default (no domain) behavior unchanged.

Links

• docs/design/honest_agent/progress.md Phase D.
• src/mcp/responder.rs, src/store/layer.rs