ADR-048: Feed Ranking v2 — 7-Signal Formula + Interaction Logging

Status: Implemented Date: 2026-04-03 Supersedes: ADR-031 (feed scoring weights — extended, not replaced)

Context

Sprint 43 extends ADR-031's 4-signal feed scoring with 3 additional signals: requester trust score, prior interaction history, and request recency. It also introduces a requests.feed_events table to log impressions and outcomes for future weight tuning.

The original 4 signals (skill match, trust distance, community relevance, urgency) captured match quality and connection strength but ignored whether a viewer has helped this person before or how fresh the request is. High-urgency old requests could crowd out timely new ones from known collaborators.

Decision

Extend FeedScoringWeights and FeedScoreInput with requesterTrustScore, priorInteractionScore, and recencyScore. Redistribute default weights to sum to 1.0 across all 7 signals. Move weight-sum validation from DB constraint to application code. Add requests.feed_events table with fire-and-forget impression/outcome logging.

Signal Definitions

Signal	Source	Range	Default Weight
skillMatchScore	calculateMatchScore() in shared	0–100	0.25
trustDistanceScore	auth.social_distances cache	0–100	0.20
communityRelevanceScore	community config enabled_request_types	0–100	0.15
urgencyScore	request urgency field	0–100	0.10
requesterTrustScore	reputation.trust_scores (already fetched)	0–100	0.15
priorInteractionScore	social_graph.connections (batch query)	0, 50, or 100	0.10
recencyScore	computed from request.created_at (no DB join)	0–100	0.05

Prior interaction scoring: type='exchange' → 100, type='community' → 50, no row → 0.

Recency scoring: 0–1 day → 100, 2–3 days → 85, 4–7 days → 70, 8–14 days → 50, 15–30 days → 30, 30+ days → 15.

Logging Strategy

requests.feed_events records three event types:

• impression — logged fire-and-forget after each /requests/curated response
• offer_made — logged when a match is created (POST /matches)
• match_completed — logged when both parties confirm completion

This creates a dataset for correlation analysis: do higher priorInteractionScore values lead to more completions? Weights can be tuned from this data in future sprints.

Weight Sum Validation

The DB CHECK constraint on communities.community_configs is dropped. Validation moves to application code in calculateFeedScore(): throws Error('Feed weights must sum to 1.0 (got X)') if |sum - 1.0| > 0.01. Caught at call time, not silently ignored.

Consequences

• Feed results will shift: requests from prior exchange partners and fresher requests rank higher.
• Skill match weight decreases from 40% to 25% of the total score.
• Community admins can override all 7 weights in community_configs (7 columns now).
• Weight-sum validation moves to application code — misconfigured DB weights throw at call time rather than at migration time.
• requests.feed_events is append-only, non-blocking. A logging failure never surfaces to the user.