The clusterer now drops a single high-tier function call in favor of
a tier-weighted sum. Tier multipliers (high=1.0, medium=0.6, low=0.2,
very_low=0.05) are tuned so the threshold (1.0) admits high-tier
agreement alone while leaving every weaker tier — and every
combination of weaker tiers — under threshold.
Per-tier discipline tested:
- high alone clusters
- medium alone does NOT cluster (supporting signal only)
- low alone does NOT cluster (fixture 1's failure mode)
- very-low alone does NOT cluster (fixture 2's failure mode)
- all three weak tiers stacked still don't reach threshold
- high + medium clusters (high already saturates)
The combination is forward-compatible: low + very-low contributions
are computed today but always project to 0.0 because the production
adapter doesn't populate credentials / ASN-edge inputs into the
fixture path yet. Their contribution becomes load-bearing in commit 7
when the low-tier landing tightens the F1 / F2 bounds.
Fixture 4 (paused_campaign) ratchet added: high-tier signal carries
the multi-day-silence campaign into one identity. Time-agnostic
invariant — silence is irrelevant to the edge weight.
Adds the four weight-tier edge functions as pure, time-agnostic
scoring primitives over an Observation projection. Each returns a
score in [0, 1]; the connected-components impl will combine + threshold
in subsequent commits.
Tier semantics (from IDENTITY_RESOLUTION.md):
- high — JA3/HASSH/payload-hash/C2-endpoint exact match
- medium — phase-bucketed command-sequence Jaccard
- low — credential-attempt-set Jaccard (defeated alone by F1)
- very low — ASN equality (defeated alone by F2)
Time-agnostic invariant is a static test: Observation has no time
fields, so no edge function can silently start using them. Fixture 7
forbids recency-decay clustering on multi-month APT campaigns.
A from_synthetic() adapter projects SyntheticAttacker corpora into
Observation; the production-row adapter lands when the clusterer
starts reading the attackers table.
