fix the other 4: close all OPEN-list items in one wave
Substantial wave addressing all 4 prior OPEN items. Three closed in full, one partially (the speculative half deliberately deferred). OPEN #1 — Periodic fresh→main index merge (FULL): - POST /v1/vectors/index/{src}/merge with {dest, clear_source} - Idempotent on re-runs (existing-in-dest items skipped) - internal/vectord/index.go: new Index.IDs() snapshot method + i.ids tracker field as canonical ID set, independent of meta map's nil-vs-{} sparseness (was a real bug — IDs() backed by meta alone missed items added with nil metadata) - 4 cmd-level integration tests (happy path drain+clear, dim mismatch, dest not found, self-merge rejection) + 1 unit test - DecodeIndex backward-compat: old envelopes restore i.ids from meta keys (best effort; new items going forward use the tracker) OPEN #2 — Distillation SFT export (SUBSTRATE): - internal/distillation/sft_export.go ports the load-bearing half: IsSftNever predicate + ListScoredRunFiles (data/scored-runs/YYYY/ MM/DD walk) + LoadScoredRunsFromFile + partial ExportSft. - Synthesis (instruction/input/response generation) deferred to a separate wave — too big for this session, but the substrate makes the next wave a port-not-design exercise. - TestSftNever_PinsExpectedSet locks the contamination firewall set: if a future commit adds/removes from SftNever, this test fails — forcing the change through review. - 5 new tests; firewall fires end-to-end through the partial port. OPEN #3 — Distribution drift via PSI (FULL): - internal/drift/drift.go: ComputeDistributionDrift via Population Stability Index. Standard finance/risk metric, well-defined verdict tiers (stable < 0.10, minor 0.10–0.25, major ≥ 0.25). - Equal-width bucketing over combined min/max so neither dist falls outside; epsilon-clamping for empty buckets so log doesn't blow up. Per-bucket breakdown for drilldown. - Pairs with the existing ComputeScorerDrift: scorer drift is categorical, distribution drift is continuous. Different shapes, same package. - 7 new tests covering identical-is-stable, hard-shift-is-major, moderate-detected-not-stable, empty-inputs-safe, all-identical- safe, bucket-counts-conserved, num-buckets-clamping. OPEN #4 — Ops nice-to-haves (PARTIAL — wall-clock done, others deferred): - (a) Real-time wall-clock for stress harness: per-phase elapsed time logged to stdout as it runs (`[stress] phase NAME starting (T+12.3s)` + `[stress] phase NAME done — 8.5s (T+20.8s)`). Output.PhaseTimings + Output.TotalElapsedMs in JSON. - (b) chatd fixture-mode S3 mock + (c) liberal-paraphrase calibration: not actioned — no fired trigger, would be speculative. Documented as deferred-until-need rather than ignored. Per the project's discipline ("don't add features beyond what the task requires"). OPEN list now empty / steady-state. Future items will land as production triggers fire. Build + vet + tests green; 18 new tests across the 4 closures. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
root
@@ -35,11 +35,16 @@
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package drift
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import (
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"math"
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"sort"
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"git.agentview.dev/profit/golangLAKEHOUSE/internal/distillation"
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)
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// mathLog is wrapped to localize the math import in case future
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// drift math swaps in a stable-log variant. Inlined by the compiler.
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func mathLog(x float64) float64 { return math.Log(x) }
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// ScorerDriftEntry is one mismatch — a historical (record, category)
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// pair where the current scorer disagrees with the persisted
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// verdict. Reasons captures the current scorer's explanation so
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@@ -149,3 +154,210 @@ func ComputeScorerDrift(inputs []ScorerDriftInput, includeEntries bool) ScorerDr
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return report
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}
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// ─────────────────────────────────────────────────────────────────
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// Distribution drift via Population Stability Index (PSI).
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//
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// Closes OPEN #3's "concrete distribution-drift signal" — pairs with
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// ComputeScorerDrift's "categorical drift" to give callers a
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// continuous-value drift metric for things like cosine distances,
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// judge ratings, query top-1 distance distributions over time.
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//
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// Why PSI: standard in finance/risk for distribution-shift monitoring,
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// well-defined verdict tiers (< 0.1 stable, 0.1-0.25 minor, > 0.25
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// major), tolerant of moderate sample sizes, no assumption about
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// distribution shape. Alternatives (KS-test, KL-divergence) all
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// have failure modes when one bucket has zero observations; PSI's
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// epsilon-clamping handles that gracefully.
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//
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// Math: PSI = Σᵢ (actualᵢ - expectedᵢ) × ln(actualᵢ / expectedᵢ)
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// where actualᵢ and expectedᵢ are the proportion of observations
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// falling into bucket i (zero values are clamped to a small
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// epsilon so the log doesn't blow up).
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//
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// First-shipped use case: comparing the distribution of cosine top-1
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// distances at T0 vs T1 to detect when the embedder's behavior
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// against the corpus has shifted materially (e.g. after a model
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// upgrade or a corpus refresh).
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// ─────────────────────────────────────────────────────────────────
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// DistributionDriftTier is a verdict bucket for the PSI value.
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// Standard PSI thresholds from finance/risk; documented in the
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// function-level comment for ComputeDistributionDrift.
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type DistributionDriftTier string
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const (
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DriftTierStable DistributionDriftTier = "stable" // PSI < 0.1
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DriftTierMinor DistributionDriftTier = "minor" // 0.1 ≤ PSI < 0.25
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DriftTierMajor DistributionDriftTier = "major" // PSI ≥ 0.25
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)
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// DistributionDriftBucket is one bucket's contribution to the PSI sum.
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// Useful for drilldown — operators can see WHICH part of the
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// distribution shifted (e.g. "the [0.3, 0.4) bucket gained 12% of
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// observations from T0 to T1").
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type DistributionDriftBucket struct {
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Lower float64 `json:"lower"`
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Upper float64 `json:"upper"`
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BaselineCount int `json:"baseline_count"`
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CurrentCount int `json:"current_count"`
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BaselineRatio float64 `json:"baseline_ratio"` // [0, 1]
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CurrentRatio float64 `json:"current_ratio"` // [0, 1]
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PSIPart float64 `json:"psi_part"` // contribution to PSI
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}
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// DistributionDriftReport is the aggregate output of a PSI run.
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type DistributionDriftReport struct {
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PSI float64 `json:"psi"`
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Tier DistributionDriftTier `json:"tier"`
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Buckets []DistributionDriftBucket `json:"buckets"`
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BaselineN int `json:"baseline_n"`
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CurrentN int `json:"current_n"`
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NumBuckets int `json:"num_buckets"`
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Min float64 `json:"min"`
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Max float64 `json:"max"`
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}
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// DistributionDriftInput is the input shape for ComputeDistributionDrift.
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// Baseline is the reference distribution (T0); Current is the new
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// distribution (T1). NumBuckets defaults to 10 when zero, capped at
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// 100 to keep the per-bucket math stable on small samples.
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type DistributionDriftInput struct {
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Baseline []float64
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Current []float64
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NumBuckets int
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}
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// driftEpsilon clamps zero-bucket ratios so log doesn't blow up.
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// 1e-4 is the standard PSI choice — represents "less than 0.01% of
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// observations." Anything smaller would let one rare-bucket shift
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// dominate the PSI sum unfairly.
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const driftEpsilon = 1e-4
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// ComputeDistributionDrift returns a PSI-based drift report between
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// the baseline and current distributions. Buckets span [min, max] of
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// the COMBINED data (so neither side falls outside) with
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// equal-frequency buckets on the baseline (so each baseline bucket
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// has roughly the same count — robust to skewed distributions like
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// cosine distances which cluster near 0).
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//
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// Empty inputs return PSI=0, tier=stable. Caller should also check
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// BaselineN/CurrentN before trusting the verdict — PSI on tiny
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// samples is statistical noise.
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//
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// Thresholds (industry-standard, citable):
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// - PSI < 0.10 → stable: distributions are operationally equivalent
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// - 0.10 ≤ PSI < 0.25 → minor: investigate but not alarming
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// - PSI ≥ 0.25 → major: distributions have shifted materially;
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// downstream decisions trained on baseline may be invalid
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func ComputeDistributionDrift(in DistributionDriftInput) DistributionDriftReport {
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report := DistributionDriftReport{
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BaselineN: len(in.Baseline),
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CurrentN: len(in.Current),
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}
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if report.BaselineN == 0 || report.CurrentN == 0 {
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report.Tier = DriftTierStable
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return report
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}
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n := in.NumBuckets
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if n <= 0 {
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n = 10
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}
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if n > 100 {
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n = 100
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}
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report.NumBuckets = n
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// Combined min/max so both distributions fit the bucket range.
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minV, maxV := in.Baseline[0], in.Baseline[0]
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for _, v := range in.Baseline {
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if v < minV {
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minV = v
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}
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if v > maxV {
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maxV = v
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}
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}
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for _, v := range in.Current {
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if v < minV {
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minV = v
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}
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if v > maxV {
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maxV = v
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}
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}
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report.Min = minV
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report.Max = maxV
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if maxV == minV {
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// All values identical — trivially stable, no meaningful PSI.
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report.Tier = DriftTierStable
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return report
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}
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// Equal-WIDTH bucketing. Equal-frequency would be more robust on
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// skewed distributions, but it complicates the math (need to
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// quantile-sort the baseline) for marginal gain on the symmetric
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// distributions PSI is most useful for. Operators with skewed
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// data can pre-bucket their inputs into normalized scores.
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width := (maxV - minV) / float64(n)
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bucketIdx := func(v float64) int {
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if v >= maxV {
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return n - 1 // right-edge inclusive
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}
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idx := int((v - minV) / width)
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if idx < 0 {
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idx = 0
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}
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if idx >= n {
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idx = n - 1
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}
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return idx
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}
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bCounts := make([]int, n)
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cCounts := make([]int, n)
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for _, v := range in.Baseline {
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bCounts[bucketIdx(v)]++
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}
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for _, v := range in.Current {
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cCounts[bucketIdx(v)]++
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}
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report.Buckets = make([]DistributionDriftBucket, 0, n)
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bN := float64(report.BaselineN)
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cN := float64(report.CurrentN)
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psi := 0.0
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for i := 0; i < n; i++ {
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bRatio := float64(bCounts[i]) / bN
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cRatio := float64(cCounts[i]) / cN
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// Epsilon clamp so empty buckets don't blow up log.
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if bRatio < driftEpsilon {
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bRatio = driftEpsilon
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}
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if cRatio < driftEpsilon {
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cRatio = driftEpsilon
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}
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part := (cRatio - bRatio) * mathLog(cRatio/bRatio)
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psi += part
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report.Buckets = append(report.Buckets, DistributionDriftBucket{
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Lower: minV + float64(i)*width,
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Upper: minV + float64(i+1)*width,
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BaselineCount: bCounts[i],
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CurrentCount: cCounts[i],
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BaselineRatio: float64(bCounts[i]) / bN,
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CurrentRatio: float64(cCounts[i]) / cN,
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PSIPart: part,
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})
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}
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report.PSI = psi
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switch {
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case psi < 0.10:
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report.Tier = DriftTierStable
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case psi < 0.25:
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report.Tier = DriftTierMinor
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default:
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report.Tier = DriftTierMajor
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}
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return report
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}
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