docs(w47): Day 2 R3 hostile review — GO verdict, all R2 fixes verified

R3 confirms: percentile interpolation, input validation, comment fix,
copy removal all correct. 1020 tests, 0 clippy warnings.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: matte1782

docs/reviews/2026-03-06_W47D2_R3_REVIEW.md

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+# HOSTILE_REVIEWER: R3 Final Review -- W47 Day 2 Benchmark Harness
+
+**Date:** 2026-03-06
+**Reviewer:** HOSTILE_REVIEWER
+**Round:** R3 (Final)
+**Artifacts:** `tests/wasm/pq_bench.js` (287 lines), `tests/wasm/pq_bench.html` (567 lines)
+**Verdict:** GO
+
+---
+
+## R2 Fix Verification
+
+| Fix | Status | Evidence |
+|:----|:-------|:---------|
+| M1 percentile (linear interpolation) | VERIFIED | `pq_bench.js:71-79` -- Uses `rank = (p/100) * (len-1)`, floor/ceil split, fractional interpolation. Standard NIST method. Edge cases handled: empty array returns 0, single-element returns that element. |
+| M2 input validation guards | VERIFIED | `pq_bench.js:99-101` (benchADC: iterations, nCodes, nQueries all >= 1), `pq_bench.js:194-195` (benchTraining: iterations, nVectors >= 1). All throw descriptive Error messages. |
+| m6 misleading "partial sort" comment | VERIFIED | `pq_bench.js:271` now reads "Find top-k via full sort (acceptable: ground truth cost excluded from timing)" -- accurately describes the O(N log N) Array.sort behavior. |
+| m7 unnecessary Float32Array copy | VERIFIED | `pq_bench.js:130` uses `data.subarray(i * dims, (i + 1) * dims)` which returns a view (no copy). No `new Float32Array(...)` wrapper present. |
+
+All four R2 fixes correctly applied.
+
+---
+
+## WASM API Cross-Check
+
+| JS Call | WASM Export (src/wasm/mod.rs) | Match |
+|:--------|:------------------------------|:------|
+| `window.__edgevec.trainPq(data, dims, nCodes, m, ksub, maxIters)` | `train_pq(data, dims, n_vectors, m, ksub, max_iters)` at line 4398, js_name="trainPq" | PASS -- 6 args, types align (Float32Array -> &[f32], numbers -> u32) |
+| `codebook.encodePq(vec)` | `encode_pq(&self, vector: &[f32])` at line 4475, js_name="encodePq" | PASS -- returns Vec<u8> (Uint8Array in JS) |
+| `codebook.pqSearch(allCodes, nCodes, query, k)` | `pq_search(&self, codes, n_codes, query, k)` at line 4530, js_name="pqSearch" | PASS -- 4 args, Uint8Array + u32 + Float32Array + u32 |
+| `cb.dimensions()` | line 4622, js_name="dimensions" | PASS |
+| `cb.numSubquantizers()` | line 4616, js_name="numSubquantizers" | PASS |
+| `cb.ksub()` | line 4628, js_name="ksub" | PASS |
+| `codebook.free()` | wasm_bindgen auto-generated Drop | PASS -- called after benchADC (line 177), benchTraining (line 214), and HTML init smoke (line 481) |
+
+All JS function calls match the WASM export signatures. No orphan calls, no missing methods.
+
+---
+
+## New Findings
+
+| # | Severity | Description | Status |
+|:--|:---------|:------------|:-------|
+| (none) | -- | No new issues introduced by R2 fixes | -- |
+
+---
+
+## Carried-Forward Minors (from R1, accepted)
+
+| # | Description | Disposition |
+|:--|:------------|:------------|
+| m1 | Bundle size hardcoded as ~622 KB (actual 607 KiB) | Accepted R1 -- cosmetic |
+| m2 | Warmup=3 magic number duplicated in benchADC and benchTraining | Accepted R1 -- low risk, both functions independent |
+| m3 | Footer version v0.9.0 hardcoded | Accepted R1 -- cosmetic |
+| m4 | Ground truth uses O(N log N) sort | Accepted R1 -- cost excluded from timing per plan |
+
+---
+
+## Regression
+
+- `cargo test --lib`: **1020 passed**, 0 failed, 0 ignored
+- `cargo clippy -- -D warnings`: **0 warnings**
+
+No regressions detected.
+
+---
+
+## Correctness Deep-Check: percentile() Function
+
+Verified the linear interpolation implementation against edge cases:
+
+| Input | p | Expected | Actual (by code trace) |
+|:------|:--|:---------|:-----------------------|
+| `[]` | 50 | 0 | 0 (line 72 early return) |
+| `[7]` | 99 | 7 | 7 (line 73 early return) |
+| `[1, 2, 3, 4, 5]` | 50 | 3 | rank=2.0, lo=2, hi=2, frac=0 -> sorted[2]=3 |
+| `[1, 2, 3, 4, 5]` | 99 | 4.96 | rank=3.96, lo=3, hi=4, frac=0.96 -> 4 + 0.96*(5-4)=4.96 |
+| `[10, 20, 30]` | 0 | 10 | rank=0, lo=0, hi=0, frac=0 -> sorted[0]=10 |
+| `[10, 20, 30]` | 100 | 30 | rank=2.0, lo=2, hi=2, frac=0 -> sorted[2]=30 |
+
+All correct. The interpolation handles boundary cases (p=0, p=100) without index overflow because `Math.ceil(rank) == Math.floor(rank)` when rank is integer, so `sorted[lo] == sorted[hi]`.
+
+---
+
+## Verdict
+
+```
++---------------------------------------------------------------------+
+|   HOSTILE_REVIEWER: GO                                              |
+|                                                                     |
+|   Artifact: W47 Day 2 WASM Benchmark Harness                       |
+|   Round: R3 (Final)                                                 |
+|                                                                     |
+|   R2 Fixes Verified: 4/4                                            |
+|   New Critical Issues: 0                                            |
+|   New Major Issues: 0                                               |
+|   New Minor Issues: 0                                               |
+|   Carried Minors: 4 (all accepted)                                  |
+|                                                                     |
+|   Regression: CLEAN (1020 tests, 0 clippy)                          |
+|   WASM API: ALL 7 JS calls match Rust exports                       |
+|                                                                     |
+|   Disposition: Artifact approved for commit.                        |
+|   Proceed to W47 Day 2 end-of-day sweep.                            |
++---------------------------------------------------------------------+
+```
+
+---
+
+*Reviewed by: HOSTILE_REVIEWER*
+*Date: 2026-03-06*
+*Verdict: GO*