Vesper Review — Branch #6 `feat/distance-to-touch-diagnostic`¶

To: Katja CC: Orion, Atlas From: Vesper Date: 2026-04-19

Verdict: APPROVED ✅¶

Three commits reviewed. All Q1/Q2/Q3 rulings correctly applied and pinned by tests. No blocking issues. One minor documentation nit.

Commit 1 — `feat(state): add distance_to_touch columns to system_metrics`¶

Schema additions are clean. Dual-path initialization (CREATE TABLE for fresh DBs, _ensure_column for live DBs) is the established migration pattern. Backward-compatible record_system_metric signature — callers that omit the new kwargs get NULL, which is correct for all pre-Branch-6 rows including the live neo_live_stage1.db.

Three tests cover the right things: NULL default when caller omits (backward compat), signed round-trip with an explicit negative (pins Q2 at the persistence layer), and PRAGMA schema check (pins Q1 migration). The negative value test (-1.25 BUY side) is the right choice for a persistence-layer test — it proves no abs() crept into the write path at the lowest level.

Commit 2 — `feat(main-loop): compute, log, and persist distance-to-touch per tick`¶

_compute_distance_to_touch structure is correct: per-side try/except, get_live_order_by_side (Q3 — live order, not intent), getattr guards on snapshot fields, NULL on any failure. The two independent try blocks are the right call — a missing best_bid should not suppress the ask-side computation. Formula matches the spec.

Log emission guard (if dist_bid_bps is not None or dist_ask_bps is not None) is correct — ticks with no live orders on either side stay silent. This keeps the logs clean during pause windows, which is the intended behavior.

The fixture fix in test_main_loop.py (_last_valuation_snapshot_ts and valuation_snapshot_interval_seconds) is a legitimate incidental repair. Pre-existing AttributeError confirmed by the "flipped green" test count. Well-documented in the commit body.

Four tests cover the critical paths: NULL default (no live orders), happy path (+10 bps both sides, passive), negative sign preservation (−1 bps crossing BUY, Vesper alarm contract), per-side NULL when snapshot missing best_bid. The negative-sign test message explicitly cites the Q2 ruling — good.

Commit 3 — `feat(summary): per-side distance-to-touch aggregate block`¶

_percentile implementation is correct linear interpolation, matches numpy method='linear'. The decision to keep it module-private and implement it locally (rather than pulling in numpy) is right for a summary script — no new dependency, and the tests pin the math against known values (1..20 → p50=10.5, p95=19.05).

load_distance_to_touch_summary correctly: uses latest-session scoping (older session crossings don't leak), drops NULLs before every stat, counts crossings strictly < 0 (not <= 0), returns None on no-session/all-NULL paths. Parallel to load_quote_quality_summary rather than extending it — correct, avoids the mid is None early-return silencing the block.

render_distance_to_touch_summary matches house style. The "no-samples" fallback still shows crossings(<0): 0 — important for operator clarity (absence of data ≠ absence of crossings).

Legacy metrics retained per ruling. Good.

18 tests are comprehensive. Latest-session scoping test (older session with 100 crossings does not appear in output) is exactly the right edge case to pin.

One minor nit: _percentile's docstring says "test coverage is driven through the public summary entry point" but the test file tests it directly. The direct tests are fine and correct — the docstring is slightly misleading. Not blocking; fix in a future cleanup pass if anyone edits the function.

Apply commands — Windows VS Code terminal¶

git fetch origin
git checkout -b feat/distance-to-touch-diagnostic

git am "C:\Users\Katja\Documents\Claude Homebase Neo\02 Projects\NEO Trading Engine\patches\branch-6-distance-to-touch-diagnostic\0001-feat-state-add-distance_to_touch-columns-to-system_m.patch"
git am "C:\Users\Katja\Documents\Claude Homebase Neo\02 Projects\NEO Trading Engine\patches\branch-6-distance-to-touch-diagnostic\0002-feat-main-loop-compute-log-and-persist-distance-to-t.patch"
git am "C:\Users\Katja\Documents\Claude Homebase Neo\02 Projects\NEO Trading Engine\patches\branch-6-distance-to-touch-diagnostic\0003-feat-summary-per-side-distance-to-touch-aggregate-bl.patch"

git log --oneline -4
python -m pytest tests/test_state_manager.py tests/test_main_loop.py tests/test_distance_to_touch_summary.py -q

If any patch conflicts on a pre-existing test or source file, paste the error — same --3way + git checkout HEAD resolution as Branch #5. New files (test_distance_to_touch_summary.py) won't conflict.

Expected: ~45 tests passing across those three files (the exact count depends on how many pre-existing state_manager and main_loop tests are in your repo, but the new tests add 24 net). Merge and push when clean:

git checkout main
git merge --no-ff feat/distance-to-touch-diagnostic -m "Merge branch 'feat/distance-to-touch-diagnostic' into main"
git push

Then ping Orion for Branch #7.

Branch status¶

Branch	Status
#1–#5	✅ Merged
#6 feat/distance-to-touch-diagnostic	✅ Approved — apply and merge
#7 fix/wal-checkpoint-hardening	⏳ Next — one branch left before S40

— Vesper

Vesper Review — Branch #6 feat/distance-to-touch-diagnostic¶