docs(research): checkpoint += artifact-mechanics; trim handoff under the 400-line bound

Checkpoint: verdict-chain row 7 (artifact-MECHANICS, DESCRIPTIVE — no verdict,
33a4dfc) + a mechanics paragraph in the CRUX section — the 4H reached-less-clean gap
is a span/duration confound (vanishes at equal span), the snapping flip is a
TF-dependent geometry; descriptive only, crux unchanged/OPEN.

Handoff: archived the pre-selection-learning 2026-06-15/06-16 Recent-Changes entries
(behaviour/context NULL, Genesis V2 phases, MTF confluence, #32 tooling, source-fib
milestones) into a single pointer — all preserved in the PAUSED/CLOSED status sections
below + log.md / log archive. 397 -> 362 lines (comfortable margin under the 400 cap).
Wiki-lint OK (no orphaned reviews), bounds OK.

Docs-only, no claim, no lock change, no matched-null, no new universe, no Genesis/1H/ETH.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: JohnCCarter

docs/research_wiki/handoff.md

@@ -36,47 +36,12 @@ append-only trail lives in [log.md](log.md).
   uncertainty-ordered worklist (`--by-uncertainty`), fail-closed swing-label validation. SENARE gated.
   Review fixes: P1 windowed-save facit-safety, P2 level-events now log-scale. Sec (PR #34):
   cryptography→49.0.0 (GHSA-537c-gmf6-5ccf). No facit/signal/auto-fib touch.
-- **2026-06-16 BTC/Fib studies — BOTH NULL, reviewed PASS / CLOSED** (commit `f4e96f1`, Lean Fib).
-  **(1) Behaviour event study:** fib ≈ placebo ≈ swing (4h reject 0.78/0.80/0.84, p=0.63/0.19).
-  **(2) Context-conditioned** (continuous MFE−MAE, rank-perm + Holm; contexts trend + deep
-  0.618/0.786): no context passes — fib beats *random placebo* only nominally (p=0.042/0.056, fails
-  Holm) and **never beats swing**. **Insight:** any faint level-reaction is generic horizontal
-  structure, not Fibonacci. Both gates fail → **no strategy work.** Code:
-  `fib_behaviour_event_study.py` (19 tests) + `fib_context_conditioned_study.py` (17); preregs +
-  results `reviews/btc-fib-*-20260616.md`.
-- **2026-06-16 Fib → Genesis V2 Phase 2.5 feature nullability policy — reviewed PASS / CLOSED**
-  (docs-only) — pins how the future bar feature table represents empty values (3 states; distances
-  null not 0/inf; empty-meta ⇔ no-known-zone; dense-table + no-imputation consumer rules).
-  Precondition for any real export. **Open (non-blocking):** is `has_robust_4tf_zone_nearby`
-  log-price- or ATR-thresholded (latter ⇒ warmup-null / availability flag).
-  [Policy](reviews/btc-fib-to-genesis-v2-feature-nullability-policy-20260616.md).
-- **2026-06-16 Fib → Genesis V2 Phase 2 dummy contract test — reviewed PASS / CLOSED** —
-  mechanical contract/dummy test **inside Fib only** (not export, not Genesis integration).
-  `research/feature_contract.py` (stdlib) validates two committed dummy CSVs vs the Phase 1
-  schema (join keys, causality, knowability floor, 1H + feature/metadata fail-closed). No fib
-  computation, no Genesis touch. 20 tests; gates green. Commit `68dc006`; **human review PASS**
-  2026-06-16. Follow-up for any *real* export: define a **nullability policy** for feature
-  columns. [Report](reviews/btc-fib-to-genesis-v2-phase2-dummy-contract-20260616.md).
-- **2026-06-15 MTF confluence CP1–CP3 CLOSED + interpretation/decision note** — first atlas
-  pack done (5 cards, 3 archetypes, all **human-approved**): c001 robust fixed-band 4-TF; c002
-  chaining-dependent contrast (NOT tight); c004/c006/c007 zero-span exact-price 3-TF.
-  [Decision note](reviews/btc-mtf-confluence-interpretation-decision-20260615.md): confluence
-  is **geometry, not edge proof** → **rec: stop MTF track**; next = pause Fib or new question.
-- **2026-06-15 Structural chart-contract snapshots (#F)** — `research/render_summary.py`
-  (stdlib): stable text summaries of map/zoom/gallery renders + golden JSON under
-  `tests/research/snapshots/`. Automatic structural regression; no PNG baselines/deps.
-- **2026-06-15 20171228 source fib corrected** — preview-first flow: anchor_a moved
-  2017-12-28T20:00 @ 13611 → 2017-12-28T08:00 @ 13145 (candidate_1). Only anchor_a + levels
-  changed; anchor_b/fib_id unchanged; guard PASS; ledger candidate → corrected. Closes the
-  declutter→correction→ledger track. [Report](reviews/btc-4h-fib-20171228-correction-20260615.md).
-- **2026-06-15 Issue #32 top-ROI tooling — DONE** (declutter edit-mode, overlap detector, review
-  ledger, artifact gallery; all stdlib). Detail in [log part 1](log-archive-btc-postreset-part1.md).
-- **2026-06-15 4H Tier 1 + Tier 2 visual reviews — complete** (11 groups; `20171228` corrected;
-  corpus clean). Archived to [log part 1](log-archive-btc-postreset-part1.md).
-- **2026-06-08→06-12 source-fib milestones (archived)** — 1M/1W/1D/4H source phases, reaction
-  reviews (1816 interactions), 4H Tier 1 maps, Addendum 2 golden-zone retirement (#30), log-scale
-  + profile fix + monthly-first reset. Detail: [log post-reset part 1](log-archive-btc-postreset-part1.md)
-  + [log.md](log.md); current counts in Verification Snapshot below.
+- **Earlier 2026-06-15/06-16 changes — archived** (kept lean for the 400-line bound): behaviour +
+  context studies **NULL/CLOSED** (`f4e96f1`); Fib→Genesis V2 Phase 2 + 2.5 nullability **PASS/CLOSED**
+  (`68dc006`); MTF confluence CP1–CP3 **CLOSED** (geometry, not edge); #32 tooling DONE + `20171228`
+  correction + chart-contract snapshots; 2026-06-08→06-12 source-fib milestones. **All preserved** in
+  the **PAUSED/CLOSED status sections below** + [log.md](log.md) /
+  [log part 1](log-archive-btc-postreset-part1.md); current counts in the Verification Snapshot.
 
 ## Status — Fib SELECTION-LEARNING line (2026-06-18, slice committed `ea6c2ea`)
 

docs/research_wiki/reviews/btc-fib-selection-learning-checkpoint-20260624.md

@@ -29,6 +29,7 @@ positive claim. Decision needs a separate explicit GO.
 | 4 | W-gap causal-availability (06-23) | **`no_causal_gap`** | gap(k=3) **−0.0045**, CI [−0.070, +0.031] incl. 0 | `b515b08`↩`61c41d1` |
 | 5 | Stage-1 per-pivot (06-24) | **`no_pivot_signal_above_prominence`** | recall **0.902**; ranking lift +0.0228, CI [−0.035, +0.079] incl. 0 | `b515b08` |
 | 6 | `cleanliness` artifact-probe (06-24) | direction guards **`inverse_surfacing`** + **`snapping_deflates`** (A7-unregistered combined → `meta:` status, NOT a verdict) | surfacing gap **−0.0557** CI [−0.1150, −0.00095]; snapping gap **−0.0219** CI [−0.0320, −0.0102]; both exclude 0 **below** | `1573b56` |
+| 7 | artifact-MECHANICS (06-24) | **DESCRIPTIVE — no verdict** | 4H reached-less-clean = **span confound** (Spearman(clean,span) **−0.69**; gap **vanishes** at equal span: +0.003 / −0.017); snapping asymmetry 4H extends (33%/1.6%) vs 1D shrinks (10%) + span↔clean Spearman flips −0.19→+0.18 | `33a4dfc` |
 
 ## What we KNOW (positive, scoped to 4h + the frozen eight features)
 
@@ -80,6 +81,16 @@ swing" question is **out of scope** (matched-null gated, A8 — **not built**; i
 **narrowed** (the inflationary mechanism is unsupported) with a sharper investigate-target: *why
 reached/snapped legs are less clean, and why snapping flips sign by TF.*
 
+**What the MECHANICS pass added** ([note](btc-fib-selection-learning-artifact-mechanics-20260624.md),
+`33a4dfc`, **descriptive — no verdict, no claim, crux unchanged**): that investigate-target is now
+partly answered. The 4H "reached less clean" gap is a **span/duration confound** — cleanliness falls
+steeply with span (Spearman −0.69), reached legs are longer (median 5 vs 3 bars), and the gap
+**vanishes when conditioning on span** (short-span +0.003, long-span −0.017): a composition effect, not
+a detector cleanliness-preference. 4H snapping deflates because detector pivots sit **outside** the
+human anchors (span extends, 33% vs 1.6%); the 1D flip is a **TF-dependent geometry** (1D shrinks more,
+10%, **and** the span↔cleanliness relationship flips sign, −0.19→+0.18) — *why* the local relationship
+reverses by TF stays an **open investigate-target**. None of this resolves the crux either way.
+
 **Secondary loose end:** set-level **`exclusivity`** (`k*=3`) was specced in the
 [§12 addendum](btc-fib-selection-learning-addendum-20260618.md) but the Stage-2 live whitelist actually
 built was `{magnitude, cleanliness, duration, prominence, structure_alignment}` — **exclusivity was