# Pre-registered protocol: unified adapter eval (written before any test numbers) Date: 2026-07-13, after val@499, before step-799 completion. No test-set number for the unified adapter exists at time of writing. 1. **Primary loop depth: k=2, for both tasks.** Chosen on val CE with the tie-breaking rule: prefer the SMALLEST k whose hard-cell val CE is within 0.01 nats of the best k. (Current val: MBPP hard k2−k4 = 0.004, GSM hard k2−k4 = 0.006 → both ties → k=2.) The full k-curve is secondary/descriptive. 2. **Checkpoint selection criterion (scalar, fixed now):** mean of the two hard-cell val CEs at k=2, tasks weighted equally: crit = (gsm_hard_k2 + mbpp_hard_k2)/2. Lowest crit among saved checkpoints wins. (At writing: step 499, crit = (0.475+0.205)/2 = 0.340.) 3. **Primary endpoints:** (a) MBPP test pass@1 hard-bucket at k=2 vs k=0; (b) GSM8K test accuracy hard-bucket at k=2 vs k=0. McNemar, paired by item. Overall accuracy is secondary (known to be underpowered at n=250/256). 4. **Same-harness rule:** all k, INCLUDING k=0 baselines, measured by the prompt-only fast-path scripts (`generate_frozen_prompt`; k=0 = plain cached generate inside the same function). No numbers carried over from the full-position-loop harness. 5. **Known missing control (not covered by this run):** a same-size, no-recurrence adapter (h -> h + MLP(h) at the L13->L14 boundary, no loop, no band re-run) trained on identical data/objective. Until it exists, "the loop does the work (vs. 1.6M new weights anywhere doing it)" is NOT established. Queued as the next training run. Note the k=0 column is gated off by construction and is a sanity check only — it is not this control. 6. **Symmetric interference check (missing):** dedicated GSM8K prompt-only adapter as the reference for "unified costs GSM nothing". Queued. Until then the no-interference claim is one-directional (MBPP side only). 7. **Band-location ablation (pre-registered 2026-07-13, before any arm ran).** Arms, all else identical (adapter size/init, data, curriculum, k, scripts; MBPP): early L2-12, mid-narrow L17-27, late L24-34 (width-matched, 11 layers); shifted L6-22 (width-matched to the original 17). Reference: workspace L14-30 (already run, 3 seeds). Prediction: workspace-centered arms (L14-30, L17-27) exceed early/late on hard-bucket pass@1 at k=2-4 by a wide margin; shifted intermediate. Falsification: near-parity across arms demotes the lens claim from "locates where to loop" to "convenient discovery tool"; to be reported either way. Primary readout: hard-bucket pass@1 at k=4, e400 checkpoints throughout. 8. **Language commitments for the writeup:** the k0->k1 CE collapse (e.g. 4.36->0.18) is format/template learning expected from any trained adapter and must not be quoted as evidence of routing/planning; informative comparisons are within k>=1 cells only. Depth ordering k2 vs k4 deltas (0.001-0.006 nats) are inside checkpoint jitter and must be described as "k>=2 fits hard items equally well; k=1 slightly worse." 9. **Anchor/entrance sweep (pre-registered 2026-07-14 ~03:00, before any arm ran).** Arms: bands (13,30), (12,30), (11,30) — injection point shifted up from L14 at fixed tap L30; plus tap-23 = (14,23). All E2B/MBPP, same recipe, e400, primary readout hard-bucket pass@1 at k=4. Competing predictions: (a) "L14 special" (last full-attention KV-computing layer, lens boundary) → anchor-13 drops; (b) "KV-channel count" (anchors 11-13 add 1-3 extra KV-recomputing attention channels) → holds or improves. Body-length confound noted: earlier anchors lengthen the loop body; if results shift, run matched-length control (12,28) before interpreting. 10. **L9 discriminator arm (pre-registered 2026-07-14 ~10:00, before running).** Band (9,30): anchor at L9 — the only other full-attention, KV-computing layer below the boundary — deep in the lens's sensor regime, tap fixed at L30. Separates the two cliff explanations: (a) "lens boundary" predicts catastrophic (like anchors 11-13: 25-34% overall); (b) "full-attention KV-layer entry" predicts partial recovery (clearly above the L11-13 trend, i.e. >40% overall or hard >25%). Registered prediction: (a) — the sensor-region content dominates; layer type does not rescue it. Same recipe/checkpoint/eval as the anchor sweep (250 items, ks 0,2,4). --- # Outcomes vs pre-registrations (scored 2026-07-14, after all arms completed) 1. **k=2 primary depth** — held. All primary comparisons reported at k=2; k-curves descriptive. k≥2 plateau confirmed (k=8 gen-eval flat). 2. **Checkpoint criterion** — applied as written for the unified adapter. Separately reported: val-CE is a poor proxy for generation accuracy; later arms therefore pre-committed to fixed steps (e400) instead. 3. **Primary endpoints (unified adapter, k=2 vs k=0)** — (a) MBPP hard 3.6% → 28.6% (direction as predicted); (b) GSM hard 0% → 6.3%, overall 10.5% → 9.0% (no overall win — the math boundary result). Both reported. 4. **Same-harness rule** — held throughout (all final tables fast-path, k=0 included). 5. **Missing weights control** — run: trained FF adapter = 17.9% hard, exactly the untrained-loop level. Loop-vs-weights gap established. 6. **Symmetric interference check** — run (dedicated GSM adapter); mixed-task training regressed both tasks; reported as negative result. 7. **Band-location ablation** — prediction CONFIRMED with a caveat: L14-30 hard 43.6% ≫ early L2-12 (23.6%, overall destroyed 22.8%) and shifted L6-22 (21.8%, overall 29.0%). Caveat discovered: L17-27 and L24-34 are structurally null (KV sharing; k>0 ≡ k=0 bit-identical), so the "mid-narrow beats late" half of the prediction was untestable at E2B; the 12B replication (no shared KV) carries that weight instead. 8. **Language commitments** — honored in PAPER.md (k0→k1 CE collapse not cited as planning evidence; k2-vs-k4 nats described as jitter). 9. **Anchor/entrance sweep** — prediction (a) "L14 special" CONFIRMED: anchor-13 hard 17.9%/overall 34.4%; 12: 28.6%/30.8%; 11: 25.0%/25.2%; monotone collapse below the boundary. Tap-23 arm died in training (never rerun); exits 27/30/32/34 within seed noise, so exit choice is free. Matched-length control not needed (results did not shift with body length in the informative direction). 10. **L9 discriminator** — registered prediction (a) CONFIRMED: band (9,30) overall 14.0-21.4%, hard ≤21.4% — catastrophic, like anchors 11-13, despite L9 being a full-attention KV-computing layer. The lens boundary, not layer type, gates the retrofit. 11. **Recurrent-regime arm (pre-registered 2026-07-15, before training).** Huginn-style retrofit on the frozen E2B band: RecurrentAdapter (learned A,B init α·I/(1−α)·I + zero-init MLP), h0 = norm-scaled noise, log-uniform random depth k∈[1,16], bptt=4, same data/steps/ checkpoint rule (e400 primary) as all merge arms. Eval ks 0,2,4,8,16,32 on the 250-item MBPP set. Competing predictions: (a) "amortization is intrinsic to frozen-band retrofits" → performance plateaus by k≈4 at or below the merge arm's level, no depth-monotone gain; (b) "fixed- point behavior was an artifact of our fixed-shallow-k training" (Huginn regime transfers) → monotone hard-bucket improvement past k=8 and reduced noise-seed sensitivity after training. Secondary readout: path independence (two noise seeds → output agreement rate) at e400. Known risk, stated in advance: 600 steps may be far too little for this regime (McLeish et al. use ~50B tokens); a null here bounds the cheap-retrofit budget only, not the regime. 12. **Parcae-constrained recurrent arm (pre-registered 2026-07-15, before training; Prairie et al. 2026 parameterization).** Same as item 11 but A = exp(−Δt·exp(a)) diagonal → ρ(A) < 1 by construction; init exactly the α=0.3 merge (verified bit-equal at init). ρ(A) logged every 10 steps in BOTH arms. Theory-derived predictions, stated in advance: (a) contraction ⇒ fixed point is a function of e ⇒ the Parcae arm SATURATES in k (no depth-monotone gain) and its converged performance is amortizable — if so, our deflationary result is a corollary of ρ<1, and our observed k≈3–4 convergence is the geometric rate 0.3^k; (b) the UNCONSTRAINED item-11 arm either drifts toward ρ≥1 (watch the ρ log: divergent runs should show ρ≥1 before loss spikes) or, if it gains monotone depth-performance, does so with ρ near 1 — the edge of stability is where genuine iteration must live. Either outcome formalizes "the anchor coefficient is the stability dial" as "the anchor coefficient is the spectral radius". 13. **Per-depth adapter arm + free-ACT probe (pre-registered 2026-07-15, before training).** (a) PerDepthAdapter: one merge adapter per iteration (n=4, Bae-style depth-wise relaxation at the entrance; breaks time-invariance — LTV, no fixed-point guarantee), standard curriculum, e400, eval ks 0,2,4,8. Prediction: lands at or below the distill/rung-2 amortization ceiling (~46% hard) because depth-indexed weights add content, not state-evolution; exceeding it would show per-iteration expressivity was binding and amend the deflationary claim. Depths >4 reuse adapter 4 (stated: k=8 cell is then fixed-point-like by construction). (b) Free-ACT probe on the standard merge arm: record per-item convergence depth (cos>0.9995) at k=8 cap. Predictions: accuracy unchanged vs fixed k (post-convergence no-ops); mean k_conv ≈ 3; hard-labeled items converge SLOWER than easy ones (adaptive compute allocates like ACT without any learned halting parameter). --- Outcome, item 11 (scored 2026-07-15, k=16/32 cells cancelled by decision after k<=8): PREDICTION (a) SUBSTANTIALLY CONFIRMED, with one twist. The unconstrained arm left contraction immediately (rho(A): 0.3 -> 3.4 by step 100, plateau ~4.5) yet trained smoothly — per-iteration norm-matching converts magnitude explosion into directional churn, so "rho>=1 => divergence" becomes "rho>=1 => divergence OR stationary churn" under a norm projection. Consequences as predicted: substrate damage (easy 98.4 -> ~69% at all k>0, far exceeding any contractive arm's tax), val CE flat k=1..16 (stationary, not progressive), hard bucket at merge level (35.7/39.3/42.9% at k=2/4/8 — a one-item-per-depth-doubling crawl that at k=8 reaches what the contractive merge reaches at k=4, never approaching the amortization ceiling from above). 4x parameters bought nothing. Depth-monotone computation did not emerge at this budget. 14. **Tied-alpha arm (pre-registered 2026-07-15, before training).** TiedAlphaAdapter: x = (1−a)⊙e + a⊙ŝ + MLP([e;ŝ]), a = σ(â) per-dim learned, init a=0.3 everywhere (bit-equal to MergeAdapter at step 0, verified). B tied to (1−a): convex combination keeps the LTI fixed point on the e–ŝ segment (substrate-anchored by construction), ρ = max(a) < 1 guaranteed, +d≈1.5K params. Standard curriculum, s0 = band(e), e400, eval ks 0,2,4,8 on 250 items. This is the one untested cell combining parcae's learnable decay with the merge's anchoring. Predictions: (a) substrate fidelity preserved (easy ≈ merge's 88%, unlike both rec arms' ~70%) because anchoring, not ρ, controls fidelity; (b) hard-bucket at merge level (no significant gain — per-dim constant α is not where capability lives, per the adaptive-α E2B result); (c) learned a drifts slightly DOWN from 0.3 (as in parcae). If (a) holds while rec arms failed it, the fixed-point-location dial is causally isolated: same learnable-decay freedom, only the tie to (1−a) differs from parcae. --- Outcome, item 12 (scored 2026-07-15): prediction (a) CONFIRMED in its dynamics half, REFUTED in its fidelity half — and the refutation is the finding. Dynamics: rho stayed in (0,1) throughout (0.300 -> 0.292, the optimizer drifting MORE contractive when confined to the stable region); loss trajectory as good as or better than the unconstrained arm at every checkpoint (the rec arm's flight to rho~4.5 was epiphenomenal — all fit lives in the MLP); eval saturates completely (hard 42.9/42.9/39.3/39.3/ 39.3 at k=2/4/8/16/32, easy flat ~71%). Fidelity: easy items were NOT preserved (71% vs the merge's 88.5%) despite guaranteed contraction — substrate fidelity is controlled by fixed-point LOCATION (anchored B + curriculum), not by rho. Conclusion: stability and fidelity are independent dials (fig_phase.png); the Parcae constraint delivers exactly what it promises (robust training, convergence, certified tail gradients) and exactly nothing more. Item 14 (tied-alpha) is the causal isolation of the fidelity dial. 15. **Fidelity factorial + capacity control + seed (pre-registered 2026-07-15 ~03:15, before any of these arms ran; overnight batch).** The fidelity loss of both rec arms (easy 88.5 -> ~71%) confounds three deltas from the winning merge: (i) learned B, (ii) random-depth training instead of the difficulty->depth curriculum, (iii) noise s0. Item 14 (tied-alpha) tests (i) with anchoring. New single-variable cells, everything else = standard merge recipe (fixed B, band(e) s0, curriculum, e400, eval ks 0,2,4,8 on 250 items): a. merge+randk — only (ii) changed (log-uniform k in [1,16], bptt 4). b. merge+noises0 — only (iii) changed. c. merge h=2048 — capacity control for the per-depth arm (6.4M shared vs 6.4M depth-indexed): if per-depth beats the ceiling but h2048 does not, time-variation (not capacity) is credited; if both do, it was capacity all along. d. parcae seed 1 — robustness of the fidelity refutation. Predictions: (a) and (b) each cost a few points of easy at most (anchored fixed point dominates); neither reproduces the ~17-point drop — the culprit is the learned/free B (with item 14 as the positive control). h2048 stays at the ceiling (hard <=46%), fidelity intact. parcae s1 reproduces easy ~71% within seed noise. --- Outcome, item 13a (scored 2026-07-15): prediction CONFIRMED — per-depth lands below/at the ceiling, never above. Detail is instructive: fidelity preserved throughout (easy 88.5/89.3/86.9 at k=2/4/8 — anchored B), but hard-bucket content is DEPTH-STRANDED: 17.9% at k=2 (adapters 3-4, which hold the hard-trained content, never execute), 35.7% at k=4, 42.9% at k=8 — where depths 5-8 reuse adapter 4, i.e. the architecture reverts to shared-map iteration and the fixed-point mechanism collects the remaining gain. Time-variation adds a fragility (content unavailable except at its training depth) and no capability; map-sharing is load-bearing for the anytime-usable gain. Depth-4 adapter overfit visible in val (hard k4 CE 0.188@99 -> 0.371@599) — LTV concentrates small-pool overfitting into single depths. --- Outcome, item 13b (scored 2026-07-15): accuracy prediction CONFIRMED (k=8 halt run 52.0/90.2/42.9 = plateau level); convergence predictions REFUTED. Per-item state-cosine (thresh 0.9995, k=8 cap): k_conv distribution 4:3, 5:57, 6:47, 7:17, never-within-8:126 — mean ~7, and NO difficulty gradient (easy 7.01 vs hard 7.00). The earlier "bit-exact by k~3-4" was the single dynamics-probe example, not the population: outputs plateau by k~2-4 while the state keeps drifting at 1e-3..1e-4 cosine scale; the fixed point is an OUTPUT-stable orbit (suffix layers + decode wash out residual state motion), not a literal state fixed point for most prompts. Free-ACT via state-cosine therefore yields no early exit at this threshold, and no ACT-like difficulty allocation falls out for free — output-level halting signals would be needed. Paper's dynamics claims softened accordingly. --- Outcome, item 14 (scored 2026-07-15): ALL THREE PREDICTIONS CONFIRMED. (a) Fidelity fully preserved: easy 93.4/91.0/90.2 at k=2/4/8 (merge: 92.6/88.5; parcae with identical decay freedom but untied B: ~71%) — the free B is causally isolated as the fidelity culprit, the anchoring tie as the protection. (b) Hard at merge level exactly (35.7/42.9/39.3 = merge's k-curve within noise); no gain from the freedom. (c) Learned a essentially unmoved: mean 0.298, range [0.285, 0.310], 0/1536 dims moved >0.05 from init — the anchor coefficient is not a useful learnable DOF; hand-tuned 0.3 was already optimal. Recipe consequence: fixed-alpha anchored merge is the recommended design; learnable-alpha safe but pointless, learnable-B harmful, per-depth strands the gain. 16. **Code→GSM8K cross-task transfer (pre-registered 2026-07-15 ~14:10, before running).** The MBPP-trained loop adapter (adapter_code, s0) and the noise-s0 variant evaluated on GSM8K test (n=256, prompt-only loop, same harness as eval_gsmonly). Extends the transfer-distance ladder (HumanEval tie -> LCB trained-hurts) across tasks. Predictions: (a) hard-bucket gain ~0 (plan content is task-local; GSM8K needs evolving state, not static plans); (b) easy items damaged at k>0 (~93 -> 50-70%), comparable to or worse than the GSM-trained merge — substrate damage on GSM8K is perturbation-driven and content-agnostic; (c) overall at k>0 below k=0 (no rescue). If instead hard gains appear (>5 points), plan-shaped content is partially task-general — would weaken the task-local claim from LCB. --- Amendment to item 15 (2026-07-15 ~13:15): noise-s0 arm EXCEEDED prediction (b) upward: hard 50.0/53.6/50.0 at k=2/4/8 with easy 88-90% — nominally the best hard cells of the project (merge best 46.4; seed mean 37.5±5.5). Paired vs tied-alpha (only same-day per-item baseline): discordants 5-1/3-0/3-0 in noise-s0's favor, each k p≈0.22-0.25 at n=28 — consistent direction, not individually significant. Denoising interpretation: training the loop to reach the fixed point from noise regularizes the content. SEED ARMS QUEUED (s1, s2, same recipe/eval, pre-registered here): if seed-mean hard(k=4) > 46.4 (the merge's best single cell), the recommended recipe gains noise-s0; if seed mean falls back into 37-46, it was a lucky seed. --- Outcome, item 15c (h2048 capacity control, scored 2026-07-15): the per-depth exoneration is CLEAN — shared 6.4M params reach hard 42.9/53.6/ 50.0 at k=2/4/8 vs per-depth's 17.9/35.7/42.9 at the same capacity; time-variation is strictly worse than weight-sharing at matched params. Fidelity prediction confirmed and exceeded (easy 95.1% at k=2 — best looped fidelity of the project; 90.2% at k=4/8). Ceiling prediction (hard <= 46%) REFUTED UPWARD like noise-s0: k=4/8 at 53.6/50.0. Two independent variations (noise s0, 4x MLP) now sit at 50-54% where the original merge reached 46.4 — suggests 46.4 was an UNDER-estimate of the recipe family's level, not a ceiling it defined. The distill-parity deflation claim is unaffected statistically (53.6 vs 45.7 at hard n=28 is within noise) but the language "every regime tops out at the same ceiling" should become "at the same level within noise" — pending the noise-s0 seed arms. --- Outcome, item 15d (parcae seed 1, scored 2026-07-15): CONFIRMED — the fidelity refutation replicates. easy 70.5/73.0/72.1 at k=2/4/8 (seed 0: 72.1/71.3/70.5); hard 32.1/39.3/35.7 (seed 0: 42.9/42.9/39.3, ordinary seed spread at n=28). Two-seed conclusion: contraction-with- free-B loses ~17 points of easy items regardless of seed; the phase diagram's Parcae point is solid. --- Outcome, item 16 (code->GSM8K transfer, scored 2026-07-15): ALL THREE PREDICTIONS CONFIRMED, emphatically. MBPP-trained loop on GSM8K: hard 0.8-1.6% at every k (prediction a: ~0 gain — plan content is task-local); easy 93.1 -> 27.6-44.8% (prediction b: damaged, in fact WORSE than the GSM-trained merge's 48%); overall strictly below k=0 at every k>0 (prediction c). noise-s0 variant identical (easy 34.5, hard 1.6). The transfer-distance ladder ends cleanly: near (HumanEval) tie, far-code (LCB) trained-hurts, cross-task (GSM8K) trained-content actively toxic while gaining nothing. Task-locality of the learned content is now a three-point monotone result. --- Closure of the item-15b/15c "ceiling nudged upward" question (2026-07-15, after ns seeds): LUCKY SEED, per the pre-registered rule. noise-s0 hard(k=4) across seeds: 53.6 / 39.3 / 35.7 -> seed mean 42.9, inside the 37-46 band. Fidelity across seeds intact (easy 90.2-94.3 — the factorial conclusion is seed-robust); the 50-54% cells (ns seed 0, h2048 single seed) were upper-tail draws of the same distribution the merge's 46.4 came from. No recipe amendment; the abstract's original "same level within noise" framing stands; single-cell records are not levels — only seed means are. 17. **GSM-only, current recipe (pre-registered 2026-07-15 ~20:45, before running).** train_merge_unified.py --tasks gsm: MergeAdapter, prompt- only loop, curriculum, GSM8K data ONLY — removes the mixed-task interference confound from the adapter_uni run, completing the "winning recipe trained on GSM" question. Eval: prompt-only, n=256, ks 0,1,2,4, e400. Predictions: (a) hard <= 10% at every k (supervision density is structural: ~3 answer tokens; the recipe's dense-output ingredient cannot exist here); (b) easy damaged at k>0 (to 40-70%); (c) overall never beats k=0. If hard exceeds 15% or overall beats k=0, task interference in the mixed run was masking a real GSM capability — would reopen the GSM chapter. Scope note (item 17): the design-space arms of items 11-15 are NOT crossed with GSM8K, deliberately. Exclusion by dominance: fidelity- failing regimes (rec, parcae) cannot improve on a task MORE fidelity- fragile than MBPP; architecture-failing (per-depth) and equivalent (tied-alpha -> merge) and k-placement-only (randk) and same-family (noise-s0, h2048) variants have no mechanism by which task change could invert their MBPP verdict. Only the recipe family's best member (this item) is informative on GSM8K. --- Outcome, item 17 (GSM-only, current recipe, scored 2026-07-15): predictions (a) and (b) CONFIRMED, (c) nominally exceeded but not meaningfully. hard 8.7/5.5/4.7% at k=1/2/4 (below the 10% bar; nowhere near the 15% reopen threshold); easy 93.1 -> 48-52% at k>0; overall 11.7/10.9/10.2 vs k0's 10.5 — the k=1 cell is +1.2 points nominal (~3 items at n=256, not significant), the rest below. Removing the mixed-task interference bought ~2 points over adapter_uni (9.4 -> 11.7 at k=1) — interference was real but marginal, not masking a capability. The GSM8K chapter is closed: the recipe family's best member, trained on GSM alone in the correct regime, delivers no usable gain and the standard fidelity damage; combined with the scope note, the boundary claim (structural: supervision density + state-evolution bottleneck) is fully supported.