revision per review: seed means in headlines, net accounting vs untrained merge, bucket definition up front, GSM12B n.s. (p=0.86), law->regularity, norm spec, compute appendix, public repo URL

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

PAPER.md

@@ -1,8 +1,9 @@
 # Latent Planning by Workspace Recurrence: an Interpretability-Placed Implant, and What It Actually Buys
 
-*Final-data draft, 2026-07-14. Base models: google/gemma-4-E2B-it and
+*Revision draft, 2026-07-14. Base models: google/gemma-4-E2B-it and
 gemma-4-12B-it, both frozen. Hardware: DGX Spark + rented 2×/8×H100 nodes.
-Code, per-item logs, and pre-registrations: `~/jspace` (git). Statistics:
+Code, per-item logs, and pre-registrations:
+https://git.draic.info/nils/jspace (public). Statistics:
 `results-loop/STATS.md`.*
 
 ## Abstract
@@ -15,53 +16,56 @@ anchor-dominant merge adapter (0.03% of parameters) at the band entrance
 turns the non-self-map band into a stable fixed-point iteration, trained with
 self-generated, verifier-filtered supervision. Looping the workspace over the
 prompt ("latent planning") raises pass@1 on plan-dependent MBPP problems from
-5.5% to 43.6% (seed mean 37.5±5.5), with zero visible tokens and zero
+5.5% to 37.5±5.5 over five seeds (best seed 43.6%), with zero visible tokens
-additional decode cost. The effect is real and highly reliable — pooled
+and zero additional decode cost. The effect is real and highly reliable —
-across MBPP, HumanEval, and Rust/MultiPL-E, the plan-dependent bucket moves
+pooled across MBPP, HumanEval, and Rust/MultiPL-E, the plan-dependent bucket
-from 4.2% to 35.6% (McNemar p≈1.5e-10) — and **placement is a law, not a
+moves from 4.2% to 35.6% (McNemar p≈1.5e-10) — and **placement is decisive,
-convenience**: the gain appears only when the loop enters at the
+not a convenience**: the gain appears only when the loop enters at the
 lens-identified boundary (L14), collapsing at L13 and below and structurally
-nulling above.
+nulling above. Roughly a third of the gross effect is generic perturbation
+(the untrained merge alone reaches ~18%; the bucket conditions on k=0
+failure, so regression-to-mean contributes to any intervention); the
+loop-specific net effect is ~+20 points over that floor.
 
-But a complete attribution program deflates the mechanism's mystique.
+A complete attribution program then deflates the mechanism's mystique: the
-(i) **The loop's content is amortizable**: distilling the model's own
+loop's content is *amortizable* (plan-distillation into the same adapter,
-explicit plans into the same-size adapter — no recurrence at inference —
+recurrence-free, matches it; nothing stacks; looping distilled weights
-matches or exceeds the loop on the same bucket (mean over 8 runs 45.7±4.6 vs
+degrades them), width rivals depth (trained pause registers reach 36.4%),
-37.5±5.5, paired difference n.s.), and the two do not stack; running the
+and compute-matched token baselines win overall accuracy outright. What
-loop on top of the distilled adapter *degrades* it. (ii) **Width rivals
+survives is precise: the implant owns exactly the plan-dependent slice at
-depth**: 16 trained pause registers reach 36.4% on the same bucket.
+zero visible tokens and zero decode cost, transfers with the substrate
-(iii) **Compute-matched token baselines are uncomfortable**: best-of-3
-sampling beats every latent arm on overall accuracy (57.2% vs ≤55.2%), and a
-50-token visible plan matches the loop on the hard bucket (40.0%). What
-survives is precise: the implant specializes in exactly the plan-dependent
-slice at zero token and zero decode cost, transfers with the substrate
 rather than the task, and its placement is dictated by the lens. At 12B a
-constant merge coefficient destroys the substrate; making the coefficient
+constant merge coefficient destroys the substrate; a state-dependent
-state-dependent (a 3.8K-parameter gate) restores it on MBPP
+coefficient (3.8K parameters) restores MBPP but not Blocksworld or GSM8K —
-(hard 11.4%→27.3% with overall preserved) but not on Blocksworld or GSM8K —
+the anchor coefficient is the stability dial that unifies this work with
-the stability dial that unifies this work with McLeish et al. (2511.07384)
+McLeish et al. (2511.07384) and Lys et al. (2602.14759), and it is task-
-and Lys et al. (2602.14759) is task- and scale-dependent.
+and scale-dependent. Details and exact numbers: §1 and §3.
 
 ## 1. What this paper claims
 
-1. **A placement law.** The retrofit works if and only if the recurrence
+*(One model family, two scales: we state findings as empirical regularities,
-   enters at the lens boundary. Entrances at L9–L13 (same adapter, data,
+not laws.)*
-   curriculum) destroy overall accuracy (14–34% vs 52%) while recovering at
+
-   most half the hard-bucket gain; entrance at L14 preserves overall and
+1. **A placement regularity.** The retrofit works if and only if the
-   maximizes the gain (fig_placement). Entrances at L17/L24 are *structurally
+   recurrence enters at the lens boundary. Entrances at L9–L13 (same
-   null* in this architecture: KV-sharing makes layers ≥15 reuse keys/values
+   adapter, data, curriculum) destroy overall accuracy (14–34% vs 52%)
-   computed at ≤14, so k>0 is bit-identical to k=0 — a hazard for any
+   while recovering at most half the hard-bucket gain; entrance at L14
-   retrofit method that skips the mechanistic check. Exit-layer choice is
+   preserves overall and maximizes the gain (fig_placement). Entrances at
-   nearly free (taps 27/30/32/34 within seed noise: hard 39–46%). This
+   L17/L24 are *structurally null* in this architecture: KV-sharing makes
-   answers the open "where to loop" problem named by McLeish et al., and it
+   layers ≥15 reuse keys/values computed at ≤14, so k>0 is bit-identical to
-   is causal, not correlational: the L9-entrance discriminator arm was
+   k=0 — a hazard for any retrofit method that skips the mechanistic check.
-   trained identically and fails.
+   Exit-layer choice is nearly free (taps 27/30/32/34 within seed noise:
+   hard 39–46%). This answers the open "where to loop" problem named by
+   McLeish et al., and it is causal, not correlational: the L9-entrance
+   discriminator arm was trained identically and fails.
 
 2. **A verified, statistically solid capability gain on a narrow slice.**
    Plan-dependent items (the model solves them with an explicit written plan
-   but not directly): pooled across three benchmarks, 4.2%→35.6%,
+   but not directly): seed-mean 37.5±5.5 on MBPP (best 43.6%); pooled across
-   p≈1.5e-10. Overall accuracy is statistically unchanged on MBPP
+   three benchmarks, 4.2%→35.6%, p≈1.5e-10. Overall accuracy is
-   (p=0.34) and improved on HumanEval transfer (58.5%→66.5%, p=0.011).
+   statistically unchanged on MBPP (p=0.34) and improved on HumanEval
+   transfer (58.5%→66.5%, p=0.011). Net of the untrained-merge floor
+   (~18%), the loop-specific effect is ~+20 points.
 
 3. **A deflationary mechanism finding.** The trained loop converges to a
    fixed point by k≈3–4 and behaves as *amortized plan content*, not
@@ -73,7 +77,7 @@ and Lys et al. (2602.14759) is task- and scale-dependent.
    adapter find plan-shaped content — content that can equally be put there
    by distillation if plans are available.
 
-4. **A width-vs-depth law.** Trained pause registers (width) capture most of
+4. **A width-vs-depth pattern.** Trained pause registers (width) capture most of
    the plan effect on code; recurrence (depth) is needed only where a state
    must *evolve* — on GSM8K generation-side carry beats registers, and on
    Blocksworld (pure planning, no world knowledge) the loop lifts hard-split
@@ -82,8 +86,10 @@ and Lys et al. (2602.14759) is task- and scale-dependent.
 
 5. **Honest economics.** The implant's costs: ≈2.9× prompt-processing FLOPs
    (parallel, prefill-shaped), zero decode overhead, bit-exact KV-cache
-   write-in, k=0 recovers the base model exactly. Its competition at matched
+   write-in, k=0 recovers the base model exactly. Its competition at
-   FLOPs: best-of-3 sampling wins overall accuracy outright (57.2%); a
+   comparable compute (accounting in Appendix A — FLOPs, wall-clock, and
+   token budget do not rank the arms the same way): best-of-3 sampling wins
+   overall accuracy outright (57.2%); a
    50-token visible plan ties the hard bucket. The value proposition is
    *only*: no visible tokens, no decode latency, and the hard-slice
    specialization (distill's 46% > budget-CoT's 40% > best-of-3's 33%).
@@ -93,8 +99,8 @@ and Lys et al. (2602.14759) is task- and scale-dependent.
    damage is present *before* adapter training (untrained-loop arm) and is
    not fixed by retuning α or LR. A per-position learned coefficient
    α=σ(w·[e;ŝ]+b) restores MBPP (overall 69.4%, hard 11.4%→27.3%) — but
-   fails to rescue Blocksworld-12B and yields only a marginal GSM8K-12B
+   fails to rescue Blocksworld-12B and yields only a nominally positive,
-   overall gain (35.9%→36.7% at k=1), the project's only overall 12B win.
+   not significant GSM8K-12B overall delta (35.9%→36.7% at k=1, p=0.86).
 
 ## 2. Method
 
@@ -107,7 +113,9 @@ follow from what the readout tracks. On gemma-4-E2B: workspace ≈ L14–30 of
 (out-space ≠ in-space). With e = L13's output (fixed anchor) and s the
 fed-back, norm-matched band output:
 
-    L14-in = (1−α)·e + α·ŝ + MLP([e ; ŝ]),   ŝ = s·|e|/|s|
+    L14-in = (1−α)·e + α·ŝ + MLP([e ; ŝ]),   ŝ = s·‖e‖₂/‖s‖₂
+
+(per-position L2 norms over the hidden dimension, computed in fp32)
 
 α=0.3 constant at 2B; at 12B, α=σ(w·[e;ŝ]+b) per position (zero-init so
 α≈α₀ initially). MLP output zero-init: the untrained adapter is exactly the
@@ -136,11 +144,23 @@ Cost at k=4: ≈2.9× prefill FLOPs, **zero** decode overhead.
 Statistics throughout: Wilson 95% CIs; paired comparisons by exact McNemar;
 all headline arms evaluated on the full 500-item MBPP test split (hard
 bucket n=55), HumanEval n=164 (hard n=38), Rust/MultiPL-E n=154 (hard n=25),
-execution-verified. Label robustness: redefining "hard" as
+execution-verified.
-labeled-hard ∧ k=0-fails-in-all-five-seeds (52/55 items) moves headline
-numbers <2 points.
 
-### 3.1 The placement law
+**Bucket definition, stated up front.** Hard labels come from labeling runs
+of the frozen base model on the test items themselves (direct vs
+plan-in-context, greedy). This is legitimate for *descriptive* slicing but
+would be circular for selection — so no arm, hyperparameter, checkpoint, or
+loop depth was ever chosen using bucket results (pre-registered;
+`PROTOCOL_UNIFIED.md` items 1–2, 8). Because the bucket conditions on k=0
+failure, regression-to-mean inflates *any* intervention's bucket score: the
+untrained merge already reaches ~18%, and we therefore report the
+loop-specific effect **net of that floor** wherever attribution is claimed.
+Robustness: redefining "hard" as labeled-hard ∧ k=0-fails-in-all-five-seeds
+(52/55 items) moves headline numbers <2 points; both definitions share the
+base model, which an independent difficulty proxy would not — we flag this
+as an open external check.
+
+### 3.1 The placement regularity
 
 ![Placement cliff](results-loop/fig_placement.png)
 
@@ -150,8 +170,8 @@ hard 43.6%, overall 53.6%. L13: hard 17.9%, overall 34.4%. L9–L12: overall
 verified bit-identical) — the 12B model has no shared-KV layers, making it
 the unconfounded replication. Exit sweep at fixed entrance (L27/30/32/34):
 hard 39.3–46.4%, within seed spread. The lens boundary is necessary; the
-exit is a free parameter. (The L23-exit arm died in training and was not
+exit is a free parameter. (The L23-exit arm died in training; a rerun is in
-rerun; the four completed exits bracket it.)
+progress — the four completed exits bracket it. [L23 PENDING])
 
 ### 3.2 The attribution ladder
 
@@ -178,6 +198,14 @@ vs stack) is **not significant** at n=55; loop vs base *overall* is not
 significant on MBPP (p=0.34). The ladder's shape is reliable; its fine
 ordering is not.
 
+**Net accounting.** The attribution-critical comparison is trained-loop vs
+*untrained merge*, not vs base: gross 5.5→37.5 (seed mean), of which the
+untrained perturbation floor is ~18 points — the loop-specific net effect
+is ~+20 points. The untrained-loop and trained-FF control rows above are
+from the 250-item era (hard n=28); full-bucket (n=55) reruns of both
+controls, enabling the paired loop-vs-untrained test, are running and will
+replace these rows. [CONTROLS-N55 PENDING]
+
 ### 3.3 The decisive tests: nothing stacks
 
 If the loop performed genuine iterative computation, plan-distilled content
@@ -199,17 +227,21 @@ distinctive value is that it finds this content *without* plan supervision
 
 ### 3.4 Compute-matched honesty
 
-At approximately matched FLOPs, token-space baselines are strong: best-of-3
+At approximately matched FLOPs (Appendix A gives the accounting, separated
-sampling wins overall accuracy against every latent arm (57.2%,
+into FLOPs, wall-clock, and token budget), token-space baselines are strong:
+best-of-3 sampling wins overall accuracy against every latent arm (57.2%,
 CI [52.8, 61.5], vs loop 53.6 [49.2, 57.9] — point estimate higher, CIs
 overlap) by preserving easy items perfectly while sampling rescues some hard
-ones. A 50-token visible plan ties the loop's hard bucket. The latent
+ones. A 50-token visible plan ties the loop's hard bucket. Both baselines
-implant's surviving advantages are qualitative: zero visible tokens (silent),
+are being rerun with per-item logs to enable paired tests against the latent
-zero decode overhead (prefill-parallel; sampling and CoT pay serially at
+arms; until those land, the overall-accuracy comparison rests on overlapping
-bandwidth-bound decode), and the hard-slice crown under distillation (46% vs
+CIs and is stated as point-estimate-level. [BASELINES-PI PENDING]
-40% budget-CoT vs 33% best-of-3). For deployment this means: the implant is
+The latent implant's surviving advantages are qualitative: zero visible
-a *latency/token-budget* technology with a side specialization in
+tokens (silent), zero decode overhead (prefill-parallel; sampling and CoT
-plan-dependent items — not an accuracy technology.
+pay serially at bandwidth-bound decode), and the hard-slice crown under
+distillation (46% vs 40% budget-CoT vs 33% best-of-3). For deployment this
+means: the implant is a *latency/token-budget* technology with a side
+specialization in plan-dependent items — not an accuracy technology.
 
 ### 3.5 Width vs depth, and the task boundary
 
@@ -219,7 +251,7 @@ prompt-side result entirely (no variant beats the weights control
 prompt-side), but generation-side *carry* — recurrence across token steps —
 doubles the pause control on hard items: arithmetic's serial state evolves
 during the answer. Blocksworld at 2B is the purest case: base 0% on hard
-splits, loop k=4 43%, everything non-recurrent ≈0. The law: **plans are
+splits, loop k=4 43%, everything non-recurrent ≈0. The pattern: **plans are
 wide; execution is deep.** Retrofit recurrence pays off precisely where a
 latent state must be *revised*, not merely *held*.
 
@@ -233,9 +265,11 @@ the damage precedes adapter training; α=0.15 and LR retuning do not fix it
 (47.6/52.6% overall). The state-dependent coefficient does, on MBPP:
 overall 69.4% (base 72.4%), hard 11.4%→27.3%. It does **not** rescue
 Blocksworld-12B (easy items destroyed at k=4; constant-α had reached hard
-40% but also destroyed easy) and yields only +0.8 points overall on
+40% but also destroyed easy) and yields a **nominally positive, not
-GSM8K-12B (35.9→36.7 at k=1, hard 1.6→10.6) — the sole overall-accuracy win
+significant** overall delta on GSM8K-12B (35.9→36.7 at k=1; paired McNemar
-of the program, and a marginal one. Conclusion: the anchor coefficient is
+on 32 discordant items, p=0.86; hard 1.6→10.6) — no arm anywhere in the
+program produced a statistically significant overall gain at 12B.
+Conclusion: the anchor coefficient is
 the load-bearing stability control, its correct *form* (not just value)
 changes with scale, and per-task tuning remains unavoidable.
 
@@ -314,7 +348,7 @@ proved a genuine rival, not a strawman (§3.2, §3.5).
 What remains distinct here: interpretability-derived placement with causal
 validation; a fully frozen base with bit-exact k=0 and zero-decode-cost KV
 write-in; the complete attribution ladder including compute-matched
-token-space baselines and stacking tests; the width/depth task law; and the
+token-space baselines and stacking tests; the width/depth task pattern; and the
 amortizability finding itself.
 
 ## 5. Limitations
@@ -324,10 +358,9 @@ are small (n=55/38/25); within-ladder orderings are not individually
 significant, and only the pooled hard effect and the HumanEval overall gain
 survive multiple-comparison scrutiny. Bucket membership derives from greedy
 labeling runs (consensus-k0 robustness check moves numbers <2 points, but
-both checks share the base model). Best-of-3/budget-CoT lack per-item logs
+both checks share the base model; an independent difficulty proxy is an
-(no paired tests against them). The L23 exit arm and a third architecture
+open external check). A third architecture family was not run;
-family were not run; LiveCodeBench (contamination-safe) was not run; rung-2
+LiveCodeBench (contamination-safe) was not run; rung-2 was not run at 12B. The easy-item perturbation tax persists wherever the
-was not run at 12B. The easy-item perturbation tax persists wherever the
 gate's precision fails. MBPP/GSM8K likely overlap pretraining data; both
 arms share contamination, and memorized items land in the easy bucket, but
 bucket composition is contamination-sensitive. The capability panel
@@ -351,3 +384,39 @@ difficulty; keep k=0 as the exact base model. What it buys: the
 plan-dependent slice at zero tokens and zero decode cost. What it does not
 buy: overall accuracy beyond what matched-compute sampling already delivers.
 Both halves of that sentence are the contribution.
+
+## Appendix A: compute accounting (FLOPs / wall-clock / tokens, separated)
+
+Let P = prompt tokens, G = generated tokens, c = FLOPs per token per full
+forward pass. The band is 17 of 35 decoder layers at E2B (fraction
+f≈0.486) and 10 of 48 at 12B (f≈0.208).
+
+**Latent loop, k=4, prompt-only.** Prefill: 1 base pass + 4 band passes
+over prompt positions = (1+4f)·cP ≈ **2.94·cP** at E2B (1.83× at 12B —
+the overhead *shrinks* with scale because lens bands grow sublinearly).
+Decode: exactly cG (looped states written to the KV cache once;
+bit-exactness verified). Wall-clock: prefill is compute-bound and
+position-parallel, but the k iterations are serial — prefill latency
+≈2.9×, typically a small fraction of end-to-end latency for G≫0.
+Visible tokens: +0.
+
+**Best-of-3 sampling.** FLOPs: with shared prompt prefill (favorable
+accounting), cP + 3·cG ≈ cP + 3cG; without sharing 3c(P+G). For MBPP
+(P≈150–300, G≈150–220), the *extra* FLOPs vs direct (≈2cG) are of the same
+order as the loop's extra (≈1.94cP) — hence "≈matched". Wall-clock: 3×G
+serial bandwidth-bound decode steps (or 3 parallel decode streams at 3×
+memory); strictly worse latency than the loop unless parallelized.
+Visible tokens: ≈3× (two discarded candidates). Requires a verifier or
+selector to pick among samples for the overall win we report (we use
+any-pass, an upper bound — see §3.4 caveat).
+
+**Budget-CoT (50-token plan).** FLOPs: ≈c(P+G+50) plus the plan tokens'
+KV in context for the remainder — the *cheapest* arm in FLOPs. Wall-clock:
++50 serial decode steps before answer tokens start (worst first-token
+latency). Visible tokens: +50.
+
+Summary: no single scalar makes these three arms "equal"; the loop
+dominates on tokens and decode latency, budget-CoT on FLOPs, best-of-3 on
+overall accuracy. §3.4's "≈matched FLOPs" refers to the extra-FLOPs
+order-of-magnitude equivalence above, not exact equality; the honest
+statement is the three-way trade-off, and we report all three axes.