Non-record: add HelixRecur v2 shared-depth recurrence submission

[fumbl8]

Title

Non-record: add HelixRecur v2 shared-depth recurrence submission

Short Summary

This PR adds a single non-record submission folder for records/track_non_record_16mb/2026-03-26_HelixRecur_v2 on top of upstream/main.

HelixRecur v2 keeps the HelixRecur recurrence stack compact with 6 shared blocks over 11 virtual passes and adds only 44 conditioning parameters to recover a small amount of depth-specific behavior. It is the active recurrence champion from the branch history, but it is being submitted honestly as exploratory non-record work rather than as a leaderboard attempt.

Key Metrics

• Quick comparison used for judgment: val_loss 7.54165596, val_bpb 4.46659346, compressed 3042658, total 3113435, step_avg 675.97ms
• Longer non-record pass: val_loss 4.63764717, val_bpb 2.74667588, compressed 4224324, total 4295101, step_avg 676.24ms
• Code bytes: 70777
• Parameter count: 15187040
• Added trainable parameters vs v1: 44

Non-record Rationale

• This branch line remained far from the accepted SOTA, so it does not justify a record claim.
• The work is best framed as an exploratory recurrence result with a favorable quality-per-byte tradeoff inside its own local line.
• Later branch work did not produce a replacement winner: v3 lost on the longer pass, and the later v2 tournament did not dethrone v2.

Why It Is Still Promising

• v2 materially improved HelixRecur v1 on the fair quick comparison while slightly shrinking total bytes.
• The model keeps a strong byte-efficiency story by reusing shared transformer blocks and spending only a negligible parameter budget on virtual-depth conditioning.
• The line established a cleaner recurrence baseline that survived both the v3 follow-up and the later micro-variant tournament.

Next Direction

The next direction is gene-coded low-rank specialization: preserve the compact shared-depth recurrent base and add tiny learned low-rank specialization paths keyed by virtual depth, instead of stacking more scalar-only rescue knobs.