[AdaWorldAPI]

This PR adds D-BAG-FOLD v4. #1938 merged before this commit was pushed, so #1938 contains only v3; v4 arrives here as its own change on top of current main.

Everything lives in the isolated crate .claude/probes/2026-11-03-d-bag-fold/probe-v4/, which has its own [workspace].

• No production code changes. mask-risc's IR is used as is, Quack is unchanged, and MaskOp::Gather runs only inside the lab crate.
• v1–v3 are unchanged.
• Arm L is not promoted, EXO-140 and EXO-46 are unchanged, and no DT64 route is added.

Results (21/21 checks)

A. Attested pointer lens. Two witnesses are minted at construction:

• Presence witness, minted from the source edge facts with the production ordered_lane::digest_of over child keys. It refuses a plane misaligned at construction, a permuted plane, and a deletion that bypasses the generation and frame.
• Pointer lens, minted by witnessed seek_from and origin-checked at mint. It refuses duplicate keys, out-of-bounds pointers, value-chosen pointers and cross-ClassId pointers.

Production FrameStore and OrderedLaneWitness refuse foreign or stale frames and versions. Remaining gap: a forged table with a re-sealed digest still passes verification, so origin can only be attested at mint.

B. Candidate-gated execution. One mask-risc program gates both Gathers by an in-program register (Range ∧ T_in).

• It matches Quack's Arm L and the oracle, and disabling either Gather turns it red.
• It scales with the candidate count, not the lane size: 1.2× faster than Quack's Arm L on the smallest lane, 4.7–46.6× on larger ones.
• Quack cannot lower it, because gate_walk only gates by one resident plane.
• Presence verification costs more than the gated execution, so it must run once per generation, not per query.

Verdict: Arm L is still NO-GO for admission. It is ready to be written up as a narrowly scoped proposal. The decision memo is REPORT-V4.md.

Board

New entry D-BAG-FOLD-V4; the entries index is regenerated.

Validation

Run cargo +1.99.0 run --release -q in probe-v4/; it exits non-zero if any check fails. The sibling ../ndarray checkout is required.

---

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Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-03T15:29:55.805586Z	6891d58	Draft marked ready

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