Prove the concrete CastUnsized layout gate

[joshlf]

Move the actual CastUnsized layout decision into a pure helper consumed
by the associated constant. Prove sized equality and accepted DST
alignment, physical offset, and complete size sequences. Check an
independent Rust sizing harness, including overflow and zero-sized tails.
These are conditional numerical guarantees, not pointer-validity proofs.

Validation: pinned extraction; independent golden/live proofs,
required-contract checks and axiom audits; targeted Rust tests.

Agent-authored-by: AI agent acting on joshlf's behalf

---

• 　  Prove record construction against independent Rust references #3744
• 　  Prove cast metadata composition against reference sizes #3777
• 　  Prove numerical cast plan selection and metadata conversion #3776
• 　  Prove cast validation and exact metadata inference #3755
• 　  Prove allocation size preparation and tail containment #3790
• 👉 Prove the concrete CastUnsized layout gate #3789
• 　  Prove split lengths and non-overlapping numerical regions #3788
• 　  Prove byte advancement and padding sequence queries #3754
• 　  Prove normalized layout padding and field extension #3753
• 　  Prove concrete pointer metadata operations #3787
• 　  Prove exact trailing sizes, padding and capacity #3752
• 　  Prove primitive layout constructors with recursive mathematical models #3751
• 　  Compare nested DST sizes with a recursive Rust oracle #3749
• 　  Model alignment and phase encoding as a bounded mathematical pair #3747
• 　  Refine recursive record semantics into normalized layouts #3743
• 　  Prove trailing-layout normalization and capacity arithmetic #3742
• 　  Reuse Aeneas specifications for views and indexed loops #3745
• 　  Strengthen arithmetic specifications and prove arithmetic corollaries #3746
• 　  Check native total and partial Aeneas specifications #3739
• 　  Prove unsigned byte-order reads, writes and updates #3800
• 　  Verify doc-owned specifications over recursive mathematical models #3738
• 　  Separate numerical cast planning from typed pointer projection #3774
• 　  Move pointer cast implementation into its own source file #3773
• 　  Share Rust mathematical models across Anneal frontends #3799

Latest Update: v3 — Compare vs v2

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Version	v2	v1	Base
v3	vs v2	vs v1	vs Base
v2		vs v1	vs Base
v1			vs Base

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-06T00:34:47.170033Z	d12c09b	PR opened
🔒 Security Review	✅ Completed 2026-10-06T00:35:09.969795Z	d12c09b	PR opened

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Codecov Report

❌ Patch coverage is 0% with 47 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (Gii2clttpvhasvgyirv6rn3tj4ushk3hd@4edd138). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
zerocopy/src/pointer/mod.rs	0.00%	47 Missing ⚠️

Additional details and impacted files

@@                         Coverage Diff                          @@
##             Gii2clttpvhasvgyirv6rn3tj4ushk3hd    #3789   +/-   ##
====================================================================
  Coverage                                     ?   53.72%           
====================================================================
  Files                                        ?       26           
  Lines                                        ?     4257           
  Branches                                     ?        0           
====================================================================
  Hits                                         ?     2287           
  Misses                                       ?     1970           
  Partials                                     ?        0           

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