Separate numerical cast planning from typed pointer projection

[joshlf]

Hoist the numerical CastPlan out of the generic pointer method. Keep
CastParams<Src, Dst> as the private connection to the selected KnownLayout
pair, and select its plan through an associated constant instead of the
local Params trait. Project then reads metadata, applies the selected plan,
and reconstructs the destination pointer.

Preserve the complete-size plan selection and unchecked arithmetic from
the base fix. Add Aeneas proofs in the following commits.

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: v9 — Compare vs v8

📚 Full Patch History

Links show the diff between the row version and the column version.

Version	v8	v7	v6	v5	v4	v3	v2	v1	Base
v9	v8	v7	v6	v5	v4	v3	v2	v1	Base
v8		v7	v6	v5	v4	v3	v2	v1	Base
v7			v6	v5	v4	v3	v2	v1	Base
v6				v5	v4	v3	v2	v1	Base
v5					v4	v3	v2	v1	Base
v4						v3	v2	v1	Base
v3							v2	v1	Base
v2								v1	Base
v1									Base

⬇️ Download this PR

Branch

git fetch origin refs/heads/Gysrrwrr4oyfrqso6dw7gdmpjocmskwtx && git checkout -b pr-Gysrrwrr4oyfrqso6dw7gdmpjocmskwtx FETCH_HEAD

Checkout

git fetch origin refs/heads/Gysrrwrr4oyfrqso6dw7gdmpjocmskwtx && git checkout FETCH_HEAD

Cherry Pick

git fetch origin refs/heads/Gysrrwrr4oyfrqso6dw7gdmpjocmskwtx && git cherry-pick FETCH_HEAD

Pull

git pull origin refs/heads/Gysrrwrr4oyfrqso6dw7gdmpjocmskwtx

Stacked PRs enabled by GHerrit.

[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 2026-10-05T15:32:15.787649Z	44c82ce	PR opened
🔒 Security Review	✅ Completed 2026-10-05T15:34:40.436000Z	44c82ce	PR opened

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 9.75610% with 74 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.43%. Comparing base (0c56a2e) to head (d612884).

Files with missing lines	Patch %	Lines
zerocopy/src/layout/cast_from.rs	9.75%	74 Missing ⚠️

Additional details and impacted files

@@                          Coverage Diff                           @@
##           Gvvdmej5q7tk5o76yu4c26esuzqpvpdca    #3774       +/-   ##
======================================================================
- Coverage                              92.94%   61.43%   -31.52%     
======================================================================
  Files                                     17       20        +3     
  Lines                                   2466     3713     +1247     
======================================================================
- Hits                                    2292     2281       -11     
- Misses                                   174     1432     +1258     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.