v4 de-prose #3291 redo: cpp.dag coproduct tag → Part 6 · CP-3229-CPP-INTEGER-OVERFLOW

[briansrls]

Summary

Redo of stale PR #3291 (its branch was 44 commits behind main and predates #3338's comment-surface rewrite of cpp.dag). Fresh from post-#3338 main.

• extdeps/languages/cpp.dag: the CppIntegerOverflowDisposition coproduct carried the non-conforming tag // 🟢 coproduct dissolution — DECISIONS.md T29-ABI + D2-REV.. The in-file one-liners directive (DECISIONS.md Part 6) mandates // 🟢|🟡|🔴 coproduct dissolution — DECISIONS.md Part 6 · <CP-3229-*|SL-3229-*>. Tag conformed.
• cpp.dag was created post-merge-base (PR v4 T-4 cpp.dag D2-resolver model (from scaffold; mirror verified canonical rust #3174@0328bee9 + encoded DECISIONS.md D2 row) #3199), so it cannot use the merge-base-only CP-3229-GREEN-TERMINAL bulk slug (DECISIONS.md is explicit that that table enumerates strict-de-prose merge-base files only). A dedicated Part-6 row CP-3229-CPP-INTEGER-OVERFLOW is added — same shape as the post-merge-base CP-3229-NAT-LE-WITNESS precedent — with a five-pattern Practice-4 ledger classifying the coproduct 🟢 GREEN terminal.

Why

The original PR #3291 fixed the tag to Part 6 · CP-3229-GREEN-TERMINAL, but that slug is reserved for merge-base files only; cpp.dag needs its own reachable Part-6 receipt. This redo lands the correct slug + ledger row.

Comment + ledger only — carrier model byte-identical (parse-inert .dag // line + markdown row). No Rust, no tests added (Rust-to-0: no quiet v3/Rust accumulation).

Test plan

• python3 scripts/strict_deprose_dag.py --check → OK (cpp.dag is not in the allowlist; the new CP-3229-CPP-INTEGER-OVERFLOW Part-6 row does not perturb the union inventory).
• CI v4: job (v2-compiler compile --source-root src/v4) is the authoritative parse gate; the change is parse-inert so the prior 0-diagnostic result holds — verified by CI on this branch.

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: 83b73ab6 · Trigger: schedule
• Thinking: 169s wall

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Non-blocking — Strengths

• src/v4/DECISIONS.md The added Part 6 receipt matches the live cpp.dag tag and the C++ draft at https://eel.is/c++draft/basic.fundamental confirms the signed-overflow/unsigned-modulo split.

✅ No blocking concerns; this is a narrow ledger/tag alignment with a reachable Practice-4 receipt.

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: e27a2af8 · Trigger: schedule
• Thinking: 197s wall

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✅ No blocking concerns in the current diff after checking the Part 6 receipt against the live tag and C++ draft authorities at https://eel.is/c++draft/basic.fundamental and https://eel.is/c++draft/expr.pre.