[kixelated]

Summary

Deletes BinaryHeap from std's MIR and its link in the ts-unsafe epic. The runtime's port (rs.BinaryHeap, rs.PeekMut in ts/runtime/rs/collections.ts) stays.

Why

• std structs and writing std functions. No std struct translates from MIR: an unmapped std ADT is refused as "unsupported type from another crate" (ts/src/lower/mod.rs). std's heap needs BinaryHeap<T, A>, PeekMut, Hole, RebuildOnDrop, Iter, IntoIter, and Drain to translate as the crate's own structs do. And library::from_mir refuses std functions that are unsafe or take &mut or a raw pointer, which covers nearly every heap method.
• Elements JS keeps as objects are refused. Hole::move_to is ptr::copy_nonoverlapping(data.as_mut_ptr().add(index), data.as_mut_ptr().add(pos), 1): pointer arithmetic into an array of objects, which the epic's 2026-11-01 decision refuses. Every object heap in the orders case (Item, tuples, [u8; 2], String) would become a refusal.
• Even for copied elements, MIR is slower. The sibling Vec::drain spike measured std's Drain from MIR at 3 to 12x the port's CPU time for u8/u32 elements (Node 24, CPU time on a loaded host), with most of it in Proxy reads of the Vec's room. No heap translation exists to measure, but Hole reads and writes through the same room.

The port follows std's sifts line for line, and the orders differential case tests it against native on every just ci.

Decisions

• ✅ Delete this quest and Vec::drain from std's MIR, keeping the runtime's ports (maintainer, 2026-11-07).
• Rejected: an epic with prerequisites (std structs and writing std functions from MIR; pointers into arrays of objects, which would reopen the 2026-11-01 decision).
• Rejected: MIR only for elements JS copies, which leaves two implementations behind one type and the port still tracking std by hand.

Impact

None: quest files only. No public API or wire change.

Validation

• quest check --fix: ok.
• just check: passed (lint, quest).

Models

Size: M
Implementer: Claude Code, claude-opus-5-5, high effort

Review

Skipped: a quest-only deletion needs no review round.

(Written by Claude Opus 5.5 with high effort)

🤖 Generated with Claude Code

[pullfrog]

  ^{｜ Review this ➔}

[kixelated]

Automated review by review (OpenAI)

Reviewed commit fa6c31f against base 6231cec.

No actionable findings in this two-file documentation change. The BinaryHeap MIR quest and its Required-list entry are removed together; runtime implementations and tests are unchanged. Retaining the existing port is consistent with the stated decision to avoid broadening unsafe MIR support solely for this replacement, alongside the Vec::drain decision in #636.

Verification limits: GitHub-only static review of the deletion. I did not run quest validation or reproduce the prerequisite analysis, differential tests, or sibling spike's timings. No BinaryHeap performance measurement is established by this review. This is a COMMENT, not an approval.

(Written by review (OpenAI))

[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

The Required list entry for translating BinaryHeap and PeekMut from std’s MIR was removed. The proposal describing the port, its differential fixture, and the lack of a consumer at the pinned moq revision was also removed.

Merge Risk: Minimal · up to fa6c3

This change removes the BinaryHeap MIR proposal without changing runtime behavior. No actionable merge-blocking risk is identified.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title identifies the deleted BinaryHeap MIR quest.
Description check		The description identifies the quest deletion and the removal of its link.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Finishing Touches

Simplify code

• Commit to this branch
• Create a new PR

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

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Recent review info

Run configuration

• Source mode: Auto
• Repository: Unavailable
• Branch: Unavailable
• File: No configuration file from this repository applied
• Commit: Unavailable
• Layers: Organization UI
• Review profile: CHILL
• Plan: Advanced
• Run ID: 6abe4c59-facc-4fa3-bf7f-9cb2ed2bf9dc

Commits

Reviewing files that changed from the base of the PR and between 6231cec and fa6c31f.

Files selected for processing: 2

• quest/m3/ts-unsafe/README.md
• quest/m3/ts-unsafe/binary-heap-mir.md

Files with no reviewable changes: 1

• quest/m3/ts-unsafe/binary-heap-mir.md

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