docs: session handoff 2026-05-27 — borrow deferred-items roundup (humans + machines)

[hyperpolymath]

Summary

Documents the entire round of work across six open PRs that together cover the four entries in the `lib/borrow.ml` deferred-items comment at lines 1483-1505. Two artefacts, one for each audience.

For humans — `docs/history/SESSION-HANDOFF-2026-05-27.adoc`

`.adoc` per the repo's DOC-FORMAT rule. Sections:

• What this session actually did
• Parallel-implementation map — which of my PRs paired with which existing PR
• PR state table (draft? auto-merge? mergeability?)
• Audit findings — the load-bearing deltas: self-assign hole + return-escape gap (feat(borrow): CORE-01 ref-to-ref binding (#177 pt3) — let r2 = r / r = s alias the borrow-graph #395), sub-place soundness divergence (feat(borrow): CORE-01 Slice C' loop soundness — 2-iteration check on while/for (Refs #177) #396), Cmd-typed-param tracking gap (feat(borrow): CORE-01 Slice D (#177 pt3) — reject @linear capture by closure at borrow check #397)
• Safe-to-close conditions per PR — the matrix the next agent needs
• Cleanup performed
• Guidance for the next agent

For machines — `.machine_readable/sessions/2026-05-27-borrow-deferred-items.a2ml`

New `sessions/` subdirectory (the existing `.machine_readable/6a2/` is the canonical state-snapshot dir; sessions are per-event records). Schema declared as `a2ml/session-record/v1`. Structured records:

• One `[[deferred-item]]` per entry in the comment block
• One `[[open-pr]]` per the six PRs
• One `[[close-condition]]` per PR with fallback paths
• `[cleanup]`, `[lessons]` blocks

Cleanup landed alongside

• `.git/gc.log` removed after `git prune` (the persistent "unreachable loose objects" warning is gone).
• Two stale parallel-Claude untracked dirs (`affinescript-vite/`, `editors/vscode/node_modules/`) not touched — they're not this session's work.

What's NOT in this PR

• No `lib/` changes. No `test/` changes.
• No closes/state-changes on the six open PRs (feat(borrow): CORE-01 ref-to-ref binding (#177 pt3) — let r2 = r / r = s alias the borrow-graph #395/feat(borrow): CORE-01 Slice C' loop soundness — 2-iteration check on while/for (Refs #177) #396/feat(borrow): CORE-01 Slice D (#177 pt3) — reject @linear capture by closure at borrow check #397/docs(adr): ADR-022 — origin variables + Polonius-style loan solver (Refs #177) #398/fix(borrow): whole-place assignment clears move-record (Refs #177) #399/fix(borrow): self-assign guard + return-escape coverage for ref-to-ref (Refs #177, follow-up to #395) #400). Per maintainer direction "keep both PR sets open", parallel implementations stay parallel.
• No edits to `STATE.a2ml` or other `6a2/` files — those are flagged STALE and updating them is a separate disciplined task.

Safe-to-close ledger (also in the docs)

PR	Close condition	Fallback
#395	auto-merge fires once CI clears	n/a
#396	auto-merge fires once CI clears	if merges without sub-place fix, #399 stays open as follow-up
#397	auto-merge fires once CI clears	audit posted a must-fix; owner can incorporate or file follow-up
#398	owner ratifies ADR-022 via the posted one-liner	do-not-close — only deferred-item that needs an architectural change
#399	#396 merges with sub-place fix	rebase as sub-place soundness correction
#400	#395 merges with self-assign-guard + return-escape test	rebase as follow-up adding the two missing pieces
this PR	safe to close once merged	n/a — pure docs

Test plan

• CI green (this PR only touches `docs/` and `.machine_readable/` — no test-relevant code).
• `asciidoctor docs/history/SESSION-HANDOFF-2026-05-27.adoc` renders without errors (if you have asciidoctor installed; CI doesn't enforce).
• The `docs/history/SESSION-HANDOFF-2026-05-27.adoc` cross-references in the body resolve to actual PR numbers / file paths in the repo.

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