agent: builder model: opus max_turns: 90 budget_usd: 18 effort: medium —
Score: the borrowing core goes to Nikaia before the parser (owner, 2026-11-03: the parts a later change to borrowing touches are Nikaia first; then the parser). The decisions are mostly Nikaia already (tools/keep.nika, tether.nika, touch.nika, sharing.nika, text_tiers.nika); what is left in Rust is listed in docs/selfhosting-plan.md, Borrowing core. Part of #125.
Owns: crates/nikaia/src/text_tiers.rs (separate_repeated_ids, wrap_item, wrapped, wrap_hole, the decision part of refine_with), the wrap_hole callbacks in check/host.rs and emit/host.rs, crates/nikaia-std/src/tools/text_tiers.nika, tools/ast.nika (a per-variant id setter only), their lowered files, new tests under tests/compiler/.
Not yours: the generic walkers each_block, visit_block_mut, visit_expr_mut (closures do not cross; they stay until one_variant.rs and assets_read_in move); refine, refine_package, beside_fields and the Parsed field writes of refine_with (they stay until Parsed is Nikaia); contracts/*.
tools/ast.nika: a set_id over the expression variants (or a rebuild helper), with a test. Then separate_repeated_ids moves to text_tiers.nika. Commit.wrap_item, wrapped and wrap_hole, plus the decision part of refine_with (the hole-wraps table, the default String type when there are lets, driving wrap_item), move to text_tiers.nika as tier_refine(mut program: Program, ...) beside tier_write (which already mutates the program the same way; model the walk on tools/type_rules.nika tr_walk_*). wrapped rebuilds instead of mem::replace (#949); fresh ids come from fresh_id() in the same order, so tests/it/expr_ids.rs does not change. The two host wrap_hole callbacks go; emit/mod.rs:1047 and tests/it/expr_ids.rs keep a one-line adapter. Commit Part of #125.Do not run nikaia fmt on tools files. A grammar result tier is decided in two places already (builder-facts); add no third.
text_tiers.rs holds only the wrappers, the Parsed writes and the walkers. nikaia test tests/compiler --both-settings and tests/errors as before plus new tests; it filtered on tier, text, expr_ids, hole and the guard set; clippy clean; lower-std fixpoint holds. Body names BC-5a as built. No changelog line.
an expression id in a test output changes; a .stderr changes; nikaia.contracts changes.
Traps of every BC slice: run lower-std and commit every lowered file it changed; tools files share one namespace (prefix new functions with the module name); declare functions sync (#1014); no mutable tuple-pattern names (NK1307); no BTreeSet::extend, no BTreeMap::entry (#950): get, then insert; no take out of a let mut view (#949): clone or rebuild; never compare contracts by ptr::eq; debug the lowering with nikaia check --tethers. The ledger order must stay byte-identical: tests/compiler/nikaia.contracts and the shipped ledger must not change.
A form Nikaia, std or the toolchain lacks is sorted per CLAUDE.md A missing form stops the work: absent on purpose (name the ADR): build it that way; not decided or not thought of: stop that piece, keep what is committed, report it with a probe of a few lines; a defect met on the way: fix it in the compiler with a test as its own commit (at most one), a second one goes under Found: with its probe.
rs2nika is deleted (docs/builder-facts.md): translate by hand and give the three costliest hand edits under Rs2nika:.
docs/builder-facts.md first. You work in /home/user/Nikaia on develop (the shared checkout). Build with CARGO_INCREMENTAL=0 cargo build --profile fast -p nikaia; use only /home/user/Nikaia/target/fast/nikaia.git add <files> only, never -a/-A; commit after each step. Never git reset, stash, checkout ., restore .; restore only your own files by name. An error in another agent’s file is escalated, not touched.lower-std changed, yours and others’. Do not edit docs/selfhosting-plan.md, docs/architect.md, docs/priorities.md, docs/bootstrap.md or scripts/self_hosting.py: rows for them go into Body: of your report.cargo fmt, cargo clippy --all-targets -- -D warnings, nikaia run scripts/pre-push.nika, and the gate of .claude/agents/builder.md. You commit; the supervisor pushes.CHANGELOG.md, badges; no new NK code. New tests in Nikaia only; never the full suite. No foreground sleep, no polling; scripts in files.NIKAIA_CACHE_LIMIT=2G; if df -h /home/user shows under 2 GB free, stop and report blocked. Never delete another checkout’s target/./home/user/Nikaia/docs/briefs/pbc5a-tier-wrapping.md.report.md)Fields of docs/architect.md, Briefs and reports: Result: done|noop|partial|blocked (the bare word alone on that line: Result: done, never a summary after it, which cuts the batch, b869a 2026-10-27; Owner: is a question for the owner or none, never a role), Files, Commit, Body (optional, one paragraph for the commit message), Fixes, Pushed, Tests, Gate (green|red), Deviation, Found, Needs, Changelog, Owner, Disk freed, and for a move Rs2nika: (the kept N of M lines of rs2nika --score, then the three costliest hand edits; none for a task that moves no Rust). none where nothing, and then the bare word: Deviation: none (a note) cuts the batch (batch.nika compares exactly); a note goes into the commit message. Found: is only for a defect outside your change (it cuts the batch); a converter draft that came out wrong is no Found:, it is one of the costliest edits under Rs2nika:, which the converter lane reads (e12-4b 2026-10-27); how you solved your own step goes into the commit message. Deviation: is only a step of the brief built otherwise than written or not built (a choice the brief left to you, such as keep what X needs and say so, is no deviation: it goes into the commit message; nor is building two steps in one commit when every step is built, e12-3a 2026-10-27, nor a step another commit on develop already built, shown by your test failing with that commit’s change reverted, b889 2026-10-27: name the commit in Body:); how you verified (e.g. a test not run against the unfixed compiler) goes under Tests:. A noop says why under Tests: (what was probed), not under Deviation:. Final answer, one line: done <sha>, report <path> (or BLOCKED: ... / PUSH REJECTED ...).
Attribution: Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com Claude-Session: https://claude.ai/code/session_01GFeMqxRbtUMiGVyDMxsvEq