agent: builder model: opus max_turns: 80 budget_usd: 15 —
Score: compiler bug (b1043’s Found, row c), false refusal (NK2605 where nothing can fail); bugs-first default of docs/priorities.md. Small, one cause traced.
Found by b1043 (row c), probed by the architect on the fast binary after 569bb244.
struct H {
f: fn(i64) -> i64,
}
fn main() {
let g = fn(x) { x + 1 }
let h = H { f: g }
println(f"{h.f(1)}")
}Expected 2. Got NK2605 “This function can fail, because H.f can fail … with ?”. A false refusal: nothing here can fail.
Rows (all on the same binary):
let g = fn(x) { 5 } (no operator in the body) - NK2605, so the body is not the cause.let g: fn(i64) -> i64 = fn(x) { x + 1 } - runs, 2.H { f: fn(x) { x + 1 } } inline - runs, 2.let k = h.f then k(1) - runs, 2.ADR-351 D1: a let bound to code records what the code calls in stored_code (check_core_stmt.nika:606-611, check_core_stmt_let), but only when the bound type holds_code; an untyped lambda that no call hands on (#997’s look-ahead check_core_stmt_handed_to only sees call arguments, :1866) is not Ty::Fn there, so the frame is popped and nothing is recorded. The field then gets the name g (check_core_places_code_into, check_core_places.nika:468-487): a local with no stored_code entry and not a parameter is unresolved, which is the ? of the message.
crates/nikaia-std/src/tools/check_core_stmt.nika: :531 check_core_stmt_let, :568 code_place, :606 the pop, :1835 check_core_stmt_lambda_by_use, :1866 check_core_stmt_handed_to.crates/nikaia-std/src/tools/check_core_places.nika: :361 check_core_places_stored, :461 check_core_places_code_into.crates/nikaia-std/src/tools/lowered/, regenerated by lower-std.let whose value is a lambda records its code in stored_code whatever type the checker gave it (a closure’s free calls are what runs, check_core_places_code_into’s Closure arm). Rows a and b then run; c, d, e unchanged.tests/compiler/tests/an_untyped_let_lambda_in_a_fn_field.nika + .stdout with rows a and b. Commit check: an untyped let lambda put into a fn field keeps its error set (Fixes #1045).The new test passes through nikaia test --project tests/compiler and fails on the unfixed compiler (run its rows on the current binary before your first edit and keep the outputs under Tests:); the tests nikaia run scripts/where.nika -- check_core_places_stored check_core_places_code_into check_core_stmt_let lists pass; tests/compiler/tests/let_lambda_string_param.nika and a_let_lambda_handed_where_a_function_is_kept.nika still pass; lower-std fixpoint clean; cargo build --profile fast -p nikaia; the guard set of .claude/agents/builder.md green; pushed. Changelog: one line. Stop about 15 turns before max_turns, commit what is finished and report partial.
An edit is needed outside check_core_stmt.nika, check_core_places.nika, their lowered twins (and lowered.rs), files lower-std rewrites because of your change, and the new test; an error in another agent’s file; the fix turns out to need a rule Part I or #997 does not give (then Result: blocked, Needs: owner decision). tests/compiler failures from a binary vanishing mid-run (another agent rebuilding) are not yours: run the named tests singly instead.
Not yours, never stage: every file git status shows modified or untracked at your start (today among them crates/rs2nika/convert/*, a stray file whose name starts ork in the tree)), and every docs/briefs/* file except your report.
docs/builder-facts.md first. develop in the main checkout; git status at start: other agents’ uncommitted files are not yours, never touch or stage them.git add <files> only; commit after each step; git push origin develop fast-forward, no rebase (rejected: report Pushed: rejected, go on committing).cargo fmt, cargo clippy --all-targets -- -D warnings, scripts/pre-push-check.sh, and the gate of .claude/agents/builder.md (#852).CHANGELOG.md, badges; no new NK code. New tests in Nikaia only; never the full suite. No foreground sleep, no polling; scripts in files.std or the toolchain lacks stops the work: no code around it unless an ADR or Part I-III refuses it (name it). Else Result: blocked, Found: gap + probe, Needs: owner decision (CLAUDE.md, A missing form stops the work).NIKAIA_CACHE_LIMIT=2G; at most two clones with target/ in the machine; delete your own clone’s target/ and target/release/nikaia-scratch at the end; report GB freed.Pushed: line names the pushed sha. A report without a Pushed: line, or with a placeholder left in (TC, DISK), is not done and cuts the batch (k3a1 2026-10-29: Result: done, nothing committed)./home/user/Nikaia/docs/briefs/b1045-let-lambda-fn-field.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 (redesign) for a brief with Shape: redesign and no Convert: line). 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 process event such as another session resetting or rewriting your files is no Found:, it goes under Needs: (m3a 2026-10-28); 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:, nor a test’s expected .stdout/.stderr taken from what the program really prints where the brief’s sketch of it was short or wrong, b934 2026-10-29: say so in Body:, nor a lowering that follows the ADR governing it where the brief’s expected lowering contradicts that ADR, b933 2026-10-29: name the ADR in Body:, nor a lowering other than the brief’s where rustc cannot take the brief’s, b1029 2026-10-31: say why in Body:, nor re-keying an allow-list entry (KNOWN) whose hash changed for the same program and the same reason, b-fixforward-sweep2 2026-10-28: say so in Body:, nor an existing test’s expected .stdout/.stderr updated because your change rightly changes the message it prints, b1012b 2026-10-31: name the test 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