agent: builder model: opus max_turns: 70 budget_usd: 18 —
Facts: Traps already met
Score: unblocks j6 (at $.contacts[1].mail, #1019 step 3d, ADR-344 D3’s error form of the typed read); S=A, O=~0.4M tokens, C=~0.3M tokens; five match arms in the backend winnow-grammar, nothing in Nikaia.
j6 run 1 (report j6-1019-error-path.md.run1.report.md) found that winnow-grammar rev 4f8e6691 pushes the item N frame (Diagnostics::item, src/error.rs 693/769/833) onto an error leaving a repetition only when it is ErrMode::Backtrack; an ErrMode::Cut takes Err(e) => return Err(e) and loses the index. Every failure inside members[S] is a Cut (k:Key => ..., fail), so a typed read cannot say which list element failed. A Cut error loses what a Backtrack error keeps: the backend is inconsistent with itself.
docs/architect.md Language decisions: obvious; no language change)e.item(k), it numbers a Cut error leaving the same element with the same k and returns it as a Cut (Err(ErrMode::Cut(e.item(k)))), and likewise for the streamed folds’ Fail (their Cut arm, if they keep one). Nothing else changes: no new pattern, no change to record, priorities or the rendered form.frame(expr, p), j6’s option b): a new grammar form for one user, where the existing frame needs only to stop vanishing. Telling which repetition a frame came from is Nikaia’s emitter’s (a marker rule around a list element, j6 run 2), not the backend’s.Work in your own clone of the backend, never in ~/.cargo/git/checkouts/ (read-only) and never through a [patch] in the Nikaia checkout (shared; other lanes build there):
git clone https://github.com/keywan-ghadami/winnow-grammar /home/user/winnow-grammar && git -C /home/user/winnow-grammar checkout -B main 4f8e6691 (HEAD of main is 4f8e6691; if origin/main has moved, build on it and say so in Body:).
src/rt.rs: repeat_recording_bounded (958, the arm at 1005), repeat_counting_bounded (1043, arm at 1082), the repetition macro around 1248 (e.item(base + seen + 1), calls stopped(..) first: keep that order for a Cut too). repeat_recording (935), repeat_counting (1032): check whether they delegate or have arms of their own.src/rt/stream.rs: 515 (Fail::Backtrack(e) in the item loop, e.item(*n + 1)), 868 (e.item(item.unwrap_or(0))): read the Fail enum first; number a Cut there only where an index is known.tests/cut_test.rs, tests/diagnostics.rs (existing item N expectations), tests/frames_test.rs; their CHANGELOG.md [0.1.0] - Unreleased takes one entry.e.item( site grep -n "\.item(" src finds) number a Cut error. Test, a new #[test] in tests/cut_test.rs (winnow-grammar is a Rust crate; Nikaia’s tests in Nikaia only rule is for this repository): a grammar list = "[" item ("," item)* "]"; item = "{" => digit+ "}" (in the crate’s own syntax, SYNTAX.md) on [{1},{2},{x}] renders a stack holding item 2 above item, and on [{x}] holds no item frame from that repetition; a repetition ("a" => "b")* on ababac numbers its Cut item 3. Each fails on 4f8e6691.cargo test in the clone passes (fix an existing expectation only where it now rightly gains an item N line, and name it in Body:); cargo clippy --all-targets -- -D warnings and cargo fmt --check there.git -C /home/user/winnow-grammar commit, message in its CHANGELOG’s style, the Attribution: lines below as trailer). Do not push (no GitHub here): the main session pushes it. Write git -C /home/user/winnow-grammar format-patch -1 -o /home/user/Nikaia/docs/briefs/tools/ and name the file under Files:, so the commit survives the clone.Cargo.toml (j6 run 2 does, after the push).cargo test green in the clone with the new test failing on 4f8e6691 (say so under Tests:); the patch file in docs/briefs/tools/; the report says Pushed: winnow-grammar <sha> (local, unpushed) and Needs: help from main session: push winnow-grammar <sha> to keywan-ghadami/winnow-grammar main. Commit the patch file and the report in Nikaia with target/fast/nikaia run scripts/commit.nika -- REPORT (its Pushed: rewrite is fine; keep the winnow-grammar sha in Body:). Changelog: none (no Nikaia change yet).
a Cut arm cannot be numbered without changing what record or the error ranking does (say which function, Needs: architect decision); an edit outside the clone, the patch and the report. Delete /home/user/winnow-grammar/target at the end (the clone itself stays for the main session) and report GB freed. Stop about 15 turns before max_turns, commit what is finished and report partial.
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 (scripts/commit.nika -- REPORT does it); commit locally after each step and never push: the driver runs the complete suite and pushes (.claude/agents/builder.md, Cheap checks only; owner, 2026-10-31).cargo build --profile fast -p nikaia, lower-std and its fixpoint when a tools/*.nika changed, cargo fmt, cargo clippy --all-targets -- -D warnings, scripts/pre-push-check.sh, the tests the brief names and the ones your change touches. No gate.nika.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: architect 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.Result: partial with what you ruled out, the probe, and the suspected file and function (.claude/agents/builder.md).target/fast/nikaia run scripts/commit.nika -- REPORT, which writes Pushed: local <sha> into it. 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/tools/j8-1019-cut-item-frame.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_01UVxJDvLe1uS47UcqA9y1U2