agent: builder model: opus max_turns: 120 budget_usd: 25 —
span(p) and here (compiler lane, Part #557)Score: the bootstrap’s critical path (docs/bootstrap.md, section 2): parser/mod.rs (2,280 Rust lines) moves as a Nikaia grammar only after #557 steps 1-3. S=3, C~8-15 M. Runs first in the fix checkout C3.
Owns: crates/nikaia/src/parser/mod.rs (only the rules that parse a grammar’s patterns, grammar_item/grammar_rule at :1896/:1906 and the pattern rules they call), crates/nikaia-std/src/tools/ast.nika (only Pattern, :1343), check_grammar.nika, emit_grammar.nika, grammar_decode.nika, crates/nikaia/src/grammar_run.rs and build_time.rs only if the build-time run of a grammar needs the new forms, new tests under tests/compiler/, the generated tools/lowered/*. Not yours: everything a move lane owns (docs/bootstrap.md, File ownership); Pattern gains variants, so every match over it in another lane’s file that stops compiling is a Needs: (look first: nikaia run scripts/where.nika -- Pattern).
span(p) yields the byte range p matched; here yields a position and consumes nothing. Part II 10.8’s table (docs/specification/20-nikaia-advance.md:648-650): over Bytes, span(p) gives a Span (two u32) and here a u32; over text a text::Match / text::Pos.span(p) must end a span at its last token (the trailing-trivia cut PrTrivia::cut that at applies), so the span table the numbering pass writes stays byte-identical when the compiler’s grammar moves.docs/bootstrap.md section 2): the compiler’s grammar will run over the source as Bytes, so build the Bytes forms. The text forms wait for #743 (text::Pos, text::Match are not in std): over text, span(p)/here are refused with the existing “not built yet” path or an existing NK code (no new code; if none fits, stop and report under Needs:).ParseError. Test tests/compiler/tests/grammar_failing_action_in_alternative.nika (rule n -> i64 = t:text(digit+) { parse(t) } where parse fails, inside a | b) with its .stdout/.stderr. If it already holds, the test alone is the step; if not, fix it. Commit, Part: #557.span(p) and here over Bytes (#557 step 2): the grammar front end (the pattern rules in parser/mod.rs, Pattern in ast.nika), the checker (check_grammar.nika: the type of the binding), the lowering (emit_grammar.nika: what the generated winnow-grammar rule writes; the Rust grammar’s own @= and .at() show how the crate hands back a range) and grammar_decode.nika if it decodes patterns. Tests: a Bytes grammar whose rule binds s:span(p) gives the same start/end as the bytes p covered (also after skipped whitespace: the span ends at the last token); here consumes nothing (a:here b:here around nothing are equal); both in a build-time run of the grammar if build_time.rs runs grammars (one test). Commit grammar: span(p) and here over Bytes (#557 step 2), Part: #557.Step 3 (same_line) is the next brief, not this one.
nikaia test tests/compiler --both-settings (every count as before plus the new tests); it tests filtered on grammar plus the guard set of .claude/agents/builder.md; clippy clean; lower-std fixpoint after the rebase. Changelog: one line for the supervisor under Changelog: (a language change raises the version; you do not).
winnow-grammar cannot hand back the range of a sub-pattern (then say what it offers: the decision is the architect’s); a .stderr of an existing test changes; a Pattern match in another lane’s file needs an arm.
Read docs/builder-facts.md.
docs/bootstrap.md section 3)docs/builder-facts.md first. You work in the worktree /home/user/nikaia-fix, not in /home/user/Nikaia (the driver’s builder works there; never edit, build or stage anything in it except your report file). Set up once: cd /home/user/Nikaia && git fetch origin develop && (test -d /home/user/nikaia-fix || git worktree add --detach /home/user/nikaia-fix origin/develop); then cd /home/user/nikaia-fix && git status (another agent of your checkout may have left files: not yours, report them). Build with CARGO_INCREMENTAL=0 cargo build --profile fast -p nikaia; use only /home/user/nikaia-fix/target/fast/nikaia, never another checkout’s binary.git add <files> only; commit after each step. Push: git fetch origin develop && git rebase origin/develop, rebuild, lower-std once more, commit any lowered file that changed (lowered: regenerate after rebase), then git push origin HEAD:develop; rejected: again, at most three times, then Pushed: rejected. A conflict in tools/lowered/*.rs or tools/lowered.rs is never merged by hand: git checkout --theirs -- <file>, git rebase --continue, rebuild, lower-std, commit.lower-std changed, yours and others’ (a compiler change re-lowers other files; that is correct in your tree). 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, 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.NIKAIA_CACHE_LIMIT=2G; at most three checkouts with target/ (C1, C2, C3); if df -h /home/user shows under 4 GB free, delete /home/user/nikaia-fix/target and report blocked. At the end delete /home/user/nikaia-fix/target/debug and /home/user/nikaia-fix/target/release/nikaia-scratch (keep /home/user/nikaia-fix/target/fast for the lane’s next brief) and report GB freed./home/user/Nikaia/docs/briefs/lane-bugs-557a-span-here.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