agent: builder model: opus max_turns: 100 budget_usd: 26 —
yaml: block scalars, node properties, aliasesThe owner’s direction: an official package yaml with a zero-copy tree pointing into the input, spans, safety limits on by default (alias expansion, depth, size), YAML 1.2 core schema, tags kept, a duplicate key an error, << not merged by itself. Every gap in the compiler, lowering or std is a finding fixed in the compiler, never routed around in the package.
Read first: docs/specification/adr/adr-yaml-1.md (D2-D5 and D8 for this brief), then packages/yaml/src/main.nika and its tests as the previous brief (docs/briefs/yaml/y1-tree-core.md, its report beside it) left them. Its Facts the architect probed hold here too: input ref Bytes, rule WS = "" -> { }, the tree built inside the grammar’s actions (#1000), entries as a struct (#999). Also read y5-escapes-and-radix.md (the brief before this one): its Facts the last builder paid for hold here, and the Scalar shape it left (a double-quoted scalar’s value decoded by the grammar, every other scalar’s value a view, ADR-yaml-1 D4 amended, D11).
The check happens once, where the knowledge is (owner, 2026-10-30; ADR-yaml-1 D5’s last paragraph, D11): what the grammar can check (a block scalar header, a tag’s shape, a %YAML version) it checks with a guard, so a mistake is a parse error with line and column, and no later function checks it again.
| and folded >, chomping -, + and clip, an explicit indentation indicator (|2), the indentation taken from the first non-empty line, leading empty lines, a comment after the header. raw is the view of the content lines; text() computes the value on request (YAML 1.2.2 8.1): it has no escapes, so nothing there is checked twice. Test tests/block_scalars.nika (each chomping with and without trailing empty lines, > folding of more-indented lines, |2 with a leading space line).&a, aliases *a (a Value::Alias node, not resolved: ADR-yaml-1 D6), tags: !local, !!str and the other core tags (they fix the kind, D5: !!str 12 is a string, !!int "12" an int; a core tag that fixes a kind checks the scalar’s shape there, in the grammar, so !!int "x" is an error at its position and as_i64 still checks nothing per digit), !<tag:yaml.org,2002:str>, a named handle !e!x. Properties before a block collection on the line above, and on an empty node. Test tests/anchors_tags_aliases.nika.The expected .stdout is what YAML 1.2.2 says; the yaml-test-suite case for a construct is the reference (read only, nothing copied: ADR-yaml-1 D9 waits for the owner); name it in a comment.
Steps 3-4 of the old y2 (explicit keys, directives, Limits) are the next brief, y2b-keys-directives-limits.md: not this run.
target/fast/nikaia test --project packages/yaml passes (the earlier tests included); the package gate below is green; each step committed and pushed; the last commit’s message says Part of #928.
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).NIKAIA_CACHE_LIMIT=2G target/fast/nikaia test --project packages/yaml green, and cargo test --profile fast -p nikaia --test it -- fmt::every_nika_file (it formats every .nika under packages/). For a change only under packages/yaml/ this is the gate the line above asks for; a change under crates/ runs the gate of .claude/agents/builder.md (#852) as well. target/fast/nikaia is built by the session hook; if it is missing, cargo build --profile fast -p nikaia once.Changelog: none, unless the brief changes crates/.Files not to touch: anything outside packages/yaml/ and the brief’s own report, unless the brief names it; never docs/briefs/batch.txt or a brief of another lane.
max_turns: commit and push every finished step, then report Result: partial with what is left under Needs:. Uncommitted work at the end is lost work (y4 ran out at 110)./home/user/Nikaia/docs/briefs/yaml/y2-tree-properties.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 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:); 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_01UVxJDveRM5qKZKyCqq6Y24