agent: builder model: opus max_turns: 90 budget_usd: 18 —
match moves out is consumed, not lent (#1092)Score: y29’s Found: (the fix for #1089), filed as #1092. Nothing in yaml needs it yet; built in this lane because the lane found it and the view-checker facts are fresh from y29. It changes crates/: name in the report what it decided (the supervisor raises the version), Changelog: one sentence. The commit says Fixes #1092.
Facts: Where things live, Traps already met
Problem. A by-value parameter nobody consumes is inferred lent (ADR-277 D17) and lowered a: &A. A match on one of its non-copy optional fields whose arm hands the payload on by value (x => x) moves the field out, so it consumes the parameter, as a.node ?? throw .. already does; but the inference does not count it, and rustc refuses the move (E0507, Cannot move out of a.node … behind a shared reference). Checked by the architect on target/fast/nikaia at 445f6064.
Probe (nikaia run p.nika; wanted 3):
struct E { msg: String }
impl Error for E { fn message(ref self) -> String { return self.msg.clone() } }
struct N { v: Vec[i64] }
struct A { node: N? }
fn owned(a: A) -> N sync throws {
let node = match a.node { null => throw E { msg: "no node" } x => x }
return node
}
fn main() throws {
let n = owned(A { node: N { v: [1, 2, 3] } })
print(f"{n.v.len()}")
}Rows: a the probe (E0507); b return a.node ?? throw E{..} prints 3 (runs, must stay); c the arm x => x.clone() (must stay; the parameter may stay lent); d an enum payload, struct B { v: V } enum V { Seq(Vec[i64]) Nothing }, fn f(b: B) -> Vec[i64] { return match b.v { V::Seq(items) => items else => [] } } (probe it first; same cause expected); e the match on the parameter itself, fn g(o: N?) -> N sync throws { return match o { null => throw .. x => x } } (probe; must print).
Suspected location (low confidence). Find where the inference of ADR-277 D17 records a consume for ?? on a parameter’s field (rg -n "lent" crates/nikaia-std/src/tools/check_flow.nika crates/nikaia-std/src/tools/check_references.nika crates/nikaia-std/src/tools/check_boundary.nika) and make a match scrutinee rooted at the parameter count the same way when an arm binds a non-copy payload and that binding is moved (returned, stored, passed by value). y29 (445f6064) touched the neighbouring check_core_flow_through_a_view / got_past_a_jump: read its diff first, do not undo it.
tools/*.nika change, lower-std regenerates its lowered/*.rs; commit both)tests/compiler/tests/match_moves_a_field_of_an_owned_parameter.nika + .stdout (all rows in one program, each printing), refused by the unfixed binary (say so in Tests:). #1057 (return s.inner of an element read) is a neighbour: do not build it.tests/compiler --both-settings green; the view tests of the gate (it text_views stored_views tethers views_kept) green; tests/compiler/tests/match_on_a_field_of_a_get_bound_local (y29) still green.Files you may change: the tools/*.nika the cause is in, with their lowered/*.rs, the new test, and an existing test’s expected output your change rightly changes (name it in Body:). If the fix needs a language decision, stop: Result: blocked, Needs: architect decision. A builder that has found no cause after about 40 turns stops and reports partial with what it ruled out.
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. Do not push: the driver runs the suite on your commit and pushes it (CLAUDE.md, Builders commit, the driver tests and pushes).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: 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.Pushed: line is local <sha> of your last commit. 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 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/y30-1092-match-moves-owned-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_01UVxJDveRM5qKZKyCqq6Y24