agent: builder model: opus max_turns: 100 budget_usd: 20 —
T? position is wrapped (Fixes #887)Score: bugs lane (docs/priorities.md, bugs-first default; three ready bugs #886-#888 found by the #879 builder, this the smallest).
fn pair(p: (String?, i64)) -> i64 { p.1 }
fn main() { println(pair(("xy", 1))) }The checker passes this program. rustc then fails with mismatched types: the "xy" at the String? position is not lowered as Some(..). A plain value passed to a T? parameter is wrapped already. Inside a tuple literal it is not.
To build
T? position whose own type is T is wrapped, as a T? argument is. The same applies to let t: (String?, i64) = ("xy", 1) and to return.tests/compiler/tests/ covering the argument, the let and the return forms.Read docs/builder-facts.md. The wrap is a checker fact the emit reads: state.facts.wrapped / nullable_args with FactWrap::Constructor (tools/check_facts.nika:14), written Some(..) by tools/emit_exprs.nika:96. The list analogue exists: check_overflow_list_into_nullables (tools/check_overflow.nika:254, called at :232 from check_widened_slot :211 and at tools/check_arguments.nika:363) marks [..] items going into Vec[T?]. Build the tuple case beside it, the same way (a nested tuple / list inside a tuple recurses). Probe also a tuple element that is a non-literal String local and an i64 into i64?; and that (null, 1) and an element already T? stay unwrapped. Tools files changed are re-lowered (docs/builder-facts.md, lowering).
Probe fails before, passes after; new test passes at both settings; nikaia test --project tests/compiler filters for nullable and tuple green. Last commit says Fixes #887.
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.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./home/user/Nikaia/docs/briefs/b887-tuple-nullable-wrap.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, Fixes, Pushed, Tests, Gate (green|red), Deviation, Found, Needs, Changelog, Owner, Disk freed. 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); 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); 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