agent: builder model: sonnet max_turns: 80 budget_usd: 12 —
+ local returned as an owned String (#864)Score: S=3 (a correct program reaches rustc and fails there; met in our own tool drive.nika), O=small (one tier rule in text_tiers.nika), bug lane 1 (docs/priorities.md).
Found by the drive.nika builder (docs/briefs/b-drive-loop.md.report.md, Found:). A function with an owned String result that returns a view of a local built with + reaches rustc and fails there (“Cannot return value referencing local variable s”): the result is lowered as &'static str (ADR-282 D29’s lasting tier), though the local is owned. A correct program must compile (the result is copied out, ADR-282 D2).
target/fast/nikaia run p.nika)fn first(t: String) -> String {
let s = t + "!"
return s.trim()
}
fn main() { print(first(" hello")) }Lowered: fn first(t: &str) -> &'static str { let s = nikaia_std::concat::plus(t, "!"); s.trim() }.
Matrix (same function, other bodies):
| body | today |
| :— | :— |
| let s = t + "!"; return s.trim() | rustc error |
| let s = t + "!"; return s.bytes[0..n].text() (fn throws) | rustc error |
| let s = t + "!"; let r = s.trim(); return r | rustc error |
| let s = t + "!"; return s | runs |
| let s = t.clone(); return s.trim() | runs |
| let s = f"{t}!"; return s.trim() | runs |
| let s = t + "!"; let r = s.trim(); return r.clone() | runs |
So the + local is the trigger: its kinds reach the result as lasting (probably the "!" literal operand), though tier_expr’s Expr::Binary arm returns owned_kinds().
crates/nikaia-std/src/tools/text_tiers.nika: tier_expr, arm Expr::Binary (about line 3349); flow_result (about line 2045); the let binding of a local’s kinds (bind_tier_local, about line 653).crates/nikaia/src/text_tiers.rs: mark (Tier::Lasting, about line 261), the adapter.crates/nikaia-std/src/tools/emit_core_types.nika:268: writes &'static str for a lasting view.tests/compiler/tests/ (program + .stdout).+ local’s tier becomes lasting (nikaia lower p.nika after each change; lower-std and rebuild when a tools/*.nika changes). Fix so a view of an owned local makes the result owned.tests/compiler/tests/a_view_of_a_concatenated_local_is_returned_owned.nika + .stdout with the three failing rows of the matrix, and one row that must stay a static view (let s = "lit"; return s.trim() in a function whose result is lasting today - check its lowering stays &'static str).Fixes #864.crates/nikaia-std/src/tools/text_tiers.nika (and its lowered/text_tiers.rs from lower-std), crates/nikaia/src/text_tiers.rs only if the adapter is the root, the new test. If the root is in emit_*.nika or the checker, stop and report under Needs.
Known facts: read docs/builder-facts.md. A tools/*.nika change needs target/fast/nikaia lower-std, then cargo build --profile fast -p nikaia, and the lowered/*.rs diff committed.
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/b864-plus-local-view.md.report.md)Fields of docs/architect.md, Briefs and reports: Result: done|noop|partial|blocked (the bare word first; 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. 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