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agent: builder model: opus max_turns: 120 budget_usd: 30 —

Brief: #859 steps 3 and 1, T::kind as a meta::Type, and a reflected field’s .ty

Score: owner’s direction (2026-10-31): #859 goes first now, because #1019 (ADR-grammar-2, the typed grammar entry Json::read[T]), json::write[T], the schema check and later yaml/toml all wait on it. Steps 4 (match on a kind) and 2 (a type as an argument) are the next run’s.

Problem (probed at 1b1ce4d with target/fast/nikaia check)

struct User { name: String, age: i64 }
fn show[T: Struct](v: T) {
    for field in T::fields {
        let k = field.ty            // today NK1180: "A field from `T::fields` has no `ty`"
        println(field.name)
    }
}
fn main() { show(User { name: "a", age: 1 }) }

User::kind is NK1171 (“User has nothing called kind”). Both are specified and unbuilt.

Decision (nothing new; the build of accepted records)

Locations

To build

  1. Step 3: T::kind (and T::name) for every kind of D3’s table, as a build-time value; meta::Type with its variants; NK1231 where one would reach run time. Tests in tests/compiler/tests/: type_kind_of_each_type.nika (+ .stdout, prints a name per kind for a struct, enum, i64, String, Vec[i64], i64?, HashMap[String, i64], a tuple, fn(i64) -> i64; reach the name through whatever build-time form exists today, e.g. T::name or an if/== decided while building, without needing step 4’s match); and type_kind_kept_at_run_time.nika + .stderr (NK1231). Commit check: T::kind is a meta::Type; T::name (ADR-330 D2, D3, D6, #859 step 3).
  2. Step 1: field.ty is the field’s type; field.ty::kind, field.ty::name work in an unrolled for. NK1180’s help text names .ty. Test reflected_field_ty.nika + .stdout (the probe above, printing each field’s name and field.ty::name). Commit check: a reflected field's .ty is its type (ADR-330 D5, ADR-329 D1, #859 step 1). No Fixes (steps 2, 4-8 remain): write Part of #859.

If printing a kind’s name needs match on a kind (step 4) and no other build-time form can show it, stop after what is verified and say so under Needs:: do not build step 4 half.

Done when

Both tests pass through nikaia test; each new test was run once against the compiler without your change and failed there (say so under Tests:); lower-std fixpoint clean; cargo build --profile fast -p nikaia; the gate of .claude/agents/builder.md; pushed. Changelog: two lines (T::kind and T::name exist, a meta::Type only while building; a reflected field’s .ty is its type).

Stop and report if

The parser needs a change for T::kind or field.ty::kind (say which form); an edit is needed outside crates/nikaia-std/src/tools/check_*.nika, emit_*.nika, crates/nikaia/src/build_time.rs, std’s declarations of meta, their lowered files and the new tests; an error in another agent’s file.

Not yours, never stage: every file git status shows modified or untracked at your start, and every docs/briefs/* file except your report.

Rules (CLAUDE.md; this block is pasted into every brief, also a fix-forward)

Report (at most 15 lines, to exactly /home/user/Nikaia/docs/briefs/b859a-type-kind.md.report.md)

Fields of docs/architect.md, Briefs and reports: Result: done|noop|partial|blocked (the bare word alone), Files, Commit, Body (optional), Fixes, Pushed, Tests, Gate (green|red), Deviation, Found, Needs, Changelog, Owner, Disk freed, Rs2nika (none). none where nothing, as the bare word. 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_01UVxJDvLe1uS47UcqA9y1U2

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