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Brief: #1032, a call inside a grammar guard is no call site for the text-tier pass

Score: a compiler defect found by y2c (#928 step 2b, blocked); the package waits on it, so it is first.

Facts earlier grammar builders paid for: a rustc error from a grammar (Mismatched types, Cannot find value) is the emitter’s or the checker’s: run nikaia check (here it refuses with NK1185, the defect itself) and nikaia lower FILE (writes the .rs, shows the rule’s lowered type) first. The backend is winnow-grammar (pinned rev, cargo checkout, not changed here). nikaia test --both-settings --project tests/compiler runs over 10 minutes: run_in_background with timeout: 3600000. If other sessions’ uncommitted files block git pull --rebase, push fast-forward and report Pushed: rejected (the driver rebases).

Issue (#1032, copied)

Found by the yaml lane (y2c, #928 step 2b, 2026-10-31): the y2 draft’s fits_node guards. A compiler defect, fixed in the compiler (CLAUDE.md).

Probe (the architect ran it on 506edc2d)

grammar G {
	rule WS = "" -> { }
	rule Word -> i64 = x:any if(x >= 'a' && x <= 'z') -> { 1 }
	entry rule top -> String = s:text(Word+) if(fits(s), "too short") eof -> { s }
}
fn ok(s: String) -> bool sync {
	let body = s.strip_prefix("-") ?? s
	return body.len() > 1
}
fn fits(s: String) -> bool sync {
	return ok(s)
}
fn other(s: String) -> bool sync {
	return ok(s)
}
fn main() {
	let r = G::top("abc") catch {
		println("error")
		return
	}
	println(r)
	println(other(r))
}

nikaia run: NK1185 at the ?? in ok (left a view, fallback String). The same with the call moved into the action (eof -> { if fits(s) { s } else { s } }) prints abc, true; so does an unused fits with no other.

Cause (architect, by reading; the probe agrees)

bind_grammar_pattern (crates/nikaia-std/src/tools/text_tiers.nika:5236, called from walk_grammar:5191) walks labels, sequences, choices, refs, repeats and groups, and drops everything else in else => {}: a Pattern::Guard { cond, .. }’s expression is never handed to tier_expr, so fits(s) is no call site and fits’ parameter (and through it ok’s) is tiered from the other callers only. The same else drops a rule call’s value arguments and a counted repeat’s bounds (unverified whether they matter).

Locations

To build (one commit)

  1. A Pattern::Guard { cond, .. } arm in bind_grammar_pattern that walks cond with tier_expr (after the labels before it are bound: the walk is in pattern order). Re-lower. Test tests/compiler/tests/grammar_a_call_in_a_guard_is_a_call_site.nika with .stdout abc, true (the probe), failing on the unfixed binary. Fixes this issue.

Done when

The new test passes and failed before, the grammar_ tests pass, the gate of .claude/agents/builder.md (#852) is green.

The commit says Fixes #1032. Changelog: one sentence (this changes crates/).

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/yaml/y11-1032-guard-call-tiers.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

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