Two RED E2E tests that pin the byte-faithful-print property of
io/print_str. Both fail today because the codegen at
crates/ailang-codegen/src/lib.rs:2754 lowers the op to a C `@puts`
call, which writes the string plus a trailing newline.
- io_print_str_does_not_append_auto_newline:
(seq (do io/print_str "a") (do io/print_str "b")) → stdout "ab"
current: "a\nb\n"
- io_print_str_does_not_double_embedded_newline:
(do io/print_str "x\n") → stdout "x\n"
current: "x\n\n"
Assertions compare RAW stdout (no .trim()) — the byte-level
property IS the assertion target.
Empirically caught in the cross-model-authoring naming-A/B run
on 2026-05-21 (experiments/2026-05-21-naming-ab/runs/r1/): Qwen3-
Coder repeatedly wrote `(do io/print_str "text\n")` with explicit
\n, expecting byte-faithful output, and got doubled newlines —
failing every t3_main_prints stdout match across all three cohorts.
GREEN side (codegen swap @puts → fputs(s, @stdout) + sweep of
existing fixtures that implicitly relied on the auto-newline) is
the next commit, via implement mini-mode.
refs #29
