-- The unknown-flag guard also rejects the `--key=value` shape. Before
-- the fix, `--engine=tree` and `--foo=bar` slipped past the guard (the
-- shape check excluded any token containing `=`) and got silently
-- consumed as positional args, surfacing as a misleading ILO-R012
-- "no functions defined" or ILO-R004 "main: expected N args, got N+1".
-- The guard now splits on `=` and shape-checks the `--key` head, so
-- `--engine=tree` is caught the same way as `--engine tree`.
--
-- To pass a `--key=value` token as literal data, insert `--` first:
-- ilo main.ilo -- --key=val
--
-- This file is exercised by the engine harness on the happy path so
-- the guard's no-op behaviour on plain positional args stays under
-- cross-engine regression coverage. The rejection path is covered by
-- tests/regression_unknown_flag_guard.rs.
main x:n>n;+x 1
-- run: main 41
-- out: 42