run-tests.fish globs tests/test-*.fish and runs each in the mode the suite
declares in its own header. Isolated is the default and no typo can
promote a suite to in-session: detection is case-insensitive so a
near-miss is caught, the value comparison is exact.
In-session suites share one sandboxed session; isolated suites each get a
--no-config child with temp XDG dirs. Counts come back through a file so
output keeps streaming.
functional.fish becomes test-session.fish, its 15 predicates rewritten as
check calls. 332 assertions, unchanged per-phase.
rootiest