I've raised the concept of "iteration hazard" elsewhere, and reiterated it in #526 as stemming from a fundamental distinction between "simple message" vs. "complex message" rather than the former being merely a degenerate case of the latter that happens to have no declarations and no matcher.

I also noted specifically in #526 (comment) that the desired unification can be achieved with a decision to start in code mode OR to start in text mode, but either way it is entangled with quoting—the requirements and interpretation for which must be consistent regardless of presence vs. absence of declarations/matchers (for example, introducing or removing an irrelevant singleton declaration and immediately following line feeds without changing any other content must not invalidate a message or change the significance of leading/trailing whitespace).

This concern may ultimately be rejected, but I hope that it would at least be acknowledged explicitly rather than as an implicit consequence of what participants considered to be isolated decisions. And I think this is the right issue for that.

Valuable exercise but not required for the 45 timeframe

I'm marking this as "Stale" for now, but welcome moving it into the 46.1 bucket if we think this is somehow still relevant/useful work. I note the existence of code-mode-introducer as a design doc. Recent changes to remove reserved-statement and its friends may have helped or hindered this effort.