| name | io-inversion |
| description | Hoist all reads to session entry and sink all writes to session exit around a pure Decision middle. Use when a host/session path mixes IO with meaning. Not name-and-seat-construct. Not organize-work. |
IO Inversion
Input: a function/path that mixes reads, decisions, and writes.
Output: the same behavior as three beats — gather → decide → effect — with types named at the seams.
Do this
- List IO. Enumerate every read (store/project/clock/rng/net) and every write (put/commit/side effect) in the path.
- Hoist reads. Move every read to the top (session entry). Gather results into an explicit input structure. No read remains in the middle.
- Name the decision. The middle becomes a pure function: inputs →
Decision (or equivalent ADT). No IO, no clock, no unseeded randomness inside it.
- Sink writes. Match on
Decision only at the bottom (session exit). All commits/effects live there. Consuming commit stays consuming.
- Check.
cargo check on the touched allowlist. Emit: input struct, Decision variants, where reads/writes now live.
- Stop. If a symbol’s zone seat is unclear, hand it to
name-and-seat-construct — do not seat inside this skill.
Do not
- Leave a store/project call inside the “pure” middle.
- Invent new product meaning while inverting — only reshape ownership of IO.
- Skip naming the Decision type (bool/flag soup is failure).
