Loop Tiers

The five-phase shape from the previous page doesn't change based on how long a loop needs to live — but the lifetime and the access it needs absolutely do. Picking the right tier is a matter of matching the loop's actual required lifetime to the narrowest mechanism that provides it, not reaching for the heaviest option by default.

The five tiers

Session loop. Vision-in, iterate-until-a-confirmed-Definition-of-Done, entirely inside one already-open session, with no per-phase human approval gate along the way — the trade being an automated self-check each iteration in exchange for running longer stretches unattended.

Session reminder. A short-lived nudge that only matters while the current session stays open — it's gone the moment the session ends, and isn't meant to substitute for anything that needs to survive past that.

Scheduled routine. Genuinely recurring maintenance that has to happen on a calendar whether or not anyone is at a terminal. It runs with no open session, which is exactly why it defaults to read-only or dry-run — there's no session there to answer an approval-gate prompt if one comes up mid-run.

Workflow loop. A bounded, deterministic pass across many independent items at once inside a single invocation — exhaust the work, then stop. Not a standing process; it finishes and ends.

Daemon with a singleton lock. The one shape none of the others cover: something that has to stay continuously connected or listening rather than waking up periodically. Guarded by a lock so a second copy can never start unnoticed alongside a live one.

Picking one

A recurring check that could just as well run inside an already-open session is over-committing to schedule it as standing infrastructure. Conversely, anything that genuinely needs to outlive the session is under-committing if it's only ever run as a one-off inside one. The fit is the point — not defaulting to the most durable-sounding option "to be safe."

The SDLC, Paper 1 names picking the narrowest tier as its own principle (P5); Paper 6 generalizes the same instinct into a project-wide discipline that reaches past loop tiers alone, alongside the other axis it documents.