trio-agent-loop: Skill for Claude Code

Set up the trio-loop mailbox in the current project.

Mailbox directory: default loop/. If $ARGUMENTS starts with dir=<path> (e.g. /trio-init dir=loop-authz add rate limiting…), use that directory instead — every loop/ reference below then means that directory. One mailbox per loop is a hard rule: two loops (or two sessions) sharing a mailbox corrupt each other's state.

1. If the mailbox's STATE.md already exists, show its current status and LOG.md tail, then ask the user to choose: (a) reset — archive the old mailbox to loop-archive-<date>/ and start fresh; (b) abort; or (c) keep it and initialize this new loop in a sibling directory (loop-<slug>/ from the new goal) — the right choice when the existing loop may still be running in another session. If STATE.md says status: running and LOG.md's last entry is recent, recommend (c) — never hijack a possibly-live mailbox.
2. Create the mailbox directory with these files:

loop/GOAL.md — from $ARGUMENTS. If arguments are empty or vaguer than one sentence of substance, interview the user briefly (what does done look like, hard constraints, what must NOT change) before writing it. Decide the profile: software (default) or data — choose data when the goal is pipelines, ETL/ELT, SQL models, notebooks, finance/reporting datasets. Structure:

# Goal
profile: software | data
<the mission, in the user's words, sharpened>
## Definition of done
<objectively checkable statements>
## Constraints
<stack, style, things that must not break, budget notes>

For profile: data, the Definition of done MUST include data ground truth, so interview for it if missing: source(s) of truth to reconcile against, tolerated row-count/aggregate deltas, key uniqueness expectations, and whether re-runs must be idempotent. Vague data goals ("clean the dataset") are the #1 cause of runaway loops — pin numbers down.

loop/STATE.md (the mission: line is the first sentence of GOAL.md's mission, verbatim — the /trio orchestrator halts if it ever stops matching GOAL.md, which catches another session repurposing the mailbox):

schema: 1
iteration: 0
max_iterations: 10
status: ready
mission: <first sentence of the goal, verbatim>

## Approaches tried and rejected
(append-only; the Lead adds one line per dead end, with why)

## Key decisions and rationale
(append-only)

loop/LOG.md with a # Trio loop log header line, and empty loop/PLAN.md, loop/REPORT.md, loop/VERDICT.md.

1. If the project is a git repo, ask the user whether loop/ should be gitignored (ephemeral) or committed (auditable history). Default suggestion: commit it.
2. Confirm setup and print next steps: /trio for a single supervised iteration (recommended first), then /loop /trio to run autonomously — if the mailbox is not loop/, say to pass it: /trio dir=<path> and /loop /trio dir=<path>. Mention Esc stops the loop, and GOAL.md + max_iterations in STATE.md are the two human control knobs while it runs.