Run

/strictlybetter:run — ONE CYCLE

This is the loop body. Follow the numbered procedure exactly once; the Stop hook re-invokes it while the campaign is running with budget left. No improvisation: every decision below is the engine's, and every number you print is quoted from its output. You are the HYPOTHESIZE agent; every other role is a spawned agent or the engine.

Three rules that the guard hook and the ledger enforce, restated so they survive compaction: never edit files yourself during a campaign (the guard denies it), never compute a statistic (no deltas, no percentages, no "roughly"), never paraphrase the engine's numbers (quote the line).

# Resolve the engine. RUN THIS BLOCK VERBATIM — do not substitute a path you guessed.
# Order: ZCode's plugin root (ZCode also exports the legacy CLAUDE_PLUGIN_ROOT, so its own
# var is checked first), Claude Code, Codex, an explicit checkout (SB_ROOT), the Claude Code
# plugin cache (newest version), and LAST the working tree's git toplevel (a contributor
# running inside the strictlybetter checkout). First one that holds scripts/sb.py wins.
SB_PY=""
SB_CACHE="$(find "$HOME/.claude/plugins/cache" -maxdepth 5 -path '*/strictlybetter/*/scripts/sb.py' 2>/dev/null | sort | tail -n 1)"
for d in "${ZCODE_PLUGIN_ROOT:-}" "${CLAUDE_PLUGIN_ROOT:-}" "${CODEX_PLUGIN_ROOT:-}" "${SB_ROOT:-}" \
         "${SB_CACHE%/scripts/sb.py}" "$(git rev-parse --show-toplevel 2>/dev/null)"; do
  [ -n "$d" ] && [ -f "$d/scripts/sb.py" ] && SB_PY="$d/scripts/sb.py" && break
done
if [ -z "$SB_PY" ]; then
  echo "strictlybetter: engine not found — set SB_ROOT to your strictlybetter checkout" >&2
  return 2 2>/dev/null || exit 2   # FAIL CLOSED: proceeding would run `python3 ""`
fi
SB_ROOT="${SB_PY%/scripts/sb.py}"
SB_REPO="$(git rev-parse --show-toplevel 2>/dev/null || pwd)"
sb() { python3 "$SB_PY" --repo "$SB_REPO" "$@"; }   # a FUNCTION, not a string: zsh does not
SB=sb                                                 # word-split "$SB"; both shells run `sb`
$SB --version | grep -q '^sb 1\.' || { echo "strictlybetter: engine did not answer (expected sb 1.x)" >&2; return 2 2>/dev/null || exit 2; }   # major version only; exact patch level is not asserted

0 · Re-anchor (never trust conversational memory)

$SB status --json                                             # the truth on disk
$SB status --json | grep -q '"campaign": null' || $SB next    # the cold-start brief, when a campaign exists

(a) The brief

$SB next --json > "$SB_REPO/.strictlybetter/inbox/brief.json"; $SB next
$SB campaign show | python3 -c 'import json,sys; c=json.load(sys.stdin); print("max_parallel", c["max_parallel"], "distill_every", c["distill_every"])'

From the brief take: status, batch_size, operator_mix (a list of [operator, count]), allowed_diff_sizes, frontier, goals, guardrails, recent_dead_ends, accepted_so_far, archive_hints, inheritance (path or null), frozen_paths, protected_paths, open_experiments, stop_requested, composition, and in a frontier campaign frontier_members, parent_member, preferred_member. Note max_parallel and distill_every from campaign show.

• status is not running → print the brief's halt_reason and stop.
• stop_requested true or batch_size 0 → skip to (f).
• open_experiments non-empty → those are a previous cycle's unfinished ids. For each, resume at the step its $SB ledger view <id> record shows (no commit: its worktree may hold uncommitted work, run (d) from submit; has judge_stat but no confirm: continue from the judge; has confirm: accept or discard). Finish them before pre-registering new ones.
• Read the inheritance body if present (Read the path) and the last few dead ends.
• composition is frontier → frontier_members lists the active members (id, commit, attempts, confirm medians per goal), parent_member is the member the next prereg will branch from, and preferred_member is the one sb/<campaign> points at. Pass nothing extra anywhere: prereg picks the parent. Quote all three in (g).

(b) Hypothesize: write batch_size files

You write these yourself, one JSON per hypothesis, with the Write tool, at $SB_REPO/.strictlybetter/inbox/hyp-<n>.json:

{"operator": "algorithmic", "target": "src/parse/lexer.rs",
 "hypothesis": "The lexer re-scans whitespace on every token; a single skip loop should raise throughput.",
 "predicted": {"bench_throughput": "+5..15%"},
 "mechanism": "removes an O(n) rescan per token in the hot loop",
 "expected_diff_size": "small"}

Rules: operator comes from operator_mix (spend the counts); target is a real path or symbol; predicted names only campaign metrics, goals first; expected_diff_size is one of allowed_diff_sizes; mechanism is one sentence a judge could check; do not repeat a recent_dead_ends entry (same operator + target) without a new mechanism; prefer the frontier's diagnostics and archive_hints over guesswork. A good hypothesis is small, falsifiable, and names where the time or bytes actually go.

(c) Pre-register and spawn experimenters

For each hypothesis file, in order:

H="$SB_REPO/.strictlybetter/inbox/hyp-1.json"
$SB prereg --file "$H"            # → {"id": "e0007", "worktree": "...", "base_commit": "...", "prereg_hash": "..."}

prereg writes the ledger line before any diff exists, creates the worktree from the campaign head, and charges the budget. In a frontier campaign the worktree is rooted at the parent member the engine picked and the output carries parent_member; never pass --parent, that flag is the human's override. If it errors (STOP file, budget exhausted, unknown operator, a predicted metric not in the campaign) print the message; fix the hypothesis file only for the last two causes and retry once; otherwise skip to (f).

Then write $SB_REPO/.strictlybetter/inbox/task-<id>.json (Write tool) exactly as skills/_shared/subagents.md shows: id, worktree, hypothesis (the hyp file's absolute path), frozen_paths, protected_paths, commands (from profile.json), inheritance, archive_hints. Pick the tier by operator: config|docs|test-add → sb-experimenter-low; algorithmic|allocation|caching|bugfix|numerics|data → sb-experimenter-medium; concurrency|model|refactor-enabling|dependency → sb-experimenter-high. Note the wall-clock (date +%s) and spawn with exactly this task text:

Implement the strictlybetter experiment in <abs path to task-<id>.json>. Edit only inside the worktree it names; do not run the benchmark yourself more than twice; return DONE <id> or BLOCKED: <reason>.

Spawn up to max_parallel experimenters in one message. Wait for all returns. Record the seconds each took.

(d) Per experiment, in return order

Work through this list for each id; stop at the first branch that ends it.

1. BLOCKED or malformed return → $SB discard <id> --reason manual:blocked. Done.
2. Submit → $SB submit <id>. Output "ok": false (exit 1) → $SB discard <id> --reason integrity. Done. (Two consecutive integrity failures halt the campaign; that is the engine's call.)
3. Stale head check (a parallel sibling may have been accepted since prereg):

   W="$($SB worktree path <id>)"; B="$(git -C "$W" rev-parse HEAD^)"; H="$($SB status --json | python3 -c 'import json,sys; print(json.load(sys.stdin)["head_commit"])')"
   [ "$B" = "$H" ] || echo "STALE <id>"
   

   STALE → $SB discard <id> --reason manual:stale-head --archive (the diff is archived; re-propose it on the new head next cycle if it still applies). Done. Frontier campaigns: skip this step. Each worktree is rooted at its parent member's commit, which never moves, and accept verifies the descent itself.
4. Screen → $SB measure <id> --fidelity screen then $SB judge <id>. Read "verdict" from the judge's first line:
   • retry-screen → run $SB measure <id> --fidelity screen and $SB judge <id> once more, then continue with the new verdict.
   • discard → $SB discard <id> --reason <reason> --archive when the judge's "improved" list is non-empty or any goal comparison line shows a positive delta; without --archive otherwise. <reason> is the judge's "reason" when its prefix (before :) is one of noise|regression|invalid; else noise. Done.
   • accept-naive (confirm wall off) → $SB confirm <id> then $SB accept <id>. Done.
   • promote → continue.
5. Blind judge → P="$($SB judge-payload <id>)", spawn sb-judge (strictlybetter:sb-judge) with only the payload path in the task text ("Judge the strictlybetter experiment described in <path>. Return only the verdict JSON."), write its four-key JSON to $SB_REPO/.strictlybetter/inbox/verdict-<id>.json with the Write tool, then $SB judge-verdict <id> --file "$SB_REPO/.strictlybetter/inbox/verdict-<id>.json".
   • gamed → $SB discard <id> --reason gamed. Done.
   • clean or suspicious → continue (the engine adds repeats for suspicious).
6. Confirm → $SB confirm <id>. Read "verdict" from its first line.
7. Cost (before the final verb, so the bandit sees it) → $SB cost <id> --wall-s <experimenter seconds> --tier <low|medium|high>. Tokens are unknown on this platform; the dollars column is an estimate from zero tokens, and the cycle summary says "estimated".
8. Final verb → confirm accept → $SB accept <id> (fast-forwards the campaign branch, ratchets the baseline). If accept reports "not a fast-forward", treat as STALE in step 3. Confirm discard → $SB discard <id> --reason <reason> --archive with <reason> the confirm line's "reason" when its prefix is in the fixed vocabulary, else noise. In a frontier campaign accept adds a member instead of fast-forwarding; its output has member, parent_member, retired, preferred_member. Quote them in (g). A confirm reason dominated:<member> is not in the discard vocabulary: discard with --reason dominated --archive (the ledger's confirm event keeps the dominated reason). In a campaign with audits (a proxy ladder, docs/15) accept may first run the real instrument: at the first accept and then every every_accepts accepts, blocking for as long as pairs pairs of it take (hours). When it did, accept prints one line before its own, and you quote it verbatim in (g):

   {"audit": {"recall": {"verdict": "direction", "p": 0.125, "n_pairs": 3, "median_improvement": 0.012}}, "wall_s": 43210.5}
   

   verdict is one of confirmed | direction | no-change | worse | invalid; direction means every pair improved but the pairs cannot reach alpha, and it is not a significance claim. A discard in such a campaign may print, before its own line, the sampled-audit line, which means the engine ran one pair of the real instrument on the discarded commit:

   {"discard_audit": "sampled", "id": "e0007"}
   

   Quote it in (g) too. Neither line changes what you do next.

Judge payload (step 5): the engine composes it, so no transcript text can leak into it:

P="$($SB judge-payload <id>)"   # writes .strictlybetter/inbox/judge-<id>.json and prints the path

The file holds the diff, the pre-registration, the screen comparisons, the affected cards' gaming_risks, the frozen paths, and the checklist path. Hand the judge that path and nothing else.

(e) Cost is recorded per experiment

Step 7 above, every experiment, including discards. Nothing else to do here.

(f) Distill on schedule

$SB distill-stats --json | tee "$SB_REPO/.strictlybetter/inbox/stats.json" | python3 -c 'import json,sys; s=json.load(sys.stdin); print("decision", s["decision"], "| experiments", s["experiments"], "accepted", s["accepted"], "| false-promotion window", s["false_promotion_rate_window"], "| budget left", s["budget_left"])'

• decision starts with stop → $SB report, then $SB campaign end unless $SB status --json says halted (a halt is for a human; ending it hides the reason). Print the report path .strictlybetter/reports/<campaign>.md. This is gate 2. Stop.

• Otherwise, if experiments % distill_every == 0, or accepted changed during this cycle: spawn sb-distiller (strictlybetter:sb-distiller) with this task text:

  Distill the strictlybetter ledger at <SB_REPO>/.strictlybetter/ledger.jsonl into an inheritance body. Current body: <SB_REPO>/.strictlybetter/inheritance.md (may be missing). Stats: <SB_REPO>/.strictlybetter/inbox/stats.json. Template: <SB_ROOT>/templates/inheritance.md.tmpl. Write the new body to <SB_REPO>/.strictlybetter/inbox/inheritance.md. Return DONE <path>.

  then $SB inheritance write --file "$SB_REPO/.strictlybetter/inbox/inheritance.md".

• explore:levelN → nothing extra; the next brief widens allowed_diff_sizes and the mix.

(g) Cycle summary (three lines, four in a frontier campaign or a proxy-ladder campaign, quoted numbers)

cycle: <n> pre-registered, <k> accepted (<ids>), <m> discarded (<id: reason>, …), <b> blocked
frontier: <goal> best=<value> sigma=<sigma>  (from `$SB next`)
frontier members: <n> active (<ids>) · preferred <id> · next parent <id>  (frontier campaigns only, from `$SB next`)
audit: <the `audit` line `accept` printed, verbatim> · discard audits sampled: <ids from the `discard_audit` lines, or none>  (campaigns with `audits` only, when either line appeared this cycle)
next: <decision from distill-stats> · budget left <…> · wall <…>s · dollars estimated $<…>

Then stop. The Stop hook decides whether another cycle runs.

Errors you may see, and what they mean

• sb: campaign status is 'halted' (…): the engine stopped itself (integrity twice, gamed twice, holdout gap, budget, baseline invalid). Print the reason; do not resume it yourself.
• sb: <id> is not promoted / has no blind-judge verdict / was judged gamed: you skipped a step; go back to it.
• strictlybetter guard: denied edit …: you or an agent tried to edit outside a worktree, a frozen path, or harness state. Do not retry the edit; the experiment is BLOCKED.
• sb: hypothesis missing 'predicted' / unknown operator: fix the hypothesis file and prereg again; nothing was charged.