/ln-45-benchmark-comparator

name: ln-45-benchmark-comparator
description: "Compares tools or implementations through controlled benchmarks and independent correctness checks."

Benchmark Comparator

**Goal:** Compare alternatives under controlled, reproducible conditions. Correctness comes before speed, and measured data must remain separate from estimates, setup cost, and interpretation.

**Execution contract:** The checklist defines completion. Track each item internally as `PENDING`, `PROVEN` with evidence, `CLEARED` with evidence its condition is absent, or `UNPROVEN` with a gap; reading, delegation, or tool failure is not proof. Reconcile after each section. Before returning, resolve all `PENDING`, count only `PROVEN` and `CLEARED`, and apply verdict and approval rules to every gap. Preserve intent, scope, and existing authorization. Continue authorized work; ask only for consequential unresolved choices or required external approval. Scale depth to material risk without skipping checks. Preserve dependency and safety order; otherwise choose an appropriate verification method. Accept equivalent user or repository evidence; no other skill, named artifact, or complete lifecycle is required. Preserve source requirement and decision IDs. Bind reused evidence to relevant source versions, dirty changes, configuration, and environment; invalidate only affected claims. On continuation, reconcile task, authorization, current state, and unresolved evidence. For long work, return a compact continuation record or update an already authorized artifact; read-only skills do not persist it. Distinguish artifact readiness, verified behavior, and external-action authority. Prepare authorized work before required approval. If blocked by an instruction, cite its exact source and unresolved boundary; do not invent approval gates from caution.

Tool Routing

| Need | Preferred tool | Use it when | Fallback | |---|---|---|---| | Canonical workload and oracle | Repository fixtures, tests, expected diffs, schemas, or independently specified outcomes | Defining what success means before either candidate runs | Create the smallest deterministic fixture that represents the decision | | Isolation | Clean Git worktrees, temporary directories, controlled environment, fixed seeds, and resettable caches | Preventing one candidate or run from contaminating another | Sequential clean-room setup with verified cleanup | | Execution | The same shell runner and wrapper for every candidate | Capturing commands, exit status, stdout, stderr, timing, and artifacts consistently | Manual execution with an explicit reproducibility limitation | | Activation proof | Logs, traces, command records, process metadata, or candidate-specific artifacts | Verifying the intended alternative actually ran and did not fall back | Treat the run as invalid when activation cannot be proven | | Correctness grading | Tests, output parser, diff, schema validation, or independent oracle | Every scenario before cost comparison | Manual blind grading against written expectations | | Performance and cost | Monotonic timer, resource metrics, token or usage telemetry, tool-call logs, and failure counts | Metrics are observable through the same method for all candidates | Label derived or estimated values and keep them out of measured aggregates | | External semantics | Official documentation and specifications | Candidate configuration or claimed behavior needs current verification | Primary-source web research; otherwise mark the claim `UNVERIFIED` |

Do not tune the scenario after observing a preferred candidate, mix measurements from different workloads, or present internal estimates as externally measured facts. Benchmarking may create temporary worktrees and artifacts but must not change the source baseline or unapproved external state.

Evidence Rules

• Hold all non-tested variables constant or record and analyze the confounder.
• Correctness failure cannot be compensated by better speed, token use, or cost unless the decision explicitly allows degraded correctness.
• Use repeated runs and report raw values, center, spread, failures, and outliers; never headline the best run.
• Keep setup or indexing cost, steady-state cost, maintenance burden, and runtime cost separate.
• Report measured, derived, estimated, and qualitative evidence in distinct fields.

Checklist

1. Define the Decision and Experiment

• [ ] State the decision the benchmark must support, the candidates, intended users, representative workloads, and explicit non-goals.
• [ ] Include ordinary cases where a simpler or built-in candidate could reasonably win as well as cases exercising each candidate's claimed advantage; do not construct a feature demo for one side.
• [ ] Define scenario inputs, expected outcomes, correctness criteria, failure conditions, and an oracle independent of candidate self-report.
• [ ] Define primary and secondary metrics, units, measurement point, acceptance threshold, allowed tradeoffs, and tie or inconclusive rules.
• [ ] Define the treatment variable, then hold other relevant variables fixed: revision, model, prompts, permissions, runtime, hardware, data, caches, and network. A variable being compared cannot also be declared fixed.
• [ ] Predeclare repetitions using existing variability evidence or a bounded pilot, or a bounded sequential rule with fixed error tolerance and maximum runs. Return `INCONCLUSIVE` if the budget cannot resolve the meaningful effect.
• [ ] Freeze and hash the scenario text, fixtures, expectations, runner, parser, and decision rule before the first candidate result is inspected.
• [ ] Read repository instructions and inspect Git state before creating worktrees, temporary data, or runners.
• [ ] Start a run-owned resource ledger with every created absolute path, worktree, process ID, cache, account, dataset, report, and temporary artifact; never register pre-existing resources or credentials as cleanup targets.
• [ ] Require side-e