Ln 840 Benchmark Compare

Paths: File paths (references/) are relative to this skill directory.

Benchmark Compare

Type: L3 Worker Category: 8XX Optimization -> 840 Benchmark

Run a clean A/B benchmark in Claude Code: one session with built-in tools only, one with hex-line. The benchmark is scenario-based, diff-validated, manifest-driven, and runtime-backed. It measures activation, correctness, time, cost, and tokens. The current runner is intentionally scoped to this internal A/B. It does not, by itself, prove best-in-class against external alternatives.

Input / Output

Prerequisites

• claude --version succeeds
• git succeeds
• mcp/hex-line-mcp/server.mjs exists
• mcp/hex-line-mcp/hook.mjs exists
• plugins/optimization-suite/skills/ln-840-benchmark-compare/references/goals.md exists
• plugins/optimization-suite/skills/ln-840-benchmark-compare/references/expectations.json exists
• plugins/optimization-suite/skills/ln-840-benchmark-compare/references/mcp-bench.json exists

Quick Run

bash plugins/optimization-suite/skills/ln-840-benchmark-compare/scripts/run-benchmark.sh \
  [plugins/optimization-suite/skills/ln-840-benchmark-compare/references/goals.md] \
  [plugins/optimization-suite/skills/ln-840-benchmark-compare/references/expectations.json]

Optional extra session profile:

EXTRA_SESSION_ID=other-mcp \
EXTRA_SESSION_LABEL="Other MCP" \
EXTRA_MCP_CONFIG=/abs/path/to/other-mcp.json \
EXTRA_SETTINGS='{"disableAllHooks":true}' \
bash plugins/optimization-suite/skills/ln-840-benchmark-compare/scripts/run-benchmark.sh

Monitor Integration (Claude Code 2.1.98+)

MANDATORY READ: Load references/monitor_integration_pattern.md

Stream benchmark progress: Monitor(command="bash plugins/optimization-suite/skills/ln-840-benchmark-compare/scripts/run-benchmark.sh 2>&1 | grep --line-buffered -E 'scenario|PASS|FAIL|error|session'", timeout_ms=3600000, description="benchmark run")

Fallback: Bash(run_in_background=true).

The runner handles:

• syntax preflight
• SessionStart preflight
• scenario extraction from goals.md
• isolated worktrees per scenario/session
• per-scenario diffs
• final comparison report

Current scope:

• built-in Claude session
• Claude plus hex-line
• optional third Claude-compatible session profile through EXTRA_SESSION_* environment variables

External baseline note:

• use the same goals.md and expectations.json
• do not rewrite scenarios to fit the external tool
• do not make "top tool" claims from the internal A/B alone
• the optional third session profile is only valid when it can emit the same stream-json log shape and diff artifacts

Workflow

Phase 1: Define The Canonical Suite

Use one canonical pair owned by this skill:

• plugins/optimization-suite/skills/ln-840-benchmark-compare/references/goals.md
• plugins/optimization-suite/skills/ln-840-benchmark-compare/references/expectations.json

Rules:

• The suite must be a balanced mix of common engineering scenarios.
• Do not design the suite to favor hex-line.
• Every scenario in goals.md must have a matching entry in expectations.json.
• expectations.json is the source of truth for correctness.
• The same pair must be reused unchanged for any future external baseline.

Supported expectation fields per scenario:

Phase 2: Preflight

The runner must pass:

• node --check server.mjs
• node --check hook.mjs
• node --check extract-scenarios.mjs
• node --check parse-results.mjs
• SessionStart smoke check from hook.mjs

If preflight fails, the benchmark is invalid and must stop before scenarios run.

Phase 3: Execute Per Scenario

For each ## scenario in goals.md:

1. generate a standalone prompt file
2. create two clean worktrees from the same commit
3. run built-in Claude session
4. run hex-line Claude session
5. save .jsonl logs and .diff.txt artifacts
6. remove both worktrees

Built-in session:

• no MCP
• hooks disabled

Hex-line session:

• resolved MCP config pointing to server.mjs
• outputStyle: "hex-line"
• PreToolUse hook through hook.mjs

Phase 4: Parse Results

parse-results.mjs evaluates each scenario for both sessions.

Scenario pass requires:

• valid run
• successful session completion
• changed files match expectations
• diff patterns match expectations
• result text patterns match expectations
• required commands were actually executed

Phase 5: Read The Report

The final report has these sections:

• Scenario Outcomes
• Activation
• Time
• Cost
• Tokens
• Tool Totals
• Validity

Interpretation rules:

• invalid run means setup/adoption failure, not product performance
• scenario FAIL means correctness contract was not met
• activation is part of product quality for hex-line, not external noise
• this report is necessary for internal A/B evaluation, but not sufficient for best-alternative claims

Report Contract

plugins/optimization-suite/skills/ln-840-benchmark-compare/results/{date}-comparison.md must answer:

• Did each scenario complete correctly?
• Did hex-line activate cleanly without discovery drift?
• What changed in wall time, API time, cost, output tokens, and total tool calls?
• Was the run valid?

Do not treat raw time/cost as sufficient without scenario correctness.

External Baseline Policy

• This skill owns the canonical suite, not a universal leaderboard.
• If maintainers compare hex-line against external alternatives, they must reuse the same goals.md, expectations.json, and diff-based evaluation rules.
• External runs may use different harnesses, but they must preserve the same task text, starting commit, and correctness contract.
• If an external tool cannot satisfy the contract format, record that as a harness limitation instead of rewriting the suite to accommodate it.
• A report that only covers built-in Claude vs hex-line must say so explicitly.

Runtime Contract

MANDATORY READ: Load references/benchmark_worker_runtime_contract.md, references/coordinator_summary_contract.md

Runtime CLI:

node references/scripts/benchmark-worker-runtime/cli.mjs start --skill ln-840-benchmark-compare --identifier suite-default --manifest-file <file>
node references/scripts/benchmark-worker-runtime/cli.mjs checkpoint --skill ln-840-benchmark-compare --identifier suite-default --phase PHASE_0_CONFIG --payload '{...}'
node references/scripts/benchmark-worker-runtime/cli.mjs record-summary --skill ln-840-benchmark-compare --identifier suite-default --payload '{...}'
node references/scripts/benchmark-worker-runtime/cli.mjs complete --skill ln-840-benchmark-compare --identifier suite-default

Required state fields:

• report_ready
• summary_recorded
• final_result
• self_check_passed

Domain checkpoints:

• PHASE_0_CONFIG
• PHASE_1_PREFLIGHT
• PHASE_2_LOAD_SUITE
• PHASE_3_RUN_SCENARIOS
• PHASE_4_PARSE_RESULTS
• PHASE_5_WRITE_REPORT
• PHASE_6_WRITE_SUMMARY
• PHASE_7_SELF_CHECK

Guard rules:

• do not advance without checkpointing the current phase
• do not complete before benchmark-worker summary is recorded
• do not complete before self-check passes

Runtime Coordination

• Managed runs may pass deterministic runId and exact summaryArtifactPath.
• Standalone runs are supported. If both are omitted, runtime creates a standalone run and writes the default summary artifact path for the benchmark-worker family.

Runtime Summary Artifact

MANDATORY READ: Load references/coordinator_summary_contract.md

Emit a benchmark-worker summary envelope after the comparison report is written.

Managed mode:

• write to the exact summaryArtifactPath

Standalone mode:

• write .hex-skills/runtime-artifacts/runs/{run_id}/benchmark-worker/ln-840-benchmark-compare--{identifier}.json

Recommended payload:

• scenarios_total
• scenarios_passed
• scenarios_failed
• activation_valid
• validity_verdict
• report_path
• warnings
• metrics

Known Pitfalls

Definition of Done

• goals.md defines the canonical balanced suite
• expectations.json fully describes scenario correctness
• Runner passes syntax and SessionStart preflight
• Each scenario runs in two clean worktrees from the same commit
• Parser evaluates activation and scenario correctness from logs plus diffs
• Final report is saved to plugins/optimization-suite/skills/ln-840-benchmark-compare/results/
• benchmark-worker summary artifact is written to the managed or standalone runtime path
• Temporary worktrees are removed
• Report states clearly whether it is internal A/B only or includes additional external baselines

Version: 2.0.0 Last Updated: 2026-03-24