About harness-similarity
harness-similarity is a callable skill that compares harnesses using numerical, categorical, and agent-topology data. It is for ranking templates, deciding whether to fork or scaffold, and finding duplicate work; it also provides per-dimension results.
Key features
- 01Combines cosine, categorical, and Jaccard similarity
- 02Compares files or persisted memory records
- 03Provides per-dimension breakdowns
- 04Handles malformed input without throwing
- 05Exposes a CLI command and MCP tool
Use cases
- 01Choose between forking a harness and scaffolding
- 02Rank templates against a repository genome
- 03Find duplicate work across team harnesses
- 04Generate similarity confidence for a recommender
MCP support
The skill registers an MCP tool, `mcp__plugin_ruflo-core_ruflo__metaharness_similarity`, for invoking the harness similarity function.
Install
Copy the command and run it in a terminal.
npx skills add https:/ / github.com/ ruvnet/ ruflo --skill harness-similarityAfter installing, type/harness-similarityin Claude Code to confirm it loaded.
Details
From the project READMESurfaces the production similarity function from scripts/_similarity.mjs as a callable skill. Use when an agent needs to:
- decide whether to fork an existing harness vs scaffold a new one
- rank candidate templates against a target repo's genome
- diff two harnesses produced by different teams to find duplicate work
- generate the confidence number that ADR-151 §3.2's Recommender wraps
Algorithm (from ADR-152 §Decision)
overall = 0.60·cosine + 0.25·categorical + 0.15·jaccard
- cosine — over a 9-dim numerical vector of normalized scorecard + genome dims
- categorical — fraction of 4 enum fields that match (
repo_type,archetype,template,recommendedMode) - jaccard —
|A ∩ B| / |A ∪ B|over theagent_topology[]array
The 3-component design is load-bearing: numerical cosine alone is too coarse (the iter-35 spike showed LEGAL vs DEVOPS at cosine=0.97 despite being unrelated verticals). Categorical + jaccard pull the composite to the correct ordering.
Reference outputs (iter-35 spike fixtures)
| Pair | overall | cosine | categorical | jaccard |
|---|---|---|---|---|
LEGAL × LEGAL (self) | 1.0000 | 1.0000 | 1.0000 | 1.0000 |
LEGAL × SUPPORT | 0.8296 | 0.9987 | 0.7500 | 0.2857 |
LEGAL × DEVOPS | 0.5840 | 0.9734 | 0.0000 | 0.0000 |
Both invariants from ADR-152 §"Smallest demonstrable spike" hold:
similarity(X, X) === 1exactlysimilarity(LEGAL, DEVOPS) < similarity(LEGAL, SUPPORT)(vertical affinity)
Architectural constraint inheritance (ADR-150)
- Removable — pure-TS function, zero static
@metaharness/*imports. - Optional — no new dep in
package.json. - Graceful — malformed inputs emit
{ degraded: true, reason }with exit code 2; never throws. - CI-gate — smoke step 17y locks the contract: module exports, spike fixtures reproduce, CLI dispatcher entry registered, MCP tool registered.
Usage
# File inputs
npx ruflo metaharness similarity --a a.json --b b.json
# Memory inputs (records persisted by oia-audit.mjs)
npx ruflo metaharness similarity --a-key harness-X --b-key harness-Y
# Per-dimension breakdown (used by ADR-151 §3.2 Recommender)
npx ruflo metaharness similarity --a a.json --b b.json --per-dimension
# Alert when too-dissimilar (used by ADR-151 §3.3 Drift Detection)
npx ruflo metaharness similarity --a a.json --b b.json --alert-below 0.5
Implementation
Production module: scripts/_similarity.mjs
CLI skill: scripts/similarity.mjs
MCP tool: mcp__plugin_ruflo-core_ruflo__metaharness_similarity (registered in v3/@claude-flow/cli/src/mcp-tools/metaharness-tools.ts)
Spike anchor: scripts/_spike-similarity.mjs (regression suite — invariants locked here)