# Agentprivacy Wiki Similarity Plugin

> The wiki-plugin-similarity package — adds semantic similarity search to a fedwiki farm via two item types (similarity search form, similar ambient panel) using in-browser cosine scoring over BGE embedding vectors. Activates when adding similarity/related-pages search to a fedwiki, or as a plugin scaffolding reference. Kept by the Librarian 🗃️.

- Skill: `mitchuski/agentprivacy-wiki-similarity-plugin` (Agent Skill)
- Install (CLI): `npx skillmds@latest add mitchuski/agentprivacy-wiki-similarity-plugin`
- Raw SKILL.md: https://api.skillmd.com/api/skills/mitchuski/agentprivacy-wiki-similarity-plugin/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- License: Apache-2.0
- Author: mitchuski (https://skillmd.com/u/mitchuski)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/mitchuski/agentprivacy-wiki-similarity-plugin

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# Similarity Plugin

This plugin adds semantic similarity search to a Federated Wiki farm. It ships two item types — **similarity** (an interactive search form) and **similar** (an ambient panel that automatically finds pages related to the one you are reading).

## Repositories

- **GitHub**: `Hitchhikers-Guide-to-the-Galaxy/wiki-plugin-similarity`
- **npm**: not yet published — install locally with `npm link` during development

## How It Works

Pages in the farm are pre-indexed as 384-dimensional embedding vectors using `BAAI/bge-small-en-v1.5` via the `fastembed` library. At query time the plugin loads these compact `semantic-vectors.json` index files directly in the browser and performs cosine similarity scoring in JavaScript — no round-trip to a remote search engine.

## Item Types

**similarity** — renders a search input. Type a query and the plugin embeds it, scans the loaded indices, and presents the top matching pages as scored links with domain attribution.

**similar** — renders silently on page load. It looks up the current page's pre-computed vector from the cached index (no embed call if the page is already indexed) and displays a *Similar Pages* link list ranked by cosine score.

## Domain DSL

The item's `text` field is a small configuration language. Write one entry per line:

```
*                        all indexed domains on this server
david.*                  glob pattern
david.hitchhikers.earth  explicit domain
# comment                ignored
---
SIMILAR: high            threshold preset  (high=0.78 / medium=0.68 / low=0.58)
THRESHOLD: 0.72          exact cosine threshold
LIMIT: 8                 max results (default 10)
```

Leave `text` empty to search the current domain at the default medium threshold.

## Server Component

The plugin's `server/server.js` registers three routes with the wiki's Express app at startup — no changes to wiki-server core required:

- `GET /system/indexed-domains.json?pattern=glob` — list domains with a built index
- `GET /system/semantic-vectors.json` — serve the vector index for the current domain
- `GET /system/embed?text=…` — proxy to a local FastAPI embedding service

The embedding service runs `fastembed` in-process and responds in ~5 ms on an M-series Mac using CoreML acceleration.

## See Also

- `agentprivacy-wiki-searching-plugins` — finding plugins (this is a scaffolding template)
- `agentprivacy-wiki-create-plugin` — scaffold a new plugin
- `agentprivacy-wiki-ghost-pages` — the ghost-page pattern this plugin's forms use

---
**Verify:** [agentprivacy.ai](https://agentprivacy.ai) · kept by the Librarian 🗃️ in the Tower's Wikis (the git-less onboarding layer)
**Upstream:** [skill.fedwiki.club/similarity-plugin](https://skill.fedwiki.club/similarity-plugin) — vendored + re-framed; not original agentprivacy authorship