---
description: Query the SecondBrain vault knowledge graph for cross-project evergreen knowledge — conventions, tool behavior, client facts, patterns that generalize beyond one repo. Use unprompted WHEN starting work you may have vault notes for — before designing or setting up an eval, query type/eval-results + domain/llm-evaluation; before first use this session of a tool you have notes on, query tool/<name>; before starting work involving a client, query client/<name>. Don't re-query a facet already queried this session.
---

**Scope:** vault at `~/Documents/SecondBrain` — cross-project evergreen knowledge, not codebase structure. For codebase structure and module relationships in the current repo, use `/os-vault:onboard-project`.

## When to query unprompted

- Before designing or setting up an eval → query `type/eval-results` + `domain/llm-evaluation`
  (and the project facet): what was already run, what the hypotheses/results were, what
  mistakes not to repeat.
- Before first use this session of a tool you have vault notes for → query `tool/<name>`.
- Before starting work involving a client → query `client/<name>`.
- Don't re-query a facet already queried this session — the note content is in context.

Use this skill when you need to retrieve evergreen knowledge from the SecondBrain vault (conventions, tool/API behavior, client facts, cross-project patterns). For **episodic questions** ("what did we do last week", "when did X happen"), use memsearch instead.

## Query commands

```bash
# Explore a topic (start here)
graphify query "<topic>" --budget 2000

# Trace a relationship between two notes
graphify path "<note-a>" "<note-b>"

# Deep-dive a specific node
graphify explain "<node-name>"

# Bounded depth-first traversal
graphify query "<topic>" --dfs --budget 2000
```

## Tag-scoped retrieval (separate path — use with caution)

Facet-tag-based graph traversal is **not yet verified** (ADR-014 open). Whether shared facet tags (e.g. `client/acme`) create graph edges is unknown. Treat tag-based filtering as a distinct, experimental path — do not assume it works like graph traversal.

For tag-scoped queries, try:
```bash
graphify query "client/acme" --budget 2000
```
…and verify the results are actually tag-filtered before trusting them.

## Episodic questions → memsearch

For questions about sessions, events, or time-ordered history, use memsearch directly with natural language — do not use graphify for episodic retrieval.

## Writing to vault

Use `/os-vault:write` when knowledge generalizes beyond the current repo. Routing heuristic: "Would this be useful outside this repo, next year?" If yes → vault via `/os-vault:write`. If no → project-graph only (no persistent write needed). See `~/.claude/CLAUDE.md` for the full routing rule.
