What it costs
Vault itself is free. MIT-licensed, no subscription, no account, no telemetry, no paywalled features. The only money involved is whatever your chosen model charges for tokens, paid to the provider — never to this project.
Prices are set by the providers, not here. They have trended down, but a provider can raise a price, retire a model or change a free tier at any time. The code stays free; the cost of running questions through it is whatever the provider charges that week.
Per session
A 3–4 hour session, 30–50 questions, against a campaign of roughly 100 KB of documents. Quoted in USD, because every one of these bills in dollars.
| Provider | Tier | Typical session | Notes |
|---|---|---|---|
| Gemini | Free | $0 | Per-minute and daily quotas cover most home games. Pace yourself during big info-dumps. |
| Gemini | Paid (Pro 2.5) | ~$0.60–$2.50 | Pay-as-you-go; spend matches what you asked. |
| OpenRouter | Mid-tier (e.g. Sonnet) | ~$0.60–$4.00 | One key, one bill, ~400 models. Live per-model pricing in the model browser. |
| OpenRouter | Frontier (e.g. Opus) | ~$4.00–$12.00 | Overkill for most questions; reserve for hard consistency problems. |
| Claude Code | Your existing plan | $0 extra | Answers through the subscription you already pay for. No API key, no metered bill. |
| Ollama | Local | $0 ongoing | Hardware you already own. Quality lags cloud frontier below ~15B params. |
The one lever that matters
How much lore goes into each prompt. With the folder source, Vault
re-reads and re-sends every file under Tusks-Lore/ on every question,
stopping at the last whole document that fits under KB_CHAR_LIMIT
(500,000 characters). A 30-PDF campaign costs noticeably more per question
than a 5-PDF one.
Pointing Vault at an Obsidian vault is the one shipped way to pay for a handful of relevant notes instead of the whole shelf — and it only starts narrowing once the vault outgrows the prompt budget, because below that, sending everything is both cheaper and better.
Capping it
Set limits at the provider, not in Vault:
- OpenRouter → Settings → Credits. It is prepaid, so the balance is the cap.
- Google AI Studio → Billing → Budget alerts.
That is where the card lives, so that is where the kill switch belongs. Vault cannot enforce a limit on a bill it never sees.
What is being done to bring it down
- Chunked retrieval for the folder source — bring to it what the Obsidian vault map already does: embed once, then retrieve only matching notes per question. The single biggest token reduction the architecture can deliver.
- Prompt caching — partly shipped. Assembly already marks the lore corpus
as the cacheable prefix and the OpenRouter adapter sets the
cache_controlbreakpoint on it, keeping per-question parts outside. Instrumenting the saving so you can see it is what remains. - Per-tier routing — easy lookups to Flash-class models, Pro/Opus reserved for questions that need them.
Ollama stays the zero-marginal-cost escape hatch, and Claude Code costs nothing extra on a plan you already have.
See the Roadmap for where these sit.
Next steps
- Choosing a provider — what each one sees, costs and needs.
- How it's built — why the corpus travels with every question.