How-to guides
How OOMU picks a model
System 1, and what it decides.
Every message you send first passes through a small model whose only job is to work out what kind of request it is. It is local, it never writes your answer, and it runs before anything else happens. OOMU calls it System 1.
The chat shows it working: "Understanding your request…"
Your choice comes first
The Model control above the composer sets the frame System 1 has to work inside:
| Choice | Behavior |
|---|---|
| Automatic | "OOMU chooses on-device or your default cloud model for each request." |
| On this Mac | "Keep reasoning on this Mac." |
| Cloud | "Always use the exact cloud service and model you select." |
Agents carry the same three-way choice, and a chat with an agent uses the agent's choice, so a research agent can be pinned to a cloud model while an everyday agent stays local.
Three things keep Automatic on this Mac, and none of them can be argued with:
- Use cloud models in Automatic in Settings → Models & Providers is off until you turn it on: "Local-only projects always stay on this Mac."
- A project set to Only this Mac removes the cloud entirely, even for a chat set to Cloud.
- Air-Gap Mode removes it globally. See Enterprise security.
With cloud allowed, Automatic still answers on this Mac by default. It turns to your cloud model when the request calls for it, for example when you ask for a named cloud model to answer.
The model
| Name | OOMU System One, running Bosun v3.1 |
| Size | 0.6 billion parameters, Q8_0, about 640 MB |
| License | Apache-2.0 |
| Runs on | Apple Silicon, through Metal |
| Reads | Your request, and whether files are attached. Up to 8,192 tokens. |
| Writes | Nothing. It scores a short list of options and OOMU takes the most likely one. |
Because it only scores options instead of writing text, System 1 returns in tens of milliseconds once it is warm. Its file is checked against the SHA-256 in OOMU's manifest before it is loaded, and each decision is recorded with that digest, the probability of each option, and how long it took.
Settings → Models & Providers shows its version and whether an update is available. OOMU checks for System 1 updates at startup and every 24 hours, separately from app updates, and you choose when to install one. A failed update keeps your current model. Air-Gap Mode stops the check.
What System 1 chooses between
| Option | When |
|---|---|
| Respond in this conversation | Explain, calculate, write code or prose, summarize attached files, or show a table. |
| Answer with an explicitly requested cloud model | You name a cloud model for the answer. |
| Coordinate multiple operations | The request needs several steps, or an action not on this list. |
| Read a local file · List a local folder | Work with files on your Mac. |
| Search the public web | Current information from public sources. |
| Add or read Apple Reminders | |
| Read Apple Mail · Create an email in Apple Mail | An email is saved as an unsent draft. |
| Read or add Apple Calendar events | |
| Save a note in Apple Notes | |
| Read battery status | Charge, charging state, and power source. |
| Run a shell command | Always shown to you for approval first. See Automating your Mac. |
| Save a Word document · Save an Excel workbook |
Options for capabilities your copy of OOMU does not offer are left off the list. If an action is chosen but macOS has not granted the access it needs, OOMU tells you which setting to open rather than failing silently.
What happens next
A plain answer goes straight to the answer. When System 1 picks Respond in this conversation, there is no planning step at all. The assistant starts writing, and you see the reply stream in as it is written.
A single clear action goes straight to that action. When System 1 is confident about one action, OOMU skips planning and goes to it directly. The assistant's only job is to fill in the details, such as the reminder's title and date, and those details are checked against the action's rules before anything runs.
Anything larger is planned. Coordinate multiple operations, or a single action System 1 is not confident about, goes to the assistant with the list of actions it may use. It can take at most eight tool steps before it has to give you an answer.
Your attachments come first. If you have attached a file, a question about it is answered from the file. OOMU does not go looking on your disk for something you already handed it.
It asks rather than guesses. If a request looks like it wants a file but names none and nothing is attached, OOMU asks: "Which documents or folder would you like me to analyze? Attach the documents or provide their path."
When you already know what you want
An @ tag skips System 1. @Calendar means the calendar, and OOMU does not second-guess it. The same is true of a Mod's tag. This is the most reliable way to work with a small local model.
Some things never need a model at all. A calculation in the Quick Launcher is evaluated by native code, exactly, and returns instantly.
When you need a clarification
If a request is genuinely ambiguous, the chat shows a small panel rather than guessing:
One detail OOMU needs a little more information.
Answer it and the turn continues. A wrong guess that runs is worse than a question that costs you three seconds.
If OOMU cannot route a request reliably at all, the chat says so plainly: "OOMU couldn't understand that request reliably. Try saying it another way." It does not fall back to guessing.
Watching it work
- The composer shows Auto-route ready · {route} once the decision lands.
- The Tuning panel shows the Active route for the session.
- The reply carries its own provenance: whether it came from this Mac, a cloud provider, or native code, and which model.
A reply from native code cannot claim a cloud provider. The provenance record enforces that, and a response with no native execution receipt behind it cannot claim one either.
Web grounding
When a request needs current information, OOMU uses web.public.retrieve. That runs one search, entirely out of sight: a direct text-only request first, and a headless pass only if that comes back empty. No browser window ever opens. The chat labels the section Web research and lists the Sources it read, so an answer that depended on the web says which pages.
Every link the answer cites is checked against the URLs the search actually returned. The prose is the model's; the citations have to be real.
Details are in Automating your Mac.
Related
- Choosing a local model: the models System 1 hands work to.
- Enterprise security: Air-Gap Mode, which removes the cloud route.
- System design overview: where routing sits in the whole.