docs(local-model): the install guide, the API and the rules

docs/local-models.md is the guide: the steps, the layout on disk, what is
written outside the folder, the failures and their next steps. The API
reference documents the install object and the five verbs, and how the list
is ordered. The rules for the server side are in CLAUDE.md and
architecture-invariants.md, the user-facing pages in the wiki.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/wiki/Custom-Model-Endpoints.md

@@ -204,6 +204,45 @@ Which harnesses show up in the Run-menu picker is read live off Codeman's own CL
 not a fixed list here, so this table can go stale before this page does — a greyed-out or
 missing entry is the more current answer.
 
+## A model that runs on this Mac
+
+If the Codeman server runs on a Mac with Apple silicon, you do not need a server of your
+own: Codeman can set one model up for you on that Mac. This is experimental.
+
+1. Press **Run a local model** on the welcome screen (or open App Settings > Models > Model
+   on this Mac).
+2. The window shows what fits this Mac. A bar shows how much of the memory the selected
+   model takes at its full context; a nearly full bar means a tight fit. Pick a model and
+   the coding agent to run it with.
+3. Press **Install on this Mac**, check the sizes and where they go, and confirm. Nothing is
+   downloaded before this click.
+4. Codeman downloads a model runtime (Ollama, about 186 MB) and the model into
+   `~/.codeman/local-model`, loads the model, checks that all of it runs on the GPU and that
+   it can call a tool, installs the coding agent if it is missing, and saves an endpoint
+   named **This Mac**. No administrator password is asked for.
+5. Press **Start a session**.
+
+Good to know:
+
+- You can close the window: the download continues while Codeman is running. **Cancel**
+  pauses it and **Continue** picks it up where it stopped. After a Codeman restart an
+  unfinished install waits for your click.
+- The memory figure is an estimate until the runtime has started once. From then on it is
+  what the runtime itself measured, and the model is judged against that before it is
+  downloaded.
+- The endpoint "This Mac" belongs to this install. It is in the list and in the Run menu,
+  but it is changed and removed in the local model window, not here.
+- Codeman starts the runtime with the server and stops it with it. **Stop** keeps it from
+  starting next time.
+- **Remove** deletes the runtime and the endpoint, and the model too if you tick that. The
+  coding agent stays installed.
+- If the model on disk is no longer the one that was installed, Codeman refuses to start a
+  session on it and tells you to remove and install it again.
+- Any program on this Mac, and any web page served from `localhost`, can reach the model
+  runtime: its port has no login. It listens on this Mac only.
+- On a Mac without Apple's developer tools, macOS will offer to install them the first time
+  a coding agent runs `git` or Python. The window tells you when that applies.
+
 ## What it does not do
 
 - **No remote or Docker sessions yet.** Both restart their agent differently under the hood

docs/wiki/Settings-Reference.md

@@ -193,19 +193,25 @@ attached.
 section to the Run dropdown, for pointing a harness at your own OpenAI-compatible server
 instead of its native cloud backend. See [Custom Model Endpoints](Custom-Model-Endpoints).
 
-**Model on this Mac** is not a setting: it is a read-only answer. When the Codeman server
-runs on a Mac with Apple silicon, it shows that Mac's chip, memory and free disk space, the
-local coding model that fits it best with the agent CLI to run it, what the model needs of
-the memory the Mac can give one, its download size and an estimated speed, and the other
-models that fit (Good or Tight for the memory, Slow or Speed unknown for the speed). A Mac
-that can only run a model under 12 billion parameters is told so in plain words, and a Mac
-with too little memory, too little free disk space or an Intel processor is told why nothing
-is offered. The numbers are estimates from a catalogue that ships with each release; nothing
-has been tested on your Mac. **Nothing is downloaded or installed from here yet**: setting
-the model up from Codeman is the next step and is not built. The same answer appears as a
-card on the welcome screen, which you can hide per device (it stays here). The group is not
-shown when the server runs on Linux or Windows, and in multi-user mode only an admin sees
-it. The "Mac" is always the machine the server runs on, not the device you are reading on.
+**Model on this Mac** is not a setting: it is the state of a model Codeman can run for you
+on the Mac the server runs on, with a button that opens the local model window. The same
+window opens from the **Run a local model** button on the welcome screen. It shows that
+Mac's chip, memory and free disk space, a bar for how much of the memory the selected model
+takes, and the models that fit, each with one tag (Best fit, Tight, Slow, Small model, or
+"Tested on a Mac like this"), a speed and a download size. **Install on this Mac** asks you
+to confirm the sizes once, then downloads a model runtime and the model into
+`~/.codeman/local-model`, checks that the model loads and can call a tool, installs the
+coding agent if it is missing, and ends on **Start a session**. No account, no API key and
+no administrator password. You can close the window while it downloads, cancel and continue
+later; after a Codeman restart an unfinished install waits for you to press Continue. Once a
+model is installed the window offers Start a session, Stop or Start, and Remove. Installing
+switches **Custom model endpoints** on and saves one endpoint named "This Mac"; Remove takes
+the endpoint away again and switches the setting back off if nothing else uses it. A Mac
+that can only run a small model is told so in plain words, and a Mac with too little memory,
+too little free disk space or an Intel processor is told why nothing is offered. The group
+is not shown when the server runs on Linux or Windows, and in multi-user mode only an admin
+sees it. The "Mac" is always the machine the server runs on, not the device you are reading
+on. Details: [Custom Model Endpoints](Custom-Model-Endpoints#a-model-that-runs-on-this-mac).
 
 ### Agents & CLIs