# Editor support

The binding language has no render errors. An unknown path renders as empty, never as the path
itself and never as `undefined`, so a typo ships silently and is found by a shopper looking at a
blank element.

`mercemur theme check` catches that at commit time. The language server catches it at keystroke
time, which is where it is cheapest to fix.

## What it does

| | |
|---|---|
| **Completion** | Only the objects **this** template kind is bound with. A product template offers `product`, not `shop`, because `shop.*` there renders empty |
| **Diagnostics** | A path that is not in the contract, an object the page was never given, an amount without the money filter |
| **Hover** | What a property holds, and whether it is an amount in minor units |

Completing an amount inserts the filter with it: choosing `price` writes `price | money`. Rendering
`1999` at a shopper is the most common binding mistake, and completion is the one moment a tool can
prevent it rather than report it.

## VS Code

There is no marketplace extension yet. Point any generic LSP client at the binary. With
[vscode-glspc](https://marketplace.visualstudio.com/items?itemName=llllvvuu.vscode-glspc):

```json settings.json
{
  "glspc.languageId": "html",
  "glspc.serverCommand": "mercemur",
  "glspc.serverCommandArguments": ["language-server"],
  "glspc.documentSelector": ["**/templates/*.liquid"]
}
```

## Neovim

```lua init.lua
vim.api.nvim_create_autocmd("FileType", {
  pattern = "liquid",
  callback = function()
    vim.lsp.start({
      name = "mercemur",
      cmd = { "mercemur", "language-server" },
      root_dir = vim.fs.dirname(vim.fs.find({ "online-store.json" }, { upward = true })[1]),
    })
  end,
})
```

## Zed

```json settings.json
{
  "lsp": {
    "mercemur": {
      "binary": { "path": "mercemur", "arguments": ["language-server"] }
    }
  }
}
```

## Working offline

The server fetches the contract once at startup, on a short timeout, and never fails if it cannot.
Without a store or a key it still runs and still reports the rules that need no schema, because an
editor that fails to start is worse than one that knows less. A laptop on a plane is a normal place
to edit a template.

The same applies to `theme check`: it says so explicitly when paths were not checked, rather than
reporting "nothing to report" and letting that read as "every path is real".

```bash
mercemur theme check --offline   # skip the fetch deliberately
```

<Note>
  `mercemur language-server` is not run by hand. An editor starts it and speaks LSP over stdin and
  stdout; stdout is the protocol channel, so the command prints nothing of its own.
</Note>