docs: replace all setup() references with vim.g.preview

Problem: viewer processes launched via a string[] `open` command were
always killed on buffer deletion with no way to opt out. Configuring
the plugin also required an explicit `setup()` call in a `config`
hook, preventing config from being declared before the plugin loads.

Solution: add a `detach` boolean to `ProviderConfig` that skips
SIGTERM on buffer unload. Auto-call `setup()` from `vim.g.preview`
at module load time, enabling config via lazy.nvim's `init` hook.
Update vimdoc and README accordingly.

README.md

@@ -21,8 +21,18 @@ Typst, Markdown, etc.)—diagnostics included.
 
 ## Installation
 
-Install with your package manager of choice or via
-[luarocks](https://luarocks.org/modules/barrettruth/preview.nvim):
+With lazy.nvim:
+
+```lua
+{
+  'barrettruth/preview.nvim',
+  init = function()
+    vim.g.preview = { typst = true, latex = true }
+  end,
+}
+```
+
+Or via [luarocks](https://luarocks.org/modules/barrettruth/preview.nvim):
 
 ```
 luarocks install preview.nvim
@@ -39,7 +49,7 @@ luarocks install preview.nvim
 **Q: How do I define a custom provider?**
 
 ```lua
-require('preview').setup({
+vim.g.preview = {
   rst = {
     cmd = { 'rst2html' },
     args = function(ctx)
@@ -49,15 +59,15 @@ require('preview').setup({
       return ctx.file:gsub('%.rst$', '.html')
     end,
   },
-})
+}
 ```
 
 **Q: How do I override a preset?**
 
 ```lua
-require('preview').setup({
+vim.g.preview = {
   typst = { env = { TYPST_FONT_PATHS = '/usr/share/fonts' } },
-})
+}
 ```
 
 **Q: How do I automatically open the output file?**
@@ -67,7 +77,7 @@ open the output with `vim.ui.open()` after the first successful compilation in
 toggle/watch mode. For a specific application, pass a command table:
 
 ```lua
-require('preview').setup({
+vim.g.preview = {
   typst = { open = { 'sioyek', '--new-instance' } },
-})
+}
 ```

doc/preview.nvim.txt

@@ -23,23 +23,20 @@ REQUIREMENTS                                          *preview.nvim-requirements
 ==============================================================================
 SETUP                                                  *preview.nvim-setup*
 
-Load preview.nvim with your package manager. For example, with lazy.nvim: >lua
+Set |vim.g.preview| before the plugin loads: >lua
     {
       'barrettruth/preview.nvim',
+      init = function()
+        vim.g.preview = { typst = true, latex = true }
+      end,
     }
 <
-Call |preview.setup()| to configure providers before use.
 
 ==============================================================================
 CONFIGURATION                                      *preview.nvim-configuration*
 
-Configure via `require('preview').setup()`.
-
-                                                            *preview.setup()*
-setup({opts?})
-
-  `opts` is a table where keys are preset names or filetypes. For each
-  key `k` with value `v` (excluding `debug`):
+Configure by setting |vim.g.preview| to a table where keys are preset names
+or filetypes. For each key `k` with value `v` (excluding `debug`):
 
   - If `k` is a preset name and `v` is `true`, the preset is registered
     as-is under its filetype.
@@ -108,6 +105,12 @@ Provider fields:~
                                        |preview.Context| and returns a
                                        string[].
 
+  `detach`           boolean           When `true`, the viewer process opened
+                                       via a string[] `open` command is not
+                                       sent SIGTERM when the buffer is deleted.
+                                       Has no effect when `open` is `true`.
+                                       Default: `false`.
+
                                                         *preview.Context*
 Context fields:~
 
@@ -120,30 +123,30 @@ Context fields:~
 
 Example enabling presets:~
 >lua
-    require('preview').setup({ typst = true, latex = true, github = true })
+    vim.g.preview = { typst = true, latex = true, github = true }
 <
 
 Example overriding a preset field:~
 >lua
-    require('preview').setup({
+    vim.g.preview = {
       typst = { open = { 'sioyek', '--new-instance' } },
-    })
+    }
 <
 
 Example overriding the output path (e.g. latexmk `$out_dir`):~
 >lua
-    require('preview').setup({
+    vim.g.preview = {
       latex = {
         output = function(ctx)
           return 'build/' .. vim.fn.fnamemodify(ctx.file, ':t:r') .. '.pdf'
         end,
       },
-    })
+    }
 <
 
 Example with a fully custom provider (key is not a preset name):~
 >lua
-    require('preview').setup({
+    vim.g.preview = {
       rst = {
         cmd = { 'rst2html' },
         args = function(ctx)
@@ -153,7 +156,7 @@ Example with a fully custom provider (key is not a preset name):~
           return ctx.file:gsub('%.rst$', '.html')
         end,
       },
-    })
+    }
 <
 
 ==============================================================================
@@ -173,14 +176,14 @@ Import them from `preview.presets`:
 
 Enable presets with `preset_name = true`:
 >lua
-    require('preview').setup({ typst = true, latex = true, github = true })
+    vim.g.preview = { typst = true, latex = true, github = true }
 <
 
 Override individual fields by passing a table instead of `true`:
 >lua
-    require('preview').setup({
+    vim.g.preview = {
       typst = { env = { TYPST_FONT_PATHS = '/usr/share/fonts' } },
-    })
+    }
 <
 
 ==============================================================================

lua/preview/compiler.lua

@@ -291,7 +291,9 @@ function M.compile(bufnr, name, provider, ctx, opts)
       callback = function()
         M.stop(bufnr)
         stop_open_watcher(bufnr)
-        close_viewer(bufnr)
+        if not provider.detach then
+          close_viewer(bufnr)
+        end
         last_output[bufnr] = nil
       end,
     })
@@ -404,7 +406,9 @@ function M.compile(bufnr, name, provider, ctx, opts)
     once = true,
     callback = function()
       M.stop(bufnr)
-      close_viewer(bufnr)
+      if not provider.detach then
+        close_viewer(bufnr)
+      end
       last_output[bufnr] = nil
     end,
   })
@@ -507,7 +511,9 @@ function M.toggle(bufnr, name, provider, ctx_builder)
     callback = function()
       M.unwatch(bufnr)
       stop_open_watcher(bufnr)
-      close_viewer(bufnr)
+      if not provider.detach then
+        close_viewer(bufnr)
+      end
       opened[bufnr] = nil
     end,
   })

lua/preview/init.lua

@@ -10,6 +10,7 @@
 ---@field clean? string[]|fun(ctx: preview.Context): string[]
 ---@field open? boolean|string[]
 ---@field reload? boolean|string[]|fun(ctx: preview.Context): string[]
+---@field detach? boolean
 
 ---@class preview.Config
 ---@field debug boolean|string
@@ -101,6 +102,7 @@ function M.setup(opts)
     end, 'false, "diagnostic", or "quickfix"')
     vim.validate(prefix .. '.open', provider.open, { 'boolean', 'table' }, true)
     vim.validate(prefix .. '.reload', provider.reload, { 'boolean', 'table', 'function' }, true)
+    vim.validate(prefix .. '.detach', provider.detach, 'boolean', true)
   end
 
   config = vim.tbl_deep_extend('force', default_config, {
@@ -246,4 +248,8 @@ M._test = {
   end,
 }
 
+if vim.g.preview then
+  M.setup(vim.g.preview)
+end
+
 return M