feat: rename watch → toggle, auto-compile on start, built-in opener

Problem: :Preview watch only registered a BufWritePost autocmd without compiling immediately, required boilerplate to open output files after first compilation, and was misleadingly named. Solution: Rename watch → toggle throughout. M.toggle now compiles immediately on activation. Add an open field to ProviderConfig: true calls vim.ui.open(), a string[] runs the command with the output path appended, tracked per-buffer so the file opens only once. All presets default to { 'xdg-open' }. Health check validates opener binaries. Guard the async compile callback against invalid buffer ids.
2026-03-02 23:37:44 -05:00 · 2026-03-02 23:37:44 -05:00 · 673573044f
commit 673573044f
parent c62c930454
12 changed files with 346 additions and 176 deletions
--- a/README.md
+++ b/README.md
@ -1,10 +1,9 @@
 # preview.nvim

-Async document compilation for Neovim.
+**Async document compilation for Neovim**

-A framework for compiling documents (LaTeX, Typst, Markdown, etc.)
-asynchronously with error diagnostics. Ships with zero defaults — you configure
-your own providers.
+An extensible framework for compiling documents (LaTeX, Typst, Markdown, etc.)
+asynchronously with error diagnostics.

 ## Features

@ -12,59 +11,68 @@ your own providers.
 - Compiler errors as native `vim.diagnostic`
 - User events for extensibility (`PreviewCompileStarted`,
  `PreviewCompileSuccess`, `PreviewCompileFailed`)
+- Built-in presets for Typst, LaTeX, Markdown, and GitHub-flavored Markdown
 - `:checkhealth` integration
 - Zero dependencies beyond Neovim 0.11.0+

 ## Requirements

- Neovim >= 0.11.0
- A compiler binary for each provider you configure
+- Neovim 0.11.0+

 ## Installation

-```lua
-- lazy.nvim
-{ 'barrettruth/preview.nvim' }
+Install with your package manager of choice or via
+[luarocks](https://luarocks.org/modules/barrettruth/preview.nvim):
+
 ```
-
-```vim
-" luarocks
-:Rocks install preview.nvim
-```
-
-## Configuration
-
-Use built-in presets for common tools:
-
-```lua
-local presets = require('preview.presets')
-vim.g.preview = {
-  providers = {
-    typst = presets.typst,
-    tex = presets.latex,
-    markdown = presets.markdown,
-  },
-}
-```
-
-Or define providers manually:
-
-```lua
-vim.g.preview = {
-  providers = {
-    typst = {
-      cmd = { 'typst', 'compile' },
-      args = function(ctx)
-        return { ctx.file }
-      end,
-      output = function(ctx)
-        return ctx.file:gsub('%.typ$', '.pdf')
-      end,
-    },
-  },
-}
+luarocks install preview.nvim
 ```

 ## Documentation

-See `:help preview.nvim` for full documentation.
+```vim
+:help preview.nvim
+```
+
+## FAQ
+
+**Q: How do I define a custom provider?**
+
+```lua
+require('preview').setup({
+  typst = {
+    cmd = { 'typst', 'compile' },
+    args = function(ctx)
+      return { ctx.file }
+    end,
+    output = function(ctx)
+      return ctx.file:gsub('%.typ$', '.pdf')
+    end,
+  },
+})
+```
+
+**Q: How do I override a preset?**
+
+```lua
+local presets = require('preview.presets')
+require('preview').setup({
+  typst = vim.tbl_deep_extend('force', presets.typst, {
+    env = { TYPST_FONT_PATHS = '/usr/share/fonts' },
+  }),
+})
+```
+
+**Q: How do I automatically open the output file?**
+
+Set `open = true` on your provider (all built-in presets have this enabled) to
+open the output with `vim.ui.open()` after the first successful compilation.
+For a specific application, pass a command table:
+
+```lua
+typst = vim.tbl_deep_extend('force', presets.typst, {
+  open = { 'sioyek', '--new-instance' },
+})
+```
+
+See `:h preview.nvim` for more information.
--- a/doc/preview.nvim.txt
+++ b/doc/preview.nvim.txt
@ -37,18 +37,21 @@ With lazy.nvim:
 ==============================================================================
 CONFIGURATION                                      *preview.nvim-configuration*

-Configure via the `vim.g.preview` global table before the plugin loads.
+Configure via `require('preview').setup()`.

-                                                            *preview.Config*
-Fields:~
+                                                            *preview.setup()*
+setup({opts?})
+
+  `opts` is a mixed table. Array entries are preset names (see
+  |preview.nvim-presets|). Hash entries with table values are custom
+  provider configs keyed by filetype.
+
+  Fields:~

  `debug`            boolean|string   Enable debug logging. A string value
                                    is treated as a log file path.
                                    Default: `false`

-  `providers`        table            Provider configurations keyed by
-                                    filetype. Default: `{}`
-
                                                    *preview.ProviderConfig*
 Provider fields:~

@ -74,6 +77,12 @@ Provider fields:~
                                       If a function, receives a
                                       |preview.Context|.

+  `open`             boolean|string[]   Open the output file after the first
+                                       successful compilation. `true` uses
+                                       |vim.ui.open()|. A string[] is run as
+                                       a command with the output path appended.
+                                       Presets default to `{ 'xdg-open' }`.
+
                                                        *preview.Context*
 Context fields:~

@ -82,38 +91,36 @@ Context fields:~
  `root`    string     Project root (git root or file directory).
  `ft`      string     Filetype.

-Example:~
+Example using preset names:~
 >lua
-    vim.g.preview = {
-      providers = {
-        typst = {
-          cmd = { 'typst', 'compile' },
-          args = function(ctx)
-            return { ctx.file }
-          end,
-          output = function(ctx)
-            return ctx.file:gsub('%.typ$', '.pdf')
-          end,
-          error_parser = function(stderr, ctx)
-            local diagnostics = {}
-            for line, col, msg in stderr:gmatch('error:.-(%d+):(%d+):%s*(.-)%\n') do
-              table.insert(diagnostics, {
-                lnum = tonumber(line) - 1,
-                col = tonumber(col) - 1,
-                message = msg,
-                severity = vim.diagnostic.severity.ERROR,
-              })
-            end
-            return diagnostics
-          end,
-        },
-        tex = {
-          cmd = { 'latexmk' },
-          args = { '-pdf', '-interaction=nonstopmode' },
-          clean = { 'latexmk', '-c' },
-        },
+    require('preview').setup({ 'typst', 'latex', 'markdown' })
+<
+
+Example with a custom provider:~
+>lua
+    require('preview').setup({
+      typst = {
+        cmd = { 'typst', 'compile' },
+        args = function(ctx)
+          return { ctx.file }
+        end,
+        output = function(ctx)
+          return ctx.file:gsub('%.typ$', '.pdf')
+        end,
+        error_parser = function(stderr, ctx)
+          local diagnostics = {}
+          for line, col, msg in stderr:gmatch('error:.-(%d+):(%d+):%s*(.-)%\n') do
+            table.insert(diagnostics, {
+              lnum = tonumber(line) - 1,
+              col = tonumber(col) - 1,
+              message = msg,
+              severity = vim.diagnostic.severity.ERROR,
+            })
+          end
+          return diagnostics
+        end,
      },
-    }
+    })
 <

 ==============================================================================
@ -122,32 +129,24 @@ PRESETS                                                *preview.nvim-presets*
 preview.nvim ships with pre-built provider configurations for common tools.
 Import them from `preview.presets`:

-  `presets.typst`      typst compile → PDF
-  `presets.latex`      latexmk -pdf → PDF (with clean support)
-  `presets.markdown`   pandoc → PDF
+  `presets.typst`              typst compile → PDF
+  `presets.latex`              latexmk -pdf → PDF (with clean support)
+  `presets.markdown`           pandoc → HTML (standalone, embedded)
+  `presets.github`             pandoc → HTML (GitHub-styled)

-Example:~
+Pass preset names as array entries to `setup()`:
 >lua
-    local presets = require('preview.presets')
-    vim.g.preview = {
-      providers = {
-        typst = presets.typst,
-        tex = presets.latex,
-        markdown = presets.markdown,
-      },
-    }
+    require('preview').setup({ 'typst', 'latex', 'markdown' })
 <

-Override individual fields with `vim.tbl_deep_extend`:
+Override individual fields using `vim.tbl_deep_extend`:
 >lua
    local presets = require('preview.presets')
-    vim.g.preview = {
-      providers = {
-        typst = vim.tbl_deep_extend('force', presets.typst, {
-          env = { TYPST_FONT_PATHS = '/usr/share/fonts' },
-        }),
-      },
-    }
+    require('preview').setup({
+      typst = vim.tbl_deep_extend('force', presets.typst, {
+        env = { TYPST_FONT_PATHS = '/usr/share/fonts' },
+      }),
+    })
 <

 ==============================================================================
@ -160,7 +159,7 @@ COMMANDS                                              *preview.nvim-commands*
    `compile`    Compile the current buffer (default if omitted).
    `stop`       Kill active compilation for the current buffer.
    `clean`      Run the provider's clean command.
-    `watch`      Toggle auto-compile on save for the current buffer.
+    `toggle`     Toggle auto-compile on save for the current buffer.
    `status`     Echo compilation status (idle, compiling, watching).

 ==============================================================================
@ -175,10 +174,10 @@ preview.stop({bufnr?})                                      *preview.stop()*
 preview.clean({bufnr?})                                    *preview.clean()*
    Run the provider's clean command for the buffer.

-preview.watch({bufnr?})                                    *preview.watch()*
+preview.toggle({bufnr?})                                  *preview.toggle()*
    Toggle watch mode for the buffer. When enabled, the buffer is
-    automatically compiled on each save (`BufWritePost`). Call again
-    to stop watching.
+    immediately compiled and automatically recompiled on each save
+    (`BufWritePost`). Call again to stop watching.

 preview.status({bufnr?})                                  *preview.status()*
    Returns a |preview.Status| table.
@ -232,6 +231,7 @@ Run `:checkhealth preview` to verify:

 - Neovim version >= 0.11.0
 - Each configured provider's binary is executable
+- Each configured provider's opener binary (if any) is executable
 - Each configured provider's filetype mapping is valid

 ==============================================================================
--- a/lua/preview/commands.lua
+++ b/lua/preview/commands.lua
@ -1,6 +1,6 @@
 local M = {}

-local subcommands = { 'compile', 'stop', 'clean', 'watch', 'status' }
+local subcommands = { 'compile', 'stop', 'clean', 'toggle', 'status' }

 ---@param args string
 local function dispatch(args)
@ -12,8 +12,8 @@ local function dispatch(args)
    require('preview').stop()
  elseif subcmd == 'clean' then
    require('preview').clean()
-  elseif subcmd == 'watch' then
-    require('preview').watch()
+  elseif subcmd == 'toggle' then
+    require('preview').toggle()
  elseif subcmd == 'status' then
    local s = require('preview').status()
    local parts = {}
@ -47,7 +47,7 @@ function M.setup()
    complete = function(lead)
      return complete(lead)
    end,
-    desc = 'Compile, stop, clean, watch, or check status of document preview',
+    desc = 'Compile, stop, clean, toggle, or check status of document preview',
  })
 end

--- a/lua/preview/compiler.lua
+++ b/lua/preview/compiler.lua
@ -9,6 +9,9 @@ local active = {}
 ---@type table<integer, integer>
 local watching = {}

+---@type table<integer, true>
+local opened = {}
+
 ---@param val string[]|fun(ctx: preview.Context): string[]
 ---@param ctx preview.Context
 ---@return string[]
@ -68,6 +71,9 @@ function M.compile(bufnr, name, provider, ctx)
    },
    vim.schedule_wrap(function(result)
      active[bufnr] = nil
+      if not vim.api.nvim_buf_is_valid(bufnr) then
+        return
+      end

      if result.code == 0 then
        log.dbg('compilation succeeded for buffer %d', bufnr)
@ -76,6 +82,16 @@ function M.compile(bufnr, name, provider, ctx)
          pattern = 'PreviewCompileSuccess',
          data = { bufnr = bufnr, provider = name, output = output_file },
        })
+        if provider.open and not opened[bufnr] and output_file ~= '' then
+          if provider.open == true then
+            vim.ui.open(output_file)
+          elseif type(provider.open) == 'table' then
+            local open_cmd = vim.list_extend({}, provider.open)
+            table.insert(open_cmd, output_file)
+            vim.system(open_cmd)
+          end
+          opened[bufnr] = true
+        end
      else
        log.dbg('compilation failed for buffer %d (exit code %d)', bufnr, result.code)
        if provider.error_parser then
@ -146,7 +162,7 @@ end
 ---@param name string
 ---@param provider preview.ProviderConfig
 ---@param ctx_builder fun(bufnr: integer): preview.Context
-function M.watch(bufnr, name, provider, ctx_builder)
+function M.toggle(bufnr, name, provider, ctx_builder)
  if watching[bufnr] then
    M.unwatch(bufnr)
    return
@ -168,6 +184,7 @@ function M.watch(bufnr, name, provider, ctx_builder)
    once = true,
    callback = function()
      M.unwatch(bufnr)
+      opened[bufnr] = nil
    end,
  })

@ -175,6 +192,8 @@ function M.watch(bufnr, name, provider, ctx_builder)
    pattern = 'PreviewWatchStarted',
    data = { bufnr = bufnr, provider = name },
  })
+
+  M.compile(bufnr, name, provider, ctx_builder(bufnr))
 end

 ---@param bufnr integer
@ -244,6 +263,7 @@ end
 M._test = {
  active = active,
  watching = watching,
+  opened = opened,
 }

 return M
--- a/lua/preview/health.lua
+++ b/lua/preview/health.lua
@ -25,6 +25,14 @@ function M.check()
    else
      vim.health.error('filetype "' .. ft .. '": ' .. bin .. ' not found')
    end
+    if type(provider.open) == 'table' then
+      local opener = provider.open[1]
+      if vim.fn.executable(opener) == 1 then
+        vim.health.ok('filetype "' .. ft .. '": opener ' .. opener .. ' found')
+      else
+        vim.health.error('filetype "' .. ft .. '": opener ' .. opener .. ' not found')
+      end
+    end
  end
 end

--- a/lua/preview/init.lua
+++ b/lua/preview/init.lua
@ -1,4 +1,5 @@
 ---@class preview.ProviderConfig
+---@field ft? string
 ---@field cmd string[]
 ---@field args? string[]|fun(ctx: preview.Context): string[]
 ---@field cwd? string|fun(ctx: preview.Context): string
@ -6,6 +7,7 @@
 ---@field output? string|fun(ctx: preview.Context): string
 ---@field error_parser? fun(stderr: string, ctx: preview.Context): preview.Diagnostic[]
 ---@field clean? string[]|fun(ctx: preview.Context): string[]
+---@field open? boolean|string[]

 ---@class preview.Config
 ---@field debug boolean|string
@ -32,10 +34,11 @@
 ---@field output_file string

 ---@class preview
+---@field setup fun(opts?: table)
 ---@field compile fun(bufnr?: integer)
 ---@field stop fun(bufnr?: integer)
 ---@field clean fun(bufnr?: integer)
---@field watch fun(bufnr?: integer)
+---@field toggle fun(bufnr?: integer)
 ---@field status fun(bufnr?: integer): preview.Status
 ---@field get_config fun(): preview.Config
 local M = {}
@ -52,39 +55,48 @@ local default_config = {
 ---@type preview.Config
 local config = vim.deepcopy(default_config)

-local initialized = false
+---@param opts? table
+function M.setup(opts)
+  opts = opts or {}
+  vim.validate('preview.setup opts', opts, 'table')

-local function init()
-  if initialized then
-    return
-  end
-  initialized = true
+  local presets = require('preview.presets')
+  local providers = {}
+  local debug = false

-  local opts = vim.g.preview or {}
-
-  vim.validate('preview config', opts, 'table')
-  if opts.debug ~= nil then
-    vim.validate('preview config.debug', opts.debug, { 'boolean', 'string' })
-  end
-  if opts.providers ~= nil then
-    vim.validate('preview config.providers', opts.providers, 'table')
+  for k, v in pairs(opts) do
+    if k == 'debug' then
+      vim.validate('preview.setup opts.debug', v, { 'boolean', 'string' })
+      debug = v
+    elseif type(k) == 'number' then
+      vim.validate('preview.setup preset name', v, 'string')
+      local preset = presets[v]
+      if preset then
+        providers[preset.ft] = preset
+      end
+    else
+      vim.validate('preview.setup provider config', v, 'table')
+      providers[k] = v
+    end
  end

-  config = vim.tbl_deep_extend('force', default_config, opts)
+  config = vim.tbl_deep_extend('force', default_config, {
+    debug = debug,
+    providers = providers,
+  })
+
  log.set_enabled(config.debug)
  log.dbg('initialized with %d providers', vim.tbl_count(config.providers))
 end

 ---@return preview.Config
 function M.get_config()
-  init()
  return config
 end

 ---@param bufnr? integer
 ---@return string?
 function M.resolve_provider(bufnr)
-  init()
  bufnr = bufnr or vim.api.nvim_get_current_buf()
  local ft = vim.bo[bufnr].filetype
  if not config.providers[ft] then
@ -97,7 +109,6 @@ end
 ---@param bufnr? integer
 ---@return preview.Context
 function M.build_context(bufnr)
-  init()
  bufnr = bufnr or vim.api.nvim_get_current_buf()
  local file = vim.api.nvim_buf_get_name(bufnr)
  local root = vim.fs.root(bufnr, { '.git' }) or vim.fn.fnamemodify(file, ':h')
@ -111,42 +122,38 @@ end

 ---@param bufnr? integer
 function M.compile(bufnr)
-  init()
  bufnr = bufnr or vim.api.nvim_get_current_buf()
  local name = M.resolve_provider(bufnr)
  if not name then
    vim.notify('[preview.nvim] no provider configured for this filetype', vim.log.levels.WARN)
    return
  end
-  local provider = config.providers[name]
  local ctx = M.build_context(bufnr)
+  local provider = config.providers[name]
  compiler.compile(bufnr, name, provider, ctx)
 end

 ---@param bufnr? integer
 function M.stop(bufnr)
-  init()
  bufnr = bufnr or vim.api.nvim_get_current_buf()
  compiler.stop(bufnr)
 end

 ---@param bufnr? integer
 function M.clean(bufnr)
-  init()
  bufnr = bufnr or vim.api.nvim_get_current_buf()
  local name = M.resolve_provider(bufnr)
  if not name then
    vim.notify('[preview.nvim] no provider configured for this filetype', vim.log.levels.WARN)
    return
  end
-  local provider = config.providers[name]
  local ctx = M.build_context(bufnr)
+  local provider = config.providers[name]
  compiler.clean(bufnr, name, provider, ctx)
 end

 ---@param bufnr? integer
-function M.watch(bufnr)
-  init()
+function M.toggle(bufnr)
  bufnr = bufnr or vim.api.nvim_get_current_buf()
  local name = M.resolve_provider(bufnr)
  if not name then
@ -154,7 +161,7 @@ function M.watch(bufnr)
    return
  end
  local provider = config.providers[name]
-  compiler.watch(bufnr, name, provider, M.build_context)
+  compiler.toggle(bufnr, name, provider, M.build_context)
 end

 ---@class preview.Status
@ -166,7 +173,6 @@ end
 ---@param bufnr? integer
 ---@return preview.Status
 function M.status(bufnr)
-  init()
  bufnr = bufnr or vim.api.nvim_get_current_buf()
  return compiler.status(bufnr)
 end
@ -174,7 +180,6 @@ end
 M._test = {
  ---@diagnostic disable-next-line: assign-type-mismatch
  reset = function()
-    initialized = false
    config = vim.deepcopy(default_config)
  end,
 }
--- a/lua/preview/presets.lua
+++ b/lua/preview/presets.lua
@ -2,6 +2,7 @@ local M = {}

 ---@type preview.ProviderConfig
 M.typst = {
+  ft = 'typst',
  cmd = { 'typst', 'compile' },
  args = function(ctx)
    return { ctx.file }
@ -9,10 +10,12 @@ M.typst = {
  output = function(ctx)
    return ctx.file:gsub('%.typ$', '.pdf')
  end,
+  open = { 'xdg-open' },
 }

 ---@type preview.ProviderConfig
 M.latex = {
+  ft = 'tex',
  cmd = { 'latexmk' },
  args = function(ctx)
    return { '-pdf', '-interaction=nonstopmode', ctx.file }
@ -23,18 +26,49 @@ M.latex = {
  clean = function(ctx)
    return { 'latexmk', '-c', ctx.file }
  end,
+  open = { 'xdg-open' },
 }

 ---@type preview.ProviderConfig
 M.markdown = {
+  ft = 'markdown',
  cmd = { 'pandoc' },
  args = function(ctx)
-    local output = ctx.file:gsub('%.md$', '.pdf')
-    return { ctx.file, '-o', output }
+    local output = ctx.file:gsub('%.md$', '.html')
+    return { ctx.file, '-s', '--embed-resources', '-o', output }
  end,
  output = function(ctx)
-    return ctx.file:gsub('%.md$', '.pdf')
+    return ctx.file:gsub('%.md$', '.html')
  end,
+  clean = function(ctx)
+    return { 'rm', '-f', (ctx.file:gsub('%.md$', '.html')) }
+  end,
+  open = { 'xdg-open' },
+}
+
+---@type preview.ProviderConfig
+M.github = {
+  ft = 'markdown',
+  cmd = { 'pandoc' },
+  args = function(ctx)
+    local output = ctx.file:gsub('%.md$', '.html')
+    return {
+      ctx.file,
+      '-s',
+      '--embed-resources',
+      '--css',
+      'https://cdn.jsdelivr.net/gh/pixelbrackets/gfm-stylesheet@master/github.css',
+      '-o',
+      output,
+    }
+  end,
+  output = function(ctx)
+    return ctx.file:gsub('%.md$', '.html')
+  end,
+  clean = function(ctx)
+    return { 'rm', '-f', (ctx.file:gsub('%.md$', '.html')) }
+  end,
+  open = { 'xdg-open' },
 }

 return M
--- a/spec/commands_spec.lua
+++ b/spec/commands_spec.lua
@ -35,10 +35,10 @@ describe('commands', function()
      end)
    end)

-    it('does not error on :Preview watch with no provider', function()
+    it('does not error on :Preview toggle with no provider', function()
      require('preview.commands').setup()
      assert.has_no.errors(function()
-        vim.cmd('Preview watch')
+        vim.cmd('Preview toggle')
      end)
    end)
  end)
--- a/spec/compiler_spec.lua
+++ b/spec/compiler_spec.lua
@ -174,7 +174,7 @@ describe('compiler', function()
    end)
  end)

-  describe('watch', function()
+  describe('toggle', function()
    it('registers autocmd and tracks in watching table', function()
      local bufnr = helpers.create_buffer({ 'hello' }, 'text')
      vim.api.nvim_buf_set_name(bufnr, '/tmp/preview_test_watch.txt')
@ -184,7 +184,7 @@ describe('compiler', function()
        return { bufnr = b, file = '/tmp/preview_test_watch.txt', root = '/tmp', ft = 'text' }
      end

-      compiler.watch(bufnr, 'echo', provider, ctx_builder)
+      compiler.toggle(bufnr, 'echo', provider, ctx_builder)
      assert.is_not_nil(compiler._test.watching[bufnr])

      helpers.delete_buffer(bufnr)
@ -208,7 +208,7 @@ describe('compiler', function()
        return { bufnr = b, file = '/tmp/preview_test_watch_event.txt', root = '/tmp', ft = 'text' }
      end

-      compiler.watch(bufnr, 'echo', provider, ctx_builder)
+      compiler.toggle(bufnr, 'echo', provider, ctx_builder)
      assert.is_true(fired)

      compiler.unwatch(bufnr)
@ -224,10 +224,10 @@ describe('compiler', function()
        return { bufnr = b, file = '/tmp/preview_test_watch_toggle.txt', root = '/tmp', ft = 'text' }
      end

-      compiler.watch(bufnr, 'echo', provider, ctx_builder)
+      compiler.toggle(bufnr, 'echo', provider, ctx_builder)
      assert.is_not_nil(compiler._test.watching[bufnr])

-      compiler.watch(bufnr, 'echo', provider, ctx_builder)
+      compiler.toggle(bufnr, 'echo', provider, ctx_builder)
      assert.is_nil(compiler._test.watching[bufnr])

      helpers.delete_buffer(bufnr)
@ -251,7 +251,7 @@ describe('compiler', function()
        return { bufnr = b, file = '/tmp/preview_test_watch_stop.txt', root = '/tmp', ft = 'text' }
      end

-      compiler.watch(bufnr, 'echo', provider, ctx_builder)
+      compiler.toggle(bufnr, 'echo', provider, ctx_builder)
      compiler.unwatch(bufnr)
      assert.is_true(stopped)
      assert.is_nil(compiler._test.watching[bufnr])
@ -273,7 +273,7 @@ describe('compiler', function()
        }
      end

-      compiler.watch(bufnr, 'echo', provider, ctx_builder)
+      compiler.toggle(bufnr, 'echo', provider, ctx_builder)
      assert.is_not_nil(compiler._test.watching[bufnr])

      compiler.stop_all()
@ -294,7 +294,7 @@ describe('compiler', function()
        return { bufnr = b, file = '/tmp/preview_test_watch_status.txt', root = '/tmp', ft = 'text' }
      end

-      compiler.watch(bufnr, 'echo', provider, ctx_builder)
+      compiler.toggle(bufnr, 'echo', provider, ctx_builder)
      s = compiler.status(bufnr)
      assert.is_true(s.watching)

--- a/spec/helpers.lua
+++ b/spec/helpers.lua
@ -20,8 +20,11 @@ function M.delete_buffer(bufnr)
 end

 function M.reset_config(opts)
-  vim.g.preview = opts
-  require('preview')._test.reset()
+  local preview = require('preview')
+  preview._test.reset()
+  if opts then
+    preview.setup(opts)
+  end
 end

 return M
--- a/spec/init_spec.lua
+++ b/spec/init_spec.lua
@ -9,13 +9,7 @@ describe('preview', function()
  end)

  describe('config', function()
-    it('accepts nil config', function()
-      assert.has_no.errors(function()
-        preview.get_config()
-      end)
-    end)
-
-    it('applies default values', function()
+    it('returns defaults before setup is called', function()
      local config = preview.get_config()
      assert.is_false(config.debug)
      assert.are.same({}, config.providers)
@ -28,26 +22,44 @@ describe('preview', function()
      assert.are.same({}, config.providers)
    end)

-    it('accepts full provider config', function()
+    it('accepts full provider config via hash entry', function()
      helpers.reset_config({
-        providers = {
-          typst = {
-            cmd = { 'typst', 'compile' },
-            args = { '%s' },
-          },
+        typst = {
+          cmd = { 'typst', 'compile' },
+          args = { '%s' },
        },
      })
      local config = require('preview').get_config()
      assert.is_not_nil(config.providers.typst)
    end)
+
+    it('resolves array preset names to provider configs', function()
+      helpers.reset_config({ 'typst', 'markdown' })
+      local config = require('preview').get_config()
+      local presets = require('preview.presets')
+      assert.are.same(presets.typst, config.providers.typst)
+      assert.are.same(presets.markdown, config.providers.markdown)
+    end)
+
+    it('resolves latex preset under tex filetype', function()
+      helpers.reset_config({ 'latex' })
+      local config = require('preview').get_config()
+      local presets = require('preview.presets')
+      assert.are.same(presets.latex, config.providers.tex)
+    end)
+
+    it('resolves github preset under markdown filetype', function()
+      helpers.reset_config({ 'github' })
+      local config = require('preview').get_config()
+      local presets = require('preview.presets')
+      assert.are.same(presets.github, config.providers.markdown)
+    end)
  end)

  describe('resolve_provider', function()
    before_each(function()
      helpers.reset_config({
-        providers = {
-          typst = { cmd = { 'typst', 'compile' } },
-        },
+        typst = { cmd = { 'typst', 'compile' } },
      })
      preview = require('preview')
    end)
--- a/spec/presets_spec.lua
+++ b/spec/presets_spec.lua
@ -13,6 +13,10 @@ describe('presets', function()
  }

  describe('typst', function()
+    it('has ft', function()
+      assert.are.equal('typst', presets.typst.ft)
+    end)
+
    it('has cmd', function()
      assert.are.same({ 'typst', 'compile' }, presets.typst.cmd)
    end)
@ -28,6 +32,10 @@ describe('presets', function()
      assert.is_string(output)
      assert.are.equal('/tmp/document.pdf', output)
    end)
+
+    it('has open enabled', function()
+      assert.are.same({ 'xdg-open' }, presets.typst.open)
+    end)
  end)

  describe('latex', function()
@ -38,6 +46,10 @@ describe('presets', function()
      ft = 'tex',
    }

+    it('has ft', function()
+      assert.are.equal('tex', presets.latex.ft)
+    end)
+
    it('has cmd', function()
      assert.are.same({ 'latexmk' }, presets.latex.cmd)
    end)
@ -59,6 +71,10 @@ describe('presets', function()
      assert.is_table(clean)
      assert.are.same({ 'latexmk', '-c', '/tmp/document.tex' }, clean)
    end)
+
+    it('has open enabled', function()
+      assert.are.same({ 'xdg-open' }, presets.latex.open)
+    end)
  end)

  describe('markdown', function()
@ -69,20 +85,84 @@ describe('presets', function()
      ft = 'markdown',
    }

+    it('has ft', function()
+      assert.are.equal('markdown', presets.markdown.ft)
+    end)
+
    it('has cmd', function()
      assert.are.same({ 'pandoc' }, presets.markdown.cmd)
    end)

-    it('returns args with file and output flag', function()
+    it('returns args with standalone and embed-resources flags', function()
      local args = presets.markdown.args(md_ctx)
      assert.is_table(args)
-      assert.are.same({ '/tmp/document.md', '-o', '/tmp/document.pdf' }, args)
+      assert.are.same(
+        { '/tmp/document.md', '-s', '--embed-resources', '-o', '/tmp/document.html' },
+        args
+      )
    end)

-    it('returns pdf output path', function()
+    it('returns html output path', function()
      local output = presets.markdown.output(md_ctx)
      assert.is_string(output)
-      assert.are.equal('/tmp/document.pdf', output)
+      assert.are.equal('/tmp/document.html', output)
+    end)
+
+    it('returns clean command', function()
+      local clean = presets.markdown.clean(md_ctx)
+      assert.is_table(clean)
+      assert.are.same({ 'rm', '-f', '/tmp/document.html' }, clean)
+    end)
+
+    it('has open enabled', function()
+      assert.are.same({ 'xdg-open' }, presets.markdown.open)
+    end)
+  end)
+
+  describe('github', function()
+    local md_ctx = {
+      bufnr = 1,
+      file = '/tmp/document.md',
+      root = '/tmp',
+      ft = 'markdown',
+    }
+
+    it('has ft', function()
+      assert.are.equal('markdown', presets.github.ft)
+    end)
+
+    it('has cmd', function()
+      assert.are.same({ 'pandoc' }, presets.github.cmd)
+    end)
+
+    it('returns args with standalone, embed-resources, and css flags', function()
+      local args = presets.github.args(md_ctx)
+      assert.is_table(args)
+      assert.are.same({
+        '/tmp/document.md',
+        '-s',
+        '--embed-resources',
+        '--css',
+        'https://cdn.jsdelivr.net/gh/pixelbrackets/gfm-stylesheet@master/github.css',
+        '-o',
+        '/tmp/document.html',
+      }, args)
+    end)
+
+    it('returns html output path', function()
+      local output = presets.github.output(md_ctx)
+      assert.is_string(output)
+      assert.are.equal('/tmp/document.html', output)
+    end)
+
+    it('returns clean command', function()
+      local clean = presets.github.clean(md_ctx)
+      assert.is_table(clean)
+      assert.are.same({ 'rm', '-f', '/tmp/document.html' }, clean)
+    end)
+
+    it('has open enabled', function()
+      assert.are.same({ 'xdg-open' }, presets.github.open)
    end)
  end)
 end)