fix(compiler): one-shot builds and :Preview open provider config (#25)

* fix(compiler): skip reload command for one-shot builds

Problem: compile() unconditionally resolved the reload command, so
:Preview build on a provider with reload = function/table (e.g. typst)
would start a long-running process (typst watch) instead of a one-shot
compile (typst compile). Error diagnostics were also lost because
typst watch does not exit non-zero on input errors.

Solution: add an opts parameter to compile() with a oneshot flag.
M.build() passes { oneshot = true } so resolve_reload_cmd() is
skipped and the one-shot path is always taken. toggle() continues
to call compile() without the flag, preserving long-running behavior
for watch mode.

* fix(compiler): respect provider open config in M.open()

Problem: :Preview open always called vim.ui.open regardless of the
provider's open field. Providers configured with a custom opener
(e.g. open = { 'sioyek', '--new-instance' }) were ignored, so the
first build opened with sioyek but :Preview open fell back to the
system default.

Solution: init.lua resolves the provider's open config and passes it
to compiler.open(). If open_config is a table, the custom command is
spawned with the output path appended. Otherwise vim.ui.open is used
as before.

* fix: normalize notify prefix to [preview.nvim]: everywhere

Problem: some vim.notify calls used [preview.nvim] (no colon) while
others used [preview.nvim]: — inconsistent with the log module format.

Solution: add the missing colon and space to all notify calls in
init.lua and compiler.lua so every user-facing message matches the
[preview.nvim]: prefix used by the log module.

* ci: format

lua/preview/compiler.lua

@@ -55,7 +55,9 @@ end
 ---@param name string
 ---@param provider preview.ProviderConfig
 ---@param ctx preview.Context
-function M.compile(bufnr, name, provider, ctx)
+function M.compile(bufnr, name, provider, ctx, opts)
+  opts = opts or {}
+
   if vim.bo[bufnr].modified then
     vim.cmd('silent! update')
   end
@@ -81,7 +83,10 @@ function M.compile(bufnr, name, provider, ctx)
     last_output[bufnr] = output_file
   end
 
-  local reload_cmd = resolve_reload_cmd(provider, resolved_ctx)
+  local reload_cmd
+  if not opts.oneshot then
+    reload_cmd = resolve_reload_cmd(provider, resolved_ctx)
+  end
 
   if reload_cmd then
     log.dbg(
@@ -403,7 +408,10 @@ end
 ---@param ctx preview.Context
 function M.clean(bufnr, name, provider, ctx)
   if not provider.clean then
-    vim.notify('[preview.nvim] provider "' .. name .. '" has no clean command', vim.log.levels.WARN)
+    vim.notify(
+      '[preview.nvim]: provider "' .. name .. '" has no clean command',
+      vim.log.levels.WARN
+    )
     return
   end
 
@@ -427,10 +435,10 @@ function M.clean(bufnr, name, provider, ctx)
     vim.schedule_wrap(function(result)
       if result.code == 0 then
         log.dbg('clean succeeded for buffer %d', bufnr)
-        vim.notify('[preview.nvim] clean complete', vim.log.levels.INFO)
+        vim.notify('[preview.nvim]: clean complete', vim.log.levels.INFO)
       else
         log.dbg('clean failed for buffer %d (exit code %d)', bufnr, result.code)
-        vim.notify('[preview.nvim] clean failed: ' .. (result.stderr or ''), vim.log.levels.ERROR)
+        vim.notify('[preview.nvim]: clean failed: ' .. (result.stderr or ''), vim.log.levels.ERROR)
       end
     end)
   )
@@ -438,13 +446,19 @@ end
 
 ---@param bufnr integer
 ---@return boolean
-function M.open(bufnr)
+function M.open(bufnr, open_config)
   local output = last_output[bufnr]
   if not output then
     log.dbg('no last output file for buffer %d', bufnr)
     return false
   end
-  vim.ui.open(output)
+  if type(open_config) == 'table' then
+    local open_cmd = vim.list_extend({}, open_config)
+    table.insert(open_cmd, output)
+    vim.system(open_cmd)
+  else
+    vim.ui.open(output)
+  end
   return true
 end
 

lua/preview/init.lua

@@ -148,12 +148,12 @@ function M.build(bufnr)
   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)
+    vim.notify('[preview.nvim]: no provider configured for this filetype', vim.log.levels.WARN)
     return
   end
   local ctx = M.build_context(bufnr)
   local provider = config.providers[name]
-  compiler.compile(bufnr, name, provider, ctx)
+  compiler.compile(bufnr, name, provider, ctx, { oneshot = true })
 end
 
 ---@param bufnr? integer
@@ -167,7 +167,7 @@ function M.clean(bufnr)
   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)
+    vim.notify('[preview.nvim]: no provider configured for this filetype', vim.log.levels.WARN)
     return
   end
   local ctx = M.build_context(bufnr)
@@ -180,7 +180,7 @@ function M.watch(bufnr)
   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)
+    vim.notify('[preview.nvim]: no provider configured for this filetype', vim.log.levels.WARN)
     return
   end
   local provider = config.providers[name]
@@ -190,8 +190,10 @@ end
 ---@param bufnr? integer
 function M.open(bufnr)
   bufnr = bufnr or vim.api.nvim_get_current_buf()
-  if not compiler.open(bufnr) then
-    vim.notify('[preview.nvim] no output file available for this buffer', vim.log.levels.WARN)
+  local name = M.resolve_provider(bufnr)
+  local open_config = name and config.providers[name] and config.providers[name].open
+  if not compiler.open(bufnr, open_config) then
+    vim.notify('[preview.nvim]: no output file available for this buffer', vim.log.levels.WARN)
   end
 end