* fix(commands): register VimLeavePre to call stop_all
Problem: spawned compiler processes and watching autocmds were never
cleaned up when Neovim exited, leaving orphaned processes running.
Solution: register a VimLeavePre autocmd in commands setup that calls
compiler.stop_all(), which kills active processes, unwatches all
buffers, and stops the reload server.
* fix(compiler): replace BufWipeout with BufUnload
Problem: cleanup autocmds used BufWipeout, which only fires for
:bwipeout. The common :bdelete path (used by most buffer managers
and nvim_buf_delete) fires BufUnload but not BufWipeout, so processes
and watches leaked on normal buffer deletion.
Solution: switch all three cleanup autocmds from BufWipeout to
BufUnload, which fires for both :bdelete and :bwipeout.
* fix(init): guard against unnamed buffer in public API
Problem: calling compile/toggle/clean/open on an unsaved scratch
buffer passed an empty string as ctx.file, producing nonsensical
output paths like ".pdf" and silently passing empty strings to
compiler binaries.
Solution: add an early return with a WARN notification in compile,
toggle, clean, and open when the buffer has no file name.
* fix(compiler): add fs_stat check to one-shot open path
Problem: the long-running process path already guarded opens with
vim.uv.fs_stat(), but the one-shot compile path and M.open() did not.
Compilation can exit 0 and produce no output, and output files can be
externally deleted between compile and open.
Solution: add the same fs_stat guard to the one-shot open branch and
to M.open() before attempting to launch the viewer.
* fix(compiler): check executable before spawning process
Problem: if a configured binary was missing or not in PATH, vim.system
would fail silently or with a cryptic OS error. The user had no
actionable feedback without running :checkhealth.
Solution: check vim.fn.executable() at the start of M.compile() and
notify with an ERROR-level message pointing to :checkhealth preview
if the binary is not found.
* fix(compiler): reformat one-shot open condition for line length
Problem: the added fs_stat condition exceeded stylua's line length
limit on the one-shot open guard.
Solution: split the boolean condition across multiple lines to match
the project's stylua formatting rules.
Problem: no way to expose compiling/watching state to statusline
plugins like lualine or heirline without polling status() and
formatting it manually.
Solution: add `require('preview').statusline()` that returns
'compiling', 'watching', or '' for direct use in statusline components.
* refactor(config): replace array preset syntax with preset_name = true
Problem: setup() mixed array entries (preset names) and hash entries
(custom providers keyed by filetype), requiring verbose
vim.tbl_deep_extend boilerplate to override presets.
Solution: unify under a single key=value model. Keys are preset names
or filetypes; true registers the preset as-is, a table deep-merges
with the matching preset (or registers a custom provider if no preset
matches), and false is a no-op. Array entries are dropped. Also adds
-f gfm to presets.github args so pandoc parses input as GFM.
* ci: format
* fix(presets): parenthesize gsub output to suppress redundant-return-value
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.
