[feat] Configurable preview window position: float, split, vsplit

[adriancmiranda]

Summary

Allow users to control where float-based previewers open (markdown, archive, cert, binary, font, key, sqlite) via a window config key and an optional :GlimpsePreview command argument.

Tasks

• Extend :GlimpsePreview to accept optional [window] and [path] arguments, passing window directly to the previewer (no config involved yet)
• Add window to global config with precedence resolution: command argument > global config > float (hard default)
• Inline previewers (image, video) respect window for initial split direction (left/right); existing preview windows are always reused on their current side regardless of window value
• Per-extension pipeline config override (pipelines[".md"] = { window = ... }), aligned with [v3] Pipeline-first architecture: delegate all conversion to external CLIs #92
• size key (columns for right/left, lines for bottom/top)
• bottom/top support for inline previewers

API

Command

:GlimpsePreview [window] [path]

[window] and [path] are both optional. When [path] is omitted, the current buffer is used. When [window] is omitted, config is consulted; if config is also absent, defaults to float.

Examples:

:GlimpsePreview                    " current buffer, float (default)
:GlimpsePreview right              " current buffer, split to the right
:GlimpsePreview float README.md
:GlimpsePreview right README.md
:GlimpsePreview bottom README.md

Config

require("glimpse").setup({
  window = 'right', -- global default: 'float' | 'right' | 'left' | 'bottom' | 'top'

  -- number: applies to all positions
  size = 80,

  -- table: per-position granularity (unset positions use Neovim's default split size)
  size = { left = 60, right = 80, bottom = 15, top = 10 },

  pipelines = {
    [".md"] = { window = 'right', size = 80 }, -- per-extension override (aligned with #92)
  },
})

Precedence

Command argument > per-extension config > global config > float (hard default, preserves current behavior)

Accepted values

Value	Behavior
float	floating window (default)
right	vertical split to the right
left	vertical split to the left
bottom	horizontal split below
top	horizontal split above

Notes

• nil is a valid global config value - it means "no preference, let the command decide"
• size accepts either a number (applies to all positions) or a table with per-position keys (left, right, bottom, top); when absent or unset for a position, Neovim's default split size applies
• auto_open always uses the global/per-extension config (no command argument in that flow)
• Aligns with the extension-first model proposed in [v3] Pipeline-first architecture: delegate all conversion to external CLIs #92

Known limitations

• Inline previewers (image, video): bottom/top not yet supported; horizontal split positioning requires a separate detection axis (row vs column). Deferred.
• Per-extension config: pipelines[ext].window override not yet implemented; deferred to [v3] Pipeline-first architecture: delegate all conversion to external CLIs #92.
• size key: not yet implemented.