chore: update readme/doc

3 files changed, 51 insertions, 13 deletions

diff --git a/README.md b/README.md
index 7fa10a8..7f5abd6 100644
--- a/README.md
+++ b/README.md
@@ -108,9 +108,44 @@ vim.api.nvim_create_autocmd("BufWritePre", {
 
 See `:help muwiki-autocmd` for more examples.
 
+## Configuration Options
+
+### text_extensions
+
+Controls which file extensions open directly in Neovim when using `file://` links. Files with matching extensions bypass `xdg-open` and open in a Neovim buffer instead.
+
+**Default:** `{}` (empty - all file:// links open with xdg-open)
+
+**Format:** Accepts extensions with or without leading dot (e.g., `'txt'` or `'.txt'`)
+
+**Example:**
+```lua
+muwiki.setup({
+  dirs = {{ name = 'default', path = '~/wiki' }},
+  -- Open these file types directly in Neovim
+  text_extensions = { 'txt', 'md', 'png' },
+})
+```
+
+This allows you to open binary files like PNG images directly in Neovim for hex editing or inspection instead of xdg-open.
+
+**Behavior:**
+
+**xdg-open:**
+
+- `[Link](https://example.com)`
+- `[Link](file:///path/to/file.mp4)`
+
+**Neovim:**
+
+- `[Link](file://../relative/path/to/image.png)` → matches text_extensions
+- `[Link](/absolute/path/to/file.txt)`
+- `[Link](../relative/path/to/file.txt)`
+- `[Link](SomePage.md)`
+
 ## Available Actions
 
-- `open_link()` - Open link under cursor (wiki→nvim, web/files→xdg-open)
+- `open_link()` - Open link under cursor
 - `next_link()` - Jump to next markdown link
 - `prev_link()` - Jump to previous markdown link
 - `create_link()` - Create link from visual selection
@@ -120,15 +155,6 @@ See `:help muwiki-autocmd` for more examples.
 
 See `:help muwiki-api` for detailed function documentation.
 
-## Link Format
-
-```text
-[Wiki page](page.md)
-[Website](https://example.com)
-[Relative path](file://../document.pdf)
-[Absolute path](file:///tmp/image.png)
-```
-
 ## Recommended Plugins
 
 These plugins work well with muwiki.nvim:
diff --git a/doc/muwiki.txt b/doc/muwiki.txt
index e4d06de..c22acb1 100644
--- a/doc/muwiki.txt
+++ b/doc/muwiki.txt
@@ -73,6 +73,14 @@ dirs                    List of wiki directories.
 index_file              Name of the index file for each wiki.
                         Default: 'index.md'
 
+                                                    *muwiki-opt-text_extensions*
+text_extensions         List of file extensions that open directly in Neovim
+                        for file:// links. Files with matching extensions
+                        bypass xdg-open and open in a Neovim buffer.
+                        Extensions can be specified with or without leading
+                        dot (e.g., 'txt' or '.txt').
+                        Default: {}
+
 Example Configuration~
 >
   local muwiki = require('muwiki')
@@ -83,6 +91,9 @@ Example Configuration~
       { name = 'work', path = '~/work/wiki' },
     },
     index_file = 'index.md',
+    -- Open these file types directly in Neovim (bypass xdg-open)
+    -- Note: Even binary files like PNG can be opened in Neovim
+    text_extensions = { 'txt', 'md', 'png' },
   })
 <
 
@@ -120,8 +131,9 @@ muwiki.setup({opts})                                   *muwiki.setup()*
 muwiki.open_link()                                     *muwiki.open_link()*
     Open the link under cursor.
     - Wiki links: open in Neovim buffer
-    - Web links: open with xdg-open
-    - File links: open with xdg-open
+    - Web links (http/https): open with xdg-open
+    - File links (file://): open with xdg-open, unless the file extension
+      matches |muwiki-opt-text_extensions|, in which case opens in Neovim
 
 muwiki.next_link()                                     *muwiki.next_link()*
     Jump to the next markdown link in the buffer.
diff --git a/lua/muwiki/config.lua b/lua/muwiki/config.lua
index a2121b1..831e406 100644
--- a/lua/muwiki/config.lua
+++ b/lua/muwiki/config.lua
@@ -3,7 +3,7 @@ local M = {}
 M.options = {
   dirs = nil,
   index_file = 'index.md',
-  text_extensions = { 'txt', 'py', 'rb', 'js', 'ts', 'lua', 'sh', 'bash', 'zsh', 'vim', 'json', 'yaml', 'yml', 'toml', 'xml', 'html', 'css' },
+  text_extensions = {},
 }
 
 function M.setup(opts)