feat: mark diff files as reviewed

docs/configuration.md

@@ -169,7 +169,7 @@ Normal `C` / `D` / `Y` change/delete/copy the cursor-to-line-end suffix through
 | Normal | `save`, `force_save`, `quit`, `force_quit`, `restart`, `force_restart`, `save_and_quit`, `force_save_and_quit`, `plugins` |
 | Normal | `edit`, `buffers`, `buffer`, `buffer_next`, `buffer_previous`, `buffer_delete`, `buffer_force_delete` |
 | Normal | `follow_link` |
-| Normal | `diff`, `diff.mode.toggle`, `diff.view.toggle`, `diff.orientation.toggle` |
+| Normal | `diff`, `diff.mode.toggle`, `diff.view.toggle`, `diff.orientation.toggle`, `diff.review.toggle` |
 | Normal, Insert, Visual, Command, Search | `diff.close` |
 | Normal, Insert, Visual, Command, Search | `word_wrap.toggle` |
 | Normal, Insert, Visual, Command, Search | `git_blame.toggle` |
@@ -249,6 +249,8 @@ The diff's changed-file explorer and floating picker use these same tree and sel
 
 Ordinary `config.core.file_picker` and `config.core.file_explorer` bindings work inside comparisons. Ctrl+w closes a focused picker/explorer, retaining its query, selection, and expansion state; the panes use the reclaimed width. Ctrl+e has no reserved diff behavior. Escape closes the revision selector in either stage, but an opened comparison still closes explicitly through `:diff.close`, its palette action, or the generated action value below. `config.core.diff` remains the opening action and exposes immutable `close`, `mode.toggle`, `view.toggle`, and `orientation.toggle` children. New comparisons default to Branch changes (merge base → selected After); Normal-mode Ctrl+b, `:diff.mode.toggle`, or the palette toggles to direct Snapshots and back, preserving the selected endpoints. Selecting Working checkout on either side forces Snapshots.
 
+`config.core.diff.review.toggle` is a non-mutating Normal-mode action, also available as `:diff.review.toggle` and in the palette. It marks/unmarks the highlighted changed-file leaf when the comparison's explorer is focused, or the current comparison file from a text pane. Read-only snapshots permit review marks. For example, `config.bind "ctrl+g", config.core.diff.review.toggle`; use the palette or a control-key binding while filtering so printable input stays in the query. No default review shortcut is installed.
+
 `config.core.pane.close` and `config.core.pane.force_close` close a focused **docked** file list instead of its editor pane, without discarding buffers or exiting the comparison. A floating picker does not intercept these actions: normal close still protects underlying dirty buffers, while force-close retains its existing discard semantics. For example, bind `config.bind "ctrl+x", config.core.pane.close`; focused tree/selection overrides and printable filter input retain priority. Palette-originated close actions retain the originating dock target through force confirmation.
 
 Focused selector/filter input receives printable text before Normal-mode action bindings, so `:` stays query text instead of opening Command input. Explicit tree/selection navigation overrides remain effective. Control-key editor action bindings and Ctrl+p remain available.

docs/editing.md

@@ -370,6 +370,10 @@ Use the ordinary **file-picker/file-explorer actions and bindings**: Space `o` o
 
 File rows show colored **A** (added, green), **M** (modified, yellow), **D** (removed, red), or **R** (renamed, cyan) markers in Tree and List views, including filtered results. Rename rows show `R old/path -> new/path`; directories have no file-status marker. Ordinary file exploration remains unannotated.
 
+Mark or unmark a diff file with **`:diff.review.toggle`** or the command-palette action. With the changed-file explorer focused, it toggles the highlighted file without opening it; from a text pane, it toggles the displayed file. Reviewed files show a green **`✓` immediately before A/M/D/R** in Tree and List views. Directories and ordinary filesystem pickers cannot be marked. There is no default shortcut; a control-key binding is useful while a filter is focused, since printable keys remain filter text.
+
+Review marks belong only to the open comparison and survive filtering, file navigation, lazy loading, tabs, and split/unified/orientation changes. A new or recomputed comparison clears them. Editing a Working After file clears only that file's mark; unchanged refreshes and saves preserve it. Marks do not change document text, undo history, or repository state, and are not persisted after closing the comparison.
+
 Text panes show change excerpts with **10 unchanged lines above and below** each change, preserving original file line numbers. Overlapping or touching excerpts merge; omitted stretches show an unchanged-line count in both panes. Files with only metadata changes show their notice or “No text changes” rather than unrelated source.
 
 In **Normal mode** with a text pane focused, **`[` expands above** and **`]` expands below** the excerpt containing the caret, revealing up to **15 lines** per keypress in either pane. In editable After's Insert mode these keys insert literal text. Expansion clamps at file boundaries and merges excerpts when they meet. Existing visible source stays anchored. Opening a file resets its excerpts to the configured initial context. Live edits recompute changes while retaining expanded context; the caret stays visible even when the last text change is reverted.