feat: dim whitespace markers and configure scope and newlines

TODO.md

@@ -1,7 +1,9 @@
-- [ ] git gutter flashes on every keystroke/change; this should be fixed.
+- [x] add option to highlight trailing whitespace (off by default)
-- [ ] make all buffers (including pickers) scrolls the window when the cursor reaches a certain threshold. setting could something like "distance from frame edges", and the value could be an integer or none:
+- [x] add option to put characters at certain whitespace characters (off by default)
-	- "none" would mean "always keep the cursor in the center of the frame" (i.e. scroll the viewport whenever the cursor moves to a different line)
+	- whitespace kind -> character map should be configurable.
-	- an integer value would be the distance from the edge of the viewport that the cursor must hit before the viewport begins to scroll. a value of 0 means the viewport scrolls only right before the cursor would otherwise have left the viewport; a value greater than half the width of the viewport behaves similarly to "none" (at least until the viewport is resized to support that range in a meaningful way).
+- [ ] diff view - design question:
+	- is it possible to angle the hatchings for empty lines more?
+	- if a character like the current one exists with a 45degree angle instead (and a top and bottom), we could use that across two columns. that would give us a perfectly 45 degree hatching.
 - [ ] github/gitlab/gitea integration (probably requries authentication with github)
 	- github pr picker (floating window)
 	- three tabs: open, closed, all

docs/architecture.md

@@ -78,6 +78,8 @@ Comparison views reserve no separate metadata header or native-buffer help foote
 
 Each comparison owns its split/unified mode and split axis; startup defaults apply only when opening a comparison. Source alignment and file-side availability stay independent of presentation. Unified display rows carry a side projection: equal context maps both sources, changed runs emit Before rows followed by After rows, and folds retain aligned coordinates. Native navigation/editing continues to bind source buffers rather than a synthetic unified document. The TUI reuses side-specific syntax/wrap/overlay pipelines in one unified region or the existing axis-based split geometry, exposing only the active logical side for unified hit-testing and directional focus.
 
+`Editor::scroll_distance()` supplies the session-wide optional edge margin. The TUI applies it to document/diff visual rows and unwrapped text columns, and retains independent picker offsets across navigation frames. Picker windows exclude their fixed chrome and align whole multi-row entries. File projections carry a monotonic viewport revision, so catalog/filter/expansion changes invalidate picker identity without hashing the entire catalog on every redraw. Metadata-only status changes do not move the viewport. Explicit LSP/wrap-toggle anchors and detached wheel views retain precedence.
+
 Mouse wheel input uses the last rendered document/panel rectangles for hit-testing. Document offsets and explorer scroll state remain frontend-owned; three-row wheel steps never become document cursor motions. Manual document views persist until logical caret-reveal, caret/selection, mode, revision, or buffer changes; offscreen primary and browsing-selection cursors are not placed. Hover wheel input reuses the existing editor-owned popup scrolling.
 
 Already-ready mouse reports share a redraw: at most 64 reports are applied in their original order before painting, without dropping or summing away wheel steps. Readiness checks do not wait. The first non-mouse event is retained for the next iteration after rendering, so keys, paste, and resizes cannot reuse geometry from before their layout changes. The batch bound keeps continuous mouse input from starving drawing or background polling.
@@ -86,7 +88,7 @@ Ratatui's bounded layout cache is enabled: unchanged geometry and constraints re
 
 The buffer viewport includes a fixed left gutter with right-aligned hybrid line numbers: the highlighted primary cursor line shows its one-based absolute number; every other line shows its distance from the primary. Secondary carets do not establish separate numbering origins. Width follows the total line count plus one separator cell, including an empty final row after a trailing newline; `git_gutter` bar/symbol modes add a blank cell and a marker cell between the number and separator. Number-color/none modes add no width. Horizontal scrolling affects only text; search/selection highlights and carets never paint over the gutter. Wrapped continuations and rows beyond the buffer have no number or marker. The gutter is hidden when it would leave no text column.
 
-Repository gutter work runs off the render/editor thread. Revision/path-validated marker vectors belong to ordinary source buffers, not historical snapshots; panes and tabs borrow their own buffer's markers. The worker compares editor text with Git HEAD or Git-backed jj's single parent, independently of save baselines and index state. The frontend paints green additions, red deletion anchors, and yellow modifications as `▌`, symbols, or number colors; current-line cyan/bold overrides repository colors in number-color mode.
+Repository gutter work runs off the render/editor thread. Revision/path-validated worker results update marker vectors belonging to ordinary source buffers, not historical snapshots; panes and tabs borrow their own buffer's markers. After text edits, the last completed markers for the same path remain visible until a current-revision result replaces them, rather than disappearing during each asynchronous refresh. The worker compares editor text with Git HEAD or Git-backed jj's single parent, independently of save baselines and index state. The frontend paints green additions, red deletion anchors, and yellow modifications as `▌`, symbols, or number colors; current-line cyan/bold overrides repository colors in number-color mode.
 
 The same cancellable worker optionally collects normal-picker status, including when line-gutter rendering is disabled. Disk metadata and dirty-buffer overlays use Git HEAD or jj's single parent without snapshotting jj or writing active refs, objects, or indexes. A private baseline index retains its stat cache across polls; conflicted jj parents are projected once per root/parent. Root, baseline, store, or builtin Git conversion-setting changes invalidate that cache. Private queries disable user filters, external diff, and textconv. Request/tab/root checks reject stale picker results; unchanged catalogs retain their ordinary scanner and filtering rules.
 

docs/configuration.md

@@ -15,6 +15,10 @@ Vamp.configure do |config|
   config.clipboard_mode = "system"
   config.git_blame = true # false disables current-line attribution
   config.git_gutter = "bar" # or "symbols", "line_numbers", "none"
+  config.scroll_distance = 0 # nonnegative edge distance, or nil to center
+  config.highlight_trailing_whitespace = false # true marks line-end whitespace in red
+  config.whitespace_characters = {} # opt in: { " " => "·", "\t" => "→", "\n" => "↵" }
+  config.whitespace_scope = "all" # or "leading" for indentation only
   config.file_explorer_side = "right"
   config.file_explorer_view = "tree"
   config.file_picker_view = "tree"
@@ -47,6 +51,22 @@ Plugin paths resolve relative to the config file, not the shell's working direct
 `config.file_explorer_side` defaults to `"right"`; other choices are `"left"`, `"top"`, and `"bottom"`. Independent `file_explorer_view` / `file_picker_view` preferences both default to `"tree"` and accept `"list"` as an alternative. Invalid preference strings report notices and retain defaults while valid bindings still install. Non-string/empty values disable the whole configuration like other Ruby type errors.
 `config.clipboard_mode` accepts `"system"` (default) or `"separate"`. An invalid policy string reports a notice and retains System while valid bindings still install; non-string/empty values reject the whole Ruby configuration.
 
+`config.scroll_distance` defaults to `0`: keep the viewport still until its primary cursor or selected picker entry would leave it. A nonnegative integer reserves that many visible rows above/below the cursor, and terminal-cell columns left/right in unwrapped text. `nil` keeps it centered; integers at least half the current viewport dimension behave the same way until resizing makes that margin usable. The start of content limits centering, while trailing blank space allows centering near the end. Whole two-row picker entries stay aligned, using the nearest entry to the center when exact margins cannot fit.
+
+The setting applies to ordinary and historical buffers, split/unified diff panes, file pickers and explorers, command/buffer palettes, completion lists, and revision selectors. Wrapped text measures visual rows, not source lines; picker distances use result rows, excluding borders, search fields, and help. Manual mouse-wheel scrolling remains detached until keyboard navigation resumes. Only `nil` or integers from `0` through the platform's Rust `usize` maximum (`18446744073709551615` on 64-bit systems) are accepted; other values reject the configuration.
+
+`config.highlight_trailing_whitespace` defaults to `false`. Set it to `true` to give trailing whitespace a red background in ordinary and historical buffers and both sides of split/unified diffs, including wrapped and horizontally scrolled text. Spaces, expanded tab cells, and Unicode whitespace at the end of a source line are highlighted; whitespace-only lines are included, but empty lines and padding beyond the text are not. Wrapping does not make interior whitespace trailing. Search, selections, and secondary carets retain their background precedence; diagnostic underlines remain visible. This changes display only, not file contents. Only literal Ruby booleans are accepted; other values reject the configuration.
+
+`config.whitespace_characters` defaults to `{}` (disabled). Assign a hash mapping literal whitespace characters to dim display markers, for example `{ " " => "·", "\t" => "→", "\u00a0" => "⍽", "\n" => "↵" }` for spaces, tabs, nonbreaking spaces, and line breaks. Unlisted characters keep their ordinary appearance. Keys and values must be single-character strings; keys must be whitespace with visible terminal width, tabs, or `"\n"`, and values must be printable one-cell characters. Carriage returns and other control characters, zero-width markers, and wide markers reject the configuration. Only indicator cells receive terminal dim styling; source-text colors, diagnostic underlines, and highlighted backgrounds remain intact.
+
+`config.whitespace_scope` defaults to `"all"`. Use `"leading"` to mark only the initial whitespace prefix of each source line; a whitespace-only line is entirely leading, but wrapping and horizontal scrolling do not create new indentation. Only the strings `"all"` and `"leading"` are accepted; other values reject the configuration.
+
+A `"\n"` map entry marks actual line breaks independently of `whitespace_scope`, including blank lines and a file's final newline when present. Soft wraps, missing final newlines, and the virtual empty EOF row do not gain markers. The glyph occupies the existing end-of-line caret cell on the final wrapped segment; a full-width line uses the existing extra caret segment. In unwrapped text, an offscreen end-of-line marker is clipped like other source cells. Newline markers inside syntax-recognized strings are suppressed along with horizontal whitespace markers.
+
+Whitespace inside strings recognized by the bundled syntax grammar stays literal, including raw/multiline strings, heredocs, interpolated strings, and strings with embedded-language highlighting. Outside strings, configured markers still apply. String boundaries come from the original source, so wrapping, horizontal scrolling, and split/unified historical diffs retain this distinction. Plain text and unknown languages have no syntax-defined string boundaries; quotes are not guessed to be strings.
+
+Markers appear in ordinary and historical buffers and both sides of split/unified diffs. Tabs and wide Unicode whitespace show the marker in their first source cell and leave remaining cells blank, preserving tab stops, wrapping, horizontal scrolling, and cursor/selection geometry. A clipped first cell hides its marker; padding beyond the source does not gain markers. Whitespace with combining characters remains intact. Syntax colors, search, selections, diagnostics, and trailing-whitespace highlighting still apply. This changes display only: editing, copying, and saving retain the original characters.
+
 `config.git_blame` defaults to `true`; set it to `false` to disable current-line inline Git blame and its background worker. Only literal Ruby booleans are accepted; other values reject the configuration. Toggle it for the running session with `:git_blame.toggle`, its palette action, or a custom binding such as `config.bind "leader b", config.core.git_blame.toggle`. There is no default shortcut.
 
 `config.git_gutter` defaults to `"bar"`: a fat `▌` with one blank column between the line number and marker and another before the text. `"symbols"` uses `+` / `-` / `~` with the same spacing. Added, removed, and modified lines use green, red, and yellow respectively. `"line_numbers"` colors the existing numbers without adding a marker column; the current line retains its cyan/bold caret highlight. `"none"` hides line-gutter repository indicators, not line numbers or picker file statuses. Other modes retain diagnostic number colors independently of repository markers. Unsupported strings, empty strings, and non-string values reject the configuration.

docs/editing.md

@@ -8,6 +8,8 @@ Ordinary documents show repository changes beside their hybrid line numbers by d
 
 The baseline is Git `HEAD` or Git-backed jj's parent `@-`, so indicators include unsaved edits and remain after saving until the repository baseline changes. A deletion marks the next surviving source row; at EOF it marks the last editor row, including the final empty row after a trailing newline. An empty file anchors removals on row 0. Replacements mark paired rows modified and extra current rows added. Historical snapshots do not show live changes. Eligible named files not yet on disk show nonempty unsaved text as added; tracked files missing on disk still compare their buffer text against the baseline. Non-repository/ignored/binary/symlink files, files over 16 MiB, and jj changes with multiple parents have no indicators.
 
+Indicators refresh asynchronously. Typing and undo/redo retain the last completed indicators until the updated comparison arrives, avoiding flashes; indicator values and row positions can briefly lag edits.
+
 ## Default editing keys
 
 | Mode | Keys |
@@ -200,6 +202,10 @@ Live file buffers automatically check disk metadata every 250 ms, including buff
 
 Paste is backend input: it is ignored in Normal, Command, Search, and Visual modes, and inserts literal text in Insert mode, with CRLF/CR normalization and a 4 MiB limit. Pasted text is one undo action, separate from typing before and after it. Rejected paste reports an error without changing text, cursor, mode, or pending insert history. Internal clipboard actions are separate from `Input::Paste` and use already-validated buffer text.
 
+## Cursor-following scrolling
+
+[Configure `scroll_distance`](configuration.md#preferences) to reserve space between the primary cursor or picker selection and the viewport edges. `0` (default) scrolls only to keep it visible; an integer reserves that many visual rows, and columns for unwrapped document text. `nil`, or a margin too large for the current viewport, centers it as far as the start of content permits. This policy applies to documents, historical/diff panes, file explorers, palettes, completion lists, and revision pickers. Reversing direction inside the margin does not move the viewport; resizing recalculates the usable margin.
+
 ## Mouse wheel scrolling
 
 Mouse-wheel up/down scrolls the document view three display rows per event without moving the primary or secondary carets, changing selections, or editing text. The caret may scroll offscreen; its terminal cursor is hidden until visible again. Navigation (including a motion blocked at the document boundary), editing, or buffer navigation restores caret-following. Idle updates preserve a wheel-scrolled view, clamped to the document; resizing preserves unwrapped views and restores caret-following in ordinary wrapped buffers.
@@ -384,7 +390,7 @@ Text panes use normal buffer interaction regardless of writability: motions and
 
 **LSP definition, hover, and diagnostics work normally in focused Before and After text panes**, including historical snapshots. Each snapshot is served with its immutable revision text and its own document URI, not the current disk contents. Completion and completion edits are available only in writable After; they use the shared buffer's normal undo history. Revision selectors and the changed-file explorer are not document-action targets.
 
-Accepted LSP definitions center the selection's caret row once in the destination pane, including wrapped visual rows and revealed diff excerpts. Centering uses the focused pane's actual height in either split orientation or unified view. The next motion does not recenter; failed or superseded definitions preserve the current logical viewport.
+Accepted LSP definitions center the selection's caret row once in the destination pane, including wrapped visual rows and revealed diff excerpts. Centering uses the focused pane's actual height in either split orientation or unified view. Subsequent motions resume the configured `scroll_distance` policy; failed or superseded definitions preserve the current logical viewport.
 
 A definition whose source range **overlaps an actual added, removed, or replaced line** stays in the same comparison and selects the correct file and side, loading file details on demand. For a location link, the symbol's full target range determines overlap and its selection range determines the caret: an unchanged declaration with a changed body still belongs in the comparison. Source coordinates belong to that side, including old paths for renames; navigation reveals the exact selection row, even when previously omitted, never the nearest excerpt. A wholly unchanged target opens a **new ordinary tab**, even when it is visible context or omitted text in a changed file. Files outside the comparison's changes also open in a new tab. The original comparison, pane layout, source caret, excerpts, and dirty buffers remain intact. Loaded targets share their existing text and undo history rather than reloading disk; references to snapshot URIs retain the historical text and read-only identity in the new tab, even after the comparison closes. Unreadable files, invalid UTF-8, invalid source ranges, and unsupported remote URIs do not create a tab or disturb the source.
 

examples/config.rb

@@ -5,6 +5,10 @@ Vamp.configure do |config|
   config.leader = "space"
   config.clipboard_mode = "system" # "separate" keeps ordinary y/d/c/p/P internal
   config.git_blame = true # false disables current-line inline blame
+  config.scroll_distance = 0 # nonnegative edge distance, or nil to center
+  config.highlight_trailing_whitespace = false # true marks line-end whitespace in red
+  config.whitespace_characters = {} # opt in: { " " => "·", "\t" => "→", "\n" => "↵" }
+  config.whitespace_scope = "all" # or "leading" for indentation only; newline markers remain independent
   config.file_explorer_side = "right"
   config.file_explorer_view = "tree"
   config.file_picker_view = "tree"

src/diff.rs

@@ -1140,6 +1140,15 @@ impl DiffState {
             .is_some_and(|file| file.loaded)
     }
 
+    /// Source rows without the editor's virtual terminal row, preserving real empty lines.
+    pub(crate) fn after_source_lines<'a>(&self, file: &'a ChangedFile) -> &'a [String] {
+        if self.live_files.contains(&self.file) {
+            live_content(&file.after, file.after_eof)
+        } else {
+            &file.after
+        }
+    }
+
     fn prepare_selected_file(&mut self) {
         if self.refresh_pending() {
             self.align_file();

src/editor.rs

@@ -25,6 +25,14 @@ use unicode_width::UnicodeWidthStr;
 const MAX_EDIT_BYTES: usize = 4 * 1024 * 1024;
 static TEMP_ID: AtomicU64 = AtomicU64::new(0);
 
+#[derive(Clone, Copy, Debug, Default, Eq, PartialEq, serde::Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum WhitespaceScope {
+    #[default]
+    All,
+    Leading,
+}
+
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 pub enum Input {
     Char(char),
@@ -1762,6 +1770,10 @@ pub struct Editor {
     bottom_bar: ChromeLine,
     popup: PopupConfig,
     labels: BTreeMap<String, String>,
+    scroll_distance: Option<usize>,
+    highlight_trailing_whitespace: bool,
+    whitespace_characters: BTreeMap<char, char>,
+    whitespace_scope: WhitespaceScope,
     battery_charge: Option<u8>,
     battery_label: String,
     git_blame: bool,
@@ -1863,6 +1875,10 @@ impl Editor {
             bottom_bar: ChromeLine::bottom(),
             popup: PopupConfig::default(),
             labels: BTreeMap::new(),
+            scroll_distance: Some(0),
+            highlight_trailing_whitespace: false,
+            whitespace_characters: BTreeMap::new(),
+            whitespace_scope: WhitespaceScope::All,
             battery_charge: None,
             battery_label: String::new(),
             git_blame: true,
@@ -2601,6 +2617,38 @@ impl Editor {
             .map_or(self.active.view.word_wrap, |diff| diff.word_wrap)
     }
 
+    pub fn scroll_distance(&self) -> Option<usize> {
+        self.scroll_distance
+    }
+
+    pub(crate) fn set_scroll_distance(&mut self, distance: Option<usize>) {
+        self.scroll_distance = distance;
+    }
+
+    pub(crate) fn highlight_trailing_whitespace(&self) -> bool {
+        self.highlight_trailing_whitespace
+    }
+
+    pub(crate) fn set_highlight_trailing_whitespace(&mut self, enabled: bool) {
+        self.highlight_trailing_whitespace = enabled;
+    }
+
+    pub(crate) fn whitespace_characters(&self) -> &BTreeMap<char, char> {
+        &self.whitespace_characters
+    }
+
+    pub(crate) fn set_whitespace_characters(&mut self, characters: BTreeMap<char, char>) {
+        self.whitespace_characters = characters;
+    }
+
+    pub(crate) fn whitespace_scope(&self) -> WhitespaceScope {
+        self.whitespace_scope
+    }
+
+    pub(crate) fn set_whitespace_scope(&mut self, scope: WhitespaceScope) {
+        self.whitespace_scope = scope;
+    }
+
     pub(crate) fn set_diff_context_options(&mut self, context_lines: usize, expand_lines: usize) {
         self.diff_context_options = (context_lines, expand_lines);
         if let Some(diff) = &mut self.diff {
@@ -4932,9 +4980,8 @@ impl Editor {
             return None;
         }
         let changes = self.active.gutter_changes.as_ref()?;
-        if changes.revision != self.active.text_revision
+        // Keep the last completed markers visible while the worker recomputes after edits.
-            || Some(changes.path.as_path()) != self.path()
+        if Some(changes.path.as_path()) != self.path() {
-        {
             return None;
         }
         changes.lines.get(row).copied().flatten()

src/files.rs

@@ -93,6 +93,7 @@ pub struct FilePicker {
     tree_for_node: Vec<usize>,
     tree_roots: Vec<usize>,
     rows: Vec<VisibleRow>,
+    viewport_revision: u64,
     expanded: HashSet<usize>,
     filter_collapsed: HashSet<usize>,
     saved_selection: [Option<usize>; 2],
@@ -298,6 +299,7 @@ impl FilePicker {
             tree: Vec::new(),
             tree_roots: Vec::new(),
             rows: Vec::new(),
+            viewport_revision: 0,
             expanded: HashSet::new(),
             filter_collapsed: HashSet::new(),
             saved_selection: [None, None],
@@ -346,6 +348,10 @@ impl FilePicker {
         tree
     }
 
+    pub(crate) fn viewport_revision(&self) -> u64 {
+        self.viewport_revision
+    }
+
     pub fn entries(&self) -> impl ExactSizeIterator<Item = FileRow<'_>> + '_ {
         self.rows.iter().map(|row| {
             let node = &self.nodes[row.node];
@@ -542,6 +548,8 @@ impl FilePicker {
     }
 
     fn project(&mut self, selected: Option<usize>, select_match: bool) {
+        static NEXT_REVISION: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(1);
+        self.viewport_revision = NEXT_REVISION.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
         let query = self.query.to_lowercase();
         let tokens: Vec<_> = query.split_whitespace().collect();
         let matches = |node: &Node| tokens.iter().all(|token| node.search_label.contains(token));

src/ruby.rs

@@ -44,6 +44,10 @@ pub struct Config {
     pub bottom_bar: ChromeLine,
     pub popup: PopupConfig,
     pub labels: BTreeMap<String, String>,
+    pub scroll_distance: Option<usize>,
+    pub highlight_trailing_whitespace: bool,
+    pub whitespace_characters: BTreeMap<char, char>,
+    pub whitespace_scope: crate::editor::WhitespaceScope,
     pub diff_context_lines: usize,
     pub diff_expand_lines: usize,
     pub diff_view_mode: crate::diff::ViewMode,
@@ -89,6 +93,10 @@ impl Default for Config {
             bottom_bar: ChromeLine::bottom(),
             popup: PopupConfig::default(),
             labels: BTreeMap::new(),
+            scroll_distance: Some(0),
+            highlight_trailing_whitespace: false,
+            whitespace_characters: BTreeMap::new(),
+            whitespace_scope: crate::editor::WhitespaceScope::All,
             diff_context_lines: 10,
             diff_expand_lines: 15,
             diff_view_mode: crate::diff::ViewMode::Split,
@@ -121,6 +129,10 @@ pub fn load_config(path: &Path) -> Result<Config, String> {
                 bottom_bar,
                 popup,
                 labels,
+                scroll_distance,
+                highlight_trailing_whitespace,
+                whitespace_characters,
+                whitespace_scope,
                 diff_context_lines,
                 diff_expand_lines,
                 diff_view_mode,
@@ -154,6 +166,10 @@ pub fn load_config(path: &Path) -> Result<Config, String> {
             config.bottom_bar = bottom_bar;
             config.popup = popup;
             config.labels = labels;
+            config.scroll_distance = scroll_distance;
+            config.highlight_trailing_whitespace = highlight_trailing_whitespace;
+            config.whitespace_characters = whitespace_characters;
+            config.whitespace_scope = whitespace_scope;
             config.diff_context_lines = diff_context_lines;
             config.diff_expand_lines = diff_expand_lines;
             config.diff_view_mode = diff_view_mode;
@@ -450,6 +466,17 @@ fn diff_expand_lines<'de, D: serde::Deserializer<'de>>(deserializer: D) -> Resul
     diff_line_count(deserializer, "diff_expand_lines", 1)
 }
 
+fn scroll_distance<'de, D: serde::Deserializer<'de>>(
+    deserializer: D,
+) -> Result<Option<usize>, D::Error> {
+    Option::<usize>::deserialize(deserializer).map_err(|error| {
+        serde::de::Error::custom(format!(
+            "scroll_distance must be nil or an Integer between 0 and {}: {error}",
+            usize::MAX
+        ))
+    })
+}
+
 // Startup-only configuration does not inflate every queued plugin response.
 #[derive(Deserialize)]
 #[serde(deny_unknown_fields)]
@@ -474,6 +501,12 @@ struct ConfigFrame {
     popup: PopupConfig,
     #[serde(deserialize_with = "crate::chrome::labels")]
     labels: BTreeMap<String, String>,
+    #[serde(deserialize_with = "scroll_distance")]
+    scroll_distance: Option<usize>,
+    highlight_trailing_whitespace: bool,
+    #[serde(deserialize_with = "whitespace_characters")]
+    whitespace_characters: BTreeMap<char, char>,
+    whitespace_scope: crate::editor::WhitespaceScope,
     #[serde(deserialize_with = "diff_context_lines")]
     diff_context_lines: usize,
     #[serde(deserialize_with = "diff_expand_lines")]
@@ -483,6 +516,30 @@ struct ConfigFrame {
     diff_follow_working_copy: bool,
 }
 
+fn whitespace_characters<'de, D: serde::Deserializer<'de>>(
+    deserializer: D,
+) -> Result<BTreeMap<char, char>, D::Error> {
+    use unicode_width::UnicodeWidthChar;
+
+    let characters = BTreeMap::<char, char>::deserialize(deserializer)?;
+    for (&whitespace, &marker) in &characters {
+        if !whitespace.is_whitespace()
+            || (!matches!(whitespace, '\t' | '\n')
+                && (whitespace.is_control() || whitespace.width().unwrap_or(0) == 0))
+        {
+            return Err(serde::de::Error::custom(
+                "whitespace_characters keys must be visible-width whitespace characters, tabs, or newlines",
+            ));
+        }
+        if marker.is_control() || marker.width() != Some(1) {
+            return Err(serde::de::Error::custom(
+                "whitespace_characters values must be printable single-cell characters",
+            ));
+        }
+    }
+    Ok(characters)
+}
+
 #[derive(Deserialize)]
 #[serde(tag = "type", deny_unknown_fields)]
 enum Response {
@@ -1217,9 +1274,9 @@ end
             assert!(load_config(&path).unwrap_err().contains(error), "{value}");
         }
         for frame in [
-            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
+            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"highlight_trailing_whitespace":false,"whitespace_characters":{},"whitespace_scope":"all","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
-            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":null,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
+            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":null,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"highlight_trailing_whitespace":false,"whitespace_characters":{},"whitespace_scope":"all","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
-            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":7,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
+            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":7,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"highlight_trailing_whitespace":false,"whitespace_characters":{},"whitespace_scope":"all","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
         ] {
             assert!(serde_json::from_str::<Response>(frame).is_err(), "{frame}");
         }
@@ -1295,6 +1352,10 @@ end
             "leader": "space", "file_explorer_side": "right", "file_picker_view": "tree",
             "file_explorer_view": "tree", "clipboard_mode": "system", "git_blame": true,
             "git_gutter": "bar",
+            "scroll_distance": 0,
+            "highlight_trailing_whitespace": false,
+            "whitespace_characters": {},
+            "whitespace_scope": "all",
             "top_bar": {}, "bottom_bar": {}, "popup": {"command": {}, "search": {}},
             "labels": {}, "diff_context_lines": 10, "diff_expand_lines": 15,
             "diff_view_mode": "split", "diff_split_orientation": "vertical",
@@ -1313,6 +1374,151 @@ end
         assert!(serde_json::from_value::<Response>(frame).is_err());
     }
 
+    #[test]
+    fn trailing_whitespace_configuration_rejects_non_booleans() {
+        let fixture = Fixture::new();
+        for value in ["nil", "0", "\"true\"", "[]", "{}"] {
+            let path = fixture.file(
+                "config.rb",
+                &format!("Vamp.configure {{ |c| c.highlight_trailing_whitespace = {value} }}"),
+            );
+            assert!(
+                load_config(&path)
+                    .unwrap_err()
+                    .contains("highlight_trailing_whitespace must be true or false")
+            );
+        }
+    }
+
+    #[test]
+    fn whitespace_characters_validate_real_ruby_configuration() {
+        let fixture = Fixture::new();
+        for value in [
+            "nil",
+            "false",
+            "[]",
+            r#"{ space: "·" }"#,
+            r#"{ " " => 1 }"#,
+            r#"{ "" => "." }"#,
+            r#"{ "  " => "." }"#,
+            r#"{ " " => ".." }"#,
+            r#"{ "x" => "." }"#,
+            r#"{ "\u000b" => "." }"#,
+            r#"{ "\r" => "." }"#,
+            r#"{ "\u000c" => "." }"#,
+            r#"{ "\u0085" => "." }"#,
+            r#"{ "\u200b" => "." }"#,
+            r#"{ " " => "\t" }"#,
+            r#"{ " " => "\n" }"#,
+            r#"{ " " => "\u0301" }"#,
+            r#"{ " " => "界" }"#,
+        ] {
+            let path = fixture.file(
+                "config.rb",
+                &format!("Vamp.configure {{ |c| c.whitespace_characters = {value} }}"),
+            );
+            assert!(load_config(&path).is_err(), "{value}");
+        }
+        let path = fixture.file(
+            "config.rb",
+            r#"Vamp.configure { |c| c.whitespace_characters = { " " => "·", "\t" => "→", "\n" => "↵", "\u00a0" => "⍽", "\u3000" => "_" } }"#,
+        );
+        assert_eq!(
+            load_config(&path).unwrap().whitespace_characters,
+            BTreeMap::from([
+                (' ', '·'),
+                ('\t', '→'),
+                ('\n', '↵'),
+                ('\u{a0}', '⍽'),
+                ('\u{3000}', '_'),
+            ]),
+        );
+    }
+
+    #[test]
+    fn whitespace_scope_validates_ruby_atomically_and_requires_valid_wire_values() {
+        use crate::editor::WhitespaceScope;
+
+        let fixture = Fixture::new();
+        let path = fixture.file("config.rb", "Vamp.configure {}");
+        assert_eq!(
+            load_config(&path).unwrap().whitespace_scope,
+            WhitespaceScope::All
+        );
+        for (value, expected) in [
+            ("all", WhitespaceScope::All),
+            ("leading", WhitespaceScope::Leading),
+        ] {
+            let path = fixture.file(
+                "config.rb",
+                &format!(r#"Vamp.configure {{ |c| c.whitespace_scope = "{value}" }}"#),
+            );
+            assert_eq!(load_config(&path).unwrap().whitespace_scope, expected);
+        }
+        for value in [
+            "nil",
+            "false",
+            "0",
+            "[]",
+            "{}",
+            ":all",
+            r#""""#,
+            r#""unknown""#,
+        ] {
+            let path = fixture.file(
+                "config.rb",
+                &format!("Vamp.configure {{ |c| c.whitespace_scope = {value} }}"),
+            );
+            assert!(load_config(&path).is_err(), "{value}");
+            let path = fixture.file(
+                "config.rb",
+                &format!(
+                    r#"Vamp.configure do |c|
+  c.whitespace_scope = "leading"
+  begin
+    c.whitespace_scope = {value}
+    raise "invalid scope accepted"
+  rescue TypeError, ArgumentError
+  end
+end"#,
+                ),
+            );
+            assert_eq!(
+                load_config(&path).unwrap().whitespace_scope,
+                WhitespaceScope::Leading
+            );
+        }
+        let mut frame = serde_json::json!({
+            "type": "config", "version": 1, "plugins": [], "lsp": {}, "bindings": [],
+            "leader": "space", "file_explorer_side": "right", "file_picker_view": "tree",
+            "file_explorer_view": "tree", "clipboard_mode": "system", "git_blame": true,
+            "git_gutter": "bar", "scroll_distance": 0, "highlight_trailing_whitespace": false,
+            "whitespace_characters": {}, "whitespace_scope": "all",
+            "top_bar": {}, "bottom_bar": {}, "popup": {"command": {}, "search": {}},
+            "labels": {}, "diff_context_lines": 10, "diff_expand_lines": 15,
+            "diff_view_mode": "split", "diff_split_orientation": "vertical",
+            "diff_follow_working_copy": true
+        });
+        for value in ["all", "leading"] {
+            frame["whitespace_scope"] = serde_json::json!(value);
+            assert!(serde_json::from_value::<Response>(frame.clone()).is_ok());
+        }
+        for value in [
+            serde_json::Value::Null,
+            serde_json::json!(false),
+            serde_json::json!(0),
+            serde_json::json!([]),
+            serde_json::json!({}),
+            serde_json::json!(""),
+            serde_json::json!("unknown"),
+        ] {
+            frame["whitespace_scope"] = value;
+            assert!(serde_json::from_value::<Response>(frame.clone()).is_err());
+        }
+        frame.as_object_mut().unwrap().remove("whitespace_scope");
+        assert!(serde_json::from_value::<Response>(frame).is_err());
+    }
+
     #[test]
     fn working_diff_tracking_rejects_non_boolean_configuration() {
         let fixture = Fixture::new();
@@ -1545,6 +1751,10 @@ end
             "bindings": [], "leader": "space", "file_explorer_side": "right",
             "file_picker_view": "tree", "file_explorer_view": "tree",
             "top_bar": {}, "bottom_bar": {}, "labels": {},
+            "scroll_distance": 0,
+            "highlight_trailing_whitespace": false,
+            "whitespace_characters": {},
+            "whitespace_scope": "all",
             "popup": {"command": {}, "search": {}},
             "clipboard_mode": "system", "diff_context_lines": 0, "diff_expand_lines": 7,
             "diff_view_mode": "split", "diff_split_orientation": "vertical",
@@ -1585,6 +1795,67 @@ end
         }
     }
 
+    #[test]
+    fn config_scroll_distance_accepts_nil_and_counts_and_rejects_invalid_values() {
+        let fixture = Fixture::new();
+        let frame = serde_json::json!({
+            "version": 1, "type": "config", "plugins": [], "lsp": {},
+            "bindings": [], "leader": "space", "file_explorer_side": "right",
+            "file_picker_view": "tree", "file_explorer_view": "tree",
+            "clipboard_mode": "system", "git_blame": true, "git_gutter": "bar",
+            "highlight_trailing_whitespace": false,
+            "whitespace_characters": {},
+            "whitespace_scope": "all",
+            "top_bar": {}, "bottom_bar": {}, "labels": {},
+            "popup": {"command": {}, "search": {}},
+            "diff_context_lines": 10, "diff_expand_lines": 15,
+            "diff_view_mode": "split", "diff_split_orientation": "vertical",
+            "diff_follow_working_copy": true, "scroll_distance": 0
+        });
+        for distance in [None, Some(0), Some(7), Some(usize::MAX)] {
+            let value = distance.map_or_else(|| "nil".into(), |value| value.to_string());
+            let path = fixture.file(
+                "config.rb",
+                &format!("Vamp.configure {{ |config| config.scroll_distance = {value} }}"),
+            );
+            assert_eq!(load_config(&path).unwrap().scroll_distance, distance);
+            let mut valid_frame = frame.clone();
+            valid_frame["scroll_distance"] = serde_json::json!(distance);
+            let response = serde_json::from_value::<Response>(valid_frame).unwrap();
+            let Response::Config(config) = response else {
+                panic!("expected a configuration frame");
+            };
+            assert_eq!(config.scroll_distance, distance);
+        }
+        for value in [
+            "-1",
+            "1.5",
+            "\"3\"",
+            "true",
+            "false",
+            "18446744073709551616",
+        ] {
+            let path = fixture.file(
+                "config.rb",
+                &format!("Vamp.configure {{ |config| config.scroll_distance = {value} }}"),
+            );
+            let error = load_config(&path).unwrap_err();
+            assert!(
+                error.contains("scroll_distance") && error.contains("must be"),
+                "{value}: {error}"
+            );
+            let mut invalid_frame = frame.clone();
+            invalid_frame["scroll_distance"] = serde_json::from_str(value).unwrap();
+            let error = serde_json::from_value::<Response>(invalid_frame)
+                .err()
+                .unwrap();
+            assert!(
+                error.to_string().contains("scroll_distance"),
+                "{value}: {error}"
+            );
+        }
+    }
+
     #[test]
     fn lsp_configuration_is_disabled_unless_explicitly_enabled() {
         let fixture = Fixture::new();
@@ -1962,6 +2233,10 @@ end"#,
             "file_picker_view": "tree", "file_explorer_view": "tree",
             "git_blame": true,
             "git_gutter": "bar",
+            "scroll_distance": 0,
+            "highlight_trailing_whitespace": false,
+            "whitespace_characters": {},
+            "whitespace_scope": "all",
             "top_bar": {}, "bottom_bar": {}, "labels": {},
             "popup": {"command": {}, "search": {}},
             "clipboard_mode": "system", "diff_context_lines": 10, "diff_expand_lines": 15,

src/ruby_config.rb

@@ -141,6 +141,10 @@ module Vamp
       @bar = BarConfig.new
       @popup = PopupConfig.new
       @labels = {}
+      @scroll_distance = 0
+      @highlight_trailing_whitespace = false
+      @whitespace_characters = {}
+      @whitespace_scope = "all"
       @diff_context_lines = 10
       @diff_expand_lines = 15
       @diff_view_mode = "split"
@@ -214,6 +218,42 @@ module Vamp
       end
     end
 
+    # @param distance [Integer, nil] nonnegative cursor margin, or nil to center
+    # @return [Integer, nil]
+    def scroll_distance=(distance)
+      @scroll_distance = distance.nil? ? nil : diff_line_count!(distance, "scroll_distance", 0)
+    end
+
+    # @param enabled [Boolean]
+    # @return [Boolean]
+    def highlight_trailing_whitespace=(enabled)
+      raise TypeError, "highlight_trailing_whitespace must be true or false" unless [true, false].include?(enabled)
+
+      @highlight_trailing_whitespace = enabled
+    end
+
+    # @param characters [Hash{String => String}] whitespace character to single-cell marker
+    # @return [Hash{String => String}]
+    def whitespace_characters=(characters)
+      raise TypeError, "whitespace_characters must be a Hash" unless characters.is_a?(Hash)
+
+      characters.each do |whitespace, marker|
+        unless [whitespace, marker].all? { |value| value.is_a?(String) && value.length == 1 }
+          raise TypeError, "whitespace_characters keys and values must be single-character Strings"
+        end
+      end
+      @whitespace_characters = characters.dup
+    end
+
+    # @param scope [String] "all" or "leading"
+    # @return [String]
+    def whitespace_scope=(scope)
+      scope = Vamp.string!(scope, "whitespace_scope")
+      raise ArgumentError, "whitespace_scope must be all or leading" unless %w[all leading].include?(scope)
+
+      @whitespace_scope = scope
+    end
+
     # @param lines [Integer] nonnegative context lines around each diff change
     # @return [Integer]
     def diff_context_lines=(lines)
@@ -285,6 +325,10 @@ module Vamp
         "file_explorer_view" => @file_explorer_view, "clipboard_mode" => @clipboard_mode,
         "git_blame" => @git_blame,
         "git_gutter" => @git_gutter,
+        "scroll_distance" => @scroll_distance,
+        "highlight_trailing_whitespace" => @highlight_trailing_whitespace,
+        "whitespace_characters" => @whitespace_characters,
+        "whitespace_scope" => @whitespace_scope,
         "top_bar" => @bar.top, "bottom_bar" => @bar.bottom, "labels" => @labels,
         "popup" => { "command" => @popup.command, "search" => @popup.search },
         "diff_context_lines" => @diff_context_lines, "diff_expand_lines" => @diff_expand_lines,

src/session.rs

@@ -256,6 +256,10 @@ impl EditorSession {
         }
         editor.set_git_blame(config.git_blame);
         editor.set_gutter_style(config.git_gutter);
+        editor.set_scroll_distance(config.scroll_distance);
+        editor.set_highlight_trailing_whitespace(config.highlight_trailing_whitespace);
+        editor.set_whitespace_characters(config.whitespace_characters);
+        editor.set_whitespace_scope(config.whitespace_scope);
         editor.set_diff_context_options(config.diff_context_lines, config.diff_expand_lines);
         editor.set_diff_display_options(config.diff_view_mode, config.diff_split_orientation);
         if let Err(error) =
@@ -1610,17 +1614,34 @@ mod tests {
         assert_eq!(session.editor.gutter_change(1), Some(Change::Modified));
         session.editor.handle(Input::Char('i'));
         session.editor.handle(Input::Char('x'));
-        assert_eq!(session.editor.gutter_change(1), None);
+        assert_eq!(session.editor.gutter_change(1), Some(Change::Modified));
+        session.editor.handle(Input::Char('y'));
+        assert_eq!(session.editor.gutter_change(1), Some(Change::Modified));
+        session.editor.handle(Input::Backspace);
+        assert_eq!(session.editor.gutter_change(1), Some(Change::Modified));
+        session.editor.handle(Input::Escape);
+        session.editor.handle(Input::Char('u'));
+        assert_eq!(session.editor.gutter_change(1), Some(Change::Modified));
+        session.editor.handle(Input::Char('U'));
+        assert_eq!(session.editor.gutter_change(1), Some(Change::Modified));
         assert!(!session.apply_gutter_result(
             second_request,
             vec![(first_buffer, Ok(vec![None, Some(Change::Removed)]))],
         ));
+        assert_eq!(session.editor.gutter_change(1), Some(Change::Modified));
         session.poll_gutter_at(now);
+        assert_eq!(session.editor.gutter_change(1), Some(Change::Modified));
         assert!(session.apply_gutter_result(
             session.gutter_request_id,
             vec![(first_buffer, Ok(vec![None, Some(Change::Added)]))],
         ));
         assert_eq!(session.editor.gutter_change(1), Some(Change::Added));
+        session.poll_gutter_at(now + Duration::from_secs(1));
+        assert!(session.apply_gutter_result(
+            session.gutter_request_id,
+            vec![(first_buffer, Ok(vec![None, None]))],
+        ));
+        assert_eq!(session.editor.gutter_change(1), None);
         session.editor.execute(&format!("buffer {second_buffer}"));
         assert_eq!(session.editor.gutter_change(0), Some(Change::Added));
     }

src/syntax.rs

@@ -24,7 +24,7 @@ pub enum SyntaxKind {
     Markup,
 }
 
-/// A syntax foreground range in the original line's bytes, excluding its newline.
+/// A syntax range in original line bytes; string coverage may include its newline.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct SyntaxSpan {
     pub start_byte: usize,
@@ -37,12 +37,14 @@ pub struct SyntaxSpan {
 pub struct SyntaxCache {
     revision: Option<u64>,
     path: Option<PathBuf>,
+    final_newline: bool,
     syntax: Option<&'static LanguageSpec>,
     source: String,
     next_source: String,
     line_starts: Vec<usize>,
     lines: Vec<Vec<SyntaxSpan>>,
     highlighted: Vec<bool>,
+    string_spans: Vec<Vec<SyntaxSpan>>,
     context: Option<LayerContext>,
     parser: Parser,
     tree: Option<Tree>,
@@ -88,6 +90,7 @@ impl SyntaxCache {
             path,
             revision,
             std::slice::from_ref(&(0..lines.len())),
+            false,
         );
     }
 
@@ -100,7 +103,26 @@ impl SyntaxCache {
         revision: u64,
         visible: &[std::ops::Range<usize>],
     ) {
-        self.update_rows(lines, path, revision, visible);
+        self.update_rows(lines, path, revision, visible, false);
+    }
+
+    /// Diff sources store a final line break separately instead of a trailing empty row.
+    pub(crate) fn update_diff(
+        &mut self,
+        lines: &[String],
+        path: Option<&Path>,
+        revision: u64,
+        final_newline: bool,
+        visible: Option<&[std::ops::Range<usize>]>,
+    ) {
+        let all_rows = 0..lines.len();
+        self.update_rows(
+            lines,
+            path,
+            revision,
+            visible.unwrap_or(std::slice::from_ref(&all_rows)),
+            final_newline && !lines.is_empty(),
+        );
     }
 
     fn update_rows(
@@ -109,9 +131,11 @@ impl SyntaxCache {
         path: Option<&Path>,
         revision: u64,
         visible: &[std::ops::Range<usize>],
+        final_newline: bool,
     ) {
         let path_changed = self.path.as_deref() != path;
-        let revision_changed = self.revision != Some(revision);
+        let revision_changed =
+            self.revision != Some(revision) || self.final_newline != final_newline;
         let syntax = if path_changed || revision_changed {
             languages::detect(path, lines.first().map(String::as_str))
         } else {
@@ -119,6 +143,7 @@ impl SyntaxCache {
         };
         let language_changed = !same_language(self.syntax, syntax);
         self.revision = Some(revision);
+        self.final_newline = final_newline;
         if path_changed {
             self.path = path.map(Path::to_path_buf);
         }
@@ -127,8 +152,9 @@ impl SyntaxCache {
         let mut edit = None;
         if revision_changed {
             self.next_source.clear();
-            let length =
+            let length = lines.iter().map(String::len).sum::<usize>()
-                lines.iter().map(String::len).sum::<usize>() + lines.len().saturating_sub(1);
+                + lines.len().saturating_sub(1)
+                + usize::from(final_newline);
             self.next_source.reserve(length);
             for (row, line) in lines.iter().enumerate() {
                 if row > 0 {
@@ -136,6 +162,9 @@ impl SyntaxCache {
                 }
                 self.next_source.push_str(line);
             }
+            if final_newline {
+                self.next_source.push('\n');
+            }
             if self.source != self.next_source {
                 edit = Some(minimal_edit(&self.source, &self.next_source));
                 std::mem::swap(&mut self.source, &mut self.next_source);
@@ -146,11 +175,15 @@ impl SyntaxCache {
                 self.line_starts.push(start);
                 start += line.len() + 1;
             }
+            if final_newline {
+                self.line_starts.push(self.source.len());
+            }
             self.lines.resize_with(lines.len(), Vec::new);
+            self.string_spans.resize_with(lines.len(), Vec::new);
             self.highlighted.resize(lines.len(), false);
         }
         if edit.is_some() || language_changed {
-            for spans in &mut self.lines {
+            for spans in self.lines.iter_mut().chain(&mut self.string_spans) {
                 spans.clear();
             }
             self.highlighted.fill(false);
@@ -183,6 +216,8 @@ impl SyntaxCache {
                     start_point: Point::new(start, 0),
                     end_point: if row < lines.len() {
                         Point::new(row, 0)
+                    } else if final_newline {
+                        Point::new(lines.len(), 0)
                     } else {
                         Point::new(
                             lines.len().saturating_sub(1),
@@ -209,7 +244,7 @@ impl SyntaxCache {
             self.injections.clear();
             self.context = None;
             self.highlighted.fill(false);
-            for spans in &mut self.lines {
+            for spans in self.lines.iter_mut().chain(&mut self.string_spans) {
                 spans.clear();
             }
         } else {
@@ -225,6 +260,12 @@ impl SyntaxCache {
         self.lines.get(row).map_or(&[], Vec::as_slice)
     }
 
+    /// String coverage before foreground overrides, including embedded-language highlighting.
+    /// An included line break has end_byte == line.len() + 1; foreground spans exclude it.
+    pub(crate) fn string_spans(&self, row: usize) -> &[SyntaxSpan] {
+        self.string_spans.get(row).map_or(&[], Vec::as_slice)
+    }
+
     /// Bundled grammar name, or `None` for unknown languages and plain text.
     pub fn language(&self) -> Option<&str> {
         self.syntax.map(|syntax| syntax.name)
@@ -415,6 +456,7 @@ impl SyntaxCache {
             &self.source,
             &self.line_starts,
             &mut self.lines,
+            &mut self.string_spans,
             &self.highlights,
             &mut self.events,
             visible,
@@ -1089,6 +1131,7 @@ fn render_spans(
     source: &str,
     starts: &[usize],
     lines: &mut [Vec<SyntaxSpan>],
+    strings: &mut [Vec<SyntaxSpan>],
     highlights: &[Highlight],
     events: &mut Vec<(usize, bool, usize)>,
     visible: &[Range],
@@ -1111,24 +1154,34 @@ fn render_spans(
     };
     let mut active: BTreeSet<(_, usize)> = BTreeSet::new();
     let mut previous = 0;
+    let mut active_strings = 0;
     for &(byte, entering, index) in events.iter() {
-        if previous < byte
+        if previous < byte {
-            && let Some((_, current)) = active.last()
+            let kind = active
-            && let Some(kind) = highlights[*current].kind
+                .last()
-        {
+                .and_then(|(_, current)| highlights[*current].kind);
+            if kind.is_some() || active_strings > 0 {
                 let start = visible.partition_point(|range| range.end_byte <= previous);
                 for range in visible[start..]
                     .iter()
                     .take_while(|range| range.start_byte < byte)
                 {
-                append_global(
+                    let low = previous.max(range.start_byte);
-                    source,
+                    let high = byte.min(range.end_byte);
-                    starts,
+                    if let Some(kind) = kind {
-                    lines,
+                        append_global(source, starts, lines, low, high, kind, false);
-                    previous.max(range.start_byte),
+                    }
-                    byte.min(range.end_byte),
+                    if active_strings > 0 {
-                    kind,
+                        append_global(source, starts, strings, low, high, SyntaxKind::String, true);
-                );
+                    }
+                }
+            }
+        }
+        if highlights[index].kind == Some(SyntaxKind::String) {
+            if entering {
+                active_strings += 1;
+            } else {
+                active_strings -= 1;
             }
         }
         if entering {
@@ -1147,6 +1200,7 @@ fn append_global(
     mut start: usize,
     end: usize,
     kind: SyntaxKind,
+    include_newline: bool,
 ) {
     if starts.is_empty() {
         return;
@@ -1156,7 +1210,7 @@ fn append_global(
         .saturating_sub(1);
     while start < end && row < lines.len() {
         let line_end = starts.get(row + 1).map_or(source.len(), |next| next - 1);
-        let high = end.min(line_end);
+        let high = end.min(line_end + usize::from(include_newline && row + 1 < starts.len()));
         if start < high {
             let spans = &mut lines[row];
             let low = start - starts[row];
@@ -1196,6 +1250,38 @@ mod tests {
         }
     }
 
+    #[test]
+    fn string_newlines_remain_literal_across_visible_row_caching_and_edits() {
+        let source = "text = \"\"\"a\n\nb\"\"\"\nplain\n";
+        let input = lines(source);
+        let path = Path::new("strings.py");
+        let mut cache = SyntaxCache::new();
+        let includes_newline = |cache: &SyntaxCache, row: usize, length: usize| {
+            cache
+                .string_spans(row)
+                .iter()
+                .any(|span| span.start_byte <= length && span.end_byte > length)
+        };
+        cache.update_visible(&input, Some(path), 0, std::slice::from_ref(&(0..1)));
+        assert!(includes_newline(&cache, 0, input[0].len()));
+        cache.update_visible(&input, Some(path), 0, std::slice::from_ref(&(1..4)));
+        assert!(includes_newline(&cache, 0, input[0].len()));
+        assert!(includes_newline(&cache, 1, input[1].len()));
+        assert!(!includes_newline(&cache, 2, input[2].len()));
+        assert!(!includes_newline(&cache, 3, input[3].len()));
+        for (row, line) in input.iter().enumerate() {
+            assert!(
+                cache
+                    .line(row)
+                    .iter()
+                    .all(|span| span.end_byte <= line.len())
+            );
+        }
+        cache.update(&lines("# a\n\nb\nplain\n"), Some(path), 1);
+        assert!(!includes_newline(&cache, 0, 3));
+        assert!(!includes_newline(&cache, 1, 0));
+    }
+
     #[test]
     fn visible_windows_match_full_colors_after_edits_and_scrolling_without_reparsing() {
         let cases = [
@@ -1893,6 +1979,7 @@ mod tests {
             source,
             &[0],
             &mut spans,
+            &mut vec![Vec::new(); 1],
             &highlights,
             &mut events,
             &[source_range(source)],
@@ -1963,6 +2050,7 @@ mod tests {
             source,
             &starts,
             &mut spans,
+            &mut vec![Vec::new(); 3],
             &highlights,
             &mut Vec::new(),
             &[source_range(source)],
@@ -2004,6 +2092,7 @@ mod tests {
                 source,
                 &starts,
                 &mut visible_spans,
+                &mut vec![Vec::new(); 3],
                 &visible_highlights,
                 &mut Vec::new(),
                 &window,