route editor config through a source-agnostic EditorSettings model (T-29)

Introduce EditorSettings as the effective, source-agnostic editor configuration
the editor and save path obey. .editorconfig is demoted to one *source*
(editorconfig.dart now returns EditorSettings); editor_settings_resolver.dart is
the single composition seam where future sources — a settings panel, a clide
settings file — layer in via merge() without the editor changing.

The registry resolves settings on buffer load and, when a .editorconfig is saved
in-app, re-resolves every open buffer and emits editor.settings-changed (a hook
in save, not a filesystem watcher — the realistic case, cheaply). Buffer JSON
carries editorSettings. 100% line coverage on the new model + resolver.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/src/editor/buffer.dart

@@ -6,7 +6,7 @@
 /// transitions.
 library;
 
-import 'editorconfig.dart';
+import 'editor_settings.dart';
 
 class Selection {
   const Selection({required this.start, required this.end});
@@ -45,7 +45,7 @@ class EditorBuffer {
     required this.content,
     Selection? selection,
     this.dirty = false,
-    this.editorConfig = EditorConfig.empty,
+    this.settings = EditorSettings.empty,
   }) : selection = selection ?? const Selection.collapsed(0);
 
   /// Stable daemon-local id (`b_1`, `b_2`, …).
@@ -70,10 +70,11 @@ class EditorBuffer {
   /// `editor.save` (or `files.save` in future).
   bool dirty;
 
-  /// Resolved `.editorconfig` properties for this file (T-29). Drives the
-  /// editor's indent/ruler rendering on the UI side and the save-time
-  /// normalization daemon-side. [EditorConfig.empty] when nothing applies.
-  EditorConfig editorConfig;
+  /// Effective editor settings for this file (T-29), resolved from its sources
+  /// (today: `.editorconfig`). Drives the editor's indent/ruler rendering on
+  /// the UI side and the save-time normalization daemon-side.
+  /// [EditorSettings.empty] when nothing applies.
+  EditorSettings settings;
 
   Map<String, Object?> toJson() => {
         'id': id,
@@ -81,7 +82,7 @@ class EditorBuffer {
         'length': content.length,
         'selection': selection.toJson(),
         'dirty': dirty,
-        'editorConfig': editorConfig.toJson(),
+        'editorSettings': settings.toJson(),
       };
 
   /// Full snapshot including [content] — for `editor.read` / tests /

lib/src/editor/editor_settings.dart

@@ -0,0 +1,140 @@
+/// [EditorSettings] — the effective, source-agnostic editor configuration for
+/// one file (T-29).
+///
+/// The editor surface and the save path obey *this* object, never a particular
+/// source file. Today the only source is the project's `.editorconfig` (parsed
+/// in `editorconfig.dart`), but a settings panel or a clide-owned settings file
+/// can layer in later via [merge] without the editor, registry, or save path
+/// changing — that is the whole point of routing everything through one model.
+///
+/// Flutter-free (no `dart:io`, no `dart:ui`): it travels from the daemon to the
+/// UI as plain JSON and is unit-tested under `dart test`.
+library;
+
+class EditorSettings {
+  const EditorSettings({
+    this.indentStyle,
+    this.indentSize,
+    this.tabWidth,
+    this.endOfLine,
+    this.maxLineLength,
+    this.trimTrailingWhitespace,
+    this.insertFinalNewline,
+  });
+
+  /// `tab` or `space`.
+  final String? indentStyle;
+
+  /// Columns per indent level.
+  final int? indentSize;
+
+  /// Width of a tab character.
+  final int? tabWidth;
+
+  /// `lf`, `crlf`, or `cr`.
+  final String? endOfLine;
+
+  /// Ruler / wrap-guide column. Null when unset.
+  final int? maxLineLength;
+
+  final bool? trimTrailingWhitespace;
+  final bool? insertFinalNewline;
+
+  /// Nothing set — the editor keeps all of its built-in defaults.
+  static const empty = EditorSettings();
+
+  bool get isEmpty =>
+      indentStyle == null &&
+      indentSize == null &&
+      tabWidth == null &&
+      endOfLine == null &&
+      maxLineLength == null &&
+      trimTrailingWhitespace == null &&
+      insertFinalNewline == null;
+
+  /// The line terminator [endOfLine] names, or null when unset.
+  String? get eolString => switch (endOfLine) {
+        'lf' => '\n',
+        'crlf' => '\r\n',
+        'cr' => '\r',
+        _ => null,
+      };
+
+  /// The text one Tab press inserts, or null to keep the editor's default
+  /// (Flutter's focus traversal) — the editor only takes over Tab when a source
+  /// has an opinion about indentation.
+  String? get indentUnit {
+    if (indentStyle == 'tab') return '\t';
+    if (indentStyle == 'space') return ' ' * (indentSize ?? 4);
+    if (indentSize != null) return ' ' * indentSize!; // a size with no style → spaces
+    return null;
+  }
+
+  /// Layer [other] on top: every field [other] sets overrides this one, fields
+  /// it leaves null fall through. The composition order (lowest precedence
+  /// first) lives in the resolver — a higher-precedence source (settings panel,
+  /// clide settings file) merges over a lower one (.editorconfig).
+  EditorSettings merge(EditorSettings other) => EditorSettings(
+        indentStyle: other.indentStyle ?? indentStyle,
+        indentSize: other.indentSize ?? indentSize,
+        tabWidth: other.tabWidth ?? tabWidth,
+        endOfLine: other.endOfLine ?? endOfLine,
+        maxLineLength: other.maxLineLength ?? maxLineLength,
+        trimTrailingWhitespace: other.trimTrailingWhitespace ?? trimTrailingWhitespace,
+        insertFinalNewline: other.insertFinalNewline ?? insertFinalNewline,
+      );
+
+  /// Only the set keys, for the IPC payload. Empty map when [isEmpty].
+  Map<String, Object?> toJson() => {
+        if (indentStyle != null) 'indent_style': indentStyle,
+        if (indentSize != null) 'indent_size': indentSize,
+        if (tabWidth != null) 'tab_width': tabWidth,
+        if (endOfLine != null) 'end_of_line': endOfLine,
+        if (maxLineLength != null) 'max_line_length': maxLineLength,
+        if (trimTrailingWhitespace != null) 'trim_trailing_whitespace': trimTrailingWhitespace,
+        if (insertFinalNewline != null) 'insert_final_newline': insertFinalNewline,
+      };
+
+  factory EditorSettings.fromJson(Object? raw) {
+    if (raw is! Map) return empty;
+    return EditorSettings(
+      indentStyle: raw['indent_style'] as String?,
+      indentSize: (raw['indent_size'] as num?)?.toInt(),
+      tabWidth: (raw['tab_width'] as num?)?.toInt(),
+      endOfLine: raw['end_of_line'] as String?,
+      maxLineLength: (raw['max_line_length'] as num?)?.toInt(),
+      trimTrailingWhitespace: raw['trim_trailing_whitespace'] as bool?,
+      insertFinalNewline: raw['insert_final_newline'] as bool?,
+    );
+  }
+
+  /// Apply the on-save text fixes these settings request: end-of-line
+  /// normalization, trailing-whitespace trimming, and final-newline
+  /// insertion/removal. Returns [content] unchanged where nothing is set.
+  String applyOnSave(String content) {
+    if (content.isEmpty) return content;
+    var out = content;
+
+    // Trim trailing spaces/tabs before any line break or end-of-string. Done
+    // first and EOL-agnostically so it composes with the EOL rewrite below.
+    if (trimTrailingWhitespace == true) {
+      out = out.replaceAll(RegExp(r'[ \t]+(?=\r\n|\r|\n|$)'), '');
+    }
+
+    final eol = eolString;
+    if (eol != null) {
+      out = out.replaceAll(RegExp(r'\r\n|\r|\n'), eol);
+    }
+
+    if (insertFinalNewline == true) {
+      if (out.isNotEmpty && !out.endsWith('\n') && !out.endsWith('\r')) {
+        out += eol ?? _detectEol(out) ?? '\n';
+      }
+    } else if (insertFinalNewline == false) {
+      out = out.replaceAll(RegExp(r'(\r\n|\r|\n)+$'), '');
+    }
+    return out;
+  }
+
+  static String? _detectEol(String s) => RegExp(r'\r\n|\r|\n').firstMatch(s)?.group(0);
+}

lib/src/editor/editor_settings_resolver.dart

@@ -0,0 +1,25 @@
+/// Composes the effective [EditorSettings] for a file from its sources (T-29).
+///
+/// This is the single seam the editor stack calls — [EditorRegistry] resolves a
+/// buffer's settings here on load and whenever a source changes. Today the only
+/// source is the project's `.editorconfig`; a workspace settings file or a
+/// settings-panel override layers in by adding another `.merge(...)` below, in
+/// increasing-precedence order. The editor and save path never learn the
+/// source — they only see the merged result.
+library;
+
+import 'dart:io';
+
+import 'editor_settings.dart';
+import 'editorconfig.dart';
+
+/// The merged settings for [relPath] (workspace-relative, `/`-separated).
+EditorSettings resolveEditorSettings(Directory workspaceRoot, String relPath) {
+  // Lowest precedence first; later sources override earlier ones.
+  var settings = EditorSettings.empty;
+  settings = settings.merge(readEditorConfig(workspaceRoot, relPath));
+  // Future sources slot in here, e.g.:
+  //   settings = settings.merge(readWorkspaceSettingsFile(workspaceRoot, relPath));
+  //   settings = settings.merge(settingsPanelOverrides(relPath));
+  return settings;
+}

lib/src/editor/editorconfig.dart

@@ -1,142 +1,33 @@
-/// EditorConfig support (T-29) — read `.editorconfig` from the workspace and
-/// resolve the properties that apply to a given file.
+/// `.editorconfig` as an [EditorSettings] source (T-29).
+///
+/// Reads `.editorconfig` files from the workspace and resolves the properties
+/// that apply to a given file into the source-agnostic [EditorSettings] model.
+/// This is one *source* feeding `editor_settings_resolver.dart`; it is not the
+/// thing the editor obeys directly.
 ///
 /// We parse the INI-ish format and match section globs ourselves (no
-/// dependency, per the prefer-zero-deps rule). Resolution walks from the file's
+/// dependency, per prefer-zero-deps). Resolution walks from the file's
 /// directory up to the workspace root, honouring `root = true` to stop the
 /// ascent, with nearer files and later sections winning on conflict — the
 /// precedence the EditorConfig spec defines.
 ///
 /// Flutter-free by construction: this runs daemon-side under `dart test`
-/// alongside [EditorRegistry], so it imports only `dart:io` + core.
+/// alongside [EditorRegistry], so it imports only `dart:io` + the model.
 library;
 
 import 'dart:io';
 
-/// The resolved, typed EditorConfig properties for one file. A `null` field
-/// means "no opinion" — the editor keeps its default and changes nothing.
-class EditorConfig {
-  const EditorConfig({
-    this.indentStyle,
-    this.indentSize,
-    this.tabWidth,
-    this.endOfLine,
-    this.maxLineLength,
-    this.trimTrailingWhitespace,
-    this.insertFinalNewline,
-  });
+import 'editor_settings.dart';
 
-  /// `tab` or `space`.
-  final String? indentStyle;
-
-  /// Columns per indent level. Follows [tabWidth] when the file says
-  /// `indent_size = tab`.
-  final int? indentSize;
-
-  /// Width of a tab character.
-  final int? tabWidth;
-
-  /// `lf`, `crlf`, or `cr`.
-  final String? endOfLine;
-
-  /// Ruler / wrap-guide column. Null when unset or `off`.
-  final int? maxLineLength;
-
-  final bool? trimTrailingWhitespace;
-  final bool? insertFinalNewline;
-
-  static const empty = EditorConfig();
-
-  bool get isEmpty =>
-      indentStyle == null &&
-      indentSize == null &&
-      tabWidth == null &&
-      endOfLine == null &&
-      maxLineLength == null &&
-      trimTrailingWhitespace == null &&
-      insertFinalNewline == null;
-
-  /// The line terminator [endOfLine] names, or null when unset.
-  String? get eolString => switch (endOfLine) {
-        'lf' => '\n',
-        'crlf' => '\r\n',
-        'cr' => '\r',
-        _ => null,
-      };
-
-  /// Only the set keys, for the IPC buffer payload. Empty map when [isEmpty].
-  Map<String, Object?> toJson() => {
-        if (indentStyle != null) 'indent_style': indentStyle,
-        if (indentSize != null) 'indent_size': indentSize,
-        if (tabWidth != null) 'tab_width': tabWidth,
-        if (endOfLine != null) 'end_of_line': endOfLine,
-        if (maxLineLength != null) 'max_line_length': maxLineLength,
-        if (trimTrailingWhitespace != null) 'trim_trailing_whitespace': trimTrailingWhitespace,
-        if (insertFinalNewline != null) 'insert_final_newline': insertFinalNewline,
-      };
-
-  /// Build from a merged raw property map (keys already lowercased). Applies
-  /// the spec's `indent_size`/`tab_width` cross-defaulting. A property whose
-  /// value is `unset` (or unparseable for its type) resolves to null.
-  factory EditorConfig.fromProps(Map<String, String> p) {
-    String? lc(String k) {
-      final v = p[k];
-      if (v == null) return null;
-      final t = v.trim().toLowerCase();
-      return t == 'unset' ? null : t;
-    }
-
-    final indentStyle = _oneOf(lc('indent_style'), const {'tab', 'space'});
-    int? tabWidth = _posInt(lc('tab_width'));
-
-    final rawIndent = lc('indent_size');
-    int? indentSize;
-    if (rawIndent == 'tab') {
-      indentSize = tabWidth;
-    } else {
-      indentSize = _posInt(rawIndent);
-    }
-    // tab_width defaults to indent_size; indent_size (for tabs) defaults to
-    // tab_width — the reciprocal defaulting from the spec.
-    tabWidth ??= indentSize;
-    if (indentStyle == 'tab') indentSize ??= tabWidth;
-
-    final maxRaw = lc('max_line_length');
-    final maxLineLength = (maxRaw == 'off') ? null : _posInt(maxRaw);
-
-    return EditorConfig(
-      indentStyle: indentStyle,
-      indentSize: indentSize,
-      tabWidth: tabWidth,
-      endOfLine: _oneOf(lc('end_of_line'), const {'lf', 'crlf', 'cr'}),
-      maxLineLength: maxLineLength,
-      trimTrailingWhitespace: _bool(lc('trim_trailing_whitespace')),
-      insertFinalNewline: _bool(lc('insert_final_newline')),
-    );
-  }
-
-  static String? _oneOf(String? v, Set<String> allowed) => (v != null && allowed.contains(v)) ? v : null;
-  static int? _posInt(String? v) {
-    if (v == null) return null;
-    final n = int.tryParse(v);
-    return (n != null && n > 0) ? n : null;
-  }
-
-  static bool? _bool(String? v) => switch (v) {
-        'true' => true,
-        'false' => false,
-        _ => null,
-      };
-}
-
-/// Resolve the EditorConfig for [relPath] (a workspace-relative, `/`-separated
-/// path) against the `.editorconfig` files under [workspaceRoot].
+/// Resolve the EditorConfig-sourced [EditorSettings] for [relPath] (a
+/// workspace-relative, `/`-separated path) against the `.editorconfig` files
+/// under [workspaceRoot].
 ///
 /// Walks from the file's directory up to (and including) the workspace root,
 /// stopping once a file declares `root = true`. Never throws — an unreadable or
 /// malformed file is skipped, so a broken `.editorconfig` can't wedge a file
 /// open or save.
-EditorConfig resolveEditorConfig(Directory workspaceRoot, String relPath) {
+EditorSettings readEditorConfig(Directory workspaceRoot, String relPath) {
   final rel = relPath.replaceAll('\\', '/').replaceAll(RegExp(r'^/+'), '');
   final segs = rel.split('/');
   final dirSegs = segs.sublist(0, segs.length - 1);
@@ -170,42 +61,63 @@ EditorConfig resolveEditorConfig(Directory workspaceRoot, String relPath) {
       }
     }
   }
-  return EditorConfig.fromProps(props);
+  return editorSettingsFromProps(props);
 }
 
-/// Apply the on-save text fixes [cfg] requests: end-of-line normalization,
-/// trailing-whitespace trimming, and final-newline insertion/removal. Returns
-/// the content unchanged where [cfg] has no opinion.
-String applyEditorConfigOnSave(String content, EditorConfig cfg) {
-  if (content.isEmpty) return content;
-  var out = content;
-
-  // Trim trailing spaces/tabs before any line break or end-of-string. Done
-  // first and EOL-agnostically so it composes with the EOL rewrite below.
-  if (cfg.trimTrailingWhitespace == true) {
-    out = out.replaceAll(RegExp(r'[ \t]+(?=\r\n|\r|\n|$)'), '');
+/// Build [EditorSettings] from a merged raw EditorConfig property map (keys
+/// already lowercased). Applies the spec's `indent_size`/`tab_width`
+/// cross-defaulting; a property valued `unset` (or unparseable for its type)
+/// resolves to null. Public for direct unit testing of the mapping.
+EditorSettings editorSettingsFromProps(Map<String, String> p) {
+  String? lc(String k) {
+    final v = p[k];
+    if (v == null) return null;
+    final t = v.trim().toLowerCase();
+    return t == 'unset' ? null : t;
   }
 
-  final eol = cfg.eolString;
-  if (eol != null) {
-    out = out.replaceAll(RegExp(r'\r\n|\r|\n'), eol);
-  }
+  final indentStyle = _oneOf(lc('indent_style'), const {'tab', 'space'});
+  int? tabWidth = _posInt(lc('tab_width'));
 
-  if (cfg.insertFinalNewline == true) {
-    if (out.isNotEmpty && !out.endsWith('\n') && !out.endsWith('\r')) {
-      out += eol ?? _detectEol(out) ?? '\n';
-    }
-  } else if (cfg.insertFinalNewline == false) {
-    out = out.replaceAll(RegExp(r'(\r\n|\r|\n)+$'), '');
+  final rawIndent = lc('indent_size');
+  int? indentSize;
+  if (rawIndent == 'tab') {
+    indentSize = tabWidth;
+  } else {
+    indentSize = _posInt(rawIndent);
   }
-  return out;
+  // tab_width defaults to indent_size; indent_size (for tabs) defaults to
+  // tab_width — the reciprocal defaulting from the spec.
+  tabWidth ??= indentSize;
+  if (indentStyle == 'tab') indentSize ??= tabWidth;
+
+  final maxRaw = lc('max_line_length');
+  final maxLineLength = (maxRaw == 'off') ? null : _posInt(maxRaw);
+
+  return EditorSettings(
+    indentStyle: indentStyle,
+    indentSize: indentSize,
+    tabWidth: tabWidth,
+    endOfLine: _oneOf(lc('end_of_line'), const {'lf', 'crlf', 'cr'}),
+    maxLineLength: maxLineLength,
+    trimTrailingWhitespace: _bool(lc('trim_trailing_whitespace')),
+    insertFinalNewline: _bool(lc('insert_final_newline')),
+  );
 }
 
-String? _detectEol(String s) {
-  final m = RegExp(r'\r\n|\r|\n').firstMatch(s);
-  return m?.group(0);
+String? _oneOf(String? v, Set<String> allowed) => (v != null && allowed.contains(v)) ? v : null;
+int? _posInt(String? v) {
+  if (v == null) return null;
+  final n = int.tryParse(v);
+  return (n != null && n > 0) ? n : null;
 }
 
+bool? _bool(String? v) => switch (v) {
+      'true' => true,
+      'false' => false,
+      _ => null,
+    };
+
 // ---------------------------------------------------------------------------
 // INI parsing
 // ---------------------------------------------------------------------------

lib/src/editor/registry.dart

@@ -12,7 +12,7 @@ import 'dart:io';
 import '../ipc/envelope.dart';
 import '../panes/event_sink.dart';
 import 'buffer.dart';
-import 'editorconfig.dart';
+import 'editor_settings_resolver.dart';
 
 class EditorRegistry {
   EditorRegistry({
@@ -57,7 +57,7 @@ class EditorRegistry {
       id: id,
       path: path,
       content: content,
-      editorConfig: resolveEditorConfig(workspaceRoot, path),
+      settings: resolveEditorSettings(workspaceRoot, path),
     );
     _buffers[id] = buf;
     _pathToId[path] = id;
@@ -150,15 +150,16 @@ class EditorRegistry {
     });
   }
 
-  /// Persist [id] to disk. Applies the buffer's `.editorconfig` save fixes
-  /// (EOL, trailing-whitespace, final-newline) first, and — when those changed
-  /// the text — reconciles the in-memory buffer + UI so disk and buffer agree.
-  /// Clears the dirty flag on success.
+  /// Persist [id] to disk. Applies the buffer's on-save settings (EOL,
+  /// trailing-whitespace, final-newline) first, and — when those changed the
+  /// text — reconciles the in-memory buffer + UI so disk and buffer agree.
+  /// Clears the dirty flag on success. Saving a `.editorconfig` re-resolves the
+  /// settings of every open buffer (its rules just changed).
   Future<bool> save(String id) async {
     final buf = _buffers[id];
     if (buf == null) return false;
 
-    final normalized = applyEditorConfigOnSave(buf.content, buf.editorConfig);
+    final normalized = buf.settings.applyOnSave(buf.content);
     final changed = normalized != buf.content;
 
     final absolute = _absolutePathOf(buf.path);
@@ -183,9 +184,29 @@ class EditorRegistry {
 
     buf.dirty = false;
     _emit('editor.saved', {'id': id, 'path': buf.path});
+
+    if (_isEditorConfigPath(buf.path)) _reresolveSettings();
     return true;
   }
 
+  /// Recompute every open buffer's effective settings from its sources and tell
+  /// the UI about the ones that changed. Called when a `.editorconfig` is saved
+  /// in-app (the file's rules changed under the open buffers).
+  void _reresolveSettings() {
+    for (final buf in _buffers.values) {
+      final next = resolveEditorSettings(workspaceRoot, buf.path);
+      if (next.toJson().toString() == buf.settings.toJson().toString()) continue;
+      buf.settings = next;
+      _emit('editor.settings-changed', {
+        'id': buf.id,
+        'path': buf.path,
+        'editorSettings': next.toJson(),
+      });
+    }
+  }
+
+  bool _isEditorConfigPath(String path) => path == '.editorconfig' || path.endsWith('/.editorconfig');
+
   /// Close a buffer. Idempotent.
   void close(String id) {
     final buf = _buffers.remove(id);