bundle Josefin Sans as the default UI face at weight 300

Vendor the JosefinSans variable font (upright + italic, weight range
100-700), OFL licensed. _AppRoot installs it as the ambient
DefaultTextStyle at weight w300 (Light); ClideText inherits rather
than re-specifying the family, so Alchemist's Ahem injection keeps
goldens deterministic per D-024 while production renders the
intended face.

typography.dart gains clideUiFamily + clideUiFamilyFallback
alongside the existing mono constants; .gitignore learns about
Alchemist's failures/ diff output dir so local re-runs don't leak
into `git status`.

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -47,6 +47,11 @@ tools/ui/.serve.pid
 coverage.*
 /tmp/
 
+# Alchemist golden-test failure artefacts (diff images written when a
+# pixel-compare fails locally; the committed fixtures live under
+# app/test/goldens/goldens/{ci,linux}/).
+app/test/goldens/failures/
+
 # -- pql per-repo state (clide dogfoods against itself; pql's index lands
 #    here when running queries locally). `pql.db` is also where the
 #    `tools/scripts/plan` stopgap writes decisions + tickets (D-040).

app/assets/fonts/josefin_sans/OFL.txt

@@ -0,0 +1,93 @@
+Copyright 2010 The Josefin Sans Project Authors (https://github.com/ThomasJockin/JosefinSansFont-master), with Reserved Font Name "Josefin Sans".
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+https://openfontlicense.org
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded, 
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.

app/lib/app.dart

@@ -70,12 +70,9 @@ class _RootShellState extends State<_RootShell> {
       style: TextStyle(
         color: tokens.globalForeground,
         fontSize: 13,
-        fontFamilyFallback: const [
+        fontWeight: clideUiDefaultWeight,
-          'Inter',
+        fontFamily: clideUiFamily,
-          'Helvetica',
+        fontFamilyFallback: clideUiFamilyFallback,
-          'Arial',
-          'sans-serif',
-        ],
       ),
       child: KeyboardListener(
         focusNode: _keyFocus,

app/lib/widgets/src/clide_text.dart

@@ -1,14 +1,22 @@
 import 'package:clide_app/kernel/src/theme/controller.dart';
+import 'package:clide_app/widgets/src/typography.dart';
 import 'package:flutter/widgets.dart';
 
-/// Theme-aware Text. Defaults pull from the global foreground token.
+/// Theme-aware Text. Defaults pull from the global foreground token
+/// and [clideUiDefaultWeight].
+///
+/// The UI font family is deliberately **not** set on this widget — it
+/// inherits from the ambient `DefaultTextStyle` which `_AppRoot`
+/// provides ([clideUiFamily] in real runs). Goldens rely on Alchemist
+/// injecting Ahem for deterministic metrics; hard-coding a family here
+/// would override that and break pixel determinism per D-024.
 class ClideText extends StatelessWidget {
   const ClideText(
     this.data, {
     super.key,
     this.color,
     this.fontSize = 13,
-    this.fontWeight = FontWeight.w400,
+    this.fontWeight,
     this.muted = false,
     this.maxLines,
     this.overflow,
@@ -18,7 +26,7 @@ class ClideText extends StatelessWidget {
   final String data;
   final Color? color;
   final double fontSize;
-  final FontWeight fontWeight;
+  final FontWeight? fontWeight;
   final bool muted;
   final int? maxLines;
   final TextOverflow? overflow;
@@ -37,8 +45,11 @@ class ClideText extends StatelessWidget {
       style: TextStyle(
         color: resolved,
         fontSize: fontSize,
+        // Null means inherit from the ambient DefaultTextStyle —
+        // _AppRoot installs clideUiDefaultWeight there; goldens get
+        // whatever Alchemist injects. Passing an explicit weight (e.g.
+        // FontWeight.bold) still wins.
         fontWeight: fontWeight,
-        fontFamilyFallback: const ['Inter', 'Helvetica', 'Arial', 'sans-serif'],
       ),
     );
   }

app/lib/widgets/src/typography.dart

@@ -1,12 +1,48 @@
 /// Typography constants shared across widgets.
 ///
-/// Terminal panes, diff views, and any other monospace surface should
+/// Two bundled families:
-/// import from here rather than hardcoding a family. The fallback chain
+///
-/// exists for web builds + platforms where the bundled `JetBrainsMono`
+/// - [clideUiFamily] — Josefin Sans, the application-wide UI face.
+///   Shipped as a variable font (weights 100-700) + italic companion;
+///   default weight is [clideUiDefaultWeight] (Light / `w300`).
+/// - [clideMonoFamily] — JetBrains Mono, for terminal panes, diff
+///   views, code editors, and any other monospace surface.
+///
+/// Fallback chains exist for web builds + harnesses where the bundled
 /// asset isn't picked up (rare, but possible during `flutter test` if
-/// assets aren't declared in the harness).
+/// asset fonts aren't declared in the harness).
 library;
 
+import 'package:flutter/widgets.dart' show FontWeight;
+
+// ---------------------------------------------------------------------------
+// UI face — Josefin Sans
+// ---------------------------------------------------------------------------
+
+/// The bundled application UI family. Always resolved first.
+const String clideUiFamily = 'JosefinSans';
+
+/// Default weight for UI text. Josefin Sans reads well at Light; the
+/// rest of the design adjusts contrast and size to stay legible.
+const FontWeight clideUiDefaultWeight = FontWeight.w300;
+
+/// System fallback chain for the UI face. Sans-serif humanist faces
+/// that sit close to Josefin's proportions, ordered by platform.
+const List<String> clideUiFamilyFallback = [
+  // User system install of Josefin, if any.
+  'Josefin Sans',
+  // Platform humanist sans defaults.
+  'Inter',
+  'Helvetica Neue',
+  'Helvetica',
+  'Arial',
+  'sans-serif',
+];
+
+// ---------------------------------------------------------------------------
+// Monospace face — JetBrains Mono
+// ---------------------------------------------------------------------------
+
 /// The bundled monospace family. Always resolved first.
 const String clideMonoFamily = 'JetBrainsMono';
 
@@ -17,9 +53,8 @@ const List<String> clideMonoFamilyFallback = [
   'SF Mono',
   'Menlo',
   'Monaco',
-  // Linux
+  // Linux — user system install under the canonical PostScript name
-  'JetBrains Mono',  // if the user has it system-installed under the
+  'JetBrains Mono',
-                     // canonical PostScript name
   'Fira Code',
   'Hack',
   'DejaVu Sans Mono',

app/pubspec.yaml

@@ -54,11 +54,21 @@ flutter:
     - lib/kernel/src/theme/themes/
     - lib/kernel/src/i18n/catalog/
 
-  # JetBrains Mono — bundled so terminal panes render consistently
+  # Bundled fonts. OFL-licensed; license files live alongside each.
-  # regardless of what the user has system-installed. OFL-licensed;
+  #
-  # see assets/fonts/jetbrains_mono/OFL.txt. Thin/Light/Medium/
+  # JosefinSans — UI default. Variable font covers weights 100-700
-  # ExtraBold weights can be added later if a theme needs them.
+  # plus an italic axis companion; we default to Light (300) per the
+  # project's aesthetic direction.
+  #
+  # JetBrainsMono — terminal / code surfaces. Static weights keep
+  # rendering predictable across xterm.dart, goldens, and CI.
   fonts:
+    - family: JosefinSans
+      fonts:
+        - asset: assets/fonts/josefin_sans/JosefinSans-VariableFont.ttf
+        - asset: assets/fonts/josefin_sans/JosefinSans-Italic-VariableFont.ttf
+          style: italic
+
     - family: JetBrainsMono
       fonts:
         - asset: assets/fonts/jetbrains_mono/JetBrainsMono-Regular.ttf