Add Fira Code as a built-in font choice

The variable face (v6.2, OFL, licence alongside) is bundled in static/ and
declared as @font-face whenever the text or heading font is "fira"; the
stack falls back through Fira Mono, Menlo and Consolas to Courier.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Sd8UPWrvyYCLj97JexNw3A

7 files changed, 117 insertions, 5 deletions

diff --git a/AGENTS.md b/AGENTS.md
index 8459d6d..5ac922d 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -194,6 +194,9 @@ internal/web/         server.go (host router, middleware, render helpers)
   thumbnail. `TagHash` lists tags as `#name` wherever they appear: the
   `posttags` partial (takes `dict "tags" … "hash" …`), the two tag modules
   and the tag page title (`tagname` template func).
+  `Font`/`HeadingFont` `fira` is Fira Code, the one built-in choice that is a
+  web font: `static/FiraCode-VF.woff2` (the variable face, OFL — licence in
+  `static/FiraCode-LICENSE.txt`), declared as `@font-face` when `UsesFira`.
   **Custom fonts** (`CustomFont`, `CustomHeadingFont`: font file ids or ""):
   a chosen file is declared as `@font-face` (`"BlogFont"` / `"BlogHeadingFont"`,
   `src:url(/media/<id>)`, same-origin so no CORS) and put first in the stack,
diff --git a/README.md b/README.md
index 8f05cfd..ec14555 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,7 @@ Server-rendered HTML, no JavaScript required, works on old browsers and phones.
   and the picture above or below the text on its own page.
 - **Design** tab: one form, one Save, organised by part of the blog — colours & fonts
   (schemes, background colour/image, text and link colours, fonts — built-in
-  stacks or your own uploaded WOFF2/WOFF/TTF/OTF files), header, menu,
+  stacks, Fira Code, or your own uploaded WOFF2/WOFF/TTF/OTF files), header, menu,
   content (dates, summaries, a rule under titles — line, dots, double dots or stripes — and
   tags shown as #tag), side columns, footer, logo & site icon. The page is five areas — header,
   left column, main content, right column, footer — each holding modules in any
diff --git a/internal/web/static/FiraCode-LICENSE.txt b/internal/web/static/FiraCode-LICENSE.txt
new file mode 100644
index 0000000..805e0b3
--- /dev/null
+++ b/internal/web/static/FiraCode-LICENSE.txt
@@ -0,0 +1,93 @@
+Copyright (c) 2014, The Fira Code Project Authors (https://github.com/tonsky/FiraCode)
+
+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:
+http://scripts.sil.org/OFL
+
+
+-----------------------------------------------------------
+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.
diff --git a/internal/web/static/FiraCode-VF.woff2 b/internal/web/static/FiraCode-VF.woff2
new file mode 100644
index 0000000..e755a9d
--- /dev/null
+++ b/internal/web/static/FiraCode-VF.woff2
diff --git a/internal/web/templates/dashboard/design.html b/internal/web/templates/dashboard/design.html
index 31913f6..fea1b92 100644
--- a/internal/web/templates/dashboard/design.html
+++ b/internal/web/templates/dashboard/design.html
@@ -71,12 +71,14 @@
       <option value="sans"{{if eq $t.Font "sans"}} selected{{end}}>Sans-serif (Helvetica/Arial)</option>
       <option value="serif"{{if eq $t.Font "serif"}} selected{{end}}>Serif (Georgia/Times)</option>
       <option value="mono"{{if eq $t.Font "mono"}} selected{{end}}>Monospace (Courier)</option>
+      <option value="fira"{{if eq $t.Font "fira"}} selected{{end}}>Fira Code</option>
     </select></label>
     <label>{{t "Heading font"}}<br><select name="heading_font">
       <option value="same"{{if eq $t.HeadingFont "same"}} selected{{end}}>{{t "Same as text"}}</option>
       <option value="sans"{{if eq $t.HeadingFont "sans"}} selected{{end}}>Sans-serif</option>
       <option value="serif"{{if eq $t.HeadingFont "serif"}} selected{{end}}>Serif</option>
       <option value="mono"{{if eq $t.HeadingFont "mono"}} selected{{end}}>Monospace</option>
+      <option value="fira"{{if eq $t.HeadingFont "fira"}} selected{{end}}>Fira Code</option>
     </select></label>
     <label>{{t "Text size"}}<br><select name="font_size">
       <option value="small"{{if eq $t.FontSize "small"}} selected{{end}}>{{t "Small"}}</option>
diff --git a/internal/web/theme.go b/internal/web/theme.go
index 53e48c5..676a01e 100644
--- a/internal/web/theme.go
+++ b/internal/web/theme.go
@@ -25,8 +25,8 @@ type Theme struct {
 	LinkUnderline  string `json:"link_underline"`  // always | hover | never
 	ContentStyle   string `json:"content_style"`   // card | flat
 	ContentPadding string `json:"content_padding"` // normal | compact | roomy
-	Font           string `json:"font"`            // sans | serif | mono
-	HeadingFont    string `json:"heading_font"`    // same | sans | serif | mono
+	Font           string `json:"font"`            // sans | serif | mono | fira (Fira Code, bundled in static/)
+	HeadingFont    string `json:"heading_font"`    // same | sans | serif | mono | fira
 	FontSize       string `json:"font_size"`       // small | normal | large
 	// Uploaded fonts (file uuids or ""): when set, the blog is typeset in the
 	// file and Font/HeadingFont are the stack readers see until it loads, or
@@ -176,8 +176,8 @@ func (t *Theme) normalize() {
 	t.LinkUnderline = pick(t.LinkUnderline, "always", "hover", "never")
 	t.ContentStyle = pick(t.ContentStyle, "card", "flat")
 	t.ContentPadding = pick(t.ContentPadding, "normal", "compact", "roomy")
-	t.Font = pick(t.Font, "sans", "serif", "mono")
-	t.HeadingFont = pick(t.HeadingFont, "same", "sans", "serif", "mono")
+	t.Font = pick(t.Font, "sans", "serif", "mono", "fira")
+	t.HeadingFont = pick(t.HeadingFont, "same", "sans", "serif", "mono", "fira")
 	t.FontSize = pick(t.FontSize, "normal", "small", "large")
 	t.CustomFont = fileID(t.CustomFont)
 	t.CustomHeadingFont = fileID(t.CustomHeadingFont)
@@ -410,10 +410,16 @@ func fontStack(name string) string {
 		return `Georgia, "Times New Roman", Times, serif`
 	case "mono":
 		return `"Courier New", Courier, monospace`
+	case "fira":
+		return `"Fira Code", "Fira Mono", Menlo, Consolas, "Courier New", monospace`
 	}
 	return `"Helvetica Neue", Helvetica, Arial, sans-serif`
 }
 
+// UsesFira says whether the bundled Fira Code face must be declared: the
+// only built-in choice that is a web font rather than a system stack.
+func (t Theme) UsesFira() bool { return t.Font == "fira" || t.HeadingFont == "fira" }
+
 // Helpers used by the CSS template. The @font-face families are named for
 // their role, so a stack is the uploaded font first and the built-in choice as
 // its fallback.
@@ -516,6 +522,9 @@ func (t Theme) HeaderImageMaxHeight() string {
 }
 
 var themeCSS = template.Must(template.New("theme").Funcs(template.FuncMap{"sub": func(a, b int) int { return a - b }}).Parse(`
+{{- if .UsesFira}}
+@font-face { font-family:"Fira Code"; src:url(/static/FiraCode-VF.woff2) format("woff2"); font-weight:300 700; font-display:swap; }
+{{- end}}
 {{- if .CustomFont}}
 @font-face { font-family:"BlogFont"; src:url(/media/{{.CustomFont}}); font-display:swap; }
 {{- end}}
diff --git a/internal/web/web_test.go b/internal/web/web_test.go
index 1ca2677..a7c189f 100644
--- a/internal/web/web_test.go
+++ b/internal/web/web_test.go
@@ -131,6 +131,11 @@ func TestThemeNormalizeAndCSS(t *testing.T) {
 	if css := DefaultTheme().CSS(); strings.Contains(css, "@font-face") || strings.Contains(css, "h1, h2") {
 		t.Errorf("default css should declare no font faces or heading rule: %s", css)
 	}
+	// Fira Code is the one built-in choice that is a web font: its face is declared when either font uses it.
+	css = ThemeFromForm(DefaultTheme(), url.Values{"heading_font": {"fira"}}).CSS()
+	if !strings.Contains(css, `@font-face { font-family:"Fira Code"; src:url(/static/FiraCode-VF.woff2)`) || !strings.Contains(css, `h1, h2, h3, h4, h5, h6 { font-family:"Fira Code", "Fira Mono"`) {
+		t.Errorf("fira css: %s", css)
+	}
 }
 
 // The rule under titles is a body class blog.css draws from, coloured by the