☕ Explore switchable theme: Catppuccin Latte

[martinciu]

🎯 Goal

Add Catppuccin Latte as a sixth selectable theme via the theme-set <name>
fish switcher, and the first light theme in the collection. Machinery
landed in #185; Mocha reference implementation in #183/#185.

Architectural significance: introduces the dark/light axis the prior
issues deferred (see "Light variant: skip unless we also commit to
Solarized Light and Catppuccin Latte" in #188). All five existing themes
are dark; Latte forces a few semantic assumptions baked into the helpers
and palettes to be re-examined.

🎨 Palette (Latte)

• bg/surface: base #eff1f5, mantle #e6e9ef, crust #dce0e8,
  surface0 #ccd0da, surface1 #bcc0cc, surface2 #acb0be
• text: text #4c4f69, subtext1 #5c5f77, subtext0 #6c6f85,
  overlay2 #7c7f93, overlay1 #8c8fa1, overlay0 #9ca0b0
• accents: blue #1e66f5, sky #04a5e5, sapphire #209fb5,
  teal #179299, green #40a02b, yellow #df8e1d, peach #fe640b,
  maroon #e64553, red #d20f39, mauve #8839ef, pink #ea76cb,
  flamingo #dd7878, rosewater #dc8a78, lavender #7287fd

📐 Architecture

Machinery is settled (#185). Slots in as one more <name> across each
tool — same shape as #188/#193/#197 — with two simplifications and one
genuine inflection point.

Simplifications (Catppuccin pairing):

• nvim already installs catppuccin/nvim for Mocha — extend
  lua/config/theme.lua resolver to set flavour = "latte" instead of
  installing a new plugin.
• lnav already vendors catppuccin.json (from ninetailedtori/catppuccin-lnav,
  MIT) — that vendor ships all four flavours; the Latte selector is a
  one-line theme-latte.json pointing at Catppuccin Latte.
• bat ships Catppuccin Latte built-in (0.26+, same vintage as Mocha).
• vivid ships catppuccin-latte (0.11+).
• Ghostty ships Catppuccin Latte built-in (1.0+).

Inflection point (first light theme):

• tmux bar bg flips from dark surface to light surface (mantle #e6e9ef
  or crust #dce0e8). Every helper that hardcoded a dark assumption for
  bar bg / muted fg needs to be re-read.
• @color_light_fg semantics: Latte's accents are still saturated (blue
  #1e66f5, green #40a02b, mauve #8839ef), so chips can keep
  light-on-saturated text (base #eff1f5). The relationship that
  changes is bar bg ↔ chip bg — chips are saturated against a light
  bar, not a dark one.

🛠️ Work breakdown

Same 8-file + plugin-spec + switch shape as #197, with the Catppuccin
simplifications folded in:

• .config/themes/latte.tmux — semantic @color_* map.
• .config/themes/delta-latte.gitconfig — syntax-theme = "Catppuccin Latte"
  (bat name, case-sensitive — verify with bat --list-themes | grep -i latte).
• .config/ghostty/theme-latte.ghostty — theme = Catppuccin Latte
• .config/starship-latte.toml — pastel_rose = '#ea76cb'
  (Latte pink — the canonical "personal" accent matching Mocha's
  #f5c2e7). cp from starship-mocha.toml + surgical Edits to
  preserve the U+E0B4 cap byte (see 🌾 Explore switchable theme: Gruvbox #188 Lesson + memory).
• .config/glow/glamour-latte.json — light-bg glamour style;
  glow doesn't ship a Latte preset (Mocha was hand-rolled, Latte
  likely needs the same).
• .config/gh-dash/theme-colors-latte.yml — clone Mocha's, swap
  theme.colors for Latte hex (new mixed-dir pattern: config-base.yml
  + theme-colors-<name>.yml concat at theme-set time).
• .config/lnav/configs/installed/theme-latte.json — one-line
  selector pointing at Catppuccin Latte (theme-defs already
  vendored via catppuccin.json).
• nvim: extended lua/config/theme.lua resolver to recognise
  latte and set flavour = "latte". No new plugin needed.
• Extended .config/fish/functions/theme-set.fish switch
  (case latte), set BAT_THEME to "Catppuccin Latte" and
  VIVID_THEME to "catppuccin-latte".
• Extended bootstrap.sh with a link line for starship-latte.toml.
• Updated scripts/test-theme-switch.sh to round-trip Latte
  (partial-coverage assertions: delta/glow/lnav/gh-dash stay on previous theme).

⚖️ Tradeoff

✅ Win: complements Mocha cleanly — Catppuccin was designed as a
light/dark pair, and Latte is the canonical light flavour. The two share
design intent (pastel-warm) so the cognitive load of switching is small.
Zero new plugin installs (nvim + lnav both already wired). Most popular
light theme right now.

❌ Loss: introduces the light/dark axis the prior issues deferred —
every future theme decision now carries a "is there a light pair?"
question. The Solarized-only tools (procs, tailspin, xh) and the
Solarized-Dark-only cheatsheets (docs/*.html) become visibly
mismatched when Latte is active. Either accept as a known limitation
(cheapest) or expand the theme indirection further (more cost).

🚦 Open questions

• 🎨 Chip text inversion: Latte's accents are saturated, not pastel
  — light-on-accent chip text should work
  (@color_light_fg = '#eff1f5', base). The bar bg → chip bg
  contrast is the new variable: with mantle #e6e9ef as bar bg, the
  saturated chips will read as darker than the bar, not lighter.
  Verify on the actual terminal before pinning.

• ☀️ Stay-Solarized tools (procs, tailspin, xh): these were
  intentionally left Solarized-only because their use-cases are
  low-stakes color hierarchies. On a Latte terminal bg, their dark-bg
  assumptions render poorly. Three options:

  • Accept as known limitation (cheapest, matches existing posture).
  • Extend theme-set to swap their configs too — moves them into the
    main indirection layer, ~3 more variant files per theme.
  • Pin xh to a light variant when on Latte (monokai-light? probe).

  Recommend status-quo for v1; revisit if it grates.

• 📄 Cheatsheets (docs/*.html): currently Solarized-Dark-styled.
  Latte being active doesn't change cheatsheet rendering. The CSS could
  be extracted to variables with a theme toggle button (called out in
  🎨 Explore switchable theme: Catppuccin ↔ Solarized #183's work breakdown but never landed). Defer to a separate issue —
  not Latte-specific.

• ☕ pastel_rose pick: Latte pink #ea76cb is the obvious
  analogue to Mocha's #f5c2e7. Flamingo #dd7878 is a softer
  alternative if pink reads too sharp on the light bg. Default to pink
  for symmetry with Mocha.

• 🎯 Unique-accent rule mapping (clean — six distinct hues, same
  layout as Mocha):

  • session chip (blue): blue #1e66f5
  • active window pin (green): green #40a02b
  • PR chip (orange): peach #fe640b
  • git main chip (violet): mauve #8839ef
  • git wt chip (yellow): yellow #df8e1d
  • usage cluster (violet + yellow): mauve + yellow

🧠 Lessons

See consolidated lessons in #188 and the Gruvbox PR (#193). One new
class of consideration enters with the first light theme:

• Light-theme chip readability is a two-step contrast check, not
  one. With dark themes, only chip-bg vs chip-text matters (the bar
  bg is also dark and chips pop against it automatically). With light
  themes, chip-bg vs bar-bg becomes a separate readability axis —
  saturated chips on a light bar can look correct in isolation but
  read as "weird coloured rectangles on a beige strip" in motion.
  Verify by switching back and forth, not just by inspecting Latte
  statically.

🔗 Links

• Homepage: https://catppuccin.com
• Palette spec: https://github.com/catppuccin/catppuccin
• Latte flavour reference: https://catppuccin.com/palette#flavor-latte