Themes

HUME colors its interface and your code from a theme: a TOML file in the Helix theme format. Set the active one with the theme option (see Configuration) or :theme <name>.

(set-option! "theme" "sand")

To see which themes are available, type :theme and press Tab.

HUME reads sand from the themes/ directories like any other theme, so editing your copy changes what you see. A built-in fallback theme is used instead when no sand theme is found or when the theme set in init.scm fails to load.

Custom themes are TOML files placed in the themes/ subdirectory of your HUME config directory, hand-authored, alongside init.scm. A theme installed by a tool instead goes in the themes/ subdirectory of your HUME data directory (see File locations); a config-dir theme of the same name wins.

HUME reads the Helix theme format and aims to support Helix themes as they are written. It is not there in every detail yet, but it is close: most Helix themes load and render unchanged. A scope can be written as a flat key ("ui.cursor" = { fg = "..." }) or as a TOML section header ([ui.cursor] / fg = "..."). HUME treats the two as equivalent, though Helix itself reads only the flat form, so a section-header theme won't travel back.

A color can be a hex literal, a palette name you define, or one of the sixteen terminal color names Helix themes use (red, light-gray, and so on). These resolve to fixed colors from the standard terminal palette rather than to whatever your own terminal happens to have those colors set to, so a theme looks the same everywhere and unfocused-pane dimming has an actual color to blend toward. A color value outside these three forms leaves that one entry unstyled rather than failing the whole load, and :messages names it.

One thing a Helix theme can contain isn't supported, but it doesn't stop the rest of the theme from loading either: the top-level rainbow array. HUME has no rainbow-bracket highlighting, so it has nothing to drive. The theme still loads, and the entry is reported in :messages like any other one HUME couldn't use.

A theme fails to load outright only when the problem is with the document rather than one entry in it: invalid TOML syntax, an inherits parent that doesn't exist or forms a cycle or nests more than eight deep, or an inherits/palette key that isn't a string/table. Loading then keeps your current theme.

Installing themes

To install a third-party theme repository, run :plum-install-theme <user/repo> (see Core Plugins → core:plum), for example:

:plum-install-theme cvlmtg/everforest.hume

INFO

cvlmtg/everforest.hume is Everforest, ported from Helix: a green-based, low-contrast color scheme designed to feel warm and comfortable on the eyes, inspired by forest colors in fall.

:theme <Tab> picks it up right away, no restart needed.

A theme editor is available online: a single-file HTML tool you download and open in a browser to edit themes visually and export them as TOML: https://raw.githubusercontent.com/cvlmtg/HUME/main/tools/theme-editor/index.html

Theme scopes

A scope not listed below behaves as Helix's own theme reference describes it. Every syntax-highlighting scope works this way, so the part of a theme that colors your code carries over as-is.

Scopes HUME adds

These have no Helix equivalent:

• ui.cursor.match.search: coloring every visible search match, falling back to ui.cursor.match when unset
• ui.popup.scroll: scrollbar thumb on a scrolled hover popup (Helix only themes a scrollbar for ui.menu)
• ui.window.focused: seam divider segments adjacent to the focused pane, falling back to ui.window
• ui.drawer: background of the bottom drawer (show-drawer-list!), a generic pick-list panel Helix doesn't have
• ui.tabline / ui.tabline.active: the tab bar's row and its active tab. .active left unset falls back to the base ui.tabline style, unlike the statusline separator below
• ui.statusline.search / .command / .sift: one more mode-tinted statusline scope per HUME mode Helix doesn't have, alongside Helix's own ui.statusline.normal/.insert/.select (.select colors Extend, HUME's name for what Helix calls Select mode; .sift colors HUME's own Sift mode, the s regex prompt)
• ui.virtual.invisible: the <200b>-style stand-in for a character the terminal must not be shown as itself (see Buffer options)
• diff.plus.line / diff.minus.line / diff.delta.line: the whole-line background tint core:git-diff paints for an added, deleted, or changed line (diff.minus.line also colors the ghost text of a deleted line, since nothing is left in the buffer to color). Falls back to nothing if left undefined. An unmodified Helix theme colors the gutter marker (below) but paints no line tint, which is the deliberate trade-off rather than a bug
• diff.plus.word / diff.minus.word: word-level highlight inside a changed line (core:git-diff's inline diff), inside the line-level .line tint above
• diagnostic.error.message / .warning.message / .info.message / .hint.message and their .message-text counterparts: the :messages log's severity badge and body text, a HUME-only feature
• error.diagnostic.inline / warning.diagnostic.inline / info.diagnostic.inline / hint.diagnostic.inline: the diagnostic summary shown at the end of an offending line. Separate from diagnostic.error and friends, which style the squiggle under the code itself, so the summary doesn't pick up that scope's underline. Each falls back to the matching error/warning/info/hint gutter color when unset

Helix scopes HUME doesn't read

Declaring any of these has no effect today. They fall into two groups, and the difference matters if you're deciding whether to keep them in a theme you maintain.

Waiting on a feature. HUME doesn't have the thing these color yet. When it does, these scopes are the natural way to theme it, so leaving them in a theme costs nothing:

• No debugger (DAP) support: ui.debug, ui.debug.breakpoint, ui.debug.active
• No which-key-style prompts: ui.popup.info, ui.help, ui.text.info
• No picker-preview highlighting: ui.highlight, ui.highlight.frameline
• No cursor-column ruler: ui.cursorcolumn, ui.cursorcolumn.primary, ui.cursorcolumn.secondary
• No per-kind completion-entry styling: ui.text.directory, ui.text.symlink
• No LSP deprecated/unnecessary diagnostic tags: diagnostic.deprecated, diagnostic.unnecessary
• No move- or conflict-specific diff styling: diff.delta.moved, diff.delta.conflict
• No snippet support: tabstop
• Ruler columns, the soft-wrap indicator, virtual jump labels, and per-kind inlay hints: ui.virtual.ruler, ui.virtual.wrap, ui.virtual.jump-label, ui.virtual.inlay-hint.parameter, ui.virtual.inlay-hint.type

HUME's interface works differently. These color a piece of Helix's UI that HUME either doesn't present the same way or styles from another scope. They may never apply, so the listed alternative is where to put the color instead:

• ui.picker.header, ui.picker.header.column, ui.picker.header.column.active: HUME's picker has no column headers to style
• ui.gutter, ui.gutter.selected: the gutter takes no background of its own; style it with ui.linenr and ui.linenr.selected
• ui.statusline.inactive, ui.text.inactive: HUME tints the whole statusline row by mode rather than dimming an unfocused one, and dims an unfocused pane wholesale instead of theming an inactive state
• ui.cursorline.secondary: only the primary selection's line is tinted, via ui.cursorline.primary
• ui.background.separator: HUME's prompt line has no separator rule beneath it
• ui.bufferline.background: the tab bar's ground comes from ui.tabline (or ui.bufferline, see below), not a separate background layer

Scopes HUME reads differently

ui.window is the seam between split panes. HUME draws the divider glyph itself, so it reads that scope's foreground; a theme that sets only a background falls back to the theme's own base text color (ui.text) for it, the same fallback every other undecorated element uses.

ui.statusline.separator divides the statusline's segments. HUME tints the whole statusline row by mode, so leaving this scope undefined takes the row's own current color rather than the untinted ui.statusline; otherwise the separator would show through a mode-tinted row as a stripe of the wrong color. Set it explicitly and that wins, in every mode.

HUME's tab bar is a saved window layout per tab (Vim's tab pages), not a per-buffer strip, so it's styled with its own ui.tabline / ui.tabline.active scopes rather than Helix's ui.bufferline / ui.bufferline.active. A theme that sets only the latter (every Helix theme, since ui.tabline is HUME's own addition) still renders correctly: ui.tabline falls back to ui.bufferline when unset, and ui.tabline.active to ui.bufferline.active, so the bar picks up a ported theme's colors without it needing to name HUME's scopes at all.