feat: improve tab and unnecessary-code highlights

CHANGELOG.md

@@ -7,6 +7,10 @@ release versions follow [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+### Changed
+
+- Highlight active tabs with the secondary accent and render LSP-tagged unnecessary code in subdued slate grey.
+
 ## [0.1.0] - 2026-07-19
 
 ### Added

README.md

@@ -91,6 +91,7 @@ Vulkanite automatically detects supported plugins installed through lazy.nvim or
 - [nvim-cmp](https://github.com/hrsh7th/nvim-cmp) and [blink.cmp](https://github.com/saghen/blink.cmp)
 - [which-key.nvim](https://github.com/folke/which-key.nvim)
 - [lazy.nvim](https://github.com/folke/lazy.nvim)
+- [bufferline.nvim](https://github.com/akinsho/bufferline.nvim)
 - [neo-tree.nvim](https://github.com/nvim-neo-tree/neo-tree.nvim) and [nvim-tree.lua](https://github.com/nvim-tree/nvim-tree.lua)
 - [noice.nvim](https://github.com/folke/noice.nvim) and [nvim-notify](https://github.com/rcarriga/nvim-notify)
 - [snacks.nvim](https://github.com/folke/snacks.nvim)

doc/vulkanite.txt

@@ -143,6 +143,7 @@ gitsigns              gitsigns.nvim
  blink                 blink.cmp
  which_key             which-key.nvim
  lazy                  lazy.nvim
+ bufferline            bufferline.nvim
  neo_tree              neo-tree.nvim
  nvim_tree             nvim-tree.lua
  noice                 noice.nvim
@@ -195,7 +196,7 @@ UI                    bg, bg_alt, bg_float, fg, fg_bright, fg_dim, comment,
                       gutter, selection
 Syntax and accents    value, docstring, accent, sky_blue, teal, bright_teal,
                       purple, ok
-Diagnostics           error, warn, info, hint
+Diagnostics           error, warn, info, hint, unnecessary
 Terminal              terminal (a 16-entry ANSI color array)
 
 `colors.roles` is internal. Override the public keys instead.

lua/vulkanite/colors.lua

@@ -42,6 +42,7 @@ local function derive_roles(colors)
     info = colors.info,
     hint = colors.hint,
     ok = colors.ok,
+    unnecessary = colors.unnecessary,
   }
   local diff = {
     add = colors.ok,
@@ -74,6 +75,7 @@ local function derive_roles(colors)
       info = diagnostic.info,
       hint = diagnostic.hint,
       ok = diagnostic.ok,
+      unnecessary = diagnostic.unnecessary,
       accent = accent.primary,
       accent_secondary = accent.secondary,
       match = accent.match,
@@ -102,6 +104,7 @@ local function resolve(opts, apply_overrides)
     hint = p.muted_blue,
     selection = p.slate_grey,
     ok = p.bright_green,
+    unnecessary = p.slate_grey,
     accent = p.bright_blue,
     sky_blue = p.sky_blue,
     purple = p.purple,

lua/vulkanite/config.lua

@@ -7,6 +7,7 @@ M.integration_keys = {
   "blink",
   "which_key",
   "lazy",
+  "bufferline",
   "neo_tree",
   "nvim_tree",
   "noice",

lua/vulkanite/groups/base.lua

@@ -100,7 +100,7 @@ function M.setup(colors, opts)
     -- Background fill after tab-page labels.
     TabLineFill = { fg = colors.ui.gutter, bg = colors.ui.bg_alt },
     -- Active tab-page label.
-    TabLineSel = { fg = colors.diagnostic.ok, bg = colors.ui.bg_alt },
+    TabLineSel = { fg = colors.accent.secondary, bg = colors.ui.bg_alt },
     -- Titles for buffers, quickfix lists, and plugin headings.
     Title = { fg = colors.accent.primary },
     -- Legacy vertical split separator.
@@ -201,6 +201,8 @@ function M.setup(colors, opts)
     DiagnosticHint = { fg = colors.diagnostic.hint },
     -- Diagnostic success text from Neovim diagnostics.
     DiagnosticOk = { fg = colors.diagnostic.ok },
+    -- Code marked unnecessary or unused by a diagnostic source.
+    DiagnosticUnnecessary = { fg = colors.diagnostic.unnecessary },
     -- Undercurl for ranges covered by error diagnostics.
     DiagnosticUnderlineError = { undercurl = true, sp = colors.diagnostic.error },
     -- Undercurl for ranges covered by warning diagnostics.

lua/vulkanite/groups/integrations/bufferline.lua

@@ -0,0 +1,12 @@
+local M = {}
+
+M.url = "https://github.com/akinsho/bufferline.nvim"
+
+function M.get(colors, opts)
+  return {
+    -- Bufferline selected buffer name.
+    BufferLineBufferSelected = { fg = colors.accent_secondary, bold = true, italic = true },
+  }
+end
+
+return M

test/vulkanite_spec.lua

@@ -79,6 +79,7 @@ local integration_probe_groups = {
   "BlinkCmpLabelMatch",
   "WhichKey",
   "LazyH1",
+  "BufferLineBufferSelected",
   "NeoTreeDirectoryName",
   "NvimTreeFolderName",
   "NoiceCmdlinePopup",
@@ -191,6 +192,11 @@ local function run()
     0x8fe0fa,
     "CursorLineNr marks the cursor line with the accent"
   )
+  assert_eq(
+    vim.api.nvim_get_hl(0, { name = "TabLineSel" }).fg,
+    0x4fa3a6,
+    "TabLineSel marks the active tab with the secondary accent"
+  )
   local search_highlight = vim.api.nvim_get_hl(0, { name = "Search", link = false })
   assert_eq(search_highlight.fg, 0x151b1e, "Search uses dark text")
   assert_eq(search_highlight.bg, 0x76c7e3, "Search uses one blue background")
@@ -344,13 +350,21 @@ local function run()
     "#e03f32",
     "diagnostic role is derived centrally"
   )
+  assert_eq(
+    semantic_colors.roles.diagnostic.unnecessary,
+    "#5c6370",
+    "unnecessary diagnostic role is derived centrally"
+  )
   assert_eq(semantic_colors.roles.accent.icon, "#9083B9", "icon role is derived centrally")
   assert_eq(vim.api.nvim_get_hl(0, { name = "ErrorMsg" }).fg, 0xe03f32, "ErrorMsg uses vivid red")
   assert_eq(
     vim.api.nvim_get_hl(0, { name = "DiagnosticError" }).fg,
     0xe03f32,
     "DiagnosticError uses vivid red"
   )
+  local unnecessary_highlight = vim.api.nvim_get_hl(0, { name = "DiagnosticUnnecessary" })
+  assert_eq(unnecessary_highlight.fg, 0x5c6370, "unnecessary code uses slate grey")
+  assert_eq(unnecessary_highlight.nocombine, nil, "unnecessary code preserves syntax styles")
   assert_eq(vim.api.nvim_get_hl(0, { name = "WarningMsg" }).fg, 0xe0af68, "WarningMsg uses yellow")
   assert_eq(
     vim.api.nvim_get_hl(0, { name = "DiagnosticWarn" }).fg,
@@ -509,6 +523,7 @@ local function run()
   require("vulkanite").load({
     on_colors = function(colors)
       colors.error = "#ff0000"
+      colors.unnecessary = "#808080"
     end,
     on_highlights = function(groups, colors)
       groups.VulkaniteOverrideProbe = { fg = colors.error }
@@ -524,13 +539,23 @@ local function run()
     0xff0000,
     "on_highlights sees colors"
   )
+  assert_eq(
+    vim.api.nvim_get_hl(0, { name = "DiagnosticUnnecessary" }).fg,
+    0x808080,
+    "on_colors mutates unnecessary diagnostics independently"
+  )
   require("vulkanite").load({})
   assert_unset("VulkaniteOverrideProbe", "reload clears callback-defined highlights")
   assert_eq(
     vim.api.nvim_get_hl(0, { name = "DiagnosticError" }).fg,
     0xe03f32,
     "reload restores default semantic colors"
   )
+  assert_eq(
+    vim.api.nvim_get_hl(0, { name = "DiagnosticUnnecessary" }).fg,
+    0x5c6370,
+    "reload restores the default unnecessary color"
+  )
 
   reset_vulkanite()
   require("vulkanite").load({
@@ -602,6 +627,10 @@ local function run()
   assert_unset("WhichKeyFloat", "obsolete which-key group is not defined")
   assert_unset("SnacksPickerGitHubIssue", "obsolete Snacks GitHub issue group is not defined")
   assert_eq(vim.api.nvim_get_hl(0, { name = "LazyValue" }).fg, 0xe05f64, "LazyValue uses value red")
+  local selected_buffer = vim.api.nvim_get_hl(0, { name = "BufferLineBufferSelected" })
+  assert_eq(selected_buffer.fg, 0x4fa3a6, "selected bufferline buffer uses the secondary accent")
+  assert_eq(selected_buffer.bold, true, "selected bufferline buffer remains bold")
+  assert_eq(selected_buffer.italic, true, "selected bufferline buffer remains italic")
   assert_eq(
     vim.api.nvim_get_hl(0, { name = "LspKindUnit" }).fg,
     0xe05f64,