Fix which-key not seeing gitsigns maps, add diagnostic maps

The gitsigns keymaps were defined in on_attach, so they were
buffer-local and created asynchronously - gitsigns shells out to git
before attaching. which-key had already built its keymap tree for the
buffer by then, and it only invalidates that cache on BufReadPost,
BufNew and LspAttach, so maps added afterwards stayed invisible.
Buf:get() returns cached mode state unless explicitly passed `update`,
which is why re-entering the buffer didn't help either.

Mapping globally instead means the maps exist before which-key builds
any tree. The gitsigns API no-ops in buffers it hasn't attached to
(checked stage/reset/preview/blame/nav in a non-git directory), so the
only change is that the maps now exist everywhere rather than just in
git-tracked buffers.

Also puts the diagnostic float and quickfix list on <leader>d. Nvim
already binds <C-W>d and ]d/[d for these, so this is a rebinding for
discoverability rather than new capability.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

neovim/config/diagnostics.lua

@@ -16,3 +16,8 @@ vim.diagnostic.config({
     },
   },
 })
+
+-- Nvim already binds ]d / [d to jump and <C-W>d to show the diagnostic under
+-- the cursor; these put the same actions on <leader> so which-key lists them.
+vim.keymap.set('n', '<leader>dd', vim.diagnostic.open_float, { desc = 'Show diagnostic' })
+vim.keymap.set('n', '<leader>dq', vim.diagnostic.setqflist, { desc = 'Diagnostics to quickfix' })

neovim/config/plugins/gitsigns.lua

@@ -1,11 +1,16 @@
 vim.pack.add({ 'https://github.com/lewis6991/gitsigns.nvim' })
 
-require('gitsigns').setup({
-  on_attach = function(bufnr)
 local gitsigns = require('gitsigns')
 
+gitsigns.setup()
+
+-- Mapped globally rather than from on_attach. Gitsigns attaches asynchronously,
+-- after which-key has already built its keymap tree for the buffer, and
+-- which-key only rebuilds that on BufReadPost/BufNew/LspAttach - so
+-- buffer-local maps added later never show up in its popup. The gitsigns API
+-- no-ops in buffers it hasn't attached to, so global maps are safe.
 local function map(mode, lhs, rhs, desc)
-      vim.keymap.set(mode, lhs, rhs, { buffer = bufnr, desc = desc })
+  vim.keymap.set(mode, lhs, rhs, { desc = desc })
 end
 
 -- Navigation, falling back to vim's own diff motions in diff mode
@@ -51,5 +56,3 @@ require('gitsigns').setup({
 -- Toggles
 map('n', '<leader>tb', gitsigns.toggle_current_line_blame, 'Toggle line blame')
 map('n', '<leader>td', gitsigns.toggle_deleted, 'Toggle deleted lines')
-  end,
-})

neovim/config/plugins/which-key.lua

@@ -4,8 +4,9 @@ local wk = require('which-key')
 
 wk.setup()
 
--- Names for the gitsigns prefixes, so the popup groups them sensibly
+-- Names for the <leader> prefixes, so the popup groups them sensibly
 wk.add({
+  { '<leader>d', group = 'diagnostics' },
   { '<leader>h', group = 'hunks' },
   { '<leader>t', group = 'toggles' },
 })