v2: spurious 'No action found for keymap' warning for function-valued window keymaps on re-registration #506

Bug

Function-valued window keymaps (e.g. a custom callback in keymap.output_window) emit a spurious warning every time window keymaps are re-processed for a buffer that already has the mapping:

No action found for keymap: <M-n> -> function: 0x...

This happens on every panel toggle (the output buffer survives, the window is recreated, setup_panel_keymaps re-runs setup_window_keymaps(..., preserve_existing=true) on the same buffer), so the warning fires repeatedly during normal use.

Repro

require('opencode').setup({
  keymap = {
    output_window = {
      ['<M-n>'] = { function() end, mode = 'n', desc = 'custom' },
    },
  },
})

Then open the opencode panel, close it, and open it again — the warning appears on the second open. Equivalently, calling require('opencode.keymap').setup_window_keymaps(cfg, buf, true) twice with the same buffer reproduces it: first call is silent, second warns.

Root cause

In lua/opencode/keymap.lua, process_keymap_entry (lines 86-93):

if callback and #modes > 0 then
  ...
  vim.keymap.set(modes, key_binding, callback, opts)
elseif type(func_name) ~= 'string' then
  vim.notify(string.format('No action found for keymap: %s -> %s', key_binding, func_name), vim.log.levels.WARN)
end

With preserve_existing, modes for which the buffer already has the mapping are filtered out, leaving modes = {} on re-processing. For function-valued entries resolve_callback always returns the function, so callback is non-nil and the elseif is reached purely because #modes == 0 — i.e. "already registered, nothing to do", not "no action found". String actions are spared only because of the type(func_name) ~= 'string' check.

In fact the branch is only reachable for function values with empty modes (string actions either resolve or warn earlier in resolve_callback), so it only ever produces false positives.

Suggested fix

Skip silently when nothing is left to do — only warn when the callback could not be resolved:

if callback and #modes > 0 then
  ...
  vim.keymap.set(modes, key_binding, callback, opts)
elseif not callback and type(func_name) ~= 'string' then
  vim.notify(...)
end

Environment

• opencode.nvim v2 branch @ e4ec704
• Neovim v0.12.5, Windows 11