fix(formatter/grep): normalize grep input handling

Normalize parts in resolve_grep_string to safely convert nil, vim.NIL, numbers, and booleans to strings and prefer input.path over input.include when present. This prevents invalid grep strings from non-string inputs.

Author: sudo-tee

lua/opencode/ui/formatter/tools/grep.lua

@@ -4,11 +4,30 @@ local M = {}
 ---@param input GrepToolInput|nil
 ---@return string
 local function resolve_grep_string(input)
+  local function normalize_part(value)
+    if value == nil or value == vim.NIL then
+      return ''
+    end
+
+    local value_type = type(value)
+    if value_type == 'string' then
+      return value
+    end
+    if value_type == 'number' or value_type == 'boolean' then
+      return tostring(value)
+    end
+
+    return ''
+  end
+
   if not input then
     return ''
   end
-  local path_part = input.path or input.include or ''
-  local pattern_part = input.pattern or ''
+  local path_part = normalize_part(input.path)
+  if path_part == '' then
+    path_part = normalize_part(input.include)
+  end
+  local pattern_part = normalize_part(input.pattern)
   return table.concat(
     vim.tbl_filter(function(p)
       return p ~= nil and p ~= ''

tests/unit/formatter_spec.lua

@@ -199,4 +199,43 @@ describe('formatter', function()
     assert.are.equal('+', add_mark.virt_text[2][1])
     assert.are.equal('OpencodeDiffAddGutter', add_mark.virt_text[1][2])
   end)
+
+  it('formats grep tools when streamed input contains vim.NIL placeholders', function()
+    local message = {
+      info = {
+        id = 'msg_1',
+        role = 'assistant',
+        sessionID = 'ses_1',
+      },
+      parts = {},
+    }
+
+    local part = {
+      id = 'prt_grep_1',
+      type = 'tool',
+      tool = 'grep',
+      messageID = 'msg_1',
+      sessionID = 'ses_1',
+      state = {
+        status = 'completed',
+        input = {
+          path = vim.NIL,
+          include = '*.lua',
+          pattern = 'eventignore',
+        },
+        metadata = {
+          matches = 3,
+        },
+        time = {
+          start = 1,
+          ['end'] = 2,
+        },
+      },
+    }
+
+    local output = formatter.format_part(part, message, true)
+
+    assert.are.equal('**  grep** `*.lua eventignore` 1s', output.lines[1])
+    assert.are.equal('Found `3` matches', output.lines[2])
+  end)
 end)