diff --git a/lua/rulebook/diagnostic-actions.lua b/lua/rulebook/diagnostic-actions.lua
index 3240033..b2d108e 100644
--- a/lua/rulebook/diagnostic-actions.lua
+++ b/lua/rulebook/diagnostic-actions.lua
@@ -2,26 +2,33 @@ local M = {}
 local notify = require("rulebook.utils").notify
 --------------------------------------------------------------------------------
 
----checks whether rule has id and source, as prescribed in nvim diagnostic structure
 ---@param diag vim.Diagnostic
----@return boolean whether rule is valid
+---@return boolean
 ---@nodiscard
-local function validDiagObj(diag)
+local function sourceUsesCodes(diag)
 	local config = require("rulebook.config").config
 	local sourcesWithNoCodes = vim.iter(config.ignoreComments)
 		:filter(function(_, conf) return conf.doesNotUseCodes end)
 		:map(function(linter, _) return linter end)
 		:totable()
-	if vim.tbl_contains(sourcesWithNoCodes, diag.source) then return true end
+	return not vim.tbl_contains(sourcesWithNoCodes, diag.source)
+end
+
+---checks whether rule has id and source, as prescribed in nvim diagnostic structure
+---@param diag vim.Diagnostic
+---@return boolean
+---@nodiscard
+local function validDiagObj(diag)
+	if not sourceUsesCodes(diag) then return true end
 
 	local issuePlea =
 		"\nIf you are using efm or nvim-lint, please check your linter config. Otherwise open an issue at the diagnostic source or the diagnostic provider."
-	if not diag.code then
-		notify("Diagnostic is missing a code (rule id)." .. issuePlea, "warn")
-		return false
-	elseif not diag.source then
+	if not diag.source then
 		notify("Diagnostic is missing a source." .. issuePlea, "warn")
 		return false
+	elseif not diag.code and sourceUsesCodes(diag) then
+		notify("Diagnostic is missing a code (rule id)." .. issuePlea, "warn")
+		return false
 	end
 	return true
 end
@@ -56,13 +63,17 @@ end
 
 ---@param diag vim.Diagnostic
 function M.ignoreRule(diag)
+	local configForSource = require("rulebook.config").config.ignoreComments[diag.source]
+	if not configForSource then
+		notify(("No ignore comment configured for %q."):format(diag.source), "warn")
+		return
+	end
 	if not validDiagObj(diag) then return end
-	local config = require("rulebook.config").config
 
 	local indent = vim.api.nvim_get_current_line():match("^%s*")
-	local ignoreComment = config.ignoreComments[diag.source].comment
+	local ignoreComment = configForSource.comment
 	if type(ignoreComment) == "function" then ignoreComment = ignoreComment(diag) end
-	local ignoreLocation = config.ignoreComments[diag.source].location
+	local ignoreLocation = configForSource.location
 
 	-- insert the comment
 	if ignoreLocation == "prevLine" then
@@ -98,7 +109,6 @@ end
 ---@param operation "lookupRule"|"ignoreRule"|"yankDiagnosticCode"
 function M.selectRule(operation)
 	local config = require("rulebook.config").config
-	local operationIsIgnore = operation == "ignoreRule"
 	local lnum = vim.api.nvim_win_get_cursor(0)[1] - 1
 	local startLine = lnum
 	local lastLine = vim.api.nvim_buf_line_count(0)
@@ -107,24 +117,12 @@ function M.selectRule(operation)
 	-- loop through lines until we find a line with diagnostics
 	while true do
 		diagsAtLine = vim.diagnostic.get(0, { lnum = lnum })
-		if operationIsIgnore then
-			-- INFO for rule search, there is no need to filter the diagnostics, since there
-			-- is a fallback mechanic
-			diagsAtLine = vim.tbl_filter(
-				function(d) return config.ignoreComments[d.source] ~= nil end,
-				diagsAtLine
-			)
-		end
-
-		-- no diagnostic -> search the next lines
-		if #diagsAtLine > 0 then break end
+		if #diagsAtLine > 0 then break end -- no diagnostic -> search the next lines
 		lnum = lnum + 1
 
 		-- GUARD
 		if lnum > lastLine or lnum > startLine + config.forwSearchLines then
-			local msg = ("No supported diagnostics found in the next %s lines."):format(
-				config.forwSearchLines
-			)
+			local msg = ("No diagnostics found in the next %s lines."):format(config.forwSearchLines)
 			notify(msg, "warn")
 			return
 		end
@@ -133,7 +131,7 @@ function M.selectRule(operation)
 	-- remove duplicate rules
 	local uniqueRule = {}
 	for _, diag in ipairs(diagsAtLine) do
-		uniqueRule[diag.source .. (diag.code or diag.message)] = diag
+		uniqueRule[(diag.source or "") .. (diag.code or diag.message)] = diag
 	end
 	diagsAtLine = vim.tbl_values(uniqueRule)
 
@@ -145,7 +143,7 @@ function M.selectRule(operation)
 
 	-- select from multiple diagnostics
 	local title
-	if operationIsIgnore then title = "Ignore Rule:" end
+	if operation == "ignoreRule" then title = "Ignore Rule:" end
 	if operation == "lookupRule" then title = "Lookup Rule:" end
 	if operation == "yankDiagnosticCode" then title = "Yank Diagnostic Code:" end
 
@@ -153,17 +151,26 @@ function M.selectRule(operation)
 		prompt = title,
 		kind = "rule_selection",
 		format_item = function(diag)
-			local source = diag.source and diag.source .. ": " or ""
-			local desc = diag.code or diag.message
-			local display = source .. desc
-			if not (diag.code and diag.source) then display = " " .. display end
+			local msg = vim.trim((diag.message or ""):sub(1, 50))
+			if not diag.source then return ("[ No source] %s %s"):format(diag.code or "", msg) end
+
+			local display = diag.source .. ": " .. (diag.code or msg)
+			if operation == "ignoreRule" then
+				local configForSource = require("rulebook.config").config.ignoreComments[diag.source]
+				if not configForSource then display = "[ No config] " .. display end
+				if sourceUsesCodes(diag) and not diag.code then
+					display = "[ No code] " .. display
+				end
+			elseif not diag.code then
+				display = "[ No code] " .. display
+			end
 			return display
 		end,
 	}, function(diag)
 		if not diag then return end -- user aborted
 
 		-- move cursor to location where we add the comment
-		if operationIsIgnore and startLine ~= lnum then
+		if operation == "ignoreRule" and startLine ~= lnum then
 			vim.api.nvim_win_set_cursor(0, { lnum + 1, 0 })
 			vim.cmd("normal! ^")
 		end