diff --git a/lua/jj/diff/codediff.lua b/lua/jj/diff/codediff.lua
index 0761e73..3bcf651 100644
--- a/lua/jj/diff/codediff.lua
+++ b/lua/jj/diff/codediff.lua
@@ -1,8 +1,111 @@
 local utils = require("jj.utils")
+local file = require("jj.file")
 
 ---@type jj.diff
 local diff = require("jj.diff")
 
+---@type {dirs: string[], files: string[]}[]
+local pending_launches = {}
+---@type table<number, {dirs: string[], files: string[]}>
+local artifacts_by_tab = {}
+local temp_cleanup_registered = false
+
+local function cleanup_artifacts(artifacts)
+	if not artifacts then
+		return
+	end
+
+	for _, file_path in ipairs(artifacts.files or {}) do
+		local bufnr = vim.fn.bufnr(file_path)
+		if bufnr ~= -1 and vim.api.nvim_buf_is_valid(bufnr) then
+			pcall(vim.api.nvim_buf_delete, bufnr, { force = true })
+		end
+	end
+
+	for _, dir_path in ipairs(artifacts.dirs or {}) do
+		vim.fn.delete(dir_path, "rf")
+	end
+end
+
+local function register_cleanup_hooks()
+	if temp_cleanup_registered then
+		return
+	end
+	temp_cleanup_registered = true
+
+	local group = vim.api.nvim_create_augroup("JJCodediffTempCleanup", { clear = true })
+
+	vim.api.nvim_create_autocmd("User", {
+		group = group,
+		pattern = "CodeDiffOpen",
+		callback = function(args)
+			local artifacts = table.remove(pending_launches, 1)
+			if not artifacts then
+				return
+			end
+			local tabpage = (args.data and args.data.tabpage) or vim.api.nvim_get_current_tabpage()
+			artifacts_by_tab[tabpage] = artifacts
+		end,
+	})
+
+	vim.api.nvim_create_autocmd("User", {
+		group = group,
+		pattern = "CodeDiffClose",
+		callback = function(args)
+			local tabpage = (args.data and args.data.tabpage) or vim.api.nvim_get_current_tabpage()
+			local artifacts = artifacts_by_tab[tabpage]
+			if artifacts then
+				cleanup_artifacts(artifacts)
+				artifacts_by_tab[tabpage] = nil
+			end
+		end,
+	})
+
+	vim.api.nvim_create_autocmd("VimLeavePre", {
+		group = group,
+		callback = function()
+			for _, artifacts in pairs(artifacts_by_tab) do
+				cleanup_artifacts(artifacts)
+			end
+			for _, artifacts in ipairs(pending_launches) do
+				cleanup_artifacts(artifacts)
+			end
+			artifacts_by_tab = {}
+			pending_launches = {}
+		end,
+	})
+end
+
+--- Write text lines to a temp file while preserving filename/extension for filetype detection.
+--- @param original_path string
+--- @param lines string[]
+--- @param had_eol boolean
+--- @return string|nil file_path
+--- @return string|nil dir_path
+local function write_temp_file_like(original_path, lines, had_eol)
+	local dir = vim.fn.tempname()
+	vim.fn.mkdir(dir, "p")
+
+	local basename = vim.fs.basename(original_path or "")
+	if not basename or basename == "" then
+		basename = "jj-codediff.tmp"
+	end
+
+	local path = dir .. "/" .. basename
+	local fh = io.open(path, "w")
+	if not fh then
+		vim.fn.delete(dir, "rf")
+		return nil, nil
+	end
+	fh:write(table.concat(lines, "\n"))
+	if had_eol then
+		fh:write("\n")
+	end
+	fh:close()
+
+	return path, dir
+end
+
 --- Givewn two changes, show their diff using codediff
 --- @param left string
 --- @param right string
@@ -53,8 +156,71 @@ diff.register_backend("codediff", {
 			return
 		end
 
-		-- Extract the commit id from opts.rev
-		local revset = opts.rev or "@-"
+		local buf_name = vim.api.nvim_buf_get_name(0)
+		local change_id, jj_path = utils.parse_jj_uri(buf_name)
+		local revset = opts.rev or (change_id and (change_id .. "-")) or "@-"
+
+		-- For jj:// buffers, compare the current in-memory buffer against <revset> for the same file.
+		if change_id and not opts.path then
+			local path = jj_path
+			if not path or path == "" then
+				utils.notify("Invalid jj:// buffer path", vim.log.levels.ERROR)
+				return
+			end
+
+			local base_lines, base_had_eol, ok_read = file.get_file_content(revset, path)
+			if not ok_read then
+				utils.notify(string.format("Could not read `%s` from `%s` for CodeDiff", path, revset), vim.log.levels.ERROR)
+				return
+			end
+			local cur_lines = vim.api.nvim_buf_get_lines(0, 0, -1, false)
+			local cur_had_eol = vim.bo[0].eol
+
+			local base_file, base_dir = write_temp_file_like(path, base_lines, base_had_eol)
+			local cur_file, cur_dir = write_temp_file_like(path, cur_lines, cur_had_eol)
+			if not base_file or not cur_file or not base_dir or not cur_dir then
+				if base_dir then
+					vim.fn.delete(base_dir, "rf")
+				end
+				if cur_dir then
+					vim.fn.delete(cur_dir, "rf")
+				end
+				utils.notify("Failed to create temporary files for CodeDiff", vim.log.levels.ERROR)
+				return
+			end
+
+			register_cleanup_hooks()
+			local artifacts = {
+				dirs = { base_dir, cur_dir },
+				files = { base_file, cur_file },
+			}
+			table.insert(pending_launches, artifacts)
+
+			local ok_cmd, err = pcall(function()
+				vim.cmd(
+					string.format("CodeDiff file %s %s", vim.fn.fnameescape(base_file), vim.fn.fnameescape(cur_file))
+				)
+			end)
+
+			if not ok_cmd then
+				-- remove the just-enqueued launch so the next CodeDiffOpen doesn't consume it
+				if pending_launches[#pending_launches] == artifacts then
+					table.remove(pending_launches)
+				else
+					for i = #pending_launches, 1, -1 do
+						if pending_launches[i] == artifacts then
+							table.remove(pending_launches, i)
+							break
+						end
+					end
+				end
+
+				cleanup_artifacts(artifacts)
+				utils.notify(err or "Could not launch CodeDiff", vim.log.levels.ERROR)
+			end
+
+			return
+		end
 
 		local commit_id = utils.get_commit_id(revset)
 		if not commit_id then
diff --git a/lua/jj/diff/diffview.lua b/lua/jj/diff/diffview.lua
index af8d83d..6e7ff81 100644
--- a/lua/jj/diff/diffview.lua
+++ b/lua/jj/diff/diffview.lua
@@ -46,15 +46,23 @@ diff.register_backend("diffview", {
 			return
 		end
 
-		-- Extract the commit id from opts.rev
-		local revset = opts.rev or "@-"
+		local buf_name = vim.api.nvim_buf_get_name(0)
+		local change_id, jj_path = utils.parse_jj_uri(buf_name)
+		local revset = opts.rev or (change_id and (change_id .. "-")) or "@-"
 
 		local commit_id = utils.get_commit_id(revset)
 		if not commit_id then
 			return
 		end
 
-		vim.cmd(string.format("DiffviewOpen %s -- %%", commit_id))
+		local raw_path = opts.path or jj_path or "%"
+		local path, err = utils.normalize_repo_path(raw_path)
+		if not path then
+			utils.notify(err or "Could not resolve file path for Diffview", vim.log.levels.ERROR)
+			return
+		end
+
+		vim.cmd(string.format("DiffviewOpen %s -- %s", commit_id, vim.fn.fnameescape(path)))
 		vim.cmd("DiffviewToggleFiles")
 	end,
 	show_revision = function(opts)
diff --git a/lua/jj/diff/native.lua b/lua/jj/diff/native.lua
index bb7c4d2..bbf085e 100644
--- a/lua/jj/diff/native.lua
+++ b/lua/jj/diff/native.lua
@@ -27,7 +27,11 @@ local function open_revision(rev, path)
 		return
 	end
 
-	local lines, had_eol = file.get_file_content(change_id, rel_path)
+	local lines, had_eol, ok_read = file.get_file_content(change_id, rel_path)
+	if not ok_read then
+		utils.notify(string.format("Could not read `%s` from `%s`", rel_path, change_id), vim.log.levels.ERROR)
+		return
+	end
 
 	local buf = vim.api.nvim_create_buf(false, true)
 
diff --git a/lua/jj/file.lua b/lua/jj/file.lua
index 8c6541b..b8a687c 100644
--- a/lua/jj/file.lua
+++ b/lua/jj/file.lua
@@ -21,6 +21,7 @@ local parser = require("jj.core.parser")
 --- @param path string Repository-relative path
 --- @return string[] lines
 --- @return boolean had_eol Whether the content had a trailing newline
+--- @return boolean ok Whether the command succeeded
 local function get_file_content(rev, path)
 	local content, ok = runner.execute_command(
 		string.format("jj file show -r %s %s", vim.fn.shellescape(rev), vim.fn.shellescape(path)),
@@ -29,14 +30,14 @@ local function get_file_content(rev, path)
 		true
 	)
 	if not ok or not content then
-		return {}, false
+		return {}, false, false
 	end
 	local lines = vim.split(content, "\n", { plain = true, trimempty = false })
 	local had_eol = #lines > 0 and lines[#lines] == ""
 	if had_eol then
 		table.remove(lines, #lines)
 	end
-	return lines, had_eol
+	return lines, had_eol, true
 end
 M.get_file_content = get_file_content
 
@@ -146,7 +147,11 @@ function M.open_target(opts)
 	end
 	local change_id = ids[1]
 
-	local lines, had_eol = get_file_content(change_id, path)
+	local lines, had_eol, ok_read = get_file_content(change_id, path)
+	if not ok_read then
+		utils.notify(string.format("Could not read `%s` from `%s`", path, change_id), vim.log.levels.ERROR)
+		return
+	end
 	local ft = vim.filetype.match({ filename = path })
 
 	local buf, _ = buffer.create({
@@ -219,7 +224,11 @@ function M.register_command()
 			local name = vim.api.nvim_buf_get_name(0)
 			local change_id, path = utils.parse_jj_uri(name)
 			if not change_id then return end
-			local lines, had_eol = get_file_content(change_id, path)
+			local lines, had_eol, ok_read = get_file_content(change_id, path)
+			if not ok_read then
+				utils.notify(string.format("Could not read `%s` from `%s`", path, change_id), vim.log.levels.ERROR)
+				return
+			end
 			local buf = vim.api.nvim_get_current_buf()
 			vim.bo[buf].modifiable = true
 			vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)