Use the config access API in the ctl config editor (#1059)

serializedConfigToString now asks a control-located config instance
whether each field is readable and writable instead of relying on a
hard-coded list per command. Hidden and unknown fields are skipped, and
field descriptions are written as comments above each value.

Object fields such as factorio.settings are now included, so they are
written as JSON, and configToKeyVal splits on the first = only so those
values survive the round trip.

Fixes #1051

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

test/ctl/config_ops.test.js

@@ -1,5 +1,6 @@
 import assert from "node:assert/strict";
-import { configToKeyVal } from "@clusterio/ctl/dist/node/src/config_ops.js";
+import * as lib from "@clusterio/lib";
+import { configToKeyVal, serializedConfigToString } from "@clusterio/ctl/dist/node/src/config_ops.js";
 
 describe("ctl/config_ops", function() {
 	it("preserves full field names with LF and CRLF input", async function() {
@@ -18,4 +19,46 @@ describe("ctl/config_ops", function() {
 			});
 		}
 	});
+
+	it("keeps = inside values", async function() {
+		assert.deepEqual(await configToKeyVal("a = {\"b\":\"c=d\"}\nempty =\nmissing\n"), {
+			"a": "{\"b\":\"c=d\"}",
+			"empty": "",
+			"missing": "",
+		});
+	});
+
+	describe("serializedConfigToString()", function() {
+		const serialized = new lib.InstanceConfig("controller").toRemote("control");
+
+		it("writes descriptions above each value", function() {
+			const output = serializedConfigToString(serialized, lib.InstanceConfig);
+			const description = lib.InstanceConfig.fieldDefinitions["instance.auto_start"].description;
+			assert(output.includes(`# ${description}\ninstance.auto_start = false\n\n`));
+			assert(output.includes("# No description found\ninstance.name = New Instance\n\n"));
+		});
+
+		it("skips hidden, inaccessible and unknown fields", function() {
+			const output = serializedConfigToString(
+				{ ...serialized, "unknown.field": "value" }, lib.InstanceConfig
+			);
+			const names = [...output.matchAll(/^([^#\n][^=]*) =/gm)].map(match => match[1]);
+			assert(!names.includes("instance.id"));
+			assert(!names.includes("instance.assigned_host"));
+			assert(!names.includes("unknown.field"));
+			for (const name of names) {
+				const def = lib.InstanceConfig.fieldDefinitions[name];
+				assert(!def.hidden, `${name} is hidden`);
+			}
+		});
+
+		it("round trips object values through configToKeyVal", async function() {
+			const settings = { name: "a=b", tags: ["x"] };
+			const output = serializedConfigToString(
+				{ ...serialized, "factorio.settings": settings }, lib.InstanceConfig
+			);
+			const parsed = await configToKeyVal(output);
+			assert.deepEqual(JSON.parse(parsed["factorio.settings"]), settings);
+		});
+	});
 });