milestone 18: collapse duplicated infrastructure into shared listener core, crud list helper, resource shells, transport race, name and line helpers, ui modules

src/config/import.zig

@@ -164,7 +164,11 @@ pub fn importSource(
 /// `std.zon.parse.Diagnostics` renders one "line:column: error: text" line per
 /// problem, plus a "note:" line each, so each rendered line becomes one
 /// `Problem` and the list keeps the parser's order.
-fn reportParseFailure(
+///
+/// `pub` because `nxdns check` parses the same file and owes the operator the
+/// same one-line-per-problem output; rendering the ZON diagnostics inline would
+/// put newlines inside a single `FAIL` record.
+pub fn reportParseFailure(
     diags: *validate.Diagnostics,
     zon_diag: *const std.zon.parse.Diagnostics,
 ) error{OutOfMemory}!void {
@@ -910,6 +914,31 @@ test "importSource reports a ZON syntax error and writes nothing" {
     try testing.expect(std.mem.indexOf(u8, text, "1:14: error: ") != null);
 }
 
+test "importSource splits a multi-line ZON failure into one problem per message" {
+    var threaded: std.Io.Threaded = .init(testing.allocator, .{});
+    defer threaded.deinit();
+    const io = threaded.io();
+
+    var database = try openMigrated();
+    defer database.close();
+
+    var diags: validate.Diagnostics = .init(testing.allocator);
+    defer diags.deinit();
+    // An unexpected field renders as an "error:" line plus a "note:" line, so
+    // the rendering the CLI prints has to be split rather than embedded whole.
+    try testing.expectError(
+        error.ParseZon,
+        importSource(io, testing.allocator, &database, ".{ .grops = .{} }", .{}, &diags),
+    );
+
+    try testing.expectEqual(@as(usize, 2), diags.problems.items.len);
+    for (diags.problems.items) |problem| {
+        try testing.expectEqual(@as(?usize, null), std.mem.findScalar(u8, problem.message, '\n'));
+    }
+    try testing.expect(std.mem.indexOf(u8, diags.problems.items[0].message, "error: ") != null);
+    try testing.expect(std.mem.indexOf(u8, diags.problems.items[1].message, "note: ") != null);
+}
+
 test "a config omitting every optional field parses into an arena and leaks nothing" {
     // The S5.1 rule as a test: `std.zon.parse.free` is never called, the arena
     // is the only release, and `std.testing.allocator` fails the test if a