fix(metadata-protocol): seed-loader pass 2 目标解析成功但源记录无 id 时,回填不再被静默丢弃 (#5127)

.changeset/plenty-poems-brush.md

@@ -0,0 +1,27 @@
+---
+'@objectstack/metadata-protocol': patch
+---
+
+seed-loader: a pass-2 back-fill dropped for a missing source-record id is now reported, not silently discarded
+
+`resolveDeferredUpdates()` looked the source record's internal id up in `insertedRecords`
+and, when it was not there, ran off the end of an `if` with no `else`. Pass 2 had already
+RESOLVED the target, and the back-fill then evaporated: no write, no entry in
+`errors`/`allErrors` (so the load still reported `success: true`), no `errored`, and not
+one log line. The only trace was the `referencesDeferred` the record booked in pass 1 and
+never gave back — a dangling number with nothing in the result explaining it, while the
+declared association stayed absent forever.
+
+It now records the loss through `recordDeferredError` (→ `errors`/`allErrors` + `errored`,
+so the load reports `success: false`) and logs it once at `error`, per the same objective
+criterion applied in #4729/#4997 and the "Degradation log levels" rule. The two ways to
+get here are worded differently because they are different failures: an EMPTY
+`recordExternalId` — `externalIdKey` returns `''` when any component of a composite
+externalId is blank — is the pure silent loss, where the row wrote perfectly, nothing else
+in the load reports anything and the reference stays NULL forever; a real key that is
+simply absent from the map means the source row never landed, and that write failure was
+already reported at `error`, so this line points at it instead of restating it.
+
+A load that hits this path previously returned `success: true` with clean counters and now
+returns `success: false` with the loss counted — the seed data was always incomplete; it
+just was not saying so.