mdcode: fields with no declared datatype are published as STRING, silently

[feixufeixu]

Found while working on a change in the same area, not from a bug report.

A model field with no declared datatype is published as STRING for both
dataType and metadataType, with no warning.

src/libts/semantic/knowledge_catalog.ts, columnDataType /
columnMetadataType — both fall through to STRING for undefined.

This is the normal path rather than an edge case: 13 of the 14 Ossie fixtures
declare no datatype at all, and 28 of 28 schema fields across the goldens
are STRING/STRING — including o_totalprice and the other decimal
columns in star_orders_customer.

Reproduce

Push any model whose fields omit datatype (e.g. star_orders_customer.yaml)
and read the emitted schema aspect:

{"name": "o_totalprice", "dataType": "STRING", "metadataType": "STRING"}

Expected: something that does not assert a type the model never stated.

Four things that seem to interact here

It cannot warn, structurally. schemaAspectData(entity) takes no
warnings parameter. The metric path handles the identical situation and does
warn — metricAspectData(metric, warnings) defaults to NUMERIC and pushes a
message.

OTHER exists for this. metadataType's enum has it, and this same file
uses it for Opaque. STRING asserts a type; OTHER admits the absence of one.

undefined and 'String' are indistinguishable in the output, so a
consumer cannot tell "the author said string" from "the author said nothing" —
which for a catalog seems like the distinction worth keeping.

Opaque disagrees with itself: columnDataType('Opaque') → 'STRING'
while columnMetadataType('Opaque') → 'OTHER'.

---

cc @libei

[libei]

#298 (merged Aug 14) already covers points 2–4. Current main emits, for o_totalprice:

{"name": "o_totalprice", "dataType": "STRING", "metadataType": "OTHER"}

not the STRING/STRING in the repro. An untyped field now maps through f.type ?? 'Opaque', so:

• OTHER is used — columnMetadataType('Opaque') → 'OTHER'.
• undefined and 'String' are distinguishable — undefined → (STRING, OTHER), authored String → (STRING, STRING).
• The Opaque STRING/OTHER split is intentional, not a disagreement: dataType is a required free-string column, so STRING is a placeholder; metadataType: OTHER carries the "type unknown" signal. Test: ['Opaque', 'STRING', 'OTHER'].

On point 1 (warn): the description is stale — the metric path no longer defaults to NUMERIC+warn. Both paths now default to Opaque and stay silent by design: warn when we guess a type, stay silent when we honestly mark it unknown. knowledge_catalog.test.ts locks this in ("No NUMERIC guess, so nothing to warn about"). Not reopening that.

Closing as resolved by #298.