feat(ai,java): admit @responseRef (template.prompt) + template.* entity-child; un-ledger ai-trace fixtures

Ports the metamodel slice of the AI-trace vertical to Java (the carve-out's Java
half, ADR-0024): @responseRef registered on template.prompt only (matching TS
promptOverlayAttrs), template.* admitted as object children, @responseRef carved
out of the cross-port registry manifest via a new TS_PILOT_VOCAB exclusion
(mirrors TS TsPilotVocab). Also maps the canonical cross-port provider name
'metaobjects-template' to Java's template-types provider in the conformance
harness alias table (TS/C#/Python expose it under that name; the fixtures'
providers.json requires it). ai-trace-prompt-nested + ai-trace-sti now load +
canonical-serialize cross-port-clean in Java; un-ledgered. registry-conformance
stays green. (The carve-out is fully closed only when all 4 non-TS ports register
@responseRef — atomic flip of expected-registry.json later.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: dmealing

server/java/metadata/conformance-expected-failures.json

@@ -1,11 +1,9 @@
 {
   "language": "java",
   "_comment": "FR-013 (@readOnly), FR-014 (TPH discriminator), and FR-015 (@parameterRef) VALIDATION passes shipped in the Java port (ValidationPhase.validateFieldReadOnly / validateDiscriminator / validateSourceParameterRef). 9 of 11 fixtures now pass byte-identically. The two remaining entries are BOTH manifestations of one pre-existing Java subtype-field-override gap (orthogonal to the validation fan-out), deferred until the Java loader's field-override provenance/serializer reconciliation: (1) error-field-readonly-downgrade — the validation fires the correct ERR_READONLY_DOWNGRADE with a single error, but the envelope source for a subtype field that OVERRIDES an inherited field is a MergedSource pointing at the base declaration (children[0]) rather than the subtype's authored json source (children[1]); Java clones+stamps MergedSource on extends-overrides, and Contributor carries no per-contributor jsonPath, so the subtype's authored path is not recoverable post-merge (the TS/Python reference models keep the override's plain JsonSource). (2) field-readonly-upgrade-on-subtype — a positive fixture that fails on canonical serialization of the same subtype @readOnly override (same root cause).",
-  "_comment_ai_pilot": "ai-trace-prompt-nested exercises the AI #1b prompt-derived-trace vertical, a deliberate TS pilot (cross-language LLM-call trace persistence). It places a template.prompt CHILD under object.entity and uses @responseRef on template.prompt. Neither is yet cross-port: Java's MetaObject child rules do not admit template.* children, and @responseRef is carved out of the cross-port registry manifest (TsPilotVocab). Under strict ADR-0023 load this happy-path fixture reports ERR_UNKNOWN here. Ledgered until the AI vertical is promoted from the TS pilot to all five ports. The sibling fixture ai-llm-call-extends (plain entity + extends) passes cross-port and is NOT ledgered. ai-trace-sti is the same TS pilot in its shared-table STI (#1c) authoring shape: a TPH base PromptTrace (@discriminator) over abstract LlmCallBase, with concrete subtypes ClassifyCall/SummarizeCall each carrying @discriminatorValue plus a nested template.prompt (@textRef/@payloadRef/@responseRef). Same cross-port gap (template.* child under object.entity + @responseRef TsPilotVocab); ledgered until the AI vertical is promoted to all five ports.",
+  "_comment_ai_pilot": "ai-trace-* fixtures now pass in Java (@responseRef + template.* child admitted)",
   "fixtures": [
     "error-field-readonly-downgrade",
-    "field-readonly-upgrade-on-subtype",
-    "ai-trace-prompt-nested",
-    "ai-trace-sti"
+    "field-readonly-upgrade-on-subtype"
   ]
 }

server/java/metadata/src/main/java/com/metaobjects/object/MetaObject.java

@@ -142,6 +142,10 @@ public static void registerTypes(MetaDataRegistry registry) {
 
             // OBJECTS CAN CONTAIN SOURCES (source.rdb and future subtypes)
             def.optionalChild("source", "*", "*");
+
+            // OBJECTS CAN CONTAIN TEMPLATES (template.prompt/output/toolcall) — FR-004 AI-trace
+            // (a nested template.prompt under object.entity drives typed LLM-call trace derivation).
+            def.optionalChild("template", "*", "*");
         });
 
         if (log != null) {

server/java/metadata/src/main/java/com/metaobjects/registry/RegistryManifest.java

@@ -229,7 +229,11 @@ public enum ExclusionReason {
         /** The {@code metadata.base} per-port inheritance anchor (deferred inheritsFrom facet). */
         INHERITANCE_ANCHOR,
         /** TS-web-presentation-only facet (the generic {@code view.*} controls). */
-        PRESENTATION_ONLY
+        PRESENTATION_ONLY,
+        /** A TS-pilot-only attr not yet promoted to all five ports (e.g. @responseRef —
+         *  the AI prompt-derived-trace vertical). Registered for load, carved out of the
+         *  cross-port manifest until the vertical ships in every port. Mirrors TS TsPilotVocab. */
+        TS_PILOT_VOCAB
     }
 
     /**
@@ -258,7 +262,8 @@ public enum ExclusionReason {
             com.metaobjects.object.MetaObject.ATTR_IS_INTERFACE, ExclusionReason.STRUCTURAL_KEYWORD,
             com.metaobjects.object.MetaObject.ATTR_OBJECT, ExclusionReason.NATIVE_BINDING,
             com.metaobjects.object.AbstractObjectRepresentation.ATTR_OBJECT_ADAPTER, ExclusionReason.NATIVE_BINDING,
-            MetaData.ATTR_DESCRIPTION, ExclusionReason.COMMON_ATTR_DUP);
+            MetaData.ATTR_DESCRIPTION, ExclusionReason.COMMON_ATTR_DUP,
+            com.metaobjects.template.TemplateConstants.ATTR_RESPONSE_REF, ExclusionReason.TS_PILOT_VOCAB);
 
     /**
      * Classify a per-type attr: an {@link ExclusionReason} (carved out) or

server/java/metadata/src/main/java/com/metaobjects/template/PromptTemplate.java

@@ -39,6 +39,8 @@ public static void registerTypes(MetaDataRegistry registry) {
                .ofType(StringAttribute.SUBTYPE_STRING).asArray();
             def.optionalAttributeWithConstraints(ATTR_MODEL)
                .ofType(StringAttribute.SUBTYPE_STRING).asSingle();
+            def.optionalAttributeWithConstraints(ATTR_RESPONSE_REF)
+               .ofType(StringAttribute.SUBTYPE_STRING).asSingle();
         });
     }
 
@@ -68,4 +70,11 @@ public String getModel() {
             ? getMetaAttr(ATTR_MODEL, false).getValueAsString()
             : null;
     }
+
+    /** Returns the raw value of {@code @responseRef}, or {@code null} if absent. */
+    public String getResponseRef() {
+        return hasMetaAttr(ATTR_RESPONSE_REF, false)
+            ? getMetaAttr(ATTR_RESPONSE_REF, false).getValueAsString()
+            : null;
+    }
 }

server/java/metadata/src/main/java/com/metaobjects/template/TemplateConstants.java

@@ -78,6 +78,16 @@ private TemplateConstants() {}
     public static final String ATTR_REQUIRED_SLOTS = "requiredSlots";
     public static final String ATTR_MODEL = "model";
 
+    /**
+     * {@code @responseRef} — optional single-valued string on {@code template.prompt}
+     * ONLY (the AI prompt-derived-trace vertical; mirrors TS {@code promptOverlayAttrs}).
+     * Names a nested template whose payload VO shapes the LLM-call trace's typed
+     * response column. NOT on the shared template base (so it is absent from
+     * {@code template.output}). A TS-pilot vocab carved out of the cross-port
+     * registry manifest until promoted to all five ports.
+     */
+    public static final String ATTR_RESPONSE_REF = "responseRef";
+
     // --- Toolcall-specific attributes (template.toolcall only — ADR-0011) ---
     //
     // Vendor-agnostic in core; vendor wire details (retry semantics, fallback

server/java/metadata/src/test/java/com/metaobjects/conformance/ConformanceTest.java

@@ -146,6 +146,15 @@ public class ConformanceTest {
             // physical RDB attributes (@column / @dbType / @dbColumnType / ...).
             "metaobjects-db", List.of(
                 "database-extensions"
+            ),
+            // The corpus's "metaobjects-template" provider (TS/C#/Python expose it
+            // under this canonical name — template.* / @responseRef / @xmlText, the
+            // AI prompt-construction vocab) maps to Java's TemplateTypesMetaDataProvider
+            // (id "template-types"). Java also folds template-types into the
+            // "metaobjects-core-types" alias; the two checks are independent set
+            // memberships, so a fixture listing both still resolves.
+            "metaobjects-template", List.of(
+                "template-types"
             )
         );