test(codegen): pin FQN @objectref payload codegen strips to bare names (Python + Kotlin) (#190)

Cross-port coverage follow-up to the TS promptRender FQN fix (54433a0). An investigation of
all four non-TS ports found the FQN-leak is TS-only — Java/C#/Kotlin/Python payload-VO codegen
already strip the package (splitFqn / StripPkg / KotlinPoet ClassName(pkg,name)) — but Python
and Kotlin lacked a test forcing a real package-qualified @objectref through that path.

- Python: test_plain_object_field_strips_fqn_to_bare_nested_payload — a plain field.object
  @objectref="acme::ai::Note" isArray on a payload VO emits list[NotePayload] + class
  NotePayload(BaseModel), never the FQN.
- Kotlin: a two-package fixture (Note in acme::ai referenced from Report in acme::demo) forces
  a real prefix through PackageMapping.splitFqn; asserts val notes: List<NotePayload> + data
  class NotePayload, no '::' in any emitted identifier.

Test-only, no product-code change (all four ports were already correct). Java + C# already had
equivalent FQN regression tests.


Claude-Session: https://claude.ai/code/session_01FaRaYFjvWVV8D6h33ejj1m

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

Author: dmealing

server/java/codegen-kotlin/src/test/kotlin/com/metaobjects/generator/kotlin/KotlinPayloadGeneratorTest.kt

@@ -1,5 +1,6 @@
 package com.metaobjects.generator.kotlin
 
+import com.metaobjects.metadata.ktx.loadDirectory
 import com.metaobjects.metadata.ktx.loadString
 import java.nio.file.Files
 import kotlin.test.Test
@@ -249,4 +250,83 @@ class KotlinPayloadGeneratorTest {
             outDir.toFile().deleteRecursively()
         }
     }
+
+    @Test fun `nested field-object objectRef given as a cross-package FQN emits bare payload names, no package-qualified identifier`() {
+        // Regression companion to the TS promptRender FQN-leak fix (0.15.17): a payload VO whose
+        // naked `field.object @objectRef` points at ANOTHER object.value declared in a DIFFERENT
+        // package. The target's resolved name is a real FQN (`acme::ai::Note`), so
+        // PackageMapping.splitFqn must strip the package for BOTH the emitted property type and
+        // the nested data-class name — an FQN contains `::`, which is not a valid Kotlin
+        // identifier. (The TS port leaked `List<acme::ai::Note>` / `data class acme::ai::Note`;
+        // Kotlin's ClassName(pkg, simpleName) construction is FQN-safe — this pins it.)
+        //
+        // Two packages ⇒ two files (a single loadString supports only one root/package), so the
+        // prefix is genuinely non-empty when it reaches splitFqn.
+        val noteJson = """{
+          "metadata.root": { "package": "acme::ai", "children": [
+            { "object.value": { "name": "Note", "children": [
+                { "field.string": { "name": "text" } }
+            ] } }
+          ] }
+        }""".trimIndent()
+        val reportJson = """{
+          "metadata.root": { "package": "acme::demo", "children": [
+            { "object.value": { "name": "Report", "children": [
+                { "field.string": { "name": "title" } },
+                { "field.object": { "name": "notes",
+                    "@objectRef": "acme::ai::Note", "isArray": true } }
+            ] } },
+            { "template.prompt": { "name": "ReportPrompt",
+                "@payloadRef": "Report", "@textRef": "demo/report" } }
+          ] }
+        }""".trimIndent()
+
+        val srcDir = Files.createTempDirectory("kpay-fqn-src-")
+        val outDir = Files.createTempDirectory("kpay-fqn-out-")
+        try {
+            // note.json sorts before report.json — but cross-file @objectRef resolution is
+            // load-order-independent (ADR-0041), so ordering is not load-bearing here.
+            Files.writeString(srcDir.resolve("note.json"), noteJson)
+            Files.writeString(srcDir.resolve("report.json"), reportJson)
+
+            val gen = KotlinPayloadGenerator()
+            gen.setArgs(mapOf("outputDir" to outDir.toString()))
+            gen.execute(loadDirectory("test-fqn", srcDir))
+
+            // Nested payload for a cross-package target co-locates in the REFERRING template's
+            // prompts package (acme.demo.prompts), keyed by the target's bare short name.
+            val parentFile = outDir.resolve("acme/demo/prompts/ReportPromptPayload.kt")
+            val nestedFile = outDir.resolve("acme/demo/prompts/NotePayload.kt")
+            assertTrue(Files.exists(parentFile),
+                "expected $parentFile; files=${Files.walk(outDir).toList()}")
+            assertTrue(Files.exists(nestedFile),
+                "expected $nestedFile; files=${Files.walk(outDir).toList()}")
+
+            val parentSrc = Files.readString(parentFile)
+            // Bare, FQN-stripped array-of-nested-payload type — NOT `List<acme::ai::Note>`.
+            assertTrue("val notes: List<NotePayload>" in parentSrc, parentSrc)
+            assertTrue("val title: String" in parentSrc, parentSrc)
+
+            val nestedSrc = Files.readString(nestedFile)
+            // Bare data-class name — NOT `data class acme::ai::Note`.
+            assertTrue("data class NotePayload" in nestedSrc, nestedSrc)
+            assertTrue("val text: String" in nestedSrc, nestedSrc)
+            assertTrue("package acme.demo.prompts" in nestedSrc, nestedSrc)
+
+            // No emitted IDENTIFIER may contain `::`. The FQN legitimately survives only in KDoc
+            // comment lines (which document the source object `acme::ai::Note`); every other line
+            // must be `::`-free. Filter comment lines (leading `*` or `/`), then assert clean.
+            for ((label, src) in listOf("parent" to parentSrc, "nested" to nestedSrc)) {
+                val offenders = src.lines().filter { line ->
+                    val t = line.trimStart()
+                    "::" in line && !t.startsWith("*") && !t.startsWith("/")
+                }
+                assertTrue(offenders.isEmpty(),
+                    "$label: no emitted identifier may contain '::'; offenders=$offenders\n$src")
+            }
+        } finally {
+            srcDir.toFile().deleteRecursively()
+            outDir.toFile().deleteRecursively()
+        }
+    }
 }

server/python/tests/codegen/test_payload_vo_generator.py

@@ -65,6 +65,16 @@ def _field_with_origin(name: str, sub: str, origin: MetaOrigin) -> MetaField:
     return f
 
 
+def _object_field(name: str, object_ref: str, *, is_array: bool = False) -> MetaField:
+    """A plain ``field.object`` carrying an ``@objectRef`` (no origin child). The
+    ref is passed in the FQN form the loader produces post-ADR-0041 (e.g.
+    ``acme::ai::Note``) so the generator's package-stripping is exercised."""
+    f = MetaField(TYPE_FIELD, fc.FIELD_SUBTYPE_OBJECT, name)
+    f.set_attr(fc.FIELD_ATTR_OBJECT_REF, object_ref)
+    f.is_array = is_array
+    return f
+
+
 def _passthrough(from_ref: str) -> MetaOrigin:
     o = MetaOrigin(TYPE_ORIGIN, ORIGIN_SUBTYPE_PASSTHROUGH, "from")
     o.set_attr(ORIGIN_ATTR_FROM, from_ref)
@@ -370,6 +380,54 @@ def test_origin_collection_nested_payload_deduped_within_file() -> None:
     assert "drafts: list[PostPayload]" in out
 
 
+# ---------------------------------------------------------------------------
+# Plain field.object @objectRef (no origin) — the FQN must be stripped to the
+# bare name for BOTH the emitted field annotation AND the nested class
+# declaration. Cross-port regression guard: the TS payload generator once
+# emitted the raw ``@objectRef`` FQN verbatim (``notes: acme::ai::Note[]`` and
+# ``interface acme::ai::Note``). Python resolves the ref to the target
+# MetaObject and names off ``target.name`` (always bare), so this must stay
+# clean — this test locks that in.
+# ---------------------------------------------------------------------------
+
+
+def test_plain_object_field_strips_fqn_to_bare_nested_payload() -> None:
+    """A ``field.object`` whose ``@objectRef`` is a package-qualified FQN
+    (``acme::ai::Note`` — the form the loader emits post-ADR-0041) must type as
+    ``list[NotePayload]`` and emit ``class NotePayload(BaseModel):`` — the BARE
+    name — never the raw FQN. Guards the cross-port payload FQN leak that was
+    TS-only (``notes: acme::ai::Note[]`` / ``interface acme::ai::Note``)."""
+    note = _value_object(
+        "Note", [_field("text", fc.FIELD_SUBTYPE_STRING)], package="acme::ai"
+    )
+    report = _value_object(
+        "Report",
+        [_object_field("notes", "acme::ai::Note", is_array=True)],
+        package="acme::ai",
+    )
+    tmpl = _template("ReportOutput", "Report")
+    root = _root([note, report, tmpl])
+    out = render_payload_vo(tmpl, root)
+    assert out is not None
+    # Field annotation types to the BARE nested-payload class, wrapped as a list.
+    assert "notes: list[NotePayload]" in out
+    # Nested payload class declared under its BARE name, before the primary class.
+    assert "class NotePayload(BaseModel):" in out
+    assert out.find("class NotePayload(BaseModel):") < out.find(
+        "class ReportOutputPayload(BaseModel):"
+    )
+    assert "text: str" in out
+    # __all__ carries both BARE class names.
+    assert '__all__ = ["ReportOutputPayload", "NotePayload"]' in out
+    # The referenced VO's FQN must NOT leak anywhere in the emitted source.
+    assert "acme::ai::Note" not in out
+    # No package separator in the emitted CODE. (The generated header comment
+    # legitimately carries the module's OWN FQN — ``acme::ai::ReportOutput`` —
+    # so the ``::``-free check is scoped to non-comment lines.)
+    code = "\n".join(ln for ln in out.splitlines() if not ln.lstrip().startswith("#"))
+    assert "::" not in code
+
+
 # ---------------------------------------------------------------------------
 # Resolution edge cases.
 # ---------------------------------------------------------------------------