Bugfix in the seriatim input adapter

internal/modules/input/seriatim/adapter_test.go

@@ -70,6 +70,35 @@ func TestParseValidMinimalTranscript(t *testing.T) {
 	}
 }
 
+func TestParseAcceptsNumericSegmentIDs(t *testing.T) {
+	raw := []byte(`{"metadata":{"application":"seriatim","version":"v1.5.0","output_schema":"seriatim-intermediate"},"segments":[{"id":1,"start":451.821,"end":469.685,"speaker":"Narrator","text":"The stone door opens.","categories":["scene"]},{"id":2,"start":470,"end":471,"speaker":"Player","text":"I step inside."}]}`)
+
+	doc, err := New().Parse(context.Background(), contracts.ParseRequest{Raw: raw})
+	if err != nil {
+		t.Fatalf("Parse() error = %v, want nil", err)
+	}
+	if got, want := doc.Metadata["output_schema"], "seriatim-intermediate"; got != want {
+		t.Fatalf("doc.Metadata[output_schema] = %#v, want %q", got, want)
+	}
+	if doc.Format != Format {
+		t.Fatalf("doc.Format = %q, want %q", doc.Format, Format)
+	}
+	if len(doc.Units) != 2 {
+		t.Fatalf("len(doc.Units) = %d, want 2", len(doc.Units))
+	}
+	if doc.Units[0].ID != "1" || doc.Units[1].ID != "2" {
+		t.Fatalf("unit IDs = %#v, want numeric IDs normalized to strings", []string{doc.Units[0].ID, doc.Units[1].ID})
+	}
+	ref := source.SourceRef{
+		SourceID:    doc.ID,
+		StartUnitID: "1",
+		EndUnitID:   "2",
+	}
+	if err := source.ValidateRef(doc, ref); err != nil {
+		t.Fatalf("ValidateRef() error = %v, want nil", err)
+	}
+}
+
 func TestParseRequestSourceIDOverridesMetadataIDs(t *testing.T) {
 	raw := readFixture(t, "testdata/valid_minimal.json")
 
@@ -176,6 +205,11 @@ func TestParseRejectsInvalidInput(t *testing.T) {
 			raw:     validJSONWithSegment(`"start":0,"end":1,"speaker":"Narrator","text":"Synthetic text."`),
 			wantErr: []string{"id", "empty"},
 		},
+		{
+			name:    "invalid segment id type",
+			raw:     validJSONWithSegment(`"id":{},"start":0,"end":1,"speaker":"Narrator","text":"Synthetic text."`),
+			wantErr: []string{"id", "string or number"},
+		},
 		{
 			name:    "whitespace segment id",
 			raw:     validJSONWithSegment(`"id":" s1 ","start":0,"end":1,"speaker":"Narrator","text":"Synthetic text."`),