From e9b5d629e16e00bddff756ba7fe2132d64fd1c9d Mon Sep 17 00:00:00 2001
From: Orual <orual@nonbinary.computer>
Date: Sun, 9 Aug 2026 17:27:04 -0400
Subject: [PATCH] PM-93: fix syntax differential authority, corpus assertion,
 TEXMAP oracle non-comparability

Epic: PM-86
Task: PM-93
---
 crates/polymodel-ldraw-core/src/lib.rs       | 17 ++++++++++++++
 crates/polymodel-ldraw-testkit/src/schema.rs | 24 ++++++++++++--------
 tools/ldraw-compat-harness/src/main.rs       | 13 +++++++----
 3 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/crates/polymodel-ldraw-core/src/lib.rs b/crates/polymodel-ldraw-core/src/lib.rs
index cf46787..5ba112e 100644
--- a/crates/polymodel-ldraw-core/src/lib.rs
+++ b/crates/polymodel-ldraw-core/src/lib.rs
@@ -757,6 +757,23 @@ mod tests {
         assert!(error.contains("fields mismatch"));
     }
 
+    #[test]
+    fn syntax_comparison_rejects_non_string_fields() {
+        let malformed = vec![serde_json::json!({
+            "line_type": 1u8,
+            "raw_tail": " data",
+            "fields": ["ok", 42, "bad"]
+        })];
+        let expected = vec![polymodel_ldraw_testkit::ExpectedSyntaxRecord {
+            line_type: 1u8,
+            raw_tail: " data".to_owned(),
+            fields: vec!["ok".to_owned(), "42".to_owned(), "bad".to_owned()],
+        }];
+        let error = polymodel_ldraw_testkit::compare_syntax_records("test", &expected, &malformed)
+            .expect_err("non-string field element must be rejected");
+        assert!(error.contains("not a string"));
+    }
+
     fn corpus_fixture(id: &str) -> polymodel_ldraw_testkit::FixtureCase {
         polymodel_ldraw_testkit::inventory()
             .into_iter()
diff --git a/crates/polymodel-ldraw-testkit/src/schema.rs b/crates/polymodel-ldraw-testkit/src/schema.rs
index 607296c..e5a173d 100644
--- a/crates/polymodel-ldraw-testkit/src/schema.rs
+++ b/crates/polymodel-ldraw-testkit/src/schema.rs
@@ -365,16 +365,20 @@ pub fn compare_syntax_records(
                 expected.raw_tail
             ));
         }
-        let actual_fields = actual
-            .get("fields")
-            .and_then(serde_json::Value::as_array)
-            .map(|fields| {
-                fields
-                    .iter()
-                    .filter_map(serde_json::Value::as_str)
-                    .collect::<Vec<_>>()
-            })
-            .unwrap_or_default();
+        let actual_fields = match actual.get("fields").and_then(serde_json::Value::as_array) {
+            Some(fields) => fields
+                .iter()
+                .map(|value| {
+                    value
+                        .as_str()
+                        .ok_or_else(|| {
+                            format!("{fixture_id} syntax[{index}] field is not a string: {value:?}")
+                        })
+                        .map(String::from)
+                })
+                .collect::<Result<Vec<_>, _>>()?,
+            None => Vec::new(),
+        };
         let expected_fields = expected
             .fields
             .iter()
diff --git a/tools/ldraw-compat-harness/src/main.rs b/tools/ldraw-compat-harness/src/main.rs
index 956f479..ad466ce 100644
--- a/tools/ldraw-compat-harness/src/main.rs
+++ b/tools/ldraw-compat-harness/src/main.rs
@@ -838,10 +838,15 @@ fn compare_candidate_to_oracle(
         .as_ref()
         .ok_or_else(|| format!("{} oracle success has no resolved geometry", fixture.id))?;
     let oracle_triangles = resolved.triangles as u64;
-    if candidate.scene.triangles != oracle_triangles
-        || candidate.scene.quads != resolved.quads as u64
-        || candidate.scene.lines != resolved.lines as u64
-        || candidate.scene.conditional_lines != resolved.conditional_lines as u64
+    let oracle_has_resolved = oracle_triangles > 0
+        || resolved.quads > 0
+        || resolved.lines > 0
+        || resolved.conditional_lines > 0;
+    if oracle_has_resolved
+        && (candidate.scene.triangles != oracle_triangles
+            || candidate.scene.quads != resolved.quads as u64
+            || candidate.scene.lines != resolved.lines as u64
+            || candidate.scene.conditional_lines != resolved.conditional_lines as u64)
     {
         return Err(format!(
             "{} resolved geometry mismatch: oracle=(triangles={},quads={},lines={},conditional_lines={}) candidate=({}, {}, {}, {})",
-- 
knotmirror 0.0.1