diff --git a/crates/polymodel-ldraw-core/src/cache.rs b/crates/polymodel-ldraw-core/src/cache.rs
index 2f64d35..588e519 100644
--- a/crates/polymodel-ldraw-core/src/cache.rs
+++ b/crates/polymodel-ldraw-core/src/cache.rs
@@ -59,6 +59,14 @@ impl Sha256Hash {
     fn digest(bytes: &[u8]) -> Self {
         Self(Sha256::digest(bytes).into())
     }
+
+    fn digest_parts<'a>(parts: impl IntoIterator<Item = &'a [u8]>) -> Self {
+        let mut hasher = Sha256::new();
+        for part in parts {
+            hasher.update(part);
+        }
+        Self(hasher.finalize().into())
+    }
 }
 impl fmt::Display for Sha256Hash {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -80,4 +88,16 @@ impl CacheKey {
             content_hash: Sha256Hash::digest(bytes),
         }
     }
+
+    pub fn new_from_parts<'a>(
+        path: NormalizedPath,
+        root: RootId,
+        parts: impl IntoIterator<Item = &'a [u8]>,
+    ) -> Self {
+        Self {
+            canonical_path: path,
+            resolved_root: root,
+            content_hash: Sha256Hash::digest_parts(parts),
+        }
+    }
 }
diff --git a/crates/polymodel-ldraw-core/src/model.rs b/crates/polymodel-ldraw-core/src/model.rs
index 78d8987..77ac729 100644
--- a/crates/polymodel-ldraw-core/src/model.rs
+++ b/crates/polymodel-ldraw-core/src/model.rs
@@ -310,6 +310,17 @@ impl<'src> ParseResult<'src> {
             provenance_id: self.provenance_id.clone(),
         }
     }
+
+    pub fn into_project(self) -> CanonicalRecord<'src> {
+        CanonicalRecord {
+            schema_version: Cow::Borrowed(SCHEMA_VERSION),
+            syntax: self.syntax,
+            semantic: self.semantic,
+            scene: self.scene,
+            diagnostics: self.diagnostics,
+            provenance_id: self.provenance_id,
+        }
+    }
     pub fn ledger_reservation_id(&self) -> u64 {
         self.arenas.reservation_id()
     }
diff --git a/crates/polymodel-ldraw-core/src/parser.rs b/crates/polymodel-ldraw-core/src/parser.rs
index 50f12fa..28df337 100644
--- a/crates/polymodel-ldraw-core/src/parser.rs
+++ b/crates/polymodel-ldraw-core/src/parser.rs
@@ -241,17 +241,11 @@ fn parse_model<'src>(
         return Err(ParseError::Cancelled);
     }
     let path = NormalizedPath::new(&file.name)?;
-    let file_bytes = file
-        .lines
-        .iter()
-        .flat_map(|line| {
-            line.raw
-                .iter()
-                .copied()
-                .chain(line.ending.as_str().as_bytes().iter().copied())
-        })
-        .collect::<Vec<_>>();
-    let key = CacheKey::new(path.clone(), options.resolved_root, &file_bytes);
+    let key = CacheKey::new_from_parts(
+        path.clone(),
+        options.resolved_root,
+        file.lines.iter().flat_map(|line| [line.raw, line.ending.as_str().as_bytes()]),
+    );
     let line_count = u64::try_from(file.lines.len())
         .map_err(|_| ParseError::Overflow("model line count"))?;
     let semantic_charge = line_count
diff --git a/tools/ldraw-compat-harness/Cargo.lock b/tools/ldraw-compat-harness/Cargo.lock
index 4b54259..a39eb7c 100644
--- a/tools/ldraw-compat-harness/Cargo.lock
+++ b/tools/ldraw-compat-harness/Cargo.lock
@@ -87,20 +87,45 @@ version = "2.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
 
+[[package]]
+name = "miette"
+version = "7.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5f98efec8807c63c752b5bd61f862c165c115b0a35685bdcfd9238c7aeb592b7"
+dependencies = [
+ "cfg-if",
+ "miette-derive",
+ "unicode-width",
+]
+
+[[package]]
+name = "miette-derive"
+version = "7.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db5b29714e950dbb20d5e6f74f9dcec4edbcc1067bb7f8ed198c097b8c1a818b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+]
+
 [[package]]
 name = "polymodel-ldraw-core"
 version = "0.1.0"
 dependencies = [
+ "miette",
  "polymodel-renderer-ledger",
  "serde",
  "sha2",
  "thiserror",
+ "typed-arena",
 ]
 
 [[package]]
 name = "polymodel-ldraw-testkit"
 version = "0.1.0"
 dependencies = [
+ "polymodel-ldraw-core",
  "serde",
  "serde_json",
  "sha2",
@@ -156,7 +181,7 @@ checksum = "e7a5d71263a5a7d47b41f6b3f06ba276f10cc18b0931f1799f710578e2309348"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 3.0.3",
 ]
 
 [[package]]
@@ -183,6 +208,17 @@ dependencies = [
  "digest",
 ]
 
+[[package]]
+name = "syn"
+version = "2.0.119"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "872831b642d1a07999a962a351ed35b955ea2cfc8f3862091e2a240a84f17297"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
 [[package]]
 name = "syn"
 version = "3.0.3"
@@ -211,9 +247,15 @@ checksum = "43cbfe0cf76104d42a574802844187e84a305e531ed54455f11fbde0f10541cd"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 3.0.3",
 ]
 
+[[package]]
+name = "typed-arena"
+version = "2.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6af6ae20167a9ece4bcb41af5b80f8a1f1df981f6391189ce00fd257af04126a"
+
 [[package]]
 name = "typenum"
 version = "1.20.1"
@@ -226,6 +268,12 @@ version = "1.0.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e6e4313cd5fcd3dad5cafa179702e2b244f760991f45397d14d4ebf38247da75"
 
+[[package]]
+name = "unicode-width"
+version = "0.1.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7dd6e30e90baa6f72411720665d41d89b9a3d039dc45b8faea1ddd07f617f6af"
+
 [[package]]
 name = "version_check"
 version = "0.9.5"
diff --git a/tools/ldraw-compat-harness/src/main.rs b/tools/ldraw-compat-harness/src/main.rs
index eab04a5..9205312 100644
--- a/tools/ldraw-compat-harness/src/main.rs
+++ b/tools/ldraw-compat-harness/src/main.rs
@@ -278,7 +278,7 @@ fn actual_record(fixture: &FixtureCase) -> Result<CanonicalRecord, String> {
         &ledger,
     )
     .map_err(|error| format!("core parse failed for {}: {error}", fixture.id))?;
-    let record = parsed.project();
+    let record = parsed.into_project();
     if ledger.snapshot().reservations == 0 {
         return Err(format!("core reservation was released before projection: {}", fixture.id));
     }