From bb68bf8c3aed40ef0ff420bbbf358e701e9ee3c9 Mon Sep 17 00:00:00 2001
From: Orual <orual@nonbinary.computer>
Date: Sun, 2 Aug 2026 18:04:14 -0400
Subject: [PATCH] PM-78: expose instance transforms

Epic: PM-86
Task: PM-78
---
 crates/polymodel-ldraw-core/src/model.rs     | 13 ++++++++++-
 crates/polymodel-ldraw-core/src/traversal.rs | 23 +++++++++++++++-----
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/crates/polymodel-ldraw-core/src/model.rs b/crates/polymodel-ldraw-core/src/model.rs
index 1bd709e..750bd01 100644
--- a/crates/polymodel-ldraw-core/src/model.rs
+++ b/crates/polymodel-ldraw-core/src/model.rs
@@ -197,10 +197,21 @@ pub struct SemanticRecord<'src> {
     pub limits: Vec<Cow<'src, str>>,
     pub texmap_events: Vec<TexmapEvent<'src>>,
 }
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct InstanceRecord {
+    pub instance_id: String,
+    pub source_model: String,
+    pub target_model: String,
+    pub transform: Transform,
+    pub inverted: bool,
+}
+
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub struct SceneRecord {
     pub model_id: String,
     pub instance_ids: Vec<String>,
+    #[serde(default)]
+    pub instances: Vec<InstanceRecord>,
     pub triangles: u64,
     pub quads: u64,
     pub lines: u64,
@@ -223,7 +234,7 @@ pub struct CanonicalRecord<'src> {
 #[derive(Clone, Debug)]
 pub(crate) struct Include<'src> {
     pub(crate) name: Cow<'src, str>,
-    pub(crate) transform: Transform,
+    pub transform: Transform,
     pub(crate) span: Span,
     pub(crate) valid: bool,
     pub(crate) inverted: bool,
diff --git a/crates/polymodel-ldraw-core/src/traversal.rs b/crates/polymodel-ldraw-core/src/traversal.rs
index c5a5c21..34dd00c 100644
--- a/crates/polymodel-ldraw-core/src/traversal.rs
+++ b/crates/polymodel-ldraw-core/src/traversal.rs
@@ -1,6 +1,6 @@
 use crate::cache::CacheKey;
 use crate::geom::{Bounds3, Point3, Transform};
-use crate::model::{ModelData, ModelSummary, SceneRecord};
+use crate::model::{InstanceRecord, ModelData, ModelSummary, SceneRecord};
 use crate::types::{
     Diagnostic, DiagnosticCode, LimitCounters, LimitKind, ParseError, ParseOptions, add_diag,
     limit_error,
@@ -18,6 +18,7 @@ pub(crate) fn traverse(
             SceneRecord {
                 model_id: String::new(),
                 instance_ids: Vec::new(),
+                instances: Vec::new(),
                 triangles: 0,
                 quads: 0,
                 lines: 0,
@@ -48,6 +49,7 @@ pub(crate) fn traverse(
     let mut stack = VecDeque::<Visit>::new();
     let mut summaries = Vec::new();
     let mut instance_ids = Vec::new();
+    let mut instances = Vec::new();
     let mut scene_bounds = Bounds3::default();
     let mut scene_triangles = 0u64;
     let mut scene_quads = 0u64;
@@ -153,12 +155,22 @@ pub(crate) fn traverse(
                     let child_name = target
                         .map(|index| models[index].path.to_string())
                         .unwrap_or_else(|| include.name.replace('\\', "/"));
-                    instance_ids.push(format!(
+                    let instance_id = format!(
                         "{}→{}#{}",
                         model.path,
                         child_name,
                         include_position + 1
-                    ));
+                    );
+                    let composed_transform = transform.compose(&include.transform);
+                    let inverted = reflected ^ include.inverted ^ include.transform.reflection();
+                    instance_ids.push(instance_id.clone());
+                    instances.push(InstanceRecord {
+                        instance_id,
+                        source_model: model.path.to_string(),
+                        target_model: child_name.clone(),
+                        transform: composed_transform,
+                        inverted,
+                    });
                     let child_depth = depth
                         .checked_add(1)
                         .ok_or(ParseError::Overflow("include depth"))?;
@@ -207,9 +219,9 @@ pub(crate) fn traverse(
                     }
                     stack.push_back(Visit::Enter {
                         index: target,
-                        transform: transform.compose(&include.transform),
+                        transform: composed_transform,
                         depth: child_depth,
-                        reflected: reflected ^ include.inverted ^ include.transform.reflection(),
+                        reflected: inverted,
                     });
                 }
             }
@@ -218,6 +230,7 @@ pub(crate) fn traverse(
     let scene = SceneRecord {
         model_id: models[0].path.to_string(),
         instance_ids,
+        instances,
         triangles: scene_triangles,
         quads: scene_quads,
         lines: scene_lines,
-- 
2.51.2