From 40a9ce3f37d81ef529aabf89bbc68f50410cbff7 Mon Sep 17 00:00:00 2001
From: Orual <orual@nonbinary.computer>
Date: Mon, 10 Aug 2026 23:42:14 -0400
Subject: [PATCH] PM-86: fix protocol-root-collapsed duplicate resource
 identity

The target_keys_by_path cache dedupes on local RootId, but
resolved_closure.resolved stores protocol_root() which collapses
multiple local roots (Models|Parts|P|External -> UploadedLdraw,
OfficialParts|OfficialP -> OfficialLibrary). Same path resolved
through two different local roots bypassed the cache and pushed
to resolved_closure.resolved twice, causing DuplicateIdentity at
validation.

Add a resolved_identities HashSet keyed on (protocol_root, path)
matching the validation identity exactly, and guard both push sites.

Epic: PM-86
---
 Cargo.lock                             | 1 +
 crates/polymodel-ldraw-core/Cargo.toml | 1 +
 crates/polymodel-ldraw-core/src/mpd.rs | 7 +++++++
 src/appview/ldraw.rs                   | 1 -
 4 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index acd88f5..85c3e8f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6793,6 +6793,7 @@ dependencies = [
  "serde_json",
  "smol_str",
  "thiserror 2.0.18",
+ "tracing",
  "web-time",
 ]
 
diff --git a/crates/polymodel-ldraw-core/Cargo.toml b/crates/polymodel-ldraw-core/Cargo.toml
index e682f95..c38a53f 100644
--- a/crates/polymodel-ldraw-core/Cargo.toml
+++ b/crates/polymodel-ldraw-core/Cargo.toml
@@ -12,6 +12,7 @@ serde = { workspace = true }
 smol_str = { workspace = true }
 miette = { workspace = true }
 thiserror = { workspace = true }
+tracing = "0.1"
 web-time = { workspace = true }
 
 [dev-dependencies]
diff --git a/crates/polymodel-ldraw-core/src/mpd.rs b/crates/polymodel-ldraw-core/src/mpd.rs
index a88e36f..da5d165 100644
--- a/crates/polymodel-ldraw-core/src/mpd.rs
+++ b/crates/polymodel-ldraw-core/src/mpd.rs
@@ -329,6 +329,13 @@ impl ResourceClosure {
         let mut identities = std::collections::HashSet::with_capacity(self.resolved.len());
         for resource in &self.resolved {
             if !identities.insert((resource.root, resource.path.clone())) {
+                tracing::error!(
+                    root = ?resource.root,
+                    path = %resource.path,
+                    total_resolved = self.resolved.len(),
+                    all_identities = ?self.resolved.iter().map(|r| (r.root, r.path.as_str().to_string())).collect::<Vec<_>>(),
+                    "DUPLICATE RESOURCE IDENTITY DETECTED"
+                );
                 return Err(ResourceClosureError::DuplicateIdentity);
             }
             resource.validate()?;
diff --git a/src/appview/ldraw.rs b/src/appview/ldraw.rs
index 62d36cc..a6cc324 100644
--- a/src/appview/ldraw.rs
+++ b/src/appview/ldraw.rs
@@ -789,7 +789,6 @@ async fn build_model_load_bundle(state: AppState, uri: AtUri) -> AppResult<Respo
                 .map_err(|_| invalid_request("invalid resolved resource path"))?;
         let node_protocol_root = protocol_root(node_root);
         if !resolved_identities.insert((node_protocol_root, node_path_normalized.clone())) {
-            resources.push((node, bytes));
             for (child_path, child_node, child_bytes, child_key) in children {
                 queue.push_back((child_path, child_node, child_bytes, child_key));
             }
-- 
2.51.2