From 838d0e86f221116dfff6b7ec845d0edb0e567d38 Mon Sep 17 00:00:00 2001
From: Mateusz Sych <151755914+SychPL@users.noreply.github.com>
Date: Fri, 16 Oct 2026 14:26:18 +0200
Subject: [PATCH] Component rename also renames its placements (#1665) (#1685)

Thanks @SychPL.
---
 crates/engine/src/cmd/component.rs        | 14 +++++++++++---
 crates/engine/src/cmd/occurrence_tests.rs | 16 ++++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/crates/engine/src/cmd/component.rs b/crates/engine/src/cmd/component.rs
index ffe5510f..80a4c5ff 100644
--- a/crates/engine/src/cmd/component.rs
+++ b/crates/engine/src/cmd/component.rs
@@ -214,10 +214,18 @@ fn rename(s: &mut Session, p: &Value) -> Result<Value> {
     let id = component(s, p, "component", cmd)?;
     let name =
         str_(p, "name").map(str::trim).filter(|n| !n.is_empty() && n.len() <= 128).ok_or_else(|| bad(cmd, "`name` must be 1…128 characters"))?;
+    let d = s.doc_mut();
     if id == 0 {
-        s.doc_mut().name = name.to_string();
-    } else if let Some(c) = s.doc_mut().components.iter_mut().find(|c| c.id == id) {
-        c.name = name.to_string();
+        d.name = name.to_string();
+    } else if let Some(c) = d.components.iter_mut().find(|c| c.id == id) {
+        let old = std::mem::replace(&mut c.name, name.to_string());
+        // Placements still named after the component ("Old:2") follow it (#1665); others keep theirs.
+        for o in d.occurrences.iter_mut().filter(|o| o.component == id) {
+            let k = o.name.strip_prefix(old.as_str()).and_then(|r| r.strip_prefix(':'));
+            if let Some(k) = k.filter(|k| !k.is_empty() && k.bytes().all(|b| b.is_ascii_digit())) {
+                o.name = format!("{name}:{k}");
+            }
+        }
     }
     Ok(json!({"component": id, "name": name}))
 }
diff --git a/crates/engine/src/cmd/occurrence_tests.rs b/crates/engine/src/cmd/occurrence_tests.rs
index 31a1bed8..c88c7f8c 100644
--- a/crates/engine/src/cmd/occurrence_tests.rs
+++ b/crates/engine/src/cmd/occurrence_tests.rs
@@ -66,6 +66,22 @@ fn instance_selection_survives_rename_move_capture_and_serde() {
     assert_eq!(roundtrip, s.selection);
 }
 
+#[test]
+fn component_rename_carries_into_placement_names() {
+    // #1665: the browser row shows the placement's name, so a rename has to reach it.
+    let mut s = Session::default();
+    let (component, first) = created(&mut s, "Block");
+    let second = run(&mut s, "occurrence.copy", json!({"component": component, "translate": [20,0,0]}))["occurrence"].as_u64().unwrap();
+    let third = run(&mut s, "occurrence.copy", json!({"component": component, "translate": [40,0,0]}))["occurrence"].as_u64().unwrap();
+    let name = |s: &Session, id: u64| s.doc.occurrences.iter().find(|o| o.id == id).unwrap().name.clone();
+    assert_eq!(name(&s, second), "Block:2");
+    // A placement named otherwise (an import's own name) keeps it.
+    s.doc_mut().occurrences.iter_mut().find(|o| o.id == third).unwrap().name = "Blockade:3".into();
+    run(&mut s, "component.rename", json!({"component": component, "name": "box"}));
+    assert_eq!([name(&s, first), name(&s, second), name(&s, third)], ["box:1", "box:2", "Blockade:3"]);
+    assert_eq!(run(&mut s, "component.list", json!({}))["components"][0]["children"][0]["name"], "box:1");
+}
+
 #[test]
 fn instance_selection_delete_removes_only_selected_instance() {
     let mut s = Session::default();