diff --git a/crates/op-editor-ui/src/widgets/ai_chat_transcript_richtext.rs b/crates/op-editor-ui/src/widgets/ai_chat_transcript_richtext.rs
index ed7b8f501..39fa294d2 100644
--- a/crates/op-editor-ui/src/widgets/ai_chat_transcript_richtext.rs
+++ b/crates/op-editor-ui/src/widgets/ai_chat_transcript_richtext.rs
@@ -220,13 +220,25 @@ pub(crate) fn paint_rich(cx: &mut PaintCx<'_>, theme: &Theme, lines: &[RichLine]
         }
         let mut x = origin.x + line.inset;
         for span in &line.spans {
-            let units: u32 = span.text.chars().map(char_display_units).sum();
-            let width = units as f32 * CHAR_UNIT_PX;
             let (color, weight) = match span.style {
                 SpanStyle::Body => (theme.muted_foreground, 400),
                 SpanStyle::Strong => (theme.foreground, 700),
                 SpanStyle::Code => (theme.foreground, 400),
             };
+            // Advance by the REAL glyph width, not the wrap estimate: paint
+            // used the same 6.6px-per-unit budget the wrapper does, so every
+            // span after the first sat at a slightly wrong x — code chips
+            // drifted off their words and the sentence read as fragments
+            // (user report 2026-07-12). Wrapping stays estimate-based (it must
+            // be backend-free and deterministic); only paint measures.
+            let measured = cx
+                .backend
+                .measure_text_weighted(&span.text, BODY_FONT, weight);
+            let width = if measured > 0.0 {
+                measured
+            } else {
+                span.text.chars().map(char_display_units).sum::<u32>() as f32 * CHAR_UNIT_PX
+            };
             if span.style == SpanStyle::Code {
                 cx.backend.fill_round_rect(
                     Rect::xywh(
diff --git a/crates/op-mcp/src/script_runner.rs b/crates/op-mcp/src/script_runner.rs
index 7cb377130..0c6f87514 100644
--- a/crates/op-mcp/src/script_runner.rs
+++ b/crates/op-mcp/src/script_runner.rs
@@ -426,12 +426,29 @@ pub(crate) fn repair_truncated_script(script: &str) -> Option<String> {
     Some(repaired)
 }
 
+/// A bare "x is not defined" tells the model nothing about WHY. Every script
+/// runs in a FRESH sandbox, so a variable that held a node in an earlier batch
+/// is gone — the model must reference that node by its id STRING. Say so
+/// (measured 2026-07-12: a batch died on `header is not defined`, where
+/// `header` was a `const` from the previous batch's script).
+fn explain_reference_error(msg: &str) -> Option<String> {
+    let name = msg.strip_suffix(" is not defined")?;
+    Some(format!(
+        "script error: {msg}. Each script runs in a FRESH sandbox — a variable \
+         from an earlier batch no longer exists. Reference nodes created in an \
+         earlier batch by their id STRING instead: I(\"n12\", {{…}}), not I({name}, {{…}})."
+    ))
+}
+
 fn describe_js_error(ctx: &rquickjs::Ctx<'_>, err: rquickjs::Error) -> String {
     if err.is_exception() {
         let caught = ctx.catch();
         if let Some(exc) = caught.as_exception() {
             let msg = exc.message().unwrap_or_default();
             if !msg.is_empty() {
+                if let Some(explained) = explain_reference_error(&msg) {
+                    return explained;
+                }
                 return format!("script error: {msg}");
             }
         }
diff --git a/crates/op-orchestrator/src/prompt.rs b/crates/op-orchestrator/src/prompt.rs
index b79bcccd4..31ba9cbb8 100644
--- a/crates/op-orchestrator/src/prompt.rs
+++ b/crates/op-orchestrator/src/prompt.rs
@@ -82,6 +82,9 @@ data array. PREFER a loop over copy-pasting near-identical I(...) calls.
 Each node object starts with type ("frame"/"text"/"rectangle"/"ellipse"/"path"/"icon_font")
 and uses camelCase props (cornerRadius, fontSize, fontWeight, justifyContent, alignItems,
 clipContent). Do NOT set x/y on children inside layout frames.
+Each script runs in a FRESH sandbox: variables from an EARLIER batch do not exist. To attach
+to a node an earlier batch created, pass its id STRING — I("n12", {...}) — never a `const` from
+that batch. Ids come back in the batch result.
 EVERY frame with children MUST declare layout ("vertical" or "horizontal"; "none" for an
 absolute stack). A section that holds a title and a card rail is layout:"vertical" — omitting
 it stacks by default, but say it, because a row is only ever a row when you write it.