diff --git a/backend/app/flow/controller.py b/backend/app/flow/controller.py
index 74410d9..aba7b51 100644
--- a/backend/app/flow/controller.py
+++ b/backend/app/flow/controller.py
@@ -351,7 +351,7 @@ class FlowController:
         except Exception as exc:
             logger.warning("Node '%s' failed to load: %s", node_id, exc)
             entry.status = NodeStatus.ERROR
-            entry.error = _short_traceback(exc)
+            entry.error = _short_error(exc)
         return entry
 
     # -------------------------------------------------------------------------
@@ -405,7 +405,21 @@ def _bound(specs: list[MessageSpec]) -> list[MessageSpec]:
     return [spec for spec in specs if spec.name]
 
 
-def _short_traceback(exc: Exception) -> str:
-    """The last frames of a failure, which is what a node author needs."""
-    lines = traceback.format_exception(type(exc), exc, exc.__traceback__)
-    return "".join(lines[-3:]).strip()
+def _short_error(exc: Exception) -> str:
+    """One line a node author can act on: what broke, and where in their code.
+
+    The frames in between belong to the loader rather than to the node, so only
+    the line in the node's own source is kept. The full traceback stays in the
+    server log.
+    """
+    if isinstance(exc, SyntaxError):
+        # Its own message already names the compiled file, which is noise here.
+        return f"{type(exc).__name__}: {exc.msg} (line {exc.lineno})"
+
+    frames = [
+        frame
+        for frame in traceback.extract_tb(exc.__traceback__)
+        if frame.filename.startswith("<node ")
+    ]
+    where = f" (line {frames[-1].lineno})" if frames else ""
+    return f"{type(exc).__name__}: {exc}{where}"
diff --git a/frontend/src/components/Flow/FlowNode.tsx b/frontend/src/components/Flow/FlowNode.tsx
index 46610c4..7efeecd 100644
--- a/frontend/src/components/Flow/FlowNode.tsx
+++ b/frontend/src/components/Flow/FlowNode.tsx
@@ -83,9 +83,13 @@ function FlowNodeComponent({ data, selected }: NodeProps) {
 
   // Whatever is wrong — it failed to load, it failed to run, or the graph
   // around it does not add up — is the same red dot with the same explanation.
-  const problem = [live?.status === "error" ? live.error : null, issueText]
+  // A load failure arrives twice, as node status and as a validation issue, so
+  // identical lines collapse into one.
+  const lines = [live?.status === "error" ? live.error : null, issueText]
     .filter(Boolean)
     .join("\n")
+    .split("\n")
+  const problem = [...new Set(lines)].join("\n")
   const status = problem ? "error" : live?.status
   const style = STATUS_STYLES[status as keyof typeof STATUS_STYLES]
 
@@ -126,7 +130,7 @@ function FlowNodeComponent({ data, selected }: NodeProps) {
                 aria-label={style.label}
               />
             </TooltipTrigger>
-            <TooltipContent className="max-w-xs whitespace-pre-line">
+            <TooltipContent className="max-h-60 max-w-xs overflow-y-auto whitespace-pre-line break-words">
               {problem || style.label}
             </TooltipContent>
           </Tooltip>
diff --git a/frontend/src/components/ui/tooltip.tsx b/frontend/src/components/ui/tooltip.tsx
index 715bf76..9f8762e 100644
--- a/frontend/src/components/ui/tooltip.tsx
+++ b/frontend/src/components/ui/tooltip.tsx
@@ -34,7 +34,7 @@ function TooltipTrigger({
 
 function TooltipContent({
   className,
-  sideOffset = 0,
+  sideOffset = 4,
   children,
   ...props
 }: React.ComponentProps<typeof TooltipPrimitive.Content>) {
@@ -50,7 +50,6 @@ function TooltipContent({
         {...props}
       >
         {children}
-        <TooltipPrimitive.Arrow className="bg-foreground fill-foreground z-50 size-2.5 translate-y-[calc(-50%_-_2px)] rotate-45 rounded-[2px]" />
       </TooltipPrimitive.Content>
     </TooltipPrimitive.Portal>
   )