Node settings arrive as keyword arguments, not a params dict

A python node's settings are constants of its own function, so they are passed
the way its ports are: by name. The controller binds them to the compiled
function, the `params` field is gone from the worker and remote protocols, and
a setting sharing a port's name is reported as a node error rather than
shadowing it. The panel's scaffold follows suit and keeps the header in step
with both ports and settings.

The demo's `pace` moves from a flow input to a setting of the training node,
which is what it always was.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NUb8YpL2s3gmN9WTACTt4q

frontend/src/components/Flow/NodePanel.tsx

@@ -73,6 +73,9 @@ const SECTION = PANEL_SECTION
 /** Settings the engine reads itself, so they are not the author's to name. */
 const RESERVED_PARAMS = new Set(["synchronous"])
 
+/** A setting reaches the function by name, so the name has to be one. */
+const IDENTIFIER = /^[A-Za-z_]\w*$/
+
 /**
  * A text field that offers what is already in use elsewhere.
  *
@@ -421,7 +424,9 @@ function FreeParamsForm({
   const entries = Object.entries(params).filter(([key]) => !reserved.has(key))
 
   const rename = (from: string, to: string) => {
-    if (to === from) return
+    // A setting is an argument of `process`, so a name it cannot take is not
+    // a rename — it is a typo on its way to a node that will not load.
+    if (to === from || !IDENTIFIER.test(to)) return
     // Rebuilt rather than patched, so the settings keep the order they were
     // typed in instead of jumping around as one is renamed.
     const next: Record<string, unknown> = {}
@@ -453,7 +458,8 @@ function FreeParamsForm({
 
       {entries.length === 0 ? (
         <p className="text-sm text-muted-foreground">
-          Values your code reads from <code>params</code>.
+          Constants of this node, passed to <code>process</code> by name like
+          its inputs.
         </p>
       ) : null}
 
@@ -855,7 +861,7 @@ const SCAFFOLD_SHAPE = (() => {
   const value = Object.values(PLACEHOLDER).map(quote).join("|")
   const entry = `"[^"]+": (?:${value})`
   return new RegExp(
-    `^${quote(SCAFFOLD_DOC)}\\n\\n\\ndef process\\(\\w+(?:, \\w+)*\\):\\n    return \\{(?:${entry}(?:, ${entry})*)?\\}\\n$`,
+    `^${quote(SCAFFOLD_DOC)}\\n\\n\\ndef process\\((?:\\w+(?:, \\w+)*)?\\):\\n    return \\{(?:${entry}(?:, ${entry})*)?\\}\\n$`,
   )
 })()
 
@@ -863,20 +869,30 @@ const SCAFFOLD_SHAPE = (() => {
 const portName = (spec: MessageSpec) =>
   spec.port || (spec.name ?? "").split(".").pop() || ""
 
-/** A `process` that takes this node's inputs and returns its outputs. */
+/**
+ * A `process` that takes this node's inputs and settings, and returns its
+ * outputs.
+ *
+ * Both arrive by name, so both are arguments — the ports first, in the order
+ * they are declared, then the settings.
+ */
 function scaffoldFor(node: NodeDef_Input): string {
   const args = [
     ...new Set(
-      (node.requires ?? [])
-        .map(portName)
-        // Anything else cannot be a keyword argument, so it cannot be a port.
-        .filter((port) => /^[A-Za-z_]\w*$/.test(port) && port !== "params"),
+      [
+        ...(node.requires ?? []).map(portName),
+        ...Object.keys(node.params ?? {}).filter(
+          (name) => !RESERVED_PARAMS.has(name),
+        ),
+      ]
+        // Anything else cannot be a keyword argument, so it cannot be one.
+        .filter((name) => IDENTIFIER.test(name)),
     ),
   ]
   const returns = (node.provides ?? [])
     .filter((spec) => portName(spec))
     .map((spec) => `"${portName(spec)}": ${PLACEHOLDER[spec.dtype ?? "float"]}`)
-  return `${SCAFFOLD_DOC}\n\n\ndef process(${[...args, "params"].join(
+  return `${SCAFFOLD_DOC}\n\n\ndef process(${args.join(
     ", ",
   )}):\n    return {${returns.join(", ")}}\n`
 }
@@ -998,13 +1014,13 @@ function PanelBody({
           type={node.type}
           schema={nodeType?.params_schema}
           params={node.params ?? {}}
-          onChange={(params) => onChange({ ...node, params })}
+          onChange={(params) => editNode({ ...node, params })}
         />
         {nodeType?.free_params ? (
           <FreeParamsForm
             params={node.params ?? {}}
             reserved={RESERVED_PARAMS}
-            onChange={(params) => onChange({ ...node, params })}
+            onChange={(params) => editNode({ ...node, params })}
           />
         ) : null}
         {hasSource ? (