fix: address Copilot review round 11 — recurse constants into nested objects

applySchemaConstants only corrected top-level pinned fields, but the deep
link's overlay replaces a nested object wholesale rather than merging into it —
so `{ config: { kind: "sms" } }` slipped past a nested read-only
`kind: { const: "email" }` the form was displaying. It now recurses into
object-valued properties, resolving each one's own root union the same way.

Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/utils/jsonUtils.test.ts

@@ -445,6 +445,27 @@ describe("root composition (#2123)", () => {
     });
   });
 
+  it("re-applies a nested object's constants", () => {
+    // The overlay replaces the whole nested object rather than merging into it,
+    // so a link naming `{ config: { kind: "sms" } }` would otherwise slip past
+    // the pinned `kind` the nested form displays.
+    const schema: InspectorFormSchema = {
+      type: "object",
+      properties: {
+        config: {
+          type: "object",
+          properties: {
+            kind: { type: "string", const: "email" },
+            to: { type: "string" },
+          },
+        },
+      },
+    };
+    expect(
+      applySchemaConstants(schema, { config: { kind: "sms", to: "a@b.c" } }),
+    ).toEqual({ config: { kind: "email", to: "a@b.c" } });
+  });
+
   it("leaves values alone when nothing is pinned", () => {
     const values = { a: 1 };
     expect(

clients/web/src/utils/jsonUtils.ts

@@ -194,14 +194,34 @@ export function applySchemaConstants(
   const { base, branches } = resolveRootUnion(schema);
   const selected = selectBranchIndex(branches, values) ?? 0;
   const properties = (branches[selected]?.schema ?? base).properties ?? {};
-  const pinned = Object.entries(properties).filter(
-    ([, fieldSchema]) => fieldSchema.const !== undefined,
-  );
-  if (pinned.length === 0) return values;
-  return Object.fromEntries([
-    ...Object.entries(values),
-    ...pinned.map(([name, fieldSchema]) => [name, fieldSchema.const]),
-  ]);
+
+  const corrections: [string, unknown][] = [];
+  for (const [name, rawSchema] of Object.entries(properties)) {
+    const fieldSchema = normalizeNullableUnion(rawSchema);
+    if (fieldSchema.const !== undefined) {
+      corrections.push([name, fieldSchema.const]);
+      continue;
+    }
+    // Recurse: a nested object renders its own read-only fields, and the
+    // overlay replaces the whole object rather than merging into it — so a
+    // link naming `{ config: { kind: "sms" } }` would otherwise slip a value
+    // past the pinned `kind` the nested form is displaying.
+    const nested = values[name];
+    if (
+      typeof nested === "object" &&
+      nested !== null &&
+      !Array.isArray(nested)
+    ) {
+      const corrected = applySchemaConstants(
+        fieldSchema,
+        nested as Record<string, unknown>,
+      );
+      if (corrected !== nested) corrections.push([name, corrected]);
+    }
+  }
+
+  if (corrections.length === 0) return values;
+  return Object.fromEntries([...Object.entries(values), ...corrections]);
 }
 
 /**