fix: address Copilot review round 19 — empty-string const in the web required gate

hasMissingRequiredFields treated every empty string as missing, so a required
field the schema pins to `""` — rendered read-only, and seeded with the only
value it accepts — left Execute and Open App permanently disabled. It now
matches the TUI check: an empty string counts as supplied when the property's
own `const` pins it there, and an ordinary blank required string still does
not.

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

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

@@ -488,6 +488,28 @@ describe("root composition (#2123)", () => {
     ).toBe(values);
   });
 
+  it("accepts an empty string a const pins the field to", () => {
+    // Rendered read-only, so treating the seeded value as missing would
+    // disable submit on a value the user cannot change.
+    const pinnedEmpty: InspectorFormSchema = {
+      type: "object",
+      properties: { kind: { type: "string", const: "" } },
+      required: ["kind"],
+    };
+    expect(hasMissingRequiredFields(pinnedEmpty, { kind: "" })).toBe(false);
+    // An ordinary required string is still missing when left blank.
+    expect(
+      hasMissingRequiredFields(
+        {
+          type: "object",
+          properties: { kind: { type: "string" } },
+          required: ["kind"],
+        },
+        { kind: "" },
+      ),
+    ).toBe(true);
+  });
+
   it("blocks submission while no branch is satisfied", () => {
     expect(hasMissingRequiredFields(UNION, {})).toBe(true);
     expect(hasMissingRequiredFields(UNION, { kind: "email" })).toBe(true);

clients/web/src/utils/jsonUtils.ts

@@ -292,7 +292,13 @@ function hasMissingIn(
       const fieldSchema = properties[field];
       return fieldSchema === undefined ? true : !admitsNull(fieldSchema);
     }
-    return value === undefined || value === "";
+    if (value === "") {
+      // A schema may pin a field to the empty string, and the form renders such
+      // a field read-only — so reporting the seeded value as missing would
+      // disable submit on a value the user cannot change (#2123).
+      return properties[field]?.const !== "";
+    }
+    return value === undefined;
   });
 }