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fix: decline a union branch requiring a name it never declares (#2224)

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`isOfferable` in `core/json/rootUnion.ts` checked that a merged branch carries
at least one property and that every property value is readable, but never that
each name in `required` resolves to a property a form can render. A branch like
`{ properties: { kind }, required: ["kind", "payload"] }` was therefore offered
in the picker, rendered no control for `payload`, and had the submit-time check
report it missing permanently — the exact dead end the function's own comment
already reasons through for a `false`-schema required field, one case short.

Judge the merge, so a branch requiring only names the ROOT declares —
`anyOf: [{ required: ["email"] }, …]` — stays offerable as before. `hasOwn`
rather than `in`, since an argument legally named `constructor` would otherwise
resolve through the prototype and read as declared.

Declining every branch of a union leaves the web form with neither a picker nor
a field, which is a different dead end. `SchemaForm` now seeds the raw-JSON
editor (#2151) in that one case — a root union that resolved to no branches and
no properties — so the arguments stay expressible. Seeded rather than forced, so
the switch still works, and re-seeded during render (never in an effect) because
the form is reused across tools rather than remounted. A tool that genuinely
takes no arguments is untouched. The TUI has no such editor; there the union is
simply not offered, which is already better than a section that can never be
submitted.

Adds a `record_shipment_by` preset and wires it into the
`root-union-schemas-http.json` showcase so the shape is reproducible by hand,
with docs/test-servers.md covering it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PxYT4eKdnx1yRw7x4bW7Ts
Signed-off-by: cliffhall <cliff@futurescale.com>
This commit is contained in:
cliffhall 2026-09-06 12:59:52 -04:00
commit 81f2115e8b
1 changed files with 312 additions and 6 deletions
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22
core/json/rootUnion.ts
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@ -162,7 +162,7 @@ function propertiesOf(schema: RootUnionSchema): Record<string, unknown> {
/**
* Whether a branch is one a form can offer as an alternative.
*
* Three ways it is not, all of which would put an option in the picker that
* Four ways it is not, all of which would put an option in the picker that
* cannot be filled in:
*
* - **It carries no fields.** A `{ type: "null" }` member — the nullable
@ -174,6 +174,12 @@ function propertiesOf(schema: RootUnionSchema): Record<string, unknown> {
* - **Its `type` rules objects out.** Tool arguments are a JSON object, so a
* `{ type: "string", properties: {…} }` member can never match — rendering it
* as a fillable form would offer a call that cannot be valid.
* - **It requires a name it never declares.** `required` is a list of names,
* not of declarations, so `{ properties: { kind: … }, required: ["kind",
* "payload"] }` is legal and says nothing about what `payload` accepts. Both
* form builders enumerate `properties` alone, so no control is rendered for
* it and the submit-time check reports it missing *permanently* — the same
* dead end a `false`-schema required field produces (#2224).
*/
function isOfferable(
branch: RootUnionSchema,
@ -191,7 +197,19 @@ function isOfferable(
// a perfectly ordinary way to say "one of these two" — and judging it on its
// own properties would decline it, leaving the gate checking the base alone
// and accepting `{}`, which the schema rejects.
const properties = Object.values(propertiesOf(merged));
const mergedProperties = propertiesOf(merged);
// Judged on the MERGE for the same reason the fields are: a member may
// require a name the root declares, which is exactly the
// `anyOf: [{ required: ["email"] }, …]` shape above. `hasOwn` rather than
// `in`, since an argument legally named `constructor` or `toString` would
// otherwise resolve to the inherited one and read as declared.
if (
requiredOf(merged).some((name) => !Object.hasOwn(mergedProperties, name))
) {
return false;
}
const properties = Object.values(mergedProperties);
return (
properties.length > 0 &&
// Every value has to be something a renderer can read AND something a