Coalesce concurrent requests for the same schema

[samlown]

Summary

Fixes schemas being fetched two or three times on editor mount, plus a related endpoint-reset issue. Two commits:

Coalesce concurrent requests for the same schema

The SchemaRegistry only caches a schema after its fetch resolves, so concurrent consumers — parallel branches of the form parser's parseSchema recursion plus the Monaco loadSchemaSet preload, all racing at mount — each missed the cache and issued their own request for the same URL.

fetchExternalSchema now keeps an in-flight map keyed by URL: the first caller starts the fetch and stores the promise, later callers await the same promise, and the entry is cleared on settle (so a failed fetch can be retried rather than caching the failure). loadSchemaSet's strict root fetch goes through the same map via a new fetchExternalSchemaStrict, preserving its throw-on-failure semantics while joining the coalescing.

The custom JSON worker's schemaRequestService is unaffected: it only runs in the enableSchemaRequest: true fallback, which the preloading path disables.

Keep the configured API endpoint when editors mount without one

apiBaseUrl defaulted to the public gobl.dev service, so any editor mounted without an explicit endpoint (e.g. a nested correct/headers modal) reset the shared client back to the default, undoing the embedder's configuration and sending stray requests to gobl.dev. The prop now defaults to an empty string, which setApiBaseUrl treats as a no-op, so editors without an explicit endpoint inherit whatever is already configured.

Testing

• npm run check — 0 errors, 0 warnings.
• npm run lint and npm run build:package clean.

🤖 Generated with Claude Code

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[Copilot]

Pull request overview

This PR reduces duplicate JSON Schema network requests during editor mount by coalescing concurrent fetches for the same schema URL in the form schema loader, so parallel consumers share a single in-flight request.

Changes:

• Add an in-flight promise cache (pendingSchemas) and a strict fetch helper to dedupe concurrent schema loads and preserve throw-on-root-load behavior.
• Route loadSchemaSet root schema loading through the same strict/coalesced fetch path.
• Adjust editor apiBaseUrl prop defaults/docs so nested editors don’t reset an embedder-configured endpoint.

Reviewed changes

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

File	Description
src/lib/editor/form/utils/schema.ts	Adds in-flight request coalescing and uses strict root fetching for schema preloads.
src/lib/types/editor.ts	Updates apiBaseUrl prop documentation to reflect “inherit existing endpoint” behavior.
src/lib/ObjectEditor.svelte	Stops defaulting apiBaseUrl to the global default to avoid nested editor resets.
src/lib/EnvelopeEditor.svelte	Same apiBaseUrl default/inheritance change as ObjectEditor.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

src/lib/editor/form/utils/schema.ts:46

• pendingSchemas is a plain object keyed by arbitrary schema IDs/URLs. Using a normal object can lead to key-collision/prototype-pollution edge cases (e.g. __proto__, constructor) if a schema reference ever contains such a value. A Map avoids these hazards and is a better fit for an in-flight cache.

const pendingSchemas: Record<string, Promise<Schema>> = {}

function fetchExternalSchemaStrict(id: string): Promise<Schema> {
  const schema = SchemaRegistry[id]
  if (schema) return Promise.resolve(schema)

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

src/lib/editor/form/utils/schema.ts:46

• pendingSchemas is a plain object keyed by URL. Since these keys ultimately come from external schema URLs / $ref values, using a Record risks special keys like __proto__ / constructor causing prototype pollution and hard-to-debug behavior. Use a Map for the in-flight cache to avoid property-key hazards.

const pendingSchemas: Record<string, Promise<Schema>> = {}

function fetchExternalSchemaStrict(id: string): Promise<Schema> {
  const schema = SchemaRegistry[id]
  if (schema) return Promise.resolve(schema)