🐛 Fixes
Coprocessor: improve handling of invalid GraphQL responses with conditional validation (PR #7731)
The router was creating invalid GraphQL responses internally, especially when subscriptions terminate. When a coprocessor is configured, it validates all responses for correctness, causing errors to be logged when the router generates invalid internal responses. This affects the reliability of subscription workflows with coprocessors.
Fix handling of invalid GraphQL responses returned from coprocessors, particularly when used with subscriptions. Added conditional response validation and improved testing to ensure correctness. Added the response_validation configuration option at the coprocessor level to enable the response validation (by default it's enabled).
By @BrynCooke in #7731
Fix several hot reload issues with subscriptions (PR #7746)
When a hot reload is triggered by a configuration change, the router attempted to apply updated configuration to open subscriptions. This could cause excessive logging.
When a hot reload was triggered by a schema change, the router closed subscriptions with a SUBSCRIPTION_SCHEMA_RELOAD error. This happened before the new schema was fully active and warmed up, so clients could reconnect to the old schema, which should not happen.
To fix these issues, a configuration and a schema change now have the same behavior. The router waits for the new configuration and schema to be active, and then closes all subscriptions with a SUBSCRIPTION_SCHEMA_RELOAD/SUBSCRIPTION_CONFIG_RELOAD error, so clients can reconnect.
By @goto-bus-stop and @bnjjj in #7777