Add inbound in-flight request deduplication to gateway runtime

[Copilot]

This introduces router-runtime style inbound request deduplication for concurrent identical GraphQL requests. The runtime now coalesces matching in-flight query operations so joiners reuse the leader execution result instead of re-executing.

• Config surface

  • Added inboundRequestDeduplication to runtime config:
    • true | false
    • { enabled?: boolean; headers?: 'all' | 'none' | { include: string[] } }
  • Keeps feature opt-in and allows controlling header participation in fingerprinting.

• Inbound dedupe implementation

  • Added useInboundRequestDeduplication plugin and wired it into createGatewayRuntime.
  • Deduplication happens at onParams level with atomic in-flight key claiming.
  • Scope is intentionally limited to GraphQL query operations (mutations are excluded).
  • Fingerprint includes:
    • schema version (increments on schema change, preventing cross-schema sharing)
    • method + pathname
    • selected headers (policy-based)
    • operation name + query + variables + extensions

• Schema-change safety

  • In-flight store is cleared on onSchemaChange.
  • Keys include schema version, so dedupe does not bridge different schema snapshots.

• Focused coverage

  • Added runtime tests for:
    • deduping parallel identical queries
    • not deduping mutations

createGatewayRuntime({
  proxy: { endpoint: 'http://localhost:4000/graphql' },
  inboundRequestDeduplication: {
    enabled: true,
    headers: { include: ['authorization', 'cookie'] },
  },
});

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• rover.apollo.dev
  • Triggering command: /opt/hostedtoolcache/node/24.14.0/x64/bin/node /opt/hostedtoolcache/node/24.14.0/x64/bin/node ./install.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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