minWaitForStreamingHelloMillis default breaks spec-compliant drivers

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    • Type: Bug
    • Resolution: Fixed
    • Priority: Blocker - P1
    • 9.1.0-rc0, 9.0.0-rc2
    • Affects Version/s: None
    • Component/s: None
    • None
    • Replication
    • Fully Compatible
    • ALL
    • v9.0, v8.3, v8.0, v7.0
    • Repl 2026-08-03
    • None
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      Context

      SERVER-128517 added minWaitForStreamingHelloMillis, which enforces a server-side floor on how long a pre-auth streamable hello is held, the drivers team understands that the effective await is

      max(client maxAwaitTimeMS, minWaitForStreamingHelloMillis)

      The default value of this floor exceeds the minimum maxAwaitTimeMS a spec-compliant driver is allowed to send, which is 500ms.

      The default was derived from the drivers default heartbeatFrequencyMS of 10s, but a floor on maxAwaitTimeMS must not exceed the driver minimum heartbeatFrequencyMS. This will break consumers that use aggressive heartbeatFrequencyMS+connectTimeout (e.g. heartbeatFrequencyMS=1 and connectTimeout=2), making the driver completely unusable. 

      Definition of Done

      Default minWaitForStreamingHelloMillis should be 500ms.

            Assignee:
            Amirsaman Memaripour
            Reporter:
            Preston Vasquez
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              Created:
              Updated:
              Resolved: