[wu-sheng]

A LangChain run's conversation can depend on something the receiver no longer has. An update that names no conversation of its own is completed from its run's start. A run that names no thread takes the conversation of a run above it. The receiver remembers both for a day, and at most 50,000 runs. When what would say the conversation was forgotten, or never came, the run landed under a name saying its identity was not supplied. That put one conversation's evidence in another.

What changes

• Such a run waits, then is not collected. It waits as a run waits for its ancestry, sharing the same counter of three passes. Once its request has waited as long as it may, these are dropped:
  • an update with no complete identity whose start was not seen;
  • a run whose own thread is not whole yet, with the rest of its key still to come;
  • a run that names no thread under a run above it that is not known: one that never came, was forgotten, or is known only from updates that named no conversation of their own.
• The receiver's memory records whether a run's start was seen. An update no longer proves a start, even with a start time.
• A dropped run leaves no conversation behind. Its start, if it comes later, decides for itself instead of taking the dropped run's fallback.
• Inheritance stops at the first run above that does not decide, and a farther run's thread is never taken past it.
• What still lands as today:
  • An update that carries its conversation's whole key lands with no start seen. All 11 captured updates from the Python client carry the project and the thread.
  • A trace whose runs are all known and name no thread lands unassigned.
  • A run whose conversation is known lands with whatever ancestry arrived.
• A complete identity is checked against every configured dimension. On an update, a metadata key in scope that is missing makes the identity incomplete. A start carries its whole metadata, so a key it leaves out is supplied empty.
• The memory moves to version 2, so what it held is forgotten once.
• The pass line says runs_not_collected=N for each pass that drops an arrival.

Tests

• Four existing inheritance tests change to the dropped outcome. They now assert the exact drop count and an empty inbox. The partial-identity test gains a case with no run below the call, so the partial guard alone holds the call back.
• lost_test.go covers:
  • a start forgotten by age and by count;
  • a run kept alive past a day by its updates;
  • a complete update with no start, alone and beside other runs;
  • an update before its start in one request, and in an earlier request;
  • a later start naming another conversation, with and without a restart;
  • a run under an ancestor known only from a dropped update;
  • an unassigned run whose root is forgotten later;
  • the scope dimensions, a start time that is not a start, a partial start, and a version-1 memory.
• cmd/asz asserts the pass line for a pass that only drops.

Each new guard was proven by reverting it. make test, the JSON v1 step (GOEXPERIMENT=nojsonv2), make scenarios, lint and the Windows build pass.