[Hardik K (hardikkaurani)]

Summary

In _drop_superseded_routed_experts (agentlightning/server/routes/events.py), an unconditional return statement was located at the end of the backwards event loop. This caused the loop to terminate immediately upon inspecting the first model_request:

1. If an intermediate model_request lacked routed_experts (or did not extend context, e.g. an unrouted turn or alternate step), the function returned early without checking earlier ancestor turns that had routed_experts.
2. In multi-turn trajectories with 3 or more turns where multiple prior turns had routed_experts, only the immediately preceding turn was updated, leaving earlier turns with outdated route tensors.
3. If token ID lists were empty ([]), prompt_ids[:len(previous_context)] == previous_context could evaluate to True even when no prompt tokens were present.

Changes

• Removed the premature return inside the event iteration loop in _drop_superseded_routed_experts so that all superseded ancestor turns in the mergeable trajectory have their routed_experts dropped as intended.
• Added explicit truthiness checks (bool(prompt_ids) and bool(previous_context)) before comparing prompt and context prefix matches.
• Added regression tests in tests/server/test_endpoints.py verifying:
  • Multi-turn rollouts (Turn 1, Turn 2, Turn 3 with routed experts) correctly retain route tensors only on the latest turn.
  • Interleaved turns without routed experts do not prematurely abort scanning earlier matching ancestor turns.
  • Query parameter include_routed_experts=False correctly excludes route tensors.

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[Hardik K (hardikkaurani)]

Hi Zhiyuan He (@hzy46), could you please take a look at this PR when you have a moment? It fixes an issue where superseded route tensors in multi-turn trajectories could be retained due to an early return in _drop_superseded_routed_experts, along with comprehensive test coverage. Thanks!