The previous approach (bounded_gather building a fresh semaphore per call)
did NOT compose: the indexing call graph nests gathers
(tree_parser -> process_large_node_recursively -> recurse, plus each node's
check_title gather), and each level got its own independent cap. Peak
in-flight LLM calls grew ~N^depth, so a deep/wide document still exhausted
file descriptors (Errno 24) — the exact failure the cap was meant to
prevent — while the flat summary phase was over-serialized. Naively sharing
one semaphore across gather levels would instead deadlock (a parent holds a
slot while awaiting children that need slots).
Move the throttle to the single chokepoint every LLM call funnels through,
llm_acompletion: one shared semaphore per event loop, acquired only around
the litellm.acompletion network call. This gives a true global cap that
composes across any nesting and can't deadlock (a parent awaiting children
holds no slot). bounded_gather is gone; the call sites revert to plain
asyncio.gather.
Also:
- Reject bool in max_concurrency validation (bool is an int subclass, so
set_max_concurrency(True) / IndexConfig(max_concurrency=True) previously
became Semaphore(1) and silently serialized). Shared _validate_max_concurrency
+ a pydantic field_validator.
- Guard check_title_appearance_in_start_concurrent against an out-of-range
or 0 physical_index (LLM can emit one): it was dereferenced during task
construction, outside the gather's return_exceptions protection, aborting
the whole build; 0 silently wrapped to the last page. Now marked 'no'.
- Propagate contextvars into agent.py's worker-thread run (mirrors
pipeline._run_async) so ContextVar settings stay consistent.
- Tests rewritten to cover the nested case the old flat tests missed, the
leaf-level throttle in llm_acompletion, bool rejection, and the
out-of-range physical_index guard.
Claude-Session: https://claude.ai/code/session_01Kx5DgKbhK1N8autqXH8SmS
