asta-nguyen8/9/2026, 9:45:22 AM

Remove global mutable token-counting state (setFastTokenCount/_fastMode)
and introduce a scoped TokenCounter interface with fastTokenCounter
(chars/4, indexing) and exactTokenCounter (BPE, retrieval) instances.
Thread the counter through the indexer parse/chunk pipeline so indexing
uses the fast strategy without mutating global state, while retrieval
continues to use exact BPE counting.

Add resolveNativeParser() to resolve and cache the native tree-sitter
capability once. Graph builds now validate the parsed_documents cache
against the expected parser version (native-v1 when available,
fallback-v1 otherwise), so the second build reuses the fallback cache
with zero re-parses when native is unavailable.

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Parent4386de6