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InferMap is pure-Python by default. An optional compiled kernel (Rust + PyO3/Arrow, crate packages/rust/extensions/infermap-native) accelerates the CPU-heavy components below. Under reference-mode the compiled path is the reference implementation and pure-Python is the byte-identical fallback — output is the same either way; native only changes wall-clock.

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The gate

One env var, INFERMAP_NATIVE, read in infermap/infermap/_native_loader.py:
  • INFERMAP_NATIVE=auto (default, or unset) — run native for any component whose kernel symbol is present on the loaded wheel, except the known-divergent components below.
  • INFERMAP_NATIVE=0 — force the pure-Python fallback everywhere.
  • INFERMAP_NATIVE=1 — require native; raise if the kernel isn’t importable (the CI parity lane).
The kernel is discovered two ways, in order: the in-tree build infermap._native (local dev / parity lane), then the distributed infermap_native._native wheel (pip install infermap[native]). When neither is importable, every path runs pure-Python unchanged.

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Components

Each component maps to the native kernel symbol(s) its auto call site invokes (the floor symbol first — a component is native-capable when any listed symbol is present, so an older wheel stays wheel-skew safe). A ✓ in Parity-signed marks a component that cleared the byte-exact sign-off recorded in _GATED_ON.

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How parity stays honest

A component joins the native path only after a parity test proves its kernel is byte-identical (or integer-exact) to the pure-Python reference. CI runs a INFERMAP_NATIVE=1 lane that builds the wheel and asserts native == pure-Python, and scripts/check_native_symbols.py reconciles the host’s kernel references against the crate’s wrap_pyfunction! exports so a referenced-but-unregistered symbol fails loudly. Because output is identical with or without the wheel, toggling the gate never changes a result — only speed.