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Platform mechanics

Several tools in the Azure Functions Python DX Toolkit depend on the same underlying runtime behavior: how the Python worker loads a function app, how it binds handler parameters, and how invocation context flows through a call. Rather than re-explaining these mechanics in every repository, the toolkit keeps one neutral, source-pinned description here — and each tool links to it.

This section is deliberately narrow. It documents the platform contract and observable behavior only:

  • What the FunctionRpc protocol and the Python worker actually do at load and invocation time.
  • Behavior you can rely on when building on top of the programming model.

It is not a tour of worker internals. Three rules keep this section honest:

  • Pinned citations. Every claim links to a tag- or commit-pinned upstream permalink, and — where a toolkit package depends on it — to the test in that package that locks the behavior in place.
  • Contract and observable behavior only, never worker internals.
  • Version-skew is called out. The behavior described here is what the Azure-hosted worker does today (worker 1.x / 4.45.x). Azure rolls the host forward on its own schedule, so each page flags where a future host could drift and which toolkit guard (the azure-functions<2.0.0 cap and the worker-nightly workflow) catches that drift early.

How these claims stay verified. Two CI lanes back this section: the hub's own mkdocs build --strict gate (.github/workflows/deploy.yml) keeps every cross-link resolvable, and the validation repo's nightly worker-nightly.yml lane exercises the live worker contract against pre-release azure-functions.

Pages

Page What it explains
How the worker binds handlers How the Python worker maps a FunctionLoadRequest to your function and binds parameters by name, and why decorator order matters.

Principles

  1. One neutral source. The mechanism narrative lives here on yeongseon.dev, not duplicated inside tool repositories. Tools link, they do not copy.
  2. Claims are locked by tests. Each behavioral claim is backed by a tag/commit-pinned upstream citation and, where applicable, a conformance test in the toolkit package that relies on it.
  3. Contract, not internals. Scope is the proto contract and observable behavior. When a page starts drifting toward explaining worker internals, that is the signal it has outgrown this section.