chore(release): 9.4.0 [skip-runtime-e2e]

[saurabhjain1592]

Release prep: both version sites move to 9.4.0 and the [Unreleased] block is cut as [9.4.0]. No functional change.

9.4.0 is a minor: additive, plus the deprecation of the simulation family. StaticPolicy.category accepting an unknown category as a plain string widens what a read tolerates rather than narrowing it.

Version sites moved

File	Site	Change	Why this site
pyproject.toml	version	9.3.1 -> 9.4.0	the registry version on PyPI
axonflow/_version.py	__version__	9.3.1 -> 9.4.0	the on-wire sdk-python/<version> value (axonflow/client.py:703)

The CHANGELOG.md [Unreleased] heading is renamed IN PLACE to [9.4.0] with today's date. It is a rename, never a heading inserted above: an inserted heading strands everything already merged beneath it, and the release workflows that publish from this file extract the block by exact heading.

Verification

• The two sites read back equal: pyproject=9.4.0 axonflow/_version.py=9.4.0 -> MATCH.
• Residual scan for the outgoing 9.3.1: three matches. Two are comments dating a behaviour (runtime-e2e/pep_handshake_extra_headers/test.py:170, tests/test_extra_headers.py:171) and the third is the CHANGELOG's own ## [9.3.1] heading. All three are historical and stay.

Provenance

The release-prep procedure, for the current train. Every merged change since the last tag wrote its own CHANGELOG entry at merge time, so this PR cuts the block rather than composing it.

For the operator, after the platform release

Nothing here is tagged, published or synced by this change. Once the platform release is live and this PR has merged:

git tag v9.4.0 <merge sha> && git push origin v9.4.0

Clients publish AFTER the platform, in that order: a published client for a platform that never shipped cannot be withdrawn.

Release notes for the GitHub release

The [9.4.0] block of CHANGELOG.md, verbatim.

Skip-runtime-e2e justification

This pull request changes no behaviour. It moves the version sites this repository's release procedure names, and renames the CHANGELOG's [Unreleased] heading in place to the released version. There is no new surface, no changed default, no changed fail direction, and nothing a runtime test could exercise that it does not already exercise at the previous version.

The on-the-wire value is verified by reading it back from something other than the file that was edited, which is the check a runtime leg would perform: the compiled package for Go, the built jar's pom.properties for Java, the generated constant re-stamped and compared by sha256 for TypeScript, and the manifest-versus-literal pair each plugin's own CI gate already asserts. Those readbacks are in the Verification section above.

Adding or updating a runtime-e2e/ test here would be an edit made to satisfy a gate rather than a demonstration of anything: the suites in this repository read the version from the package at run time, so they assert the same thing before and after this change.

Approved by the operator on 2026-09-14T13:50Z: "Of course skip-runtime-e2e is fine on them and they should be merged - clearly no runtime e2e test makes sense for version change."