Audit conformance experiments for complete first-party SDK coverage

[rmcdaniel]

Request

The owner requested an audit of the existing experiments so portable behavior is not tested in just PHP, Python, or Rust by accident. Scheduled after the current Cloud pricing/contact rollout.

Acceptance

• Inventory current experiment definitions and map them to the public conformance runbook.
• Replace unjustified language-only instructions with explicit PHP/Python/Rust coverage and every meaningful supported workflow/activity direction, including cross-language child and Nexus behavior where applicable.
• Identify genuinely language-specific or embedded-only cases explicitly; do not invent meaningless Cartesian combinations.
• Cover authoring, inputs/results, retries, timeouts, heartbeats, cancellation, signals/queries/updates, replay/restarts, upgrades, and failure recovery as applicable to each experiment.
• Keep executable instructions, prerequisites, expected outcomes, and cleanup clear for a new human or agent using only public repositories.
• Keep Cloud account data, infrastructure, provisioning and chaos procedures in the private Cloud repository; link the private follow-up there without exposing its details here.
• Run focused representative checks for changed instructions and report outcomes on GitHub. Do not commit generated per-run evidence or rebuild a conformance pipeline.

GitHub remains the source of truth. Reuse ordinary repository commands and GitHub Actions for public happy paths; maintainers handle exceptions directly.

[rmcdaniel]

Concrete audit finding from server#140: an exploratory unrestricted Server PHPUnit run includes legacy conformance-runner contract tests outside the current feature qualification command. The first failing assertion, ActivityConformanceRunnerContractTest::test_runner_rejects_local_repo_root_vendor_runtime_probe, expects the phrase "local product source probe" while the actual rejection identifies forbidden local source and missing pinned-image evidence. This reproduces identically on unchanged main e918f0c4; no Nexus change causes it. Include runner-test relevance and clean executable prerequisites in this existing experiment audit, alongside first-party SDK coverage. Do not turn obsolete message assertions into another release coordinator. Server release qualification is independently green on the documented 2,132-test command.