Conformance (Python)

The conformance corpus is the executable half of the protocol spec. It is language-neutral: the runner plays the gateway, and any SDK that can stand up a host from a fixture document can be checked against it.

From the tesseron-python repository root:

uv sync --locked
TESSERON_CONFORMANCE_UNSUPPORTED=host-minted-claim,uds pnpm dlx @tesseron/conformance@1.2.1 --host "uv run --locked python -m conformance_host"

In PowerShell, set $env:TESSERON_CONFORMANCE_UNSUPPORTED = 'host-minted-claim,uds' before the pnpm dlx command instead of using the Bash environment prefix. The runner uses its bundled corpus; pass --fixtures <path> to test a hub checkout's current fixtures.

The current result on both Linux and Windows is 29 passed, 10 skipped, 0 failed across the 39-fixture corpus.

The runner cross-checks the unsupported list against the four capability flags the host declares in tesseron/hello. A capability declared true in the SDK and named as unsupported fails the run, so this list cannot be used to hide a gap in something the host claims to do.

• host-minted-claim skips the nine bind/* fixtures. This host takes gateway-minted claims only.
• uds skips uds/file-mode. This host speaks WebSocket only. Set this tag on both platforms.

Those are the only ten skips. WebSocket-only is by design for this release. The canonical examples exercise the same actions through the real gateway.

Neither transport is a negotiated capability, so neither is covered by the four flags. Everything the host declares, streaming, subscriptions, sampling, and elicitation, is exercised by the fixtures that run.

conformance_host/ reads a fixture document and registers what it declares. It sits beside src/tesseron rather than inside it and imports the published package like any other consumer, so uv build produces a wheel with the SDK and nothing else.

The runner starts one host process per fixture with TESSERON_CONFORMANCE_FIXTURE pointing at the document, waits for a single readiness line on stdout, then plays the gateway against the endpoint that line names:

tesseron-conformance-url=ws://127.0.0.1:62454/

Exactly one stdout line. Every diagnostic goes to stderr, because a second stdout line fails the fixture. The process ends when the runner closes its stdin.

Anything in the fixture grammar the host cannot serve is refused at launch rather than ignored. A fixture requiring uds, a fixture that mints its own claim, a fixture member the adapter does not know, and an inputSchema using a JSON Schema keyword the adapter cannot enforce all fail the launch. A fixture that would otherwise pass because a keyword was silently dropped fails the run instead.

The porting guide covers the contract. The Python adapter is a reasonable second reference next to the Rust one. It uses no test framework and touches nothing private: the fixture document goes in, and the same public API an application would call comes out.