chore(conformance): run against 0.2.0-alpha.12 (#1336)

* chore(conformance): run against 0.2.0-alpha.12

0.2.0-alpha.11 added the json-schema-2020-12-preservation client
scenario. The conformance client does not handle it and exits with
"Unsupported conformance scenario", so both client suites fail on it
once CI moves past alpha.10.

Handle the scenario as it asks: list tools, then send the inputSchema of
json_schema_2020_12_tool back through json_schema_echo. rmcp keeps every
keyword the scenario checks. Bump CONFORMANCE_VERSION to alpha.12.

* chore(conformance): fail the schema preservation run on a tool error

The json_schema_echo result was dropped, so a tool-level error still let
the client exit 0. Check is_error so local runs fail loudly.

Author: SergeevDmitry

.github/workflows/conformance.yml

@@ -12,7 +12,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  CONFORMANCE_VERSION: "0.2.0-alpha.10"
+  CONFORMANCE_VERSION: "0.2.0-alpha.12"
 
 permissions:
   contents: read

conformance/src/bin/client.rs

@@ -993,6 +993,37 @@ async fn run_elicitation_defaults_client(server_url: &str) -> anyhow::Result<()>
     Ok(())
 }
 
+/// SEP-1613/SEP-2106: send the focal tool's `inputSchema` back through the
+/// echo tool, so the scenario can diff it against what the server listed.
+async fn run_json_schema_preservation_client(server_url: &str) -> anyhow::Result<()> {
+    let transport = StreamableHttpClientTransport::from_uri(server_url);
+    let client = FullClientHandler
+        .serve_with_lifecycle(transport, conformance_lifecycle())
+        .await?;
+    let tools = client.list_tools(Default::default()).await?;
+    let tool = tools
+        .tools
+        .iter()
+        .find(|t| t.name.as_ref() == "json_schema_2020_12_tool")
+        .ok_or_else(|| anyhow::anyhow!("json_schema_2020_12_tool was not listed"))?;
+    let mut args = serde_json::Map::new();
+    args.insert(
+        "schema".to_string(),
+        Value::Object(tool.input_schema.as_ref().clone()),
+    );
+    let result = client
+        .call_tool(call_tool_params("json_schema_echo".into(), Some(args)))
+        .await?;
+    if result.is_error == Some(true) {
+        anyhow::bail!(
+            "json_schema_echo returned a tool error: {:?}",
+            result.content
+        );
+    }
+    client.cancel().await?;
+    Ok(())
+}
+
 fn conformance_protocol_version() -> ProtocolVersion {
     std::env::var("MCP_CONFORMANCE_PROTOCOL_VERSION")
         .ok()
@@ -1115,6 +1146,9 @@ async fn run_scenario(
         // close is sufficient; the scenario's mock server does not implement
         // the discover lifecycle, so `run_discover_client` hangs against it.
         "json-schema-ref-no-deref" => run_basic_client(server_url).await?,
+        "json-schema-2020-12-preservation" => {
+            run_json_schema_preservation_client(server_url).await?
+        }
         "tools_call" => run_tools_call_client(server_url, ctx).await?,
         "elicitation-sep1034-client-defaults" => {
             run_elicitation_defaults_client(server_url).await?