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Return -32022 for strict-mode protocol version rejections #15

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Merged
jonpspri merged 1 commit into from
Jul 26, 2026
Merged

Return -32022 for strict-mode protocol version rejections #15

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3 changes: 2 additions & 1 deletion mcp-servers/rust/fast-time-server/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -234,7 +234,8 @@ a mismatching `MCP-Protocol-Version` header is rejected with `HeaderMismatch`

`--strict` makes the served set exact. `--protocol 2026-07-28 --strict` runs a
pure `2026-07-28` server: every `initialize` call — including ones naming
`2025-11-25` — is rejected with JSON-RPC error `-32602` whose `data.supported`
`2025-11-25` — is rejected with an `UnsupportedProtocolVersionError` (`-32022`)
whose `data.supported`
lists only the configured revisions, and `server/discover` advertises only
`2026-07-28`. To run a strict server that still accepts the legacy handshake,
enable both revisions explicitly:
Expand Down
6 changes: 3 additions & 3 deletions mcp-servers/rust/fast-time-server/src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -556,7 +556,7 @@ fn mcp_initialize_response(
if config.strict && (!config.legacy || requested != Some(MCP_PROTOCOL_VERSION)) {
return mcp_error_response(
id,
-32602,
ERR_UNSUPPORTED_PROTOCOL_VERSION,
"Unsupported protocol version",
Some(json!({
"supported": config.supported_versions(),
Expand Down Expand Up @@ -1739,7 +1739,7 @@ mod tests {
assert_eq!(response.status(), StatusCode::OK);
assert!(response.headers().get(SESSION_HEADER).is_none());
let body = response_json(response).await;
assert_eq!(body["error"]["code"], -32602);
assert_eq!(body["error"]["code"], -32022);
assert_eq!(body["error"]["message"], "Unsupported protocol version");
assert_eq!(
body["error"]["data"]["supported"],
Expand Down Expand Up @@ -1776,7 +1776,7 @@ mod tests {
assert_eq!(response.status(), StatusCode::OK);
assert!(response.headers().get(SESSION_HEADER).is_none());
let body = response_json(response).await;
assert_eq!(body["error"]["code"], -32602);
assert_eq!(body["error"]["code"], -32022);
assert_eq!(body["error"]["message"], "Unsupported protocol version");
assert_eq!(
body["error"]["data"]["supported"],
Expand Down
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