Derive Mcp-Name from the body in the modern transport test helper - #494
Merged
koic merged 1 commit intoAug 8, 2026
Merged
Conversation
## Motivation and Context modelcontextprotocol#490 and modelcontextprotocol#492 merged independently green but broke each other on main: modelcontextprotocol#492 made the modern path reject a name-bearing POST whose body carries a target name without `Mcp-Name` (-32020, HTTP 400) and taught the `modern_rack_request` helper to derive `Mcp-Method` from the body, while modelcontextprotocol#490, merged in between, added five modern `tools/call` tests that build their requests through that helper and therefore send no `Mcp-Name`. Since the modelcontextprotocol#492 merge every CI run on main fails those five tests with 400 where 200 is expected; the library behavior itself is correct. The helper now derives `Mcp-Name` the same way it derives `Mcp-Method`: from `params.name` or `params.uri` when the body's method is one of the name-bearing three. That is what a conforming client sends per the 2026-07-28 specification, and what the TypeScript SDK's client, the bundled `MCP::Client::HTTP`, and the conformance harness's standard headers all do, so tests built through the helper model a compliant client by default. `name_header: nil` omits the header for tests of the requirement itself, symmetric with `method_header: nil`, and an explicit `headers:` entry still overrides the derived value, which keeps the base64 mismatch tests exercising their divergent names. ## How Has This Been Tested? The five failing tests pass again without being touched, and the modelcontextprotocol#492 requirement tests (missing `Mcp-Method`, missing `Mcp-Name`, header mismatches, base64 decoding) still pass: the transport test file reports 217 runs with zero failures. `bundle exec rake` is green, including RuboCop and the `--requirements 2025-11-25` conformance baseline. ## Breaking Changes None. The change is confined to a test helper; the shipped gem is untouched.
Member
Author
|
Merging via bypass to restore the CI as quickly as possible. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Motivation and Context
#490 and #492 merged independently green but broke each other on main: #492 made the modern path reject a name-bearing POST whose body carries a target name without
Mcp-Name(-32020, HTTP 400) and taught themodern_rack_requesthelper to deriveMcp-Methodfrom the body, while #490, merged in between, added five moderntools/calltests that build their requests through that helper and therefore send noMcp-Name. Since the #492 merge every CI run on main fails those five tests with 400 where 200 is expected; the library behavior itself is correct.The helper now derives
Mcp-Namethe same way it derivesMcp-Method: fromparams.nameorparams.uriwhen the body's method is one of the name-bearing three. That is what a conforming client sends per the 2026-07-28 specification, and what the TypeScript SDK's client, the bundledMCP::Client::HTTP, and the conformance harness's standard headers all do, so tests built through the helper model a compliant client by default.name_header: nilomits the header for tests of the requirement itself, symmetric withmethod_header: nil, and an explicitheaders:entry still overrides the derived value, which keeps the base64 mismatch tests exercising their divergent names.How Has This Been Tested?
The five failing tests pass again without being touched, and the #492 requirement tests (missing
Mcp-Method, missingMcp-Name, header mismatches, base64 decoding) still pass: the transport test file reports 217 runs with zero failures.bundle exec rakeis green, including RuboCop and the--requirements 2025-11-25conformance baseline.Breaking Changes
None. The change is confined to a test helper; the shipped gem is untouched.
Types of changes
Checklist