## Stack Context
PR 6 of 6 in a stack that migrates every Coder MCP surface from the
archived `github.com/mark3labs/mcp-go` library to the official
`github.com/modelcontextprotocol/go-sdk` v1.7.0.
Stack: #28056 -> #28057 -> #28058 -> #28059 -> #28060 -> #28061
## Why
With every production surface migrated, this PR removes the mark3labs
dependency entirely and converts the remaining test fixtures.
- Migrates the remaining mark3labs test fixtures (coderd MCP e2e tests,
chatd fixtures, mcpclient fixtures, and the Force On MCP policy tests)
to official stateless SDK servers.
- Removes `github.com/mark3labs/mcp-go` from `go.mod` and drops the
corresponding dependabot ignore entry. Zero references remain repo-wide.
- Updates the MCP docs for the 2026-07-28 protocol: stateless Streamable
HTTP behavior, the supported 2024-11-05 through 2026-07-28 protocol
range, and explicit non-features (resources, prompts, structured output,
elicitation, MCP Tasks).
- The e2e ping assertion is removed because MCP 2026-07-28 removed the
ping method.
> Mux created this PR on Mike's behalf.
Michael Suchacz