go-sdk review: paginateAll page-limit guard, test server logger, handler convention docs

[Copilot]

Implements the high-value actionable items from the Go Fan module review of modelcontextprotocol/go-sdk. Three targeted improvements addressing resilience, test observability, and internal convention documentation.

Changes

• paginateAll max-pages guard (internal/mcp/connection.go): Unbounded pagination loop could be exploited by a misbehaving backend to consume arbitrary memory/time. Added paginateAllMaxPages = 100 constant and a page counter; exceeding the limit returns an error instead of running forever.

  for pageCount := 1; cursor != ""; pageCount++ {
      if pageCount >= paginateAllMaxPages {
          return nil, fmt.Errorf("list%s: backend serverID=%s returned more than %d pages; aborting...", ...)
      }
      ...
  }

• Test server logger (internal/testutil/mcptest/server.go): sdk.ServerOptions{} was created without a logger, suppressing SDK-level protocol errors during test failures. Added Logger: logger.Discard() to match the pattern used in production servers and surface SDK diagnostics.

• Three-argument handler convention godoc (internal/server/tool_registry.go): The internal func(ctx, req, state) → (result, data, error) handler signature diverges from the SDK's native two-argument form with no explanation at the definition site. Expanded the registerToolWithoutValidation doc to explain both extra parameters (jq middleware pipeline; DIFC write-sink), and added an explicit note that Server.AddTool vs sdk.AddTool validation bypass must be re-verified on each SDK upgrade.

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[Copilot]

Pull request overview

This PR implements several follow-ups from the Go SDK review to improve pagination resilience, test-time SDK visibility, and internal handler conventions documentation.

Changes:

• Add a max-pages guard to paginateAll to prevent unbounded pagination loops.
• Add unit tests covering paginateAll single-page, multi-page, and max-pages error behavior.
• Expand internal godoc explaining the package’s three-argument tool handler convention and schema-validation bypass rationale.

Show a summary per file

File	Description
internal/mcp/connection.go	Adds paginateAllMaxPages and enforces a page-limit abort to prevent runaway pagination.
internal/mcp/connection_test.go	Adds focused tests for paginateAll, including the new page-limit guard.
internal/testutil/mcptest/server.go	Sets an explicit SDK server logger in test server options.
internal/server/tool_registry.go	Documents the internal 3-arg handler signature and validation-bypass implications.
internal/config/config_stdin.go	Formatting/alignment adjustments in StdinGatewayConfig struct fields.

Copilot's findings

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• Files reviewed: 4/5 changed files
• Comments generated: 1

[Copilot]

logger.Discard() returns a slog.Logger backed by io.Discard, so SDK logs are still suppressed. If the intent here is to make protocol/SDK errors visible during failing tests, use a logger that writes to os.Stderr (or reuse logger.NewSlogLoggerWithHandler(logger.New("testutil:mcptest"))), or make the logger configurable so tests can opt into output when needed.

[lpcox]

@copilot apply changes based on the comments in this thread