Refactor duplicated MCP handler config setup in transport and routed server paths

[Copilot]

CreateHTTPServerForMCP and CreateHTTPServerForRoutedMode were each assembling nearly identical mcpHandlerConfig values before calling buildMCPHandler, creating a small but recurring maintenance seam. This change centralizes that shared config construction while preserving the per-mode server-factory behavior.

• Shared config construction

  • Added buildDefaultHandlerConfig(...) in internal/server/middleware.go to build the common mcpHandlerConfig fields (sessionTimeout, unifiedServer) plus caller-provided options (handlerLog, logTag, apiKey, hmacSecret).
  • Introduced defaultHandlerConfigOptions so string fields are passed by name instead of positional arguments.

• Call-site deduplication

  • Updated internal/server/transport.go to use the helper for unified mode (logTag: "unified").
  • Updated internal/server/routed.go to use the helper inside the backend loop (logTag: "routed:"+backendID).

• Focused coverage

  • Added TestBuildDefaultHandlerConfig in internal/server/middleware_test.go to validate field mapping and keep future config-field additions centralized.

finalHandler := buildMCPHandler(serverFactory, buildDefaultHandlerConfig(
    unifiedServer,
    sessionTimeout,
    defaultHandlerConfigOptions{
        handlerLog: logTransport,
        logTag:     "unified",
        apiKey:     apiKey,
        hmacSecret: hmacSecret,
    },
))

[Copilot]

Pull request overview

This PR refactors MCP HTTP server setup by centralizing construction of the common mcpHandlerConfig used by both unified (transport) and routed server modes, reducing duplicated config wiring in multiple call paths.

Changes:

• Added buildDefaultHandlerConfig(...) to construct shared mcpHandlerConfig fields in one place.
• Updated unified and routed server creation paths to use the new helper.
• Added a focused unit test to validate config field mapping.

Show a summary per file

File	Description
internal/server/transport.go	Replaces inline mcpHandlerConfig{...} construction with buildDefaultHandlerConfig(...) for unified mode.
internal/server/routed.go	Replaces inline mcpHandlerConfig{...} construction with buildDefaultHandlerConfig(...) per backend in routed mode.
internal/server/middleware.go	Introduces the shared buildDefaultHandlerConfig(...) helper that returns an mcpHandlerConfig.
internal/server/middleware_test.go	Adds TestBuildDefaultHandlerConfig to assert field mapping from helper inputs to config fields.

Copilot's findings

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

[lpcox]

@copilot address review feedback

[Copilot]

@copilot address review feedback

Addressed in commit 5f10b06 by changing buildDefaultHandlerConfig to take a named options struct (removing positional string arguments), and updating both call sites plus the middleware test.