chore: refactors components composing StreamableHttpRunner into their own files and moves nested function to their own methods

[himanshusinghs]

Proposed changes

The StreamableHttpRunner starts a HealthCheckServer and an McpHttpServer both based on Express. All these components currently live in the same file. This PR splits the inidividual components into their own files and moves the nested function created in setupRoutes method to their own class methods.

The PR has no logic changes, pure refactor.

Please review the PR commit by commit:

1. Commit 1: Moves individual components in StreamableHttpRunner file to their own files. This change improves scanability of the code.
2. Commit 2 Moves the nested functions in setupRoutes method of McpHttpServer to their own class methods. This is a good change to ensure that we don't depend on lexical scope in the callbacks for some of the variables to be present.

Checklist

• I have signed the MongoDB CLA

[Copilot]

Pull request overview

This PR refactors the StreamableHttpRunner module by splitting the monolithic src/transports/streamableHttp.ts file into a directory structure with individual files for each component. It also converts nested functions within the setupRoutes method of MCPHttpServer into proper class methods.

Changes:

• Splits streamableHttp.ts into four files: streamableHttpRunner.ts, mcpHttpServer.ts, healthCheckServer.ts, and expressBasedHttpServer.ts under src/transports/streamableHttp/.
• Converts nested functions (reportSessionError, handleSessionRequest, initializeServer) in MCPHttpServer.setupRoutes into private class methods.
• Updates all import paths across source and test files to reference the new file locations.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/transports/streamableHttp.ts	Deleted — original monolithic file removed
src/transports/streamableHttp/streamableHttpRunner.ts	New file containing the StreamableHttpRunner class
src/transports/streamableHttp/httpServers/mcpHttpServer.ts	New file containing MCPHttpServer with nested functions refactored to methods
src/transports/streamableHttp/httpServers/healthCheckServer.ts	New file containing the HealthCheckServer class
src/transports/streamableHttp/httpServers/expressBasedHttpServer.ts	New file containing the ExpressBasedHttpServer abstract base class
src/lib.ts	Updated import path for StreamableHttpRunner
src/index.ts	Updated import path for StreamableHttpRunner
tests/integration/transports/*.test.ts	Updated import paths for StreamableHttpRunner (4 files)

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[coveralls]

Pull Request Test Coverage Report for Build 23048488605

Details

• 391 of 476 (82.14%) changed or added relevant lines in 6 files are covered.
• 34 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.3%) to 81.991%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/index.ts	0	1	0.0%
src/transports/streamableHttp/httpServers/expressBasedHttpServer.ts	59	70	84.29%
src/transports/streamableHttp/streamableHttpRunner.ts	112	130	86.15%
src/transports/streamableHttp/httpServers/mcpHttpServer.ts	200	255	78.43%

Files with Coverage Reduction	New Missed Lines	%
src/tools/mongodb/mongodbTool.ts	5	83.33%
src/common/session.ts	6	85.12%
src/tools/atlas/connect/connectCluster.ts	23	71.38%

Totals
Change from base Build 23016560869:	-0.3%
Covered Lines:	8160
Relevant Lines:	9849

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💛 - Coveralls