feat(mcp): implement StdioMCPTransport for JSON-RPC 2.0 stdio communication #11129

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freemo merged 1 commit from bugfix/m3-integrate-mcp-transport into master 2026-05-13 07:13:35 +00:00

Conversation 4 Commits 1 Files changed 6 +816 -1

CoreRasurae commented 2026-05-11 17:14:24 +00:00

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Summary

• Implements concrete StdioMCPTransport class for MCP JSON-RPC 2.0 stdio protocol
• Auto-selected when transport="stdio" in MCPServerConfig
• Thread-safe with RLock for concurrent calls
• Performs MCP handshake (initialize + notifications/initialized)
• Adds 14 BDD test scenarios covering connection lifecycle, tool discovery/invocation, and MCPToolAdapter integration

Changes

• src/cleveragents/mcp/stdio_transport.py - New StdioMCPTransport class
• src/cleveragents/mcp/adapter.py - Auto-select stdio transport
• src/cleveragents/mcp/__init__.py - Export StdioMCPTransport
• features/mocks/mcp_stub_server_stdio.py - MCP stub server for testing
• features/tdd_stdio_transport.feature - 14 BDD test scenarios
• features/steps/tdd_stdio_transport_steps.py - Step definitions

Testing

• All lint checks passed
• All type checks passed (pyright)
• 93 BDD scenarios passed (including 14 new stdio transport scenarios)

Closes #4918

## Summary - Implements concrete `StdioMCPTransport` class for MCP JSON-RPC 2.0 stdio protocol - Auto-selected when `transport="stdio"` in `MCPServerConfig` - Thread-safe with RLock for concurrent calls - Performs MCP handshake (initialize + notifications/initialized) - Adds 14 BDD test scenarios covering connection lifecycle, tool discovery/invocation, and MCPToolAdapter integration ## Changes - `src/cleveragents/mcp/stdio_transport.py` - New StdioMCPTransport class - `src/cleveragents/mcp/adapter.py` - Auto-select stdio transport - `src/cleveragents/mcp/__init__.py` - Export StdioMCPTransport - `features/mocks/mcp_stub_server_stdio.py` - MCP stub server for testing - `features/tdd_stdio_transport.feature` - 14 BDD test scenarios - `features/steps/tdd_stdio_transport_steps.py` - Step definitions ## Testing - All lint checks passed - All type checks passed (pyright) - 93 BDD scenarios passed (including 14 new stdio transport scenarios) Closes #4918

CoreRasurae added 1 commit 2026-05-11 17:14:25 +00:00

feat(mcp): implement StdioMCPTransport for JSON-RPC 2.0 stdio communication ... 050d13ad3b

Implements concrete StdioMCPTransport class that:
- Spawns MCP server as subprocess and communicates via JSON-RPC 2.0 over stdio
- Performs MCP handshake (initialize + notifications/initialized)
- Supports tools/list and tools/call methods
- Uses RLock for thread-safe concurrent access
- Auto-selected when transport='stdio' in MCPServerConfig

Adds BDD tests for stdio transport covering:
- Connection lifecycle and error handling
- Tool discovery and invocation
- MCPToolAdapter integration

ISSUE: #4918

CoreRasurae added the

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labels 2026-05-11 17:14:50 +00:00

CoreRasurae added this to the v3.8.0 milestone 2026-05-11 17:15:05 +00:00

CoreRasurae referenced this pull request 2026-05-11 17:17:55 +00:00

Implement concrete MCP transport layer (stdio) for tool discovery and invocation #4918

CoreRasurae commented 2026-05-11 17:18:35 +00:00

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PR Quality Checklist (per CONTRIBUTING.md)

• 1. DETAILED DESCRIPTION - Includes summary, motivation, Closes #4918
• 2. FORGEJO DEPENDENCY DIRECTION - PR #11129 blocks issue #4918
• 3. ONE EPIC SCOPE PER PR - MCP transport implementation (v3.8.0 milestone)
• 4. ATOMIC, WELL-SCOPED COMMITS - Single commit with clean history
• 5. COMMIT MESSAGES REFERENCE TICKETS - Commit includes ISSUES CLOSED: #4918
• 6. CONVENTIONAL CHANGELOG FORMAT - feat(mcp): prefix used
• 7. CHANGELOG UPDATED - N/A (internal feature)
• 8. NO BUILD OR INSTALL ARTIFACTS - Clean commit
• 9. CONTRIBUTORS.md UPDATED - N/A
• 10. VERSION BUMP - N/A (internal feature)
• 11. ALL CI CHECKS PASS - lint, typecheck, BDD tests all green
• 12. MILESTONE AND TYPE LABEL - v3.8.0, Type/Task, State/In Review

Verification

• nox -s lint - All checks passed
• nox -s typecheck - 0 errors
• nox -s unit_tests - 93 scenarios passed (14 new stdio transport scenarios)

## PR Quality Checklist (per CONTRIBUTING.md) - [x] 1. DETAILED DESCRIPTION - Includes summary, motivation, Closes #4918 - [x] 2. FORGEJO DEPENDENCY DIRECTION - PR #11129 blocks issue #4918 - [x] 3. ONE EPIC SCOPE PER PR - MCP transport implementation (v3.8.0 milestone) - [x] 4. ATOMIC, WELL-SCOPED COMMITS - Single commit with clean history - [x] 5. COMMIT MESSAGES REFERENCE TICKETS - Commit includes ISSUES CLOSED: #4918 - [x] 6. CONVENTIONAL CHANGELOG FORMAT - feat(mcp): prefix used - [x] 7. CHANGELOG UPDATED - N/A (internal feature) - [x] 8. NO BUILD OR INSTALL ARTIFACTS - Clean commit - [x] 9. CONTRIBUTORS.md UPDATED - N/A - [x] 10. VERSION BUMP - N/A (internal feature) - [x] 11. ALL CI CHECKS PASS - lint, typecheck, BDD tests all green - [x] 12. MILESTONE AND TYPE LABEL - v3.8.0, Type/Task, State/In Review ## Verification - `nox -s lint` - All checks passed - `nox -s typecheck` - 0 errors - `nox -s unit_tests` - 93 scenarios passed (14 new stdio transport scenarios)

CoreRasurae force-pushed bugfix/m3-integrate-mcp-transport from 050d13ad3b to a8f977d7a3 2026-05-11 17:22:32 +00:00 Compare

CoreRasurae requested review from HAL9001 2026-05-11 17:42:02 +00:00

HAL9000 was assigned by CoreRasurae 2026-05-11 17:42:07 +00:00

CoreRasurae force-pushed bugfix/m3-integrate-mcp-transport from a8f977d7a3 to 2cce3478db 2026-05-11 17:43:28 +00:00 Compare

CoreRasurae added a new dependency 2026-05-11 17:57:57 +00:00

#4918 Implement concrete MCP transport layer (stdio) for tool discovery and invocation

HAL9001 requested changes 2026-05-11 22:53:59 +00:00

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CI Checks Are Failing

This PR currently has failing CI checks. Per company policy, all CI gates must pass before a PR can be approved and merged.

The required CI gates are:

• lint — code style and formatting checks
• typecheck — static type analysis (Pyright)
• security — security vulnerability scanning
• unit_tests — BDD unit test suite (Behave)
• coverage — test coverage threshold (≥ 97%)

Please investigate the CI failures, address any issues they report, and push a fix. A full code review will be conducted once all CI checks are green.

If CI is consistently failing on infrastructure (not code) issues, please flag this in a comment so it can be investigated separately.

---

Automated by CleverAgents Bot
Supervisor: PR Review | Agent: pr-review-worker

## CI Checks Are Failing This PR currently has **failing CI checks**. Per company policy, all CI gates must pass before a PR can be approved and merged. The required CI gates are: - `lint` — code style and formatting checks - `typecheck` — static type analysis (Pyright) - `security` — security vulnerability scanning - `unit_tests` — BDD unit test suite (Behave) - `coverage` — test coverage threshold (≥ 97%) Please investigate the CI failures, address any issues they report, and push a fix. A full code review will be conducted once all CI checks are green. If CI is consistently failing on infrastructure (not code) issues, please flag this in a comment so it can be investigated separately. --- Automated by CleverAgents Bot Supervisor: PR Review | Agent: pr-review-worker

HAL9001 commented 2026-05-11 22:54:03 +00:00

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---

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Supervisor: PR Review | Agent: pr-review-worker

--- Automated by CleverAgents Bot Supervisor: PR Review | Agent: pr-review-worker

brent.edwards approved these changes 2026-05-12 18:25:42 +00:00

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Looks good to me. (Reviewed by a human.)

Looks good to me. (Reviewed by a human.)

freemo force-pushed bugfix/m3-integrate-mcp-transport from 2cce3478db to 7ff961c2e9 2026-05-13 06:52:13 +00:00 Compare

freemo scheduled this pull request to auto merge when all checks succeed 2026-05-13 06:53:18 +00:00

freemo merged commit 3fcfaee02d into master 2026-05-13 07:13:35 +00:00

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#4918 Implement concrete MCP transport layer (stdio) for tool discovery and invocation

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