feat(mcp): add types and interfaces for MCP server

[galligan]

Add core type definitions for MCP server implementation:

• ServerOptions: Configuration for server creation
• Handler<I,O,E>: Generic handler function type
• ToolDefinition/ResourceDefinition: MCP entity schemas
• ServerContext: Request context with logger
• McpError: TaggedError subclass for MCP failures

Co-Authored-By: Claude Opus 4.5 noreply@anthropic.com

Contributes to #46

[galligan]

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• chore(outfitter): sync templates on pack #108
• chore(changesets): ignore app package #107
• fix(errors): avoid TaggedError extends warnings #106
• chore(release): align package versions to 0.1.0 #105
• docs: add README and CHANGELOG for testing, kit, outfitter #95
• feat(templates): add daemon project template #94
• feat(templates): add MCP server project template #93
• feat(templates): add CLI project template #92
• fix(cli): implement confirmDestructive prompts #104
• fix(cli): implement createCLI and command builder #103
• feat(kit): add @outfitter/kit meta-package #91
• docs(daemon): add README and CHANGELOG #90
• fix(daemon): fix locking module bugs (GREEN phase) #89
• test(daemon): add locking module tests (RED phase) #88
• feat(daemon): add errors, platform, and locking module stubs #87
• feat(outfitter): add doctor command for environment validation #86
• feat(outfitter): add init command with project scaffolding #85
• feat(daemon): add IPC communication and health checks #84
• feat(daemon): add types and lifecycle management #83
• feat(index): add FTS5 full-text search implementation #82
• feat(index): add types for FTS5 full-text search #81
• feat(testing): add MCP and CLI test harnesses #80
• feat(testing): add test fixture utilities #79
• feat(mcp): add MCP server implementation with typed handlers #78
• feat(mcp): add types and interfaces for MCP server #77 👈 (View in Graphite)
• feat(ui): add Shape discriminated union and render() #76
• feat(ui): add createTokens semantic color layer #75
• feat(state): add pagination helpers #74
• feat(logging): add DEFAULT_PATTERNS for common secret redaction #73
• feat(ui): add formatRelative() for human-readable timestamps #72
• feat(state): add encodeCursor/decodeCursor for pagination #71
• feat(types): add hashId() for deterministic short identifiers #70
• feat(contracts): add Logger.child() and fix AssertionError category #69
• feat(config): centralize environment variable access with Zod validation #42
• fix(logging): enable redaction by default when global rules exist #41
• docs(ui): add README, CHANGELOG, and TSDoc comments #39
• docs(state): add README, CHANGELOG, and TSDoc comments #38
• docs(file-ops): add README, CHANGELOG, and TSDoc comments #37
• docs(logging): add README, CHANGELOG, and TSDoc comments #36
• docs(config): add README, CHANGELOG, and TSDoc comments #35
• fix(cli): enforce cursor TTL #114
• fix(tests): remove placeholder tests #113
• chore(gitattributes): prefer ours for bun lockfiles #115
• main

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[greptile-apps]

Greptile Summary

• Adds foundational type definitions and interfaces for the MCP (Model Context Protocol) server framework as part of implementing dual-transport architecture (CLI + MCP)
• Creates new packages/mcp package with comprehensive type system including ToolDefinition, ResourceDefinition, McpError, and McpServer interfaces
• Integrates with existing contracts package using Handler<I,O,E> pattern and extends TaggedError system with JSON-RPC error codes for MCP failures

Important Files Changed

Filename	Overview
packages/mcp/src/types.ts	New file establishing core type definitions for MCP server including tool/resource definitions, error handling, and server interface contracts
packages/mcp/package.json	New package configuration with modular exports structure and dependencies on MCP SDK and internal packages

Confidence score: 4/5

• This PR is safe to merge with minimal risk as it only adds type definitions without runtime implementation
• Score reflects well-structured types that properly integrate with existing contracts, but includes complex generic signatures that warrant code review
• Pay close attention to packages/mcp/src/types.ts for the handler integration patterns and error taxonomy alignment

Sequence Diagram

sequenceDiagram
    participant User
    participant Client as "MCP Client"
    participant Server as "McpServer"
    participant Tool as "ToolDefinition"
    participant Handler as "Tool Handler"

    User->>Client: "Request tool execution"
    Client->>Server: "invokeTool(name, input)"
    Server->>Server: "Validate input against schema"
    Server->>Tool: "Find registered tool"
    Server->>Handler: "handler(validatedInput, context)"
    Handler->>Handler: "Process business logic"
    Handler-->>Server: "Return Result<output, error>"
    Server-->>Client: "Return tool execution result"
    Client-->>User: "Present result"

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[galligan]

Addressed review feedback: added McpError coverage to ensure the package has tests and kept the entrypoint export in place. Submitted the update with gt.

[galligan]

Restacked after downstack update (formatRelative test stabilization); no additional changes in this PR.