---
phase: 01-core-capture-pipeline
plan: 01
subsystem: mcp
tags: [mcp-sdk, zod, typescript, stdio, stdout-guard]

# Dependency graph
requires: []
provides:
  - MCP server skeleton with stdio transport handshake
  - Stdout guard preventing transport corruption
  - Stderr-only logger module
  - Shared TypeScript types and Zod schemas for tool inputs
  - Stub tools (start_capture, get_capture_status) and resource template (capture-grid)
affects: [01-02, 01-03]

# Tech tracking
tech-stack:
  added: ["@modelcontextprotocol/sdk ^1.29.0", "zod ^3.25.0", "node-screenshots ^0.2.8", "sharp ^0.34.5", "tsx ^4.0.0", "tsup ^8.0.0"]
  patterns: ["stdout guard as first code in entry point", "stderr-only logging via logger module", "Zod schema validation on MCP tool inputs", "registerTool/registerResource API pattern"]

key-files:
  created: [package.json, tsconfig.json, src/index.ts, src/server.ts, src/logger.ts, src/types.ts, src/foundation.test.ts]
  modified: []

key-decisions:
  - "Used registerTool/registerResource API (not deprecated .tool()/.resource())"
  - "Stdout guard checks for string starting with '{' for JSON-RPC passthrough"
  - "Logger uses console.error internally for stderr output"

patterns-established:
  - "Stdout guard: first code in index.ts, before any imports"
  - "Logger: all application logging through logger.info/warn/error/debug to stderr"
  - "Types: Zod schemas for external API, TypeScript interfaces for internal types"
  - "MCP tools: registerTool with Zod inputSchema, async handler returning content array"

requirements-completed: [MCP-01, MCP-04]

# Metrics
duration: 4min
completed: 2026-04-12
---

# Phase 01 Plan 01: Project Foundation Summary

**MCP server scaffold with stdout guard, stderr logger, Zod-validated tool schemas, and stdio handshake working end-to-end**

## Performance

- **Duration:** 4 min
- **Started:** 2026-04-12T13:25:13Z
- **Completed:** 2026-04-12T13:28:51Z
- **Tasks:** 2
- **Files modified:** 9

## Accomplishments
- MCP server starts and completes protocol handshake over stdio with tools+resources capabilities
- Stdout guard prevents any non-JSON-RPC output from reaching stdout (console.log/warn/info all redirect to stderr)
- Two stub tools (start_capture, get_capture_status) and one resource template (capture://{sessionId}/grid) registered
- 6 passing tests covering logger, stdout guard, JSON-RPC passthrough, and Zod schema validation

## Task Commits

Each task was committed atomically:

1. **Task 1: Project scaffold, stdout guard, logger, and shared types** - `aadc020` (feat)
2. **Task 2: MCP server skeleton with stub tools and resource template** - `37a9009` (feat)

## Files Created/Modified
- `package.json` - Project manifest with MCP SDK, zod, node-screenshots, sharp dependencies
- `tsconfig.json` - TypeScript config with NodeNext module resolution and strict mode
- `src/index.ts` - Entry point with stdout guard and console.log override (D-19)
- `src/server.ts` - McpServer with start_capture, get_capture_status tools and capture-grid resource
- `src/logger.ts` - Stderr-only logger with info/warn/error/debug methods (D-18)
- `src/types.ts` - SessionState, CaptureConfig, CaptureFrame, CaptureSession types + Zod schemas
- `src/foundation.test.ts` - 6 tests for logger, stdout guard, and schema validation
- `.gitignore` - Excludes node_modules, dist, tsbuildinfo

## Decisions Made
- Used `registerTool`/`registerResource` API (not deprecated `.tool()`/`.resource()` methods) per research findings
- Stdout guard uses string-starts-with-'{' heuristic for JSON-RPC passthrough, matching research pattern
- Logger uses `console.error` internally (simplest stderr approach, works with Node.js test runner)

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
None

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- Server skeleton ready for capture engine integration (Plan 01-02)
- Stub tool handlers ready to be replaced with real session management
- Resource template ready to serve grid images once grid compiler is built
- All Zod schemas in types.ts ready for reuse in tool handlers

## Self-Check: PASSED

- All 8 created files verified present on disk
- Commit aadc020 (Task 1) verified in git log
- Commit 37a9009 (Task 2) verified in git log

---
*Phase: 01-core-capture-pipeline*
*Completed: 2026-04-12*