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Mark Stuart

© 2026 Mark StuartSource

Projects

Open source projects, plus core contributions from my time at PayPal.

Featured

peek

DevTools for coding agents: session composition, cost attribution, compaction forensics, and config A/B benchmarking across Claude Code, Codex, and pi.Author

vitals

Local-first archive and baseline-deviation detector for Google Health API v4 (Fitbit, Pixel Watch) data.Author

tare

Lossless-by-default context compression for LLM coding agents: proxy, library, CLI, and MCP server. Local-first, cache-correct, reversible.Author

mcp-prune

Audit MCP server usage from Claude Code transcripts. Find idle servers to prune.Author

ai-statusline

Customizable status line for AI coding assistants: real-time display of model, tokens, cost, git status, and more.Author

graphql-agent-toolkit

Turn any GraphQL API into AI-agent-ready tools: MCP servers, LangChain tools, and standalone SDKs.Author

Core contributions

zoid

Cross-domain component framework for embedding rich UI widgets across origins.Core contributor

lusca

Application security middleware for Node.js, covering CSRF, CSP, and other common protections.Core contributor

paypal-checkout-components

UI components powering the PayPal Checkout integration used across the web.Core contributor

post-robot

Cross domain post-messaging on the client side using a simple listener/client pattern.Core contributor

beaver-logger

Client-side logging with super powers.Core contributor

jwt-csrf

Stateless CSRF protection using jsonwebtoken (JWT).Core contributor

All repositories53

53 results

pypi-axiRead-only PyPI wrapper - compact, token-efficient output for coding agents homebrew-axiRead-only Homebrew wrapper - compact, token-efficient output for coding agents peekDevTools for coding agents - session composition, cost attribution, compaction forensics, and config A/B benchmarking across Claude Code, Codex, and pi vitalsLocal-first archive and baseline-deviation detector for Google Health API v4 (Fitbit, Pixel Watch) data tareLossless-by-default context compression for LLM coding agents - proxy, library, CLI, and MCP server. Local-first, cache-correct, reversible.mstuart mcp-pruneAudit MCP server usage from Claude Code transcripts. Find idle servers to prune.pr-babysitterAI-powered PR babysitter - automatically fixes merge conflicts, failing CI, and unresolved review comments using Claude Code mcp-tool-lintStatic linter for MCP tool definitions - catch quality defects before deployment mcp-replayRecord and replay MCP server interactions for deterministic CI testing - nock/msw for MCP graphql-schema-policiesSemantic GraphQL schema design policy enforcement for CI pipelines graphql-contractConsumer-driven contract testing for GraphQL APIs - no Pact Broker required fetch-resilienceComposable resilience policies (retry, timeout, circuit breaker, bulkhead) for native fetch - edge-safe, zero dependencies graphql-operation-storeFramework-agnostic persisted query and trusted document store for GraphQL openapi-sentinelRuntime OpenAPI 3.1 request/response validation middleware - detect spec drift live versionkitFramework-agnostic API versioning with RFC 8594 Sunset and RFC 9745 Deprecation headers perf-fnMeasure async and sync function execution time using the Performance API has-disposableCheck if a value implements the Disposable or AsyncDisposable protocol mem-pressureMonitor Node.js memory usage and emit events when thresholds are exceeded graphql-hashGenerate a deterministic hash of a GraphQL query for caching and persisted queries is-runtimeDetect the current JavaScript runtime environment has-permissionCheck and assert Node.js Permission Model permissions at runtime signal-composeCompose multiple AbortSignals with AND, OR, and timeout semantics stream-to-valueConsume a Web ReadableStream into a string, Uint8Array, JSON object, or array of chunks set-extrasSet algebra operations - union, intersection, difference, symmetric difference, subset, superset portacachePortable key-value cache that auto-selects the best storage backend error-serializeSerialize and deserialize Error objects to plain objects, preserving cause chains abort-timerCreate an AbortSignal that aborts after a timeout, with reset and clear offload-fnRun a function in a Worker thread and get back a promise problem-responseRFC 9457 Problem Details for HTTP APIs - framework-agnostic, TypeScript-first error responses abort-raceRace multiple async operations with automatic AbortSignal cleanup for losers weakref-storeA WeakRef-based cache that automatically evicts entries when values are garbage collected web-stream-transformFunctional transform helpers for Web Streams - map, filter, take, batch, and tap dep-perf-analyzerMeasure the runtime performance impact of npm dependencies schema-guardCreate lightweight runtime type guards from a plain object schema deep-diff-patchCompute a minimal JSON-serializable diff between objects and apply it as a patch using-safeSafely use and dispose resources, even without the using declaration disposable-fromCreate Disposable wrappers for timers, event listeners, intervals, and custom cleanup graphql-pluck-typesExtract TypeScript interface definitions from a GraphQL schema SDL string context-localErgonomic typed context for async flows using AsyncLocalStorage api-perf-budgetDefine and enforce per-route latency budgets for Node.js APIs in CI error-with-causeCreate typed error classes with error codes, cause chains, and type guards map-extrasUtility functions for JavaScript Map - mapValues, filterEntries, merge, invert, and groupBy memcheck-nodeAutomated memory leak regression testing for Node.js iterable-opsLazy utility functions for sync and async iterables - map, filter, take, chunk, zip, flatten graphql-cost-guardianAnalyze and limit the cost of GraphQL queries using configurable field costs ai-statuslineCustomizable status line for AI coding assistants - real-time display of model, tokens, cost, git status, and more code-memoryPersistent memory for AI coding - semantic search, git history, and intelligent context preservation graphql-watchdogGraphQL performance toolkit - N+1 detection, normalized caching, cost analysis, and CI regression testing graphql-sentinelComprehensive GraphQL security scanner and runtime shield graphql-agent-toolkitTurn any GraphQL API into AI-agent-ready tools - MCP servers, LangChain tools, and standalone SDKs xoom-graphql-workshop⚡GraphQL Workshop @ Xoom - Spring 2019 🏎️graphql-workshop⚡GraphQL Workshop @ Venmo - Fall 2018 🏎️

Also on npm

zoid, post-robot, beaver-logger, jwt-csrf, memcookies