Jeffallan

Design controlled failure experiments for distributed systems to examine how services recover. Produce failure injection scripts, monitoring plans, rollback procedures, and exercise guides, then turn findings into documented improvements.

• Planning controlled failure experiments
• Testing recovery after Kubernetes Pod failures
• Checking service behavior under network delays

Build cross-platform apps with Flutter and Dart, from reusable interface components to state management and navigation. The skill covers Riverpod or Bloc, GoRouter routing, automated tests, and profiling to reduce stuttering and unnecessary screen updates.

• Building reusable Flutter widgets and animations
• Managing application state with Riverpod or Bloc
• Setting up navigation and deep links with GoRouter

Build and debug Java applications with Spring Boot 3.x. This skill guides application design, API implementation, database query tuning, authentication, and testing, including WebFlux applications that process requests without blocking.

• Build APIs with Spring Boot
• Improve slow JPA queries
• Configure OAuth2/JWT authentication

Analyze and tune PostgreSQL databases using query execution plans, which show how queries run. This skill guides index design, JSONB searches, replication setup, maintenance, and monitoring, with checks to compare behavior before and after changes.

• Investigate slow queries with EXPLAIN
• Design indexes for JSONB searches
• Configure replication and monitor lag

Build NestJS APIs with TypeScript code for modules, request handlers, services, authentication, input validation, and database access. The skill also prepares Swagger API documentation and unit and end-to-end tests for the implemented features.

• Building a NestJS REST API
• Adding JWT and Passport authentication
• Connecting TypeORM or Prisma

Develop Salesforce workflows, interface components, and integrations using Apex and Lightning Web Components. The skill guides database queries, bulk processing, platform resource limits, testing, and deployment through Salesforce DX.

• Automating CRM tasks with Apex triggers
• Building Lightning Web Components
• Improving bulk processing and database queries

Clean, combine, summarize, and reshape tabular data with pandas DataFrames, Python's table-like data structures. Produces transformation code and validation checks, including time series processing and memory-conscious approaches for large datasets.

• Fill missing values and correct data types
• Combine tables using multiple matching columns
• Create grouped summaries and pivot tables

Build MCP servers and clients that connect AI systems to external tools and data. The skill defines validated inputs, implements tool and resource handlers, configures communication methods, and checks protocol behavior with the MCP Inspector.

• Expose external tools and data to AI systems through MCP
• Start an MCP project in TypeScript or Python
• Validate inputs and investigate protocol errors

Design and implement command-line tools with subcommands, options, interactive prompts, and progress indicators. Get command structures, configuration handling, clear error messages, and shell completion scripts, with guidance for automated use and testing across operating systems.

• Build a command-line tool with subcommands and options
• Add interactive prompts and progress indicators
• Provide bash, zsh, and fish command completion

Build PHP 8.3+ applications with Laravel or Symfony, including typed models, services, APIs, and tests. Use static analysis, which checks code without running it, alongside automated tests to verify the implementation.

• Building APIs with Laravel or Symfony
• Separating business logic from controllers
• Creating typed data objects and domain models

Investigate errors, crashes, and unexpected behavior by reproducing failures, tracing execution, and comparing logs. Tests one explanation at a time, then provides a verified fix, supporting evidence, and tests or safeguards to prevent recurrence.

• Investigate error messages and execution traces
• Find the cause of an application crash
• Compare logs to locate a failure

Design cloud architectures and migration plans for AWS, Azure, and GCP. Produce service diagrams, selection rationale, security designs, cost estimates, and recovery strategies, with deployment and rollback plans that account for availability and operational monitoring.

• Design a cloud architecture and explain service choices
• Plan a cloud migration and cutover checks
• Review cloud spending and resource sizes

Implement Kotlin applications with asynchronous tasks, shared code across platforms, Android interfaces, and servers. The skill covers state modeling, cancellation handling, tests, and code checks, with guidance for Compose, Ktor, and Flow data streams.

• Implement asynchronous tasks with coroutines and Flow
• Design shared code for Kotlin Multiplatform
• Build Android interfaces with Jetpack Compose

Design REST or GraphQL APIs by defining data relationships, requests, responses, and authentication. Produce OpenAPI specifications, machine-readable API descriptions, with consistent errors, pagination, and versioning plans, then validate contracts using a mock server.

• Designing a new API from business requirements
• Creating and validating OpenAPI specifications
• Standardizing errors and paginated responses

Build Angular 17+ applications with standalone components, routing, and shared application state. Covers reactive data handling with RxJS, performance improvements, and unit and integration tests, with code and explanations of architecture choices.

• Building Angular screens with standalone components
• Managing shared application state with NgRx
• Configuring lazy-loaded routes and access guards

Design and implement RAG systems, which retrieve documents to inform AI answers. Get document preparation strategies, vector database comparisons, combined keyword and meaning-based search, result reranking, and an evaluation plan for retrieval quality.

• Design an AI application that answers using internal documents
• Compare vector databases and document splitting strategies
• Improve search through keyword matching and result reranking

Build Go services and command-line tools with clear interfaces, explicit error handling, and concurrent tasks using goroutines and channels. Use pprof to investigate performance, then check behavior with benchmarks, structured test cases, fuzzing, and race detection.

• Implementing concurrent tasks with cancellation and error handling
• Building gRPC or REST services and command-line tools
• Investigating Go performance with pprof and benchmarks

Build machine learning workflows that connect data checks, training, evaluation, and deployment. The skill implements experiment tracking, model version management, and automated retraining, with reproducible environments and explicit validation thresholds before models enter production.

• Automate model training and retraining workflows
• Record and compare machine learning experiments
• Build a feature store for model input data

Create Kubernetes deployment files and Helm charts, reusable application packages. Configure permissions, network isolation, and persistent storage, then investigate pod failures and resource usage to adjust workloads and verify deployment health.

• Create deployment YAML and Helm charts
• Configure access permissions and network isolation
• Set up persistent storage and sensitive configuration

Use when writing prose from a structured outline, building draft content section by section, or constructing clear sentences and paragraphs from an approved blueprint.

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Use when creating nonlinear outlines, generating mindmap diagrams for article structure, mapping a knowledge domain visually, or bridging raw ideas into structured options for the user to select from.

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Use when scoring finished content against quality dimensions, evaluating whether a piece meets publishable standards, or determining which workflow phase needs rework based on quality gaps.

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Use when ingesting source material for a writing project, building a knowledge map from notes and documents, identifying research gaps, or preparing a research corpus for content creation.

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Use when capturing research artifacts to a vault or knowledge base, formatting source citations, saving synthesized connections from a writing project, or enriching a knowledge base with produced content.

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