* chore(stdlib): add conformance tooling for the skills library
The library had no gate that could express what a valid skill is, so
malformed frontmatter, over-budget files and credential literals went
unnoticed. These scripts define and enforce that contract.
- validate-skills.py: extend with Agent Skills v1.0 conformance -
naming rules and directory agreement, an explicit activation trigger
in the description, canonical layout, the 500-line SKILL.md budget,
relative-link integrity, and two security rules (no unrestricted
Bash(*) grant, no credential literals). Structural checks now read a
skill as a whole so material moved into references/ still counts.
- split-skill-references.py: move the heaviest sections of an oversized
SKILL.md into references/. Verifies line by line that every source
line lands in exactly one output and refuses to write otherwise.
- generate-skill-inventory.py: derive SKILLS_INVENTORY.md and
DIRECTORY_STRUCTURE.md from the tree so they cannot drift.
- generate-skill-catalog.py: index the canonical layout only, count
references/ toward a skill's size, and stop truncating descriptions
at 200 characters - the catalog is the discovery surface and must
carry the activation trigger.
- .gitignore: Python bytecode from these scripts, and local .pcl state.
Reviewed-by: Security Analyst, Compiler Engineer, DevX Engineer
* fix(stdlib): bring all 174 skills to Agent Skills v1.0 conformance
No skill in the library was conformant. 41 of 175 failed the existing
validator outright, and none satisfied the spec. This pass fixes the
tree and records the result. See stdlib/CHANGELOG.md for the per-skill
versioning and migration notes.
BREAKING CHANGE: one skill removed, five moved, seven with a capability
withdrawn. Library version 2.0.0 -> 3.0.0.
Structure
- Convert 71 skills stored as flat files to <category>/<name>/SKILL.md,
the layout the spec requires and the only one able to carry companion
resources.
- Rename 5 directories that disagreed with their declared name:, so
resolution by path and by name stop giving different answers. The
repository docs already referenced the corrected paths.
- Merge the duplicate legal-technology skills into legaltech-expert and
delete legal-tech-expert, carrying over everything the survivor
lacked.
Metadata
- Repair 20 unparseable frontmatters: an H1 preceded the --- block and
the key was skill_id: instead of name:, so any parser reading
frontmatter at offset 0 saw no metadata at all. The objectives,
prerequisites and outcome they carried become real body sections.
- Add the missing version: to 21 skills, fold keywords into tags, move
expertise_level under metadata, and align 10 category: values with
their directory.
Discoverability
- Give all 174 descriptions an explicit "Use when ..." trigger, built
from each skill's own tags and section headings. 152 previously said
only what the skill was about, leaving an agent nothing to match on.
Progressive disclosure
- Split 127 oversized skills, moving bulk material into references/ read
on demand and leaving an index behind. A SKILL.md now averages 277
lines instead of 644 and none exceeds 500. Verified lossless line by
line against the previous revision.
Security
- Withdraw the unrestricted Bash(*) grant from 7 skills; none of the six
non-financial ones contained a single shell command. finance-expert
documents code that charges cards and reads bank accounts, so it now
grants no shell at all.
- Remove credential literals: Stripe keys, two JWT signing keys, an
Express session secret, a Redis password and WiFi credentials, all
inlined in examples. They load from the environment now.
- finance-expert: idempotency keys were documented but absent, so a
retry double-charged; webhook signature failures were not caught, so a
forged event raised uncaught instead of being rejected;
int(amount * 100) truncated fractions of a cent. All fixed, plus a
money-movement guardrails section.
- trading-expert: place_order routed without any pre-trade risk check
although a RiskManager sat unused in the next section. Risk validation
now runs before routing and raises rather than returning a boolean a
caller can ignore; live routing is opt-in.
- Correct an Ansible Vault example that showed plaintext under an
"encrypted" label.
Also fixes 8 broken documentation links and a prematurely closed code
fence in skill-creator-expert that leaked template content into prose.
Per the repository file-organization policy, four stale progress reports
(SKILLS_MANIFEST, COMPLETE_SKILLS_LIBRARY, COMPLETE_LIBRARY_MANIFEST,
PHASE_3_DATA_ANALYTICS) move out of stdlib/ into the gitignored
.roadmap/status/stdlib/; they claimed 31 of 100 skills complete. They
appear here as deletions because .roadmap/ is not tracked.
Reviewed-by: Security Analyst, Language Designer, DevX Engineer,
Documentation Specialist
* fix(skills): resolve standard library skills from their real layout
No stdlib skill was resolvable. SkillResolver looked for
`<stdlibDir>/<name>.md` with stdlibDir defaulting to `stdlib/skills`, a
directory that does not exist, and the path ignored the category level
the library actually uses. The two LSP providers had the same wrong
directory and scanned only one level deep, so neither completion nor
go-to-definition could see a skill either.
- skill-discovery.ts: enumerate skill entry points across the shapes in
use - a flat `<name>.md`, `<name>/SKILL.md`, and
`<category>/<name>/SKILL.md` - while skipping references/, scripts/
and assets/, which hold supporting material rather than entry points.
- skill-resolver.ts: point stdlibDir at `stdlib`, and look the name up
as a directory under any category as well as the two legacy shapes, so
existing custom stdlib directories keep working. The name is used as a
single path segment and rejected if it contains a separator or
traversal, so a reference cannot escape the stdlib root.
- Rewire both LSP providers onto the shared discovery helper.
Tests: 13 new cases covering the layouts, ordering, the references/
exclusion, path-traversal rejection, and an integration test that
resolves real shipped skills by bare name.
Reviewed-by: Compiler Engineer, Runtime Architect, Security Analyst
* feat(stdlib): add 17 skills covering the library's largest gaps
Selection was driven by cross-referencing coverage against observed usage
rather than by intuition: Stack Overflow and GitHub Octoverse data for
which technologies matter, and install rankings on public agent-skill
registries for the shape of skills people actually use.
That comparison found a mismatch of form, not only of coverage. The
most-installed skills in the ecosystem are procedures - tdd, refactoring,
frontend design, browser automation - while all 174 existing skills were
domain knowledge shaped as <domain>-expert. The new workflows/ category
closes that gap and introduces the <activity>-workflow convention.
New category workflows/ (4)
- tdd-workflow, refactoring-workflow, debugging-workflow,
code-review-workflow. code-review-workflow complements rather than
replaces code-review-expert: procedure versus judgement. Merge them if
the split proves confusing in use.
Applied AI (3) - the largest coverage gap
- llm-engineering-expert, rag-expert, agent-engineering-expert.
The library referenced LLMs in tags but covered none of it: pgvector
appeared zero times across 174 skills, LangChain once, MCP twice
despite the repository shipping an MCP integration guide.
Capabilities (2)
- document-processing-expert (PDF, DOCX, XLSX, PPTX in one skill),
browser-automation-expert (a client against third-party sites,
distinct from playwright-expert which tests your own application).
Data (3)
- mysql-expert, the second most used database and previously absent
while rarer stores had skills; analytical-databases-expert;
stream-processing-expert.
Security (3)
- secrets-management-expert, supply-chain-security-expert (OWASP A03
2025), identity-access-expert (OWASP A01).
Interface and meta (2)
- accessibility-expert: design/ held only design-expert, which despite
its name covers software architecture, so WCAG had no home.
- skill-router: find and compose skills across 191, with a
disambiguation table for overlapping pairs.
Grouping by decision context rather than by technology keeps the growth
to 17 skills for roughly 50 topics. Five vector stores live inside
rag-expert; four document formats inside document-processing-expert.
Per-tool depth sits in references/, which the progressive-disclosure work
in 3.0.0 made cheap.
Four further gaps are better served by extending existing skills -
PyTorch and TensorFlow in ml-expert, OpenTelemetry in monitoring-expert,
Pulumi and Crossplane in terraform-expert - and are not in this change.
Library 3.0.0 -> 3.1.0, additive only. Adds the workflows label to the
inventory generator; catalogue, inventory, structure and CHANGELOG
regenerated.
Reviewed-by: Product Strategist, Security Analyst, DevX Engineer,
Documentation Specialist
* fix(test): create test directories with mkdtempSync
CodeQL flagged js/insecure-temporary-file (CWE-377) on both suites.
`join(tmpdir(), <predictable name>)` followed by mkdirSync creates a
world-readable directory at a guessable path, so another local user can
pre-create it or plant a symlink between the name being computed and the
directory being created.
mkdtempSync creates the directory atomically with a random suffix and
0700 permissions, which closes both the disclosure and the race.
One occurrence is new in this branch (skill-discovery); the other
pre-dates it in skill-resolver and is fixed in the same pass rather than
left as a known finding in a file this branch already touches.
5.5 KiB
name, version, description, category, tags, allowed-tools, metadata
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| serverless-expert | 1.1.0 | Design and implement production-grade serverless applications with optimal performance, cost efficiency, and scalability. Use when the user mentions serverless or FaaS, AWS Lambda, Azure Functions, Cloud Functions, cold starts, event-driven architecture, or API Gateway-fronted workloads. | domains |
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Serverless Expert
Design and implement production-grade serverless applications with optimal performance, cost efficiency, and scalability.
Learning Objectives
- Master serverless architecture patterns and best practices
- Build event-driven systems with AWS Lambda and Azure Functions
- Implement Function-as-a-Service (FaaS) applications
- Design for cold starts and optimization strategies
- Integrate serverless with API Gateway and event sources
Prerequisites
- Strong cloud platform knowledge (AWS/Azure/GCP)
- Understanding of event-driven architectures
- Knowledge of microservices patterns
- Familiarity with Infrastructure as Code
Core Concepts
Function-as-a-Service (FaaS)
Cloud computing model where functions execute in response to events without managing servers. Platform automatically provisions, scales, and manages infrastructure based on demand.
Event-Driven Architecture
Design paradigm where functions react to events from various sources (HTTP requests, database changes, file uploads, queues). Enables loose coupling and scalability.
Cold Starts & Warm Starts
Cold start occurs when function executes for first time or after idle period, requiring initialization. Warm starts reuse existing execution environment for faster response times.
Serverless Orchestration
Coordination of multiple serverless functions in workflows using services like AWS Step Functions or Azure Durable Functions. Enables complex business logic across distributed functions.
Serverless Security
Security considerations including IAM roles, function permissions, API authentication, secrets management, and VPC networking for serverless workloads.
Best Practices
Function Design
- Keep functions small and single-purpose
- Design for idempotency to handle retries safely
- Use environment variables for configuration
- Implement proper error handling and logging
- Return appropriate HTTP status codes
- Version functions for gradual rollouts
- Minimize cold start impact with provisioned concurrency
Performance Optimization
- Reuse connections and clients outside handler
- Use connection pooling for databases
- Minimize package size and dependencies
- Enable Lambda layers for shared code
- Optimize memory allocation (CPU scales with memory)
- Use async/await for concurrent operations
- Implement caching strategies
Event-Driven Patterns
- Use dead letter queues for failed events
- Implement exponential backoff for retries
- Design for eventual consistency
- Use event sourcing for audit trails
- Implement circuit breakers for external services
- Batch process events when possible
- Use fan-out patterns for parallel processing
Cost Optimization
- Right-size memory allocation
- Use reserved concurrency carefully
- Implement request throttling
- Archive logs to S3 after retention period
- Use S3 lifecycle policies
- Monitor and alert on cost anomalies
- Consider compute savings plans
Anti-Patterns
Common Mistakes
- Long-running functions exceeding timeout limits
- Not handling cold starts appropriately
- Synchronous processing of independent tasks
- Storing state in function memory
- Hardcoding configuration values
- Not implementing proper monitoring
- Ignoring concurrency limits
- Recursive function calls without limits
Design Issues
- Functions doing too much (violating single responsibility)
- Tight coupling between functions
- Not using infrastructure as code
- Inadequate error handling and retries
- Missing dead letter queues
- Not implementing tracing
- Ignoring security best practices
- Poor secret management
Reference Documentation
Detailed material lives alongside this skill and is read on demand:
- Code Examples — AWS Lambda with Advanced Patterns, Serverless Framework Configuration
Resources
Serverless Platforms
- AWS Lambda - Leading FaaS platform
- Azure Functions - Microsoft serverless
- Google Cloud Functions
- Cloudflare Workers - Edge computing
- Vercel Functions - Frontend-focused
- Netlify Functions
Frameworks & Tools
- Serverless Framework - Multi-cloud IaC
- AWS SAM - AWS native framework
- Terraform - Infrastructure as code
- Pulumi - Modern IaC with programming languages
- LocalStack - Local AWS emulation
- serverless-offline - Local development
Monitoring & Observability
- AWS X-Ray - Distributed tracing
- CloudWatch - Logs and metrics
- Datadog - APM and monitoring
- New Relic - Observability platform
- Lumigo - Serverless monitoring
- Thundra - Debugging and profiling
Learning Resources
- AWS Well-Architected Serverless Lens
- Serverless Architecture Patterns
- Azure Serverless Computing Cookbook
- Serverless Stack - Full-stack tutorial
- Production-Ready Serverless course
- AWS Lambda Power Tuning
Part of the PCL Standard Library - Build scalable, cost-effective applications without managing servers.