Delegate independent tasks to specialized agents working concurrently with isolated context.
295.4K 206.3K
View 
Epistemic Checkpoint
epistemic-checkpoint
Force verification before answering questions involving versions, dates, status, or "current" state. Prevents hallucinations at the REASONING level by checking assertions.yaml and WebSearch before forming beliefs. Triggers on software versions, release status, dates, and package versions.
SKILL.md
Full skill instructions
Epistemic Checkpoint
Force verification before answering questions involving versions, dates, status, or "current" state.
Purpose
Prevents the ROOT CAUSE of hallucinations - not just blocking wrong output, but preventing wrong REASONING. Claude's training data is stale; this skill forces verification before forming beliefs.
Triggers
Activate this skill when the question involves ANY of:
- Software versions (.NET, Node, React, Python, etc.)
- Release status (preview, LTS, GA, RC, deprecated)
- "Current" or "latest" anything
- Dates that might be after training cutoff
- Package versions
- API deprecations
MANDATORY Protocol
Step 1: Recognize Uncertainty
Say to yourself: "My training data may be stale for: [topic]"
Step 2: Check Local Ground Truth
Read ${CLAUDE_PLUGIN_ROOT}/blackboard/assertions.yaml
Search for relevant entries
If found - use that value with high confidence.
Step 3: If Not in Assertions - WebSearch
WebSearch("[software] [version] release date site:official-docs")
WebSearch("[software] LTS release 2025")
Prefer official sources:
- microsoft.com/dotnet for .NET
- nodejs.org for Node
- python.org for Python
Step 4: State Verified Facts
Say: "Based on [source], [software] [version] is [status] as of [date]."
Step 5: THEN Proceed
Only now answer the actual question with the verified baseline.
Red Flag Thoughts (REJECT THESE)
| If you think... | Actually do... |
|---|---|
| "I'm pretty sure .NET 10 is..." | WebSearch to verify |
| "This is probably still preview" | Check assertions.yaml |
| "I remember this from training" | Training is stale, verify |
| "This is a simple factual question" | Simple facts are often WRONG |
| "The user said it's preview" | User might be wrong too, verify |
Anti-Pattern Examples
WRONG:
"If targeting .NET 10 preview, use C# 14 extension types..."
CORRECT:
"Let me verify .NET 10 status... [WebSearch] ...
.NET 10 is LTS (released November 2025), not preview.
Standard extension methods work fine."
WRONG:
"React 19 is still in beta, so..."
CORRECT:
"Checking React 19 status... [WebSearch] ...
React 19 was released December 2024 as stable.
Proceeding with React 19 stable patterns."
Common Danger Patterns
| Topic | Danger Pattern | Likely Truth |
|---|---|---|
| .NET | "preview", "not released" | .NET 10 LTS since Nov 2025 |
| React | "beta", "experimental" | React 19 stable since Dec 2024 |
| Node | "current" without version | Always specify exact version |
| Python | "3.x is latest" | Verify - 3.13+ exists |
Output Format
When this skill activates, structure your verification as:
Epistemic Checkpoint
Claim to verify: [what you were about to assume]
Source checked: [assertions.yaml / WebSearch / official docs]
Verified fact: [the actual truth]
Confidence: [high/medium/low]
Proceeding with verified baseline...
More Other skills
Other
brand-guidelines
Applies Anthropic's official brand colors and typography to any sort of artifact that may benefit from having Anthropic's look-and-feel. Use it when brand colors or style guidelines, visual formatting, or company design standards apply.
179.7K 100.1K
View Other
theme-factory
Toolkit for styling artifacts with a theme. These artifacts can be slides, docs, reportings, HTML landing pages, etc. There are 10 pre-set themes with colors/fonts that you can apply to any artifact that has been creating, or can generate a new theme on-the-fly.
179.7K 89.5K
View Other
internal-comms
A set of resources to help me write all kinds of internal communications, using the formats that my company likes to use. Claude should use this skill whenever asked to write some sort of internal communications (status reports, leadership updates, 3P updates, company newsletters, FAQs, incident reports, project updates, etc.).
179.7K 76.1K
View Fundamental design principles for writing maintainable, testable Python code.
40.2K 21.9K
View 
Other
responsive-design
Modern responsive layouts using container queries, fluid typography, CSS Grid, and mobile-first strategies.
40.2K 20K
View Generate Playwright tests from scenarios using interactive browser exploration and validation.
39.7K 18.2K
View Automated website exploration and test case generation using Playwright.
39.7K 14.9K
View Modern React state management with Redux Toolkit, Zustand, Jotai, and React Query for every state category.
40.2K 14.7K
View Other
gdpr-data-handling
GDPR-compliant data handling with consent management, data subject rights, and privacy controls.
40.2K 14.3K
View Python error handling patterns including input validation, exception hierarchies, and partial failure handling. Use when implementing validation logic, designing exception strategies, handling batch processing failures, or building robust APIs.
40.2K 13.5K
View 
Other
refactor-plan
Detailed multi-file refactor planning with safety checks and rollback guidance.
39.7K 13K
View