XMTP commands and validation

Best practices for handling commands, validating input, and filtering messages.

When to apply

Reference these guidelines when:

• Implementing slash commands
• Validating hex strings and addresses
• Filtering message types
• Using type guards instead of type assertions

Rule categories by priority

Priority	Category	Impact	Prefix
1	Validators	CRITICAL	validators-
2	Filters	HIGH	filters-
3	Type Guards	HIGH	guards-

Quick reference

Validators (CRITICAL)

• validators-hex - Use validHex() for hex string validation
• validators-address - Validate Ethereum addresses

Filters (HIGH)

• filters-message-types - Filter by message type (SDK 2.0+: use direct imports isText, isReaction, isReply, etc. from @xmtp/agent-sdk; keep filter.fromSelf, filter.hasDefinedContent)
• filters-sender - Filter out self-messages
• filters-content - Check for defined content

Type Guards (HIGH)

• guards-codec - Use usesCodec() instead of type assertions
• guards-content-type - Use filter helpers for type safety

How to use

Read individual rule files for detailed explanations:

rules/validators-hex.md
rules/filters-message-types.md
rules/guards-codec.md