API reference

Index of public types, traits, and error codes in Meerkat.

This page is a quick-lookup index. For detailed usage with examples, see the Rust SDK reference.

Core types

Type	Module	Purpose
Agent	meerkat_core	Main agent execution engine
AgentBuilder	meerkat_core	Builder pattern for agent construction
Session	meerkat_core	Conversation state container
SessionId	meerkat_core	Unique session identifier (UUIDv7)
Message	meerkat_core	Conversation message enum (System, User, Assistant, ToolResults)
ToolDef	meerkat_core	Tool definition (name, description, JSON Schema)
ToolCall	meerkat_core	Tool invocation request from the model
ToolCallView	meerkat_core	Zero-allocation borrowed view of a tool call
ToolResult	meerkat_core	Tool execution result
Usage	meerkat_core	Token usage tracking
StopReason	meerkat_core	Why the LLM stopped (EndTurn, ToolUse, MaxTokens, StopSequence, ContentFilter, Cancelled)
RunResult	meerkat_core	Agent execution result (text, session ID, usage, structured output)
AgentEvent	meerkat_core	Streaming events during execution
AgentError	meerkat_core	Error types (LLM, tool, budget, hook, cancellation)
BudgetLimits	meerkat_core	Resource constraints (tokens, duration, tool calls)
RetryPolicy	meerkat_core	Exponential backoff configuration

Traits

Trait	Module	Purpose	Detailed docs
AgentLlmClient	meerkat_core	LLM provider abstraction	Rust SDK: providers
AgentToolDispatcher	meerkat_core	Tool routing abstraction	Rust SDK: tool system
AgentSessionStore	meerkat_core	Session persistence abstraction	Rust SDK: session stores
SessionService	meerkat_core::service	Session lifecycle (create/turn/interrupt/read/list/archive)	Rust SDK: sessions
Compactor	meerkat_core	Context compaction strategy	Memory guide
MemoryStore	meerkat_core	Semantic memory indexing	Memory guide
SkillEngine	meerkat_core::skills	Skill loading and injection	Skills guide
SkillSource	meerkat_core::skills	Skill discovery from various sources	Skills guide
HookEngine	meerkat_core	Hook pipeline execution	Hooks guide

SDK entry points

Function / Type	Purpose	Detailed docs
AgentFactory::new(cwd)	Create a factory for building agents	Rust SDK
build_ephemeral_service(factory, config, cap)	Build an in-memory session service	Rust SDK
meerkat::with_anthropic(key)	Quick-start builder for Anthropic	Rust SDK
Config::load()	Load layered configuration from disk	Configuration

Structured output types

Type	Purpose
OutputSchema	Schema definition with compat/strict/format options
MeerkatSchema	Normalized JSON Schema newtype
SchemaCompat	Lossy (best-effort lowering) or Strict (reject unsupported features)
SchemaFormat	Schema format version (MeerkatV1)
SchemaWarning	Provider-specific compilation warning
CompiledSchema	Provider-compiled schema output
SchemaError	InvalidRoot or UnsupportedFeatures

See the structured output guide for usage details.

Hook types

Type	Purpose
HookPoint	8 extension points (RunStarted through TurnBoundary)
HookCapability	Observe, Guardrail, Rewrite
HookExecutionMode	Foreground (blocking) or Background (async)
HookEntryConfig	Per-hook configuration (id, point, priority, runtime, failure policy)
HookRunOverrides	Per-run hook customization (add entries, disable by ID)
HookDecision	Allow or Deny with reason code
HookPatch	Mutations: LlmRequest, AssistantText, ToolArgs, ToolResult, RunResult
HookFailurePolicy	FailOpen or FailClosed

See the hooks guide for usage details.

Skill types

Type	Purpose
SkillId	Newtype skill identifier
SkillScope	Builtin, Project, User
SkillDescriptor	Skill metadata (id, name, description, required capabilities)
SkillDocument	Loaded skill with body content
SkillError	NotFound, CapabilityUnavailable, Ambiguous, Load, Parse

See the skills guide for usage details.

Wire types (meerkat-contracts)

Type	Purpose
CapabilityId	All known capabilities (Sessions, Streaming, Hooks, Shell, etc.)
CapabilityStatus	Available, DisabledByPolicy, NotCompiled, NotSupportedByProtocol
ErrorCode	Stable error codes with projections to JSON-RPC, HTTP, and CLI exit codes
WireError	Canonical error envelope (code, message, details, capability hint)
ContractVersion	Semver version (0.1.0 currently)
CoreCreateParams	Session creation parameters
StructuredOutputParams	Schema + retry count
CommsParams	Host mode + agent name
HookParams	Hook override entries
SkillsParams	Skill enablement + references

Error code reference

Every ErrorCode maps to a stable string, JSON-RPC code, HTTP status, and CLI exit code:

Error	Code string	JSON-RPC	HTTP	CLI
Session not found	SESSION_NOT_FOUND	-32001	404	10
Session busy	SESSION_BUSY	-32002	409	11
Session not running	SESSION_NOT_RUNNING	-32003	409	12
Provider error	PROVIDER_ERROR	-32010	502	20
Budget exhausted	BUDGET_EXHAUSTED	-32011	429	21
Hook denied	HOOK_DENIED	-32012	403	22
Agent error	AGENT_ERROR	-32013	500	30
Capability unavailable	CAPABILITY_UNAVAILABLE	-32020	501	40
Skill not found	SKILL_NOT_FOUND	-32021	404	41
Skill resolution failed	SKILL_RESOLUTION_FAILED	-32022	422	42
Invalid params	INVALID_PARAMS	-32602	400	2
Internal error	INTERNAL_ERROR	-32603	500	1

Provider clients

Client	Provider	Detailed docs
AnthropicClient	Anthropic Claude	Rust SDK: providers
OpenAiClient	OpenAI GPT	Rust SDK: providers
GeminiClient	Google Gemini	Rust SDK: providers

All implement LlmClient and normalize responses to LlmEvent (text deltas, tool call deltas, usage updates, done).

LlmError variants: RateLimited, ServerOverloaded, NetworkTimeout, ConnectionReset, ServerError, InvalidRequest, AuthenticationFailed, ContentFiltered, ContextLengthExceeded, ModelNotFound, InvalidApiKey, Unknown. Use error.is_retryable() to check if an error should be retried.

Storage implementations

Store	Feature flag	Purpose	Detailed docs
JsonlStore	jsonl-store (default)	File-based JSONL persistence	Rust SDK: session stores
RedbSessionStore	session-store	Embedded database (redb)	Rust SDK: session stores
MemoryStore	memory-store	In-memory (testing)	Rust SDK: session stores

See also

• Rust SDK reference - full API with examples
• Architecture - crate structure and agent loop
• Capability matrix - build profiles and feature behavior
• Session contracts - lifecycle operational contracts