Error Handling

iii has two broad error classes: SDK/local errors and engine/remote invocation errors. Agents should branch on the error code instead of matching only message strings.

Error Codes

Branch on exact code strings, but keep engine wire codes separate from SDK-local codes.

Code	Emitted by	Meaning	Typical handling
`function_not_found`	Engine and SDK local dispatch	No registered function is available under that ID	Check function ID, worker install/startup, discovery, and trigger type hints
`invocation_error`	Engine invocation/router path	Engine failed to route, remember, or complete the invocation	Inspect engine logs, protocol state, and worker connectivity
`invocation_stopped`	Engine invocation handler	Invocation was cancelled or stopped by the engine/runtime	Treat as failed work; decide whether caller should retry
`FORBIDDEN`	RBAC / worker-gated engine functions	RBAC denied the action	Do not retry blindly; inspect policy, auth context, and allowed functions
`timeout`	Engine/worker wire error when a worker reports lowercase timeout	Invocation exceeded a timeout reported through the wire protocol	Treat as timeout, but do not assume every SDK maps it to a timeout subclass
`function_not_invokable`	SDK local dispatch	Registration exists but cannot be invoked as a normal local function	Inspect registration/invocation type
`invocation_failed`	SDK worker handler wrappers	Local worker handler, HTTP-invoked function wrapper, or SDK-side handler path failed	Inspect handler logs, stacktrace, and payload validation
`TIMEOUT`	Node/Python SDK caller timeout	Client waited longer than `trigger()` timeout	Increase timeout only if the workload is expected to run long; otherwise optimize or enqueue

iii-error-handling

Error Handling

Error Codes