iii-trigger-conditions

Original：🇺🇸 English

Translated

Registers a boolean condition function and attaches it to triggers via condition_function_id so handlers only fire when the condition passes. Use when gating triggers on business rules, checking user permissions, validating data before processing, filtering high-value orders, rate-limiting events, or conditionally skipping handlers based on payload content.

3installs

Sourceiii-hq/skills

Added on2026-04-21

NPX Install

npx skill4agent add iii-hq/skills iii-trigger-conditions

SKILL.md Content

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Trigger Conditions

Comparable to: Middleware guards, event filters

Key Concepts

Use the concepts below when they fit the task. Not every trigger needs a condition.

A Condition Function is a registered function that returns a boolean (
```
true
```
or
```
false
```
)
The engine calls the condition function before the handler; the handler runs only if
```
true
```
Attach a condition to any trigger type via
```
condition_function_id
```
in the trigger config
The condition function receives the same event data as the handler would
Works with all trigger types: http, queue, cron, state, stream, subscribe

Architecture

When a trigger fires, the engine first invokes the condition function with the event data. If the condition returns true, the handler executes normally. If false, the handler is skipped silently with no error or retry.

iii Primitives Used

Primitive	Purpose
`registerFunction({ id }, handler)` (condition)	Register the condition function (returns boolean)
`registerFunction({ id }, handler)` (handler)	Register the handler function
`registerTrigger({ type, function_id, config: { condition_function_id } })`	Bind trigger with condition gate

Reference Implementation

See ../references/trigger-conditions.js for the full working example — a condition-gated trigger

Also available in Python: ../references/trigger-conditions.py

Also available in Rust: ../references/trigger-conditions.rs where a business rule function filters events before the handler processes them.

Common Patterns

Code using this pattern commonly includes, when relevant:

registerFunction({ id: 'conditions::is-high-value' }, async (input) => input.new_value?.amount >= 1000)

— condition function

registerFunction({ id: 'orders::notify-high-value' }, async (input) => { ... })

— handler function

registerTrigger({ type: 'state', function_id: 'orders::notify-high-value', config: { scope: 'orders', key: 'status', condition_function_id: 'conditions::is-high-value' } })

— bind with condition

Condition returns
```
true
```
— handler executes
Condition returns
```
false
```
— handler is skipped silently
Use
```
conditions::
```
prefix for condition function IDs to keep them organized

Adapting This Pattern

Use the adaptations below when they apply to the task.

Replace the condition logic with your business rules (threshold checks, role validation, feature flags)
Conditions work on all trigger types — use them on HTTP triggers for auth guards, on queue triggers for message filtering
Keep condition functions lightweight and fast since they run on every trigger fire
Combine multiple business rules in a single condition function rather than chaining conditions
Condition functions can call
```
trigger()
```
internally to check state or other functions

Pattern Boundaries

For registering functions and triggers in general, prefer
```
iii-functions-and-triggers
```
.
For state change triggers specifically, prefer
```
iii-state-reactions
```
.
For invocation modes (sync/void/enqueue), prefer
```
iii-trigger-actions
```
.
Stay with
```
iii-trigger-conditions
```
when the primary problem is gating trigger execution with a condition check.

When to Use

Use this skill when the task is primarily about
```
iii-trigger-conditions
```
in the iii engine.
Triggers when the request directly asks for this pattern or an equivalent implementation.

Boundaries

Never use this skill as a generic fallback for unrelated tasks.
You must not apply this skill when a more specific iii skill is a better fit.
Always verify environment and safety constraints before applying examples from this skill.