AxAgent Observability For Rust

Use when writing Rust code with axllm for agent tracing, centralized and multi-tenant usage accounting, action logs, runtime diagnostics, replay, and production debugging.

Install

Install only this skill for Rust:

Shell

npx skills add https://ax-llm.github.io/ax/rust/ --skill 'ax-rust-agent-observability'

Published skill file: ax-rust-agent-observability/SKILL.md.

Source

Source: packages/rust/skills/ax-rust-agent-observability/SKILL.md
Version: 23.0.5

Skill Instructions

This skill helps an agent write Rust code with the generated Ax package axllm. Use the generated package API, examples, and manifests; do not import TypeScript-only APIs unless you are editing the TypeScript package.

When To Use

Inspect agent traces, runtime envelopes, usage, or action logs.
Register the process-wide usage observer and attribute model calls by tenant, user, request, run, or feature.
Attach callbacks for model/tool activity and runtime progress.
Debug agent loops through generated package state and examples.

Package Facts

Language: Rust.
Package: axllm.
Package API docs: API.md and axir-api.json.
Capability manifest: axir-capabilities.json.
Runnable examples: examples/.
Real network support: yes.
Scripted no-key transport support: yes.
Runtime profiles: javascript-quickjs.

Core Pattern

Rust

let helper = axllm::agent("question:string -> answer:string")?;
let out = helper.forward(&llm, inputs, None)?;

Centralized Usage Observer

Use the process-wide usage observer for application accounting across many agents, API routes, tenants, and users. Keep per-agent usage accessors for inspecting one agent instance after a run.

Rust

set_usage_observer(Some(Arc::new(move |event| {
    usage_queue.push(event);
})));
// Later: set_usage_observer(None);

The observer receives one normalized event for each completed chat or embedding call that reports provider usage. A fully consumed stream emits once; an unconsumed or cancelled stream may not emit.
Events include the operation, AI/provider name, model, normalized tokens, streaming flag, optional usage context, and available session or remote request IDs.
Attach usageContext in AI service options for stable application or environment defaults. Attach it in call or agent-forward option maps for tenant, user, request, run, and feature attribution.
Per-call context overrides service defaults. Nested attributes are shallow-merged.
The observer is process-wide, best-effort, and fail-open. Registering again replaces the previous observer. Clear it during test teardown or shutdown when appropriate.
The observer runs on the request path. Production callbacks should synchronously enqueue into a bounded concurrent queue and return immediately, then persist or aggregate out of band. Use a shared durable pipeline across processes or serverless instances.
Keep identifiers opaque and attributes low-cardinality. Do not attach prompts, responses, secrets, or other sensitive payloads.
Calculate currency cost downstream against a versioned provider/model pricing table.
Runnable provider example: src/examples/rust/generation/usage_observer.rs.

Relevant API Surface

AxAI: ai, OpenAICompatibleClient, OpenAIResponsesClient, GoogleGeminiClient, AnthropicClient, AxUsageContext, AxUsageEvent, AxUsageObserver, set_usage_observer, AxBalancer, AxBalancerAdaptiveStrategy, AxBalancerStatsStore, AxInMemoryBalancerStatsStore, create_balancer_route_stats, update_balancer_route_stats, sample_balancer_route_health, MultiServiceRouter, ProviderRouter
Agents And RLM: agent, AxAgent
Runtime Profiles: ProcessCodeRuntime, RuntimeCapabilities, RuntimeEnvelope, javascript-quickjs

Guardrails

Start from package examples for exact native syntax before inventing a new call shape.
Use provider-api examples only when the user explicitly has provider credentials available.
Use no-key examples for deterministic local checks and provider request mapping.
Treat AxIR as the source of generated package truth: if package docs disagree with source code, update the compiler and regenerate packages.
Do not copy repo-maintainer skills from tools/*/skills/ into user packages.