AxAgent Observability For Rust

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, typesafe, AxAITypesafeClient, AxCancellationToken, AxAIServiceAbortedError, get_supported_ai_models, AxCredentialRequest, AxCredentialProvider, AxAIClient::owned_worker_factory, AxChatSession, AxChatStream, OpenAICompatibleClient, OpenAIResponsesClient, GoogleGeminiClient, AnthropicClient, AxUsageContext, AxUsageEvent, AxUsageObserver, set_usage_observer, AxRuntimeHooks, AxRateLimitInfo, AxRateLimiter, AxTracer, AxMeter, AxGlobals, set_rate_limiter, set_tracer, set_meter, AxBalancer, AxBalancerAdaptiveStrategy, AxBalancerStatsStore, AxInMemoryBalancerStatsStore, create_balancer_route_stats, update_balancer_route_stats, sample_balancer_route_health, MultiServiceRouter, ProviderRouter
• Agents And RLM: agent, AxAgent, AxAgent::with_child_agent
• 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.