Agent Observability

Rule

The observability system auto-instruments every agent run with zero configuration. Traces, automated evals, and feedback collection work out of the box. All data lives in the app's own SQL database — no external services required. Templates can optionally export to Langfuse, Datadog, or any OTel-compatible platform.

Five Pillars

1. Traces

Every runAgentLoop() call is automatically instrumented via instrumentAgentLoop() in packages/core/src/observability/traces.ts. It captures:

• agent_run span — top-level parent with total duration and cost
• llm_call span — model name, token counts (input, output, cache read/write), cost
• tool_call spans — one per action invocation, with duration and success/error

The run span is NAMED by what started it, because the trace list shows that name and nothing else: a scheduled job is background_automation_run:<job name>, a chat turn is agent_run, and a turn a feature sent on the user's behalf is agent_run:<usageLabel> when the caller named it:

sendToAgentChat({
  message: "Enrich this record from the web",
  newTab: true,
  usageLabel: "crm:enrich-record", // → usage row label + `agent_run:crm:enrich-record`
});

Content (prompts, tool args, tool results) is redacted by default. Opt in through the declared observability config domain:

// server/plugins/config.ts
import { defineAppConfig } from "@agent-native/core/server";

export default defineAppConfig({
  observability: {
    enabled: true,
    capturePrompts: false,
    captureToolArgs: true, // capture action input args
    captureToolResults: false, // include tool results/error text on tool spans and $ai_generation entries
    evalSampleRate: 0.05, // 5% of runs get LLM-as-judge eval
    inferredSentimentEnabled: false,
    inferredSentimentSampleRate: 0,
    inferredSentimentModel: "gpt-5-6-luna",
  },
});

Optional inferred sentiment

Self-hosted apps default to no inferred sentiment. First-party apps hosted on agent-native.com automatically classify 100% of eligible user replies with gpt-5-6-luna; an explicit stored inferredSentimentEnabled: false remains an opt-out. Deployment overrides are AGENT_NATIVE_INFERRED_SENTIMENT=on|off, AGENT_NATIVE_INFERRED_SENTIMENT_SAMPLE_RATE=0..1, and AGENT_NATIVE_INFERRED_SENTIMENT_MODEL=<model>; off is always the emergency kill switch.

Classification uses only the original visible user text, capped at 2,000 characters, with no tools, temperature 0, an eight-token output, and a five second timeout. It skips attachment-only turns, internal continuations, chained background chunks, and first turns that have no preceding response to attribute. The managed Builder engine runs the classifier after the main response has streamed, so it does not contend with the user's response.

Successful classifications emit a content-free $ai_sentiment tracking event:

• sentiment: positive, negative, or neutral
• method: llm
• model / $ai_model: model that generated the preceding assistant response
• run_id / $ai_trace_id: preceding response run
• thread_id / $ai_session_id: conversation
• classification_trigger_run_id: run started by the classified user reply
• classifier_model and classifier_engine: classifier attribution

No raw message, prompt, or response text is persisted or tracked.

2. Feedback

Explicit — ThumbsFeedback component renders inline thumbs up/down on every agent message in the chat UI. Thumbs down opens a category popover (Inaccurate, Not helpful, Wrong tool, Too slow). Already wired into AssistantChat.tsx via React.lazy.

Implicit — computeSatisfactionScore(threadId) computes a Frustration Index (0-100) from conversation signals:

• Rephrasing detection (weight 30): consecutive similar user messages
• Abandonment (weight 20): session ends shortly after agent response
• Sentiment (weight 15): negative language patterns
• Length trend (weight 15): declining message lengths
• Retry patterns (weight 20): "try again", "no that's wrong"

Score interpretation: 0-20 healthy, 20-40 friction, 40-60 dissatisfied, 60+ broken.

Satisfaction scoring fires automatically after each feedback POST with a threadId.

3. Evals

Three layers, configured via evalSampleRate in the observability config:

Automated (every run): Deterministic scorers that run after every traced run:

• tool_success_rate — % of tool calls without errors
• step_efficiency — 1.0 for no-tool runs; penalizes excessive LLM iterations for tool-using runs
• latency_score — normalized against 10s/tool baseline
• cost_efficiency — normalized against 50 centicents/tool baseline
• error_recovery — 1.0 if the run recovered from tool errors or had none

LLM-as-judge (sampled): Runs on evalSampleRate fraction of runs. Calls the configured engine with a judge prompt that scores against custom criteria.

Dataset evaluation: runDatasetEval(datasetId) runs a golden dataset through the agent and scores each case.

Custom criteria use natural language rubrics:

const criteria: EvalCriteria = {
  name: "helpfulness",
  description: "Was the response helpful and complete?",
  rubric: "0.0 = completely unhelpful, 0.5 = partially helpful, 1.0 = fully resolved the user's need",
};

Evals (CI gate)

The three layers above score real production runs after the fact. For an active, deterministic gate, use the first-class *.eval.ts primitive from @agent-native/core/eval (source: packages/core/src/eval/*). It runs the actual agent loop against fixed inputs and exits non-zero below threshold, so it gates CI/deploys.

// evals/faq.eval.ts
import { defineEval, contains, llmJudge } from "@agent-native/core/eval";

export default defineEval({
  name: "answers the FAQ",
  input: { prompt: "What is your return policy?" },
  threshold: 0.7,
  scorers: [contains("30 days"), llmJudge({ criteria: "accuracy" })],
});

• Built-in scorers: exactMatch / contains / usesTool (pure JS) and llmJudge (provider-agnostic judge).
• Custom scorers: createScorer with the 4-step preprocess → analyze → generateScore → generateReason pipeline (only generateScore is required).
• Run as a gate: agent-native eval [pattern] [--json] [--threshold N] — discovers **/*.eval.ts and evals/*.ts, runs the agent, and exits non-zero if any eval is below its threshold. An app with no eval files exits 0. Complements (does not replace) the post-hoc scoring in evals.ts. See the Evals doc.

4. Experiments

A/B testing with sticky user-level assignment:

import { insertExperiment, updateExperiment } from "@agent-native/core/observability";

const exp = {
  id: crypto.randomUUID(),
  name: "sonnet-vs-haiku",
  status: "draft" as const,
  variants: [
    { id: "control", weight: 50, config: { model: "claude-sonnet-4-6" } },
    { id: "treatment", weight: 50, config: { model: "claude-haiku-4-5-20251001" } },
  ],
  metrics: ["cost", "latency", "satisfaction"],
  assignmentLevel: "user" as const,
  startedAt: null,
  endedAt: null,
  createdAt: Date.now(),
};
await insertExperiment(exp);
// Move it to "running" when ready to start collecting assignments.
await updateExperiment(exp.id, { status: "running" });

The agent loop reads active experiments via resolveActiveExperimentConfig() and applies the variant's model override automatically. Assignment uses consistent hashing — same user always gets the same variant.

Compute results with POST /_agent-native/observability/experiments/:id/results.

In production, experiment management routes require the caller's email in the comma-separated AGENT_NATIVE_EXPERIMENT_ADMIN_EMAILS allowlist. This gate is separate from normal app/org admin roles because an experiment affects every user in that deployment.

5. Dashboard

ObservabilityDashboard is a React component with 5 tabs:

• Overview — metric cards (runs, cost, latency, tool success, thumbs up rate, eval score)
• Conversations — trace list with drill-down to span detail
• Evals — eval stats and criteria breakdown bars
• Experiments — experiment list with status badges, drill-down to results
• Feedback — feedback stream, thumbs ratio, category badges

Add a dashboard route to any template:

// app/routes/observability.tsx
import { ObservabilityDashboard } from "@agent-native/core/client/observability";

export default function ObservabilityPage() {
  return (
    <div className="min-h-screen bg-background p-6">
      <ObservabilityDashboard />
    </div>
  );
}

API Endpoints

All auto-mounted at /_agent-native/observability/*:

Method	Path	Purpose
GET	/	Overview stats
GET	/traces	List trace summaries
GET	/traces/:runId	Trace detail (summary + spans)
GET	/traces/:runId/evals	Evals for a run
POST	/feedback	Submit feedback
GET	/feedback	List feedback entries
GET	/feedback/stats	Feedback aggregation
GET	/satisfaction	Satisfaction scores
GET	/evals/stats	Eval statistics
POST	/experiments	Create experiment
GET	/experiments	List experiments
GET	/experiments/:id	Experiment detail
PUT	/experiments/:id	Update experiment status
POST	/experiments/:id/results	Compute experiment results
GET	/experiments/:id/results	Get experiment results

All endpoints support ?since=N (ms timestamp) and ?limit=N query params.

SQL Tables

9 tables created automatically via ensureObservabilityTables():

• agent_trace_spans — individual trace spans
• agent_trace_summaries — aggregated run summaries
• agent_feedback — explicit user feedback
• agent_satisfaction_scores — computed frustration index
• agent_evals — evaluation results
• agent_eval_datasets — golden test datasets
• agent_experiments — experiment definitions
• agent_experiment_assignments — user → variant assignments
• agent_experiment_results — computed metric results

All tables are dialect-agnostic (SQLite + Postgres) and strictly additive.

Key Files

File	Purpose
packages/core/src/observability/types.ts	Shared type definitions
packages/core/src/observability/store.ts	SQL tables + CRUD
packages/core/src/observability/traces.ts	Auto-instrumentation
packages/core/src/observability/posthog-ai.ts	$ai_trace / $ai_span / survey sent emission, content bounding, $ai_error
packages/core/src/observability/feedback.ts	Feedback + Frustration Index
packages/core/src/observability/evals.ts	Eval engine (3 layers)
packages/core/src/observability/experiments.ts	A/B testing system
packages/core/src/observability/routes.ts	HTTP API handlers
packages/core/src/client/observability/ObservabilityDashboard.tsx	Admin dashboard
packages/core/src/client/observability/ThumbsFeedback.tsx	Inline feedback buttons
packages/core/src/client/observability/useObservability.ts	React Query hooks

Export to External Platforms

Core emits gen_ai.* semantic convention spans and deliberately registers no OpenTelemetry provider or exporter itself (observability/tracing.ts). To reach Langfuse, Datadog, Grafana, New Relic, or any OTel-compatible backend, the app registers its own TracerProvider.

There is no framework config field for an export endpoint or token, and there should not be: the backend credential belongs in the vault and in the app's own provider wiring, not in a config object or a settings row.

Live OpenTelemetry Spans (Optional)

The agent loop emits live OpenTelemetry spans for every run, model call, and tool call, so a host that already runs an OTel collector sees agent activity alongside its other distributed traces.

This layer is optional and no-op by default:

• @opentelemetry/api is an optional dependency. If it isn't installed, the span helpers degrade to silent no-ops — they never throw into the agent loop.
• Even with the api package installed, it ships a default no-op tracer. Spans become real only once the host registers a TracerProvider (via @opentelemetry/sdk-node or similar). The framework deliberately does not depend on the heavy SDK/exporter packages and never registers a provider itself — instrumentation is opt-in by the embedding app.

The loop emits agent.run (with agent.run_id, agent.thread_id, agent.user_id, agent.model), tool.call (tool.name + status), and llm.call spans, each finished with OK/ERROR status. This is purely additive to the in-house agent_trace_spans / agent_trace_summaries tables. Source: packages/core/src/observability/tracing.ts + traces.ts. See the Observability doc for the full table.

Tracking Bridge

Instrumented agent loops emit server-side tracking events for every run through track() from @agent-native/core/tracking, so configured PostHog, Agent-Native Analytics, Mixpanel, Amplitude, and webhook providers receive them through the same best-effort fan-out as other tracking events.

• Events: $ai_trace per run, $ai_span per tool call, and $ai_generation per model call. Every node carries the run id as $ai_trace_id and links upward through $ai_parent_id so a backend can rebuild the tree. $ai_session_id is the thread; the browser session is separate and ships as $session_id, read from X-Agent-Native-Session-Id via RequestContext.browserSessionId. The agent chat and the action client both send that header, so a UI action call and the agent's own call during one visit share a session. setAnalyticsSessionId() from @agent-native/core/client/analytics pins a custom id and opts it out of the 30-minute idle rotation. Emission lives in posthog-ai.ts.
• Each event is stamped with when it happened, not when the run flushed. The whole tree is emitted in one burst at run end, so track() takes an occurredAt and the trace tree keeps a real timeline.
• Agent-Native Analytics shape: the same event lands in analytics_events with mirrored query-friendly properties such as run_id, thread_id, cost_cents_x100, duration_ms, tool_calls, successful_tools, failed_tools, and status. A content-free tools array includes at most 50 tool names, start offsets, durations, statuses, and coarse error classes; interrupted calls are finalized as errors, and failed runs still emit with zero or known usage. tools_truncated marks longer runs while the rollup counts remain complete. Delegated runs add delegation_protocol, caller_app, a2a_task_id, and parent_run_id when available. parent_turn_id is separate because one logical turn may span multiple concrete runs.

Constraints that are not visible from the emit site:

• The trace event carries no latency, tokens, or cost under $ai_*. PostHog DERIVES those from a trace's children: its trace query sums $ai_latency over every event whose $ai_parent_id is the trace or is absent, and sums tokens/cost over $ai_generation / $ai_embedding only. An $ai_latency on the $ai_trace event is therefore added to its own children's and reports roughly twice the real duration. Run totals ride along as duration_ms, input_tokens, output_tokens, and cost_usd for the backends that do no such aggregation.

• The generation's $ai_latency is model time, not run time. Tool calls are siblings under the same trace and PostHog adds their latency to the generation's, so tool duration is subtracted out. duration_ms on the same event is still the full run — the two differ on purpose.

• $ai_http_status is absent, not defaulted, when the status is unknown. A generation that streamed to completion reports 200, and the call the run died in reports whatever status the engine named (EngineError.statusCode, or a provider SDK error's status). A failure that carried no status — a socket drop, an SDK throw — omits the field: a defaulted 200 would report the drop as a healthy call, and a defaulted 500 would invent a rejection the provider never made. Only the failing round-trip claims the error's status; earlier calls that completed keep their 200.

• PostHog's $ai_* latency fields are seconds; ours are milliseconds. $ai_latency and $ai_time_to_first_token are seconds; duration_ms and time_to_first_token_ms are the millisecond siblings the first-party dashboards read. Feeding a millisecond value to a seconds field is invisible in the payload and inflates the metric 1000x.

• Custom properties never take an $ai_ prefix. That namespace belongs to PostHog's schema; a name it does not define today it may define tomorrow with a different meaning. Ours are plain (duration_ms, input_truncated, spans_dropped), which also keeps them out of PostHog's $ai_* aggregation.

• $ai_trace carries no $ai_input_state / $ai_output_state. Content rides the generations; a trace-level copy repeated the run's prompt and answer on a second event. PostHog reads a trace's input and output from that event and from nowhere else, so the visible cost is that traces list with a null input and a conversation is titled from the first generation's $ai_input instead. Measured, not assumed — check whether that title is still wrong before trading the duplication back.

• One generation per model round-trip. Engines that bracket their calls with model_stream get one $ai_generation each, with that call's tools as its children. Only an engine that never brackets falls back to a single aggregate generation covering the whole run, and it is reported as one.

• Messages are rewritten into PostHog's shape before they ship. toPostHogMessages() in posthog-ai.ts maps engine parts onto the OpenAI/Anthropic conventions PostHog reads: tool-call becomes tool_calls, and a tool-result — which the engine has to carry inside a user message, because EngineMessage has no tool role — becomes its own role: "tool" message. Skipping this is not cosmetic: PostHog dumps raw JSON for shapes it does not know, and the byte-ceiling rescue in boundAiContent keeps "the last user message", which in engine shape is the last tool result rather than the question. Attachment bodies become a marker naming the media type and size — base64 renders as nothing in PostHog and spends the whole ceiling.

• A tool call and its result pair on the id the MODEL issued. The span id is a separate namespace that never appears in the transcript, so emitting it on tool_calls[].id leaves PostHog with a call and a result that never match and every tool call renders with no output. Span id is the fallback only for emitters that report no call id.

• Disabled capture omits the field rather than sending an empty one. An empty array is indistinguishable from a run that genuinely had no messages. Truncated content is marked, and a run over the span cap stamps spans_dropped — a truncated run must not read as a complete one. The one deliberate exception is a tool span's $ai_output_state with captureToolResults off: it carries an explicit "withheld" marker, because an absent output state reads as a tool that returned nothing, and the tool did answer.

• A tool that RETURNS an error envelope is a success here. $ai_is_error and failed_tools follow the tool event's isError, which the agent sets when an action throws. An action that returns { error: ... } instead is counted as a healthy call by every rollup on this page. Fix it in the action (fail()), not by teaching this layer to sniff payload shapes.

• The structural tool-call list ships even when content capture is off. Backends derive their tool tags from tool-call blocks inside the output choices and from nothing else, so tool names (without arguments) are always emitted. The parallel first-party tools array stays because the dashboards read it; that duplication is deliberate, not cleanup.

• Only thumbs carry sentiment. All four feedback types are reported, but a category follow-up to a thumbs-down is detail about the same vote — counting it again inflates the metric.

• Never invent an external id to make an integration light up. Survey-based feedback is emitted only when a real survey id is configured, and nothing is sent otherwise.

Do not build a separate LLM-observability ingestion API unless there is a clear reason the tracking provider registry cannot express the use case. Keep prompt, tool input, and model output content out of tracking by default; use the existing observability config flags for local trace content capture.