Error Reporting

config.observability wires error reporting into the Hono API, the browser, and the desktop and mobile apps if you ship them. It ships off, and off loads nothing: each surface checks its provider's credential before dynamically importing an SDK. This is capture, not tracing - for per-request timing logs see performance monitoring.

Turn it on

observability: {
  sentry: { dsn: "https://examplePublicKey@o0.ingest.sentry.io/0" },
  posthog: { publicKey: "phc_yourkey", host: "https://us.i.posthog.com", llmContent: false }
},

Presence is the switch - no enabled flag, no provider selector. A provider reports when its credential is non-empty, and both may run at once. Keys are committed rather than env because they authorize sending only; SENTRY_DSN and POSTHOG_API_KEY override them server-side, but posthog.host does not, so an env key alone never arms PostHog.

Choose a provider

On the phone

The mobile app reads the same config.observability, and EXPO_PUBLIC_SENTRY_DSN / EXPO_PUBLIC_POSTHOG_KEY override it per build so one project can report to its own Sentry or PostHog. PostHog still needs its config block, which is where host lives.

What gets captured

From your own code: await captureServerError(err, { userId }) (@repo/api/observability) on the server, captureClientError(err) (apps/web/lib/observability.ts) in the browser. Both no-op when off, and neither needs a flush.

LLM analytics (PostHog only)

With a PostHog key and AI enabled, every model call is recorded as a $ai_generation. Built-in and BYOK runs both report; BYOK sends tokens and latency but no cost, since that is the user's own provider bill.

What this does not include

Capture only. Each gap is a deliberate opt-in:

• Automatic tracing - needs init() before every other module loads. Move it to instrument.mjs: node --import ./instrument.mjs ....
• Source-map upload - traces arrive minified. Add the Sentry bundler plugin (or posthog-cli) plus SENTRY_AUTH_TOKEN in CI.
• The framework SDK - this is vanilla @sentry/browser + @sentry/node. Run the @sentry/nextjs wizard, then drop initBrowserReporting from instrumentation-client.ts. Replace the body of lib/observability.ts rather than deleting it (the boundaries import from it), keeping its isReportableError line.
• Boot crashes on fullstack - the frontend loads @repo/api on the first request, so add initServerReporting() to the existing register() in apps/web/instrumentation.ts; never replace that file. separate arms at process start already.