Notice when the ingest API refuses an event

[fiskus]

Fifth code unit of quiltdata/quilt-specs#37 (w-delivery-observable), after #820, #822, #823 and #824.

Problem

The client never asked the ingest API whether it accepted an event, so it never read the status field: a rejected event came back HTTP 200 and was reported as a success. A malformed property would fail silently, forever, and the only way to find out was to go and look in Mixpanel.

verbose: true is the whole client-side fix. What it needs beside it is a decision about what a failure deserves — turning detection on without one would trade silence for noise.

A refusal and an unreachable API are different facts

• Refused — the API took the request and said no. That is our bug (a bad token, a property it will not accept) and it fails every event until someone fixes it, so it must be visible.
• Unreachable — no verdict came back. That is somebody's wifi. Reporting those would fill the crash reporter with other people's tunnels and bury the refusals among them.

DeliveryFailure::classify splits them per variant rather than by category, so a new client error has to be placed deliberately. A failure that never reached the network at all — a payload we could not serialize — counts as ours by definition.

A refusal is reported once per run

It fails every event alike, so the second report says nothing the first did not. Without this, one bad token becomes one crash report per user action. Same shape as the login-episode rule in #824: count the problem, not each discovery of it.

The subtlety worth its own test: a network failure must not spend the one refusal report, or the first flaky tunnel masks a real misconfiguration for the whole run. Classifying before deciding is what avoids that.

Note

This is observable at all only because #823 gave fault reporting a seam. Before it, "did we report the refusal?" was unanswerable — which is also why the previous telemetry change's post-release verification could confirm that events arrive but never that none are dropped.

Verification

just lint exit 0, cargo fmt --check exit 0, 317 quilt-sync tests, workspace green (55 / 458 / 317 / 84 / 1).

Five new tests: the classification per variant (three refusal kinds, four unreachable kinds), a serialization failure counting as ours, a refusal reported exactly once across five occurrences, an unreachable API never reported, and a network failure not spending the refusal report.

🤖 Generated with Claude Code

Greptile Summary

This PR enables verbose Mixpanel responses so rejected events become observable, then separates systematic refusals from transient connectivity failures.

• Classifies delivery failures as refused or unreachable.
• Reports the first refusal per process while logging unreachable API failures.
• Adds tests for classification, serialization failures, deduplication, and network-failure handling.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete blocking or independently actionable non-blocking issue established.

The new path detects rejected events, reports systematic failures once per process, and keeps transient network failures out of crash reporting, with tests covering the intended classification and deduplication behavior.

Important Files Changed

Filename	Overview
quilt-sync/src-tauri/src/telemetry.rs	Adds process-lifetime, concurrency-safe refusal-report deduplication and routes delivery failures through classification.
quilt-sync/src-tauri/src/telemetry/mixpanel.rs	Enables verbose ingest responses, introduces delivery-failure classification, and adds focused behavioral tests.

Sequence Diagram

sequenceDiagram
  participant App
  participant Telemetry
  participant Mixpanel
  participant Sentry
  App->>Telemetry: track(event)
  Telemetry->>Mixpanel: "track(verbose=true)"
  alt Event accepted
    Mixpanel-->>Telemetry: success
  else Event refused
    Mixpanel-->>Telemetry: refusal error
    Telemetry->>Telemetry: classify Refused
    opt First refusal this run
      Telemetry->>Sentry: report error
    end
  else API unreachable
    Mixpanel-->>Telemetry: transport/server error
    Telemetry->>Telemetry: classify Unreachable
    Telemetry->>Telemetry: write warning
  end

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Context used:

• Knowledge Base — QuiltSync desktop backend (src-tauri)