Mobile App Insights: small slice (Mac Catalyst)

[davidortinau]

Ships the first-increment (~3 hour) mobile Application Insights slice per Captain's path 1 go approval. Wires Azure.Monitor.OpenTelemetry.Exporter into the existing MAUI OTel pipeline, subscribes to MauiExceptions.UnhandledException, and embeds the connection string in appsettings.Production.json (write-only ingestion key — embedding is the documented pattern; per the decisions memo wash-mobile-appinsights-answers).

In scope

• Azure resource sstudio-mobile-ai in rg-sstudio-prod, workspace-linked to law-3ovvqiybthkb6, daily cap 0.5 GB.
• Azure.Monitor.OpenTelemetry.Exporter 1.7.0 added to SentenceStudio.MauiServiceDefaults. Bumped OpenTelemetry.Extensions.Hosting / Exporter.OTLP / Instrumentation.Http to 1.15.x to satisfy Azure Monitor's transitive floor.
• cloud_RoleName set explicitly via ResourceBuilder.AddService("SentenceStudio.Mobile.<DeviceInfo.Platform>").
• SentenceStudioAppBuilder.InitializeApp subscribes once to MauiExceptions.UnhandledException → ILogger.LogCritical → best-effort ForceFlush(3000) on all three OTel providers before the process dies.
• appsettings.Production.json updated with AzureMonitor:ConnectionString.
• Fixed pre-existing Release-build break: MacCatalyst/MauiProgram.cs had unguarded using Microsoft.Maui.DevFlow.* even though those packages are Condition='$(Configuration)'=='Debug'. Wrapped the usings in #if DEBUG.

Out of scope (deferred to full plan)

• Blazor WebView JS error bridge (window.onerror, unhandledrejection)
• Android / iOS linker preserve directives for Release link-time trimming
• PrivacyInfo.xcprivacy (Captain confirmed no App Store submission planned)
• Windows head, marketing site
• Custom telemetry processors / sampling / session replay / live metrics

Validation

Built Release Mac Catalyst, launched with SENTENCESTUDIO_CRASH_TEST=1, temp thread threw InvalidOperationException 10s after launch. Waited 4 minutes. KQL query:

exceptions
| where timestamp > ago(15m)
| where cloud_RoleName contains "SentenceStudio"
| project timestamp, type, outerMessage, cloud_RoleName, operation_Id
| order by timestamp desc

Result (truncated):

timestamp	type	outerMessage	cloud_RoleName
2026-04-20T03:09:14Z	System.InvalidOperationException	AppInsights pipeline validation (wash: squad/mobile-appinsights-slice)	SentenceStudio.Mobile.MacCatalyst
2026-04-20T03:09:04Z	System.InvalidOperationException	Model building is not supported when publishing with NativeAOT…	SentenceStudio.Mobile.MacCatalyst
2026-04-20T03:09:04Z	System.InvalidOperationException	HelpKit could not select a presenter automatically…	SentenceStudio.Mobile.MacCatalyst

The forced exception (AppInsights pipeline validation…) is there, plus bonus evidence the pipeline is already catching caught-and-logged exceptions from startup code paths (EF NativeAOT model-build, HelpKit presenter). cloud_RoleName is correct. Temp validation code reverted before commit.

operation_Id is empty because we throw from a bare Thread, not inside an OTel-instrumented activity. Real crashes inside an HttpClient span will populate it and correlate to the API once the server-side companion ships.

Secret management

Committed the connection string to appsettings.Production.json (which is already a tracked file containing service-discovery endpoints). Rationale, per .squad/decisions.md wash-mobile-appinsights-answers:

• InstrumentationKey is write-only: it authorizes ingestion push; it cannot read telemetry or touch any other Azure resource.
• Microsoft's documented pattern for mobile/desktop/JS clients is to ship it in the bundle.
• Worst case is fake-telemetry spam, bounded by the 0.5 GB/day ingestion cap we set.
• All "secure" alternatives (fetch-at-startup, per-user keys, Key Vault) are strictly worse for mobile — chicken-and-egg if the API is down, or require an Azure identity the app doesn't have.

If Captain prefers an env-var / non-committed override path later, that is easy to add (the config system reads env vars already).

Follow-ups before full rollout

• Server-side Azure Monitor exporter in SentenceStudio.Api so W3C traceparent correlates mobile → API spans.
• Blazor WebView JS bridge.
• Android/iOS linker preserve + Android Release smoke test.
• iOS device smoke test on DX24 (Release).
• Windows head.

Resource

• App Insights: /subscriptions/a25bc5f2-e641-47b9-89a8-5e5fd428d9d6/resourceGroups/rg-sstudio-prod/providers/microsoft.insights/components/sstudio-mobile-ai
• AppId: 74e94530-d17f-404a-8726-b7266724b70f
• Daily cap: 0.5 GB, notifications on cap

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com