fix(ga4): GA4 sidebar shows generic error for all customers [ES-433]

[Tyler (tylerwashington888)]

Problem

Since June 30, every customer using the Google Analytics 4 sidebar sees "We couldn't load Google Analytics data" even though the lambda is returning valid data.

What's happening end-to-end

1. The GA4 sidebar calls the lambda's /api/run_report endpoint via a signed request
2. The lambda fetches data from Google's Analytics Data API (gRPC/Protobuf) and returns a 200 with valid rows
3. The frontend runs the response through a Zod schema (ZRunReportData) before rendering
4. The schema fails → throws MalformedApiResponse error type → ErrorDisplay has no handler for it → falls to default → shows the generic message

Why the schema fails

PR #11042 introduced ZRunReportData with this metadata shape:

metadata: z.object({
  currencyCode: z.string(),      // required
  dataLossFromOtherRow: z.boolean(),
  timeZone: z.string(),          // required
  _currencyCode: z.string(),     // required — THIS IS THE PROBLEM
  _timeZone: z.string(),         // required — THIS IS THE PROBLEM
}),
propertyQuota: z.null(),

_currencyCode and _timeZone are internal protobuf/protobufjs implementation details — they exist on the in-memory JS object that protobufjs produces when decoding the binary gRPC response, but they are undefined and get silently dropped when the lambda calls res.json(). They are never part of the actual JSON payload the frontend receives. The schema was written by inspecting the raw JS object rather than the actual API contract.

The actual JSON the lambda sends looks like:

"metadata": {
  "dataLossFromOtherRow": false,
  "currencyCode": "USD",
  "timeZone": "America/New_York"
}

_currencyCode and _timeZone are never there. z.string() on a missing field fails for every single customer.

Additionally, propertyQuota: z.null() would fail for any high-traffic property where Google returns a QuotaStatus object instead of null.

Why only reported for some customers

The Zod failure affects all customers — the "3 customers" in the report are just the ones who surfaced it. The bug has been live since June 30.

Fix

Make the fields that are never actually present optional, and widen propertyQuota to accept any value:

metadata: z.object({
  currencyCode: z.string().optional(),     // absent for non-ecommerce properties
  dataLossFromOtherRow: z.boolean(),
  timeZone: z.string().optional(),
  _currencyCode: z.string().optional(),    // protobuf internal — never in JSON
  _timeZone: z.string().optional(),        // protobuf internal — never in JSON
}),
propertyQuota: z.unknown(),               // null normally, object when quota is tracked

The frontend only reads rows and rowCount from the response — none of the loosened fields are accessed anywhere in UI code.

Test plan

• Open the GA4 sidebar on any entry — analytics data should render instead of the generic error
• Confirm properties with and without currency tracking both work
• npm run test:ci in apps/google-analytics-4/frontend passes

🤖 Generated with Claude Code on behalf of Tyler

[ryunsong-contentful]

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[ryunsong-contentful]

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[ryunsong-contentful]

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[ryunsong-contentful]

Please make code changes in the comments before merging

[Tyler (tylerwashington888)]

Removed all three inline comments per your feedback. No other changes.

[ryunsong-contentful]

Ship it