1. Agency MCC with dozens of client accounts
Who: A performance agency whose overnight jobs pause/enable campaigns across an MCC.
Task: Find every undeclared campaign before April 1, 2026 so one forgotten client cannot freeze mutates for shared automation.
Steps: Enumerate customer IDs, run missing-declaration GAQL per account, store CSV locally, route CONTAINS vs DOES_NOT_CONTAIN decisions to account owners, then declare-only mutate in batches. Re-query to zero.
Result: Checklist shows inventory + declare path; failure symptom avoided: April 2 pager for EU_POLITICAL_ADVERTISING_DECLARATION_REQUIRED on a routine bid job.
2. In-house ads platform creating campaigns via API
Who: A product team whose “create campaign” endpoint forgot the declaration field on legacy versions.
Task: Backfill undeclared rows and fix creates before the account-level lock.
Steps: Use the checklist GAQL to quantify backlog. Ship a declare-only migrator. Update create payloads to set contains_eu_political_advertising. Add a CI assert that rejects creates missing the field where your API version requires it.
Result: Path badges highlight API risk; method sample reminds ScheduleExperiment and criterion mutates are in the blast radius. Failure symptom avoided: creates succeed but later criterion edits fail account-wide.
3. Scripts-only advertiser who rarely opens API docs
Who: A small advertiser using Google Ads Scripts for weekly label and budget mutates.
Task: Understand whether April 1 affects Scripts the same way, and how to declare without a custom app.
Steps: Select API/Scripts on the checklist. Prefer UI account-level declaration if available, or a one-off Script that only sets the declaration field. Confirm reporting dashboards still load even if a mutate fails.
Result: Operator knows reporting ≠ mutate health. Failure symptom avoided: assuming “Scripts are fine because the UI loads.”