3 November 2025 · instrumentation
Instrumentation debt in mobile apps
Debt is not the absence of a vendor. It is two hundred events, four owners, and a screen that still does not emit the tap you need for a refund argument.
Mobile teams inherit SDKs the way houses inherit wiring. A previous agency turned on auto-capture. A growth experiment added properties “just in case.” A privacy review asked for deletions that never quite reached production. The workspace looks rich. The log is a junk drawer with timestamps.
Interest payments
Every unused event still has to be implemented, tested, and explained when a contractor asks. Double-firing permission prompts — a Funnel Forensics specimen — often come from two libraries listening to the same callback. The chart looks like drop-off. The packet is a stutter.
UK GDPR does not make this cheaper. Unexplained identifiers in a property bag are not a rainy-day growth asset; they are a purpose you cannot state. The buying conversation for a new SDK should start with processors and retention, not with a demo funnel. That essay-shaped argument lives in our privacy notice as a smaller version of the same discipline.
Paying it down
We ask Foundry Circle teams for a one-page sketch: what you measure, what you pretend to measure, what you are frightened to delete. Deletion is the actual repayment. Adding a cleaner event without sunsetting the old one is a balance-transfer offer.
Cohort Craft will not teach server-side tagging in Firebase. It will teach you to document silence. For naming that survives the next release, read why event names rot. For the stance behind the questions, see app analytics.