OC-301d · Module 3
Long-Term Module Maintenance
3 min read
A module's cost is not the development effort. It is the maintenance effort over its lifetime. A module developed in 40 hours that requires 5 hours per month of maintenance costs more over two years (160 hours maintenance) than the original development. Maintenance-first design makes the ongoing cost sustainable.
The maintenance checklist: documentation (can someone who did not write the module understand how to modify it?), test coverage (do the tests catch regressions when the module is changed?), monitoring (does the module report its health and performance to the observability stack?), and dependency currency (are dependencies updated regularly, or are they accumulating technical debt?). Each of these four areas gets a quarterly review. The review produces a maintenance backlog — specific tasks required to keep the module production-grade. The backlog is prioritized alongside feature work, not deferred indefinitely.
Do This
- Budget maintenance time at 10-15% of development time per month — maintenance is not optional overhead
- Run quarterly maintenance reviews: documentation accuracy, test coverage, dependency currency, monitoring completeness
- Track the module's Technical Debt Ledger — every shortcut has a projected cost, and costs compound
Avoid This
- Treat module development as a one-time cost — the ongoing maintenance cost exceeds the build cost within 18 months
- Defer maintenance until something breaks — by then the accumulated debt makes the fix 3x harder
- Skip documentation because "the code is self-explanatory" — code explains what, not why