The Psychology of Overengineering

1. of Overengineering Why smart teams build software that's hard to understand
3. A system for everything.
4. A system for everything.
5. Some code feels like the roadster.
6. Some code feels like the roadster.
7. Bad code is code
8. Bad code is code The ideas behind it: where things live, how they fit together, why.
9. The team knows its domain a hundred times better than I do.
10. The team knows its domain a hundred times better than I do.
11. The team knows its domain a hundred times better than I do.
12. We know what good code looks like.
13. We know what good code looks like. ?
15. A perfect solution.
16. A perfect solution.
17. made sense on its own.
18. made sense on its own. they did not
19. Complexity later.
20. Complexity later. Many of these problems start in our heads.
21. I keep running into.
22. I keep running into. I've fallen for every one of them.
25. orders/ orders-v2/ orders-legacy/ // please don't use export class OrderWrapper { // so we can swap it out one day private orders = inject(OrderService); private ordersV2 = inject(OrderServiceV2); shared/ load() { if (flags.newCheckout2023) { return this.ordersV2.load(); } return this.orders.load(); order-wrapper.service.ts feature-flags.ts // newCheckout2023 } }
26. orders/ orders-v2/ orders-legacy/ // please don't use export class OrderWrapper { // so we can swap it out one day private orders = inject(OrderService); private ordersV2 = inject(OrderServiceV2); shared/ load() { if (flags.newCheckout2023) { return this.ordersV2.load(); } return this.orders.load(); order-wrapper.service.ts feature-flags.ts // newCheckout2023 } } The box gets a little heavier each time.
27. Losing something feels worse
28. Losing something feels worse ?
29. Do you ? Base model 99,900 ✓ Sport package ✓ 21-inch wheels ✓ Heated seats ✓ All-wheel drive ✓ Ambient lighting ✓ Panorama roof ✓ Night vision ✓ Sport exhaust + 4,800 + 2,400 + 650 + 3,900 + 480 + 1,950 + 2,700 + 3,100
30. Do you ? For the trip to the bakery. Base model 99,900 ✓ Sport package ✓ 21-inch wheels ✓ Heated seats ✓ All-wheel drive ✓ Ambient lighting ✓ Panorama roof ✓ Night vision ✓ Sport exhaust + 4,800 + 2,400 + 650 + 3,900 + 480 + 1,950 + 2,700 + 3,100
31. export class DataView { data = input.required<Row[]>(); columns = input<Column[]>([]); layout = input<'table' | 'grid' | 'cards'>('table'); sortable = input(true); filterable = input(true); pageSize = input(25); density = input<'compact' | 'comfortable'>('comfortable'); config = input<DataViewConfig>(DEFAULT_CONFIG); dataSource = input<DataSource<Row>>(new DefaultDataSource()); // ... five more inputs // in case we ever go multi-tenant tenantId = input<string>();
32. export class DataView { data = input.required<Row[]>(); columns = input<Column[]>([]); layout = input<'table' | 'grid' | 'cards'>('table'); sortable = input(true); filterable = input(true); pageSize = input(25); density = input<'compact' | 'comfortable'>('comfortable'); config = input<DataViewConfig>(DEFAULT_CONFIG); dataSource = input<DataSource<Row>>(new DefaultDataSource()); // ... five more inputs // in case we ever go multi-tenant tenantId = input<string>(); An option nobody uses still costs something every time it's read.
33. Paradox
34. Paradox
35. We say we want simple software.
36. We say we want simple software.
37. We say we want simple software. Software can and will change!
38. "Add a button that saves the form."
39. "Add a button that saves the form." ✓ Created FormSaveService
40. "Add a button that saves the form." ✓ Created FormSaveService ✓ Added FormSaveFacade
41. "Add a button that saves the form." ✓ Created FormSaveService ✓ Added FormSaveFacade ✓ Introduced a SaveFormRequested event
42. "Add a button that saves the form." ✓ Created FormSaveService ✓ Added FormSaveFacade ✓ Introduced a SaveFormRequested event ✓ Defined SaveStrategy + DefaultSaveStrategy
43. "Add a button that saves the form." ✓ Created FormSaveService ✓ Added FormSaveFacade ✓ Introduced a SaveFormRequested event ✓ Defined SaveStrategy + DefaultSaveStrategy ✓ Added a saveForm slice to the store
44. "Add a button that saves the form." ✓ Created FormSaveService ✓ Added FormSaveFacade ✓ Introduced a SaveFormRequested event ✓ Defined SaveStrategy + DefaultSaveStrategy ✓ Added a saveForm slice to the store ✓ Wrote adapters for three future storage backends
45. "Add a button that saves the form." ✓ Created FormSaveService ✓ Added FormSaveFacade ✓ Introduced a SaveFormRequested event ✓ Defined SaveStrategy + DefaultSaveStrategy ✓ Added a saveForm slice to the store ✓ Wrote adapters for three future storage backends ✓ Added a plugin hook for custom save behaviour
46. "Add a button that saves the form." ✓ Created FormSaveService ✓ Added FormSaveFacade ✓ Introduced a SaveFormRequested event ✓ Defined SaveStrategy + DefaultSaveStrategy ✓ Added a saveForm slice to the store ✓ Wrote adapters for three future storage backends ✓ Added a plugin hook for custom save behaviour ...
47. "Add a button that saves the form." ✓ Created FormSaveService ✓ Added FormSaveFacade ✓ Introduced a SaveFormRequested event ✓ Defined SaveStrategy + DefaultSaveStrategy ✓ Added a saveForm slice to the store ✓ Wrote adapters for three future storage backends ✓ Added a plugin hook for custom save behaviour ... ?
48. “Why not” used to cost something.
49. “Why not” used to cost something.
50. “Why not” used to cost something.
51. Software you couldn't build before.
52. Software you couldn't build before.
53. Best Code is no code
54. Best Code is no code
56. ?
57. Ten of you.
58. Ten of you.
59. The code http.get('/api/orders') The app this.api.fetchOrders() 12.10.2026 10/12/2026 fetch('/api/orders') httpResource('/api/orders') 2026-10-12
60. Dashboard Export Role concept Custom layout Reports Notifications Themes Offline mode
61. What we were missing:
62. What we were missing:
63. What we were missing:
64. Build everyone's feature.
65. Build everyone's feature. Support both approaches.
66. Build everyone's feature. Support both approaches.
67. Build everyone's feature. Support both approaches.
68. It only works through
69. Our code has
70. Our code has A colleague who shows up for the first time, every single morning.
71. Our code has A colleague who shows up for the first time, every single morning.
72. ? Test #1001
73. ? Test #1001 ?
74. I may not read every line.
75. I may not read every line.
76. changes shape.
77. changes shape. Knowledge moves from heads into the repo.
78. changes shape. Knowledge moves from heads into the repo. Or the model makes a very confident guess.
79. agent-01 agent-02 agent-03 agent-04 agent-05 worktree/ checkout worktree/ search worktree/ profile worktree/ export worktree/ roles █ █ █ █ █ agent-06 agent-07 agent-08 agent-09 agent-10 worktree/ reports worktree/ i18n worktree/ tests worktree/ layout worktree/ offline █ █ █ █ █
80. agent-01 agent-02 agent-03 agent-04 agent-05 worktree/ checkout worktree/ search worktree/ profile worktree/ export worktree/ roles █ █ █ █ █ agent-06 agent-07 agent-08 agent-09 agent-10 worktree/ reports worktree/ i18n worktree/ tests worktree/ layout worktree/ offline █ █ █ █ █
82. Small changes one can follow
83. Small changes one can follow Consistent over clever
84. Small changes one can follow Consistent over clever "Do I understand this?"
85. Small changes one can follow Consistent over clever "Do I understand this?" Conventions in a file the whole team looks after
86. I expected AI to make code quality matter less.
87. I expected AI to make code quality matter less.
88. Difficult human decisions
89. Difficult human decisions
90. Any fool can make things bigger, more complex, and more violent. It takes a touch of genius – and – to move in the opposite direction. · Small Is Beautiful, 1973
92. What am I afraid of?
93. What am I afraid of? Who pays for this decision later?
94. What am I afraid of? Who pays for this decision later? What would I build if I knew I could change it later?
95. ?
96. ? Having feels safer than needing.
97. ? Having feels safer than needing. Being prepared feels more responsible than choosing.
98. ? Having feels safer than needing. Being prepared feels more responsible than choosing. AI makes building so cheap that it's all easier than ever.
99. ? Having feels safer than needing. Being prepared feels more responsible than choosing. AI makes building so cheap that it's all easier than ever. Adding a feature feels easier than a difficult conversation.
100. ? Having feels safer than needing. Being prepared feels more responsible than choosing. AI makes building so cheap that it's all easier than ever. Adding a feature feels easier than a difficult conversation.
101. Not all complexity is unnecessary.
102. Not all complexity is unnecessary.
103. I don't need our software to do everything.
104. I don't need our software to do everything.
106. https://offering.solutions