Cursor rule

1---
2alwaysApply: false
3---
4 
5## Avoid Boolean Prop Proliferation
6 
7Don't add boolean props like `isThread`, `isEditing`, `isDMThread` to customize
8component behavior. Each boolean doubles possible states and creates
9unmaintainable conditional logic. Use composition instead.
10 
11**Incorrect (boolean props create exponential complexity):**
12 
13```tsx
14function Composer({
15  onSubmit,
16  isThread,
17  channelId,
18  isDMThread,
19  dmId,
20  isEditing,
21  isForwarding,
22}: Props) {
23  return (
24    <form>
25      <Header />
26      <Input />
27      {isDMThread ? (
28        <AlsoSendToDMField id={dmId} />
29      ) : isThread ? (
30        <AlsoSendToChannelField id={channelId} />
31      ) : null}
32      {isEditing ? (
33        <EditActions />
34      ) : isForwarding ? (
35        <ForwardActions />
36      ) : (
37        <DefaultActions />
38      )}
39      <Footer onSubmit={onSubmit} />
40    </form>
41  )
42}
43```
44 
45**Correct (composition eliminates conditionals):**
46 
47```tsx
48// Channel composer
49function ChannelComposer() {
50  return (
51    <Composer.Frame>
52      <Composer.Header />
53      <Composer.Input />
54      <Composer.Footer>
55        <Composer.Attachments />
56        <Composer.Formatting />
57        <Composer.Emojis />
58        <Composer.Submit />
59      </Composer.Footer>
60    </Composer.Frame>
61  )
62}
63 
64// Thread composer - adds "also send to channel" field
65function ThreadComposer({ channelId }: { channelId: string }) {
66  return (
67    <Composer.Frame>
68      <Composer.Header />
69      <Composer.Input />
70      <AlsoSendToChannelField id={channelId} />
71      <Composer.Footer>
72        <Composer.Formatting />
73        <Composer.Emojis />
74        <Composer.Submit />
75      </Composer.Footer>
76    </Composer.Frame>
77  )
78}
79 
80// Edit composer - different footer actions
81function EditComposer() {
82  return (
83    <Composer.Frame>
84      <Composer.Input />
85      <Composer.Footer>
86        <Composer.Formatting />
87        <Composer.Emojis />
88        <Composer.CancelEdit />
89        <Composer.SaveEdit />
90      </Composer.Footer>
91    </Composer.Frame>
92  )
93}
94```
95 
96Each variant is explicit about what it renders. We can share internals without
97sharing a single monolithic parent.
98