← /daily-startup-idea
June 22, 2026

Mutex

“Mutual exclusion for friend group crises. Only one of you is allowed to be unhinged at a time. The lock is held by Sarah until Thursday.”

The Problem

Your friend group is a shared resource with zero concurrency control. Tara got dumped Sunday. Marcus thinks he has cancer (it’s heartburn). Jenna’s mom is “fine,” which means a 2am voice memo is inbound. You have four emotional file descriptors and seventeen people racing for them. Something is going to deadlock. Probably you.

The Solution

One lock per friend group. Whoever holds it gets the floor — crying, oversharing, eleven-paragraph voice memos, unsolicited tarot. Everyone else gets EAGAIN and joins the queue. The lock releases when the situation resolves, the holder falls asleep, or the bartender cuts them off.

mutex.lock · group: brunch_???
held by SARAH · 41h 12m
HOLDER
Sarah K.
cause: “he liked her photo”
critical_section_t = 41h 12m
🔒
WAIT QUEUE (4)
  1. ① Marcus — chest pains (heartburn)
  2. ② Jenna — mom (“fine”)
  3. ③ Devon — landlord email
  4. ④ You — existential, low-pri

Lock Acquisition States

Lifted directly from pthread.h, adapted for people who need to be witnessed.

0
EOKLock acquired. The floor is yours. Cry freely.
EAGAIN
Try AgainSarah is still going. Approx. 6h left.
EBUSY
Busy“sorry I’m kind of in it rn”
EDEADLK
DeadlockYou and Marcus both need each other to listen first.
EPERM
Not PermittedIt’s a workday. Reschedule for the weekend.
ETIMEDOUT
Timed OutYou held the lock 11 days. Friends moved on.

The Priority Scheduler

Not every crisis is created equal. We reorder the queue by severity so Marcus’s heartburn doesn’t starve a real one.

niceeventmax hold
-20
Someone died.
indefinite
-15
Diagnosis. Real one.
2 weeks
-10
Engagement collapsed in the parking lot.
10 days
-5
Fired (with severance).
6 days
0
Breakup, 8+ months.
3 days
+5
Situationship ended (it never started).
8 hrs
+10
Boss seemed weird in the standup.
20 min
+19
You think your roommate is mad at you.
the elevator ride

Deadlock Detector

The classic case: two friends both holding a lock the other one needs. Our cycle detector breaks ties by paging the person with more therapy hours logged.

THREAD A
Marcus
needs: Jenna’s attention
cycle
THREAD B
Jenna
needs: Marcus to ask first
Resolution: kill -9 Marcus. He had 14 unanswered texts anyway.

Pricing

Single-threaded
free
$0
1 lock. 4 friends. No queue depth limit; messages dropped on overflow.
Multi-threaded
default
$12 / mo
Priority scheduling. Deadlock detection. Voice-memo length cap (8 min).
Real-time
founders’ pick
talk to sales
Preemptive locks (interrupt anyone). 24/7 oncall counselor. Reserved slot Sunday 9pm.

TAM

Concurrent unresolved feelings (global)
2.1B friend groups × $12 ARPU × 12 mo
= $302B / yr
Sarah, alone, is a Series B.

The Ask

$5M seed. Builds: a fairness-preserving scheduler, a sentiment model to classify “real crisis” vs “Mercury retrograde,” and a referee mode where we put two friends in a Zoom and the loser gets SIGTERM.

Series A pitch:“We’re Kubernetes for people who can’t let things go.”