I know there are a few people on this forum who have a lot of software development experience. I would appreciate help in reviewing a possible approach to managing a situation I'm encountering.
I'm working on a system for tracking what the frontmost windows are in each Desktop Workspace. I have two triggers, Window Changed and Space Changed, that are often going to be triggered at the same time (or within microseconds) and sometimes only one or only the other, and there are tasks that I want done by either of them, whenever either is triggered, but not done by both, and I don't know which of the two triggers will be first or if it will be first under all circumstances.
This sounds like a situation that may occur often in multitasking UI systems, so I imagine that there are multiple solutions that have been worked out over the years. But I am not familiar with any of these solutions and don't know which will mostly be fastest, under what conditions, or which will have fewer logistical problems or risks, or which may be more easily implemented in KBM.
I posed the above question to Claud.ai and got the following response:
{ Begin Claude:
You've identified a classic concurrency problem! This is indeed common in UI systems. Let me outline the main solutions and which might work best for KBM:
Common Solutions:
1. Debouncing/Coalescing
- Both triggers set a "pending update" flag and schedule a single handler to run after a brief delay (e.g., 0.1 seconds)
- If both triggers fire within that window, only one handler executes
- Pros: Simple, prevents duplicate work
- Cons: Adds latency, may feel sluggish
2. Mutex/Lock Pattern
- First trigger to fire sets a "processing" lock
- Second trigger sees the lock and exits immediately
- First trigger releases lock when done
- Pros: No duplicate work, immediate response
- Cons: Second trigger's info might be lost
3. State Comparison (Idempotent Operations)
- Both triggers run the same handler
- Handler compares current state to last recorded state
- Only acts if something actually changed
- Pros: Doesn't matter which fires first or if both fire
- Cons: Handler runs more often, must check all conditions
4. Event Queue
- Each trigger adds its event to a queue
- Single processor handles queue with deduplication logic
- Pros: No events lost, ordered processing
- Cons: Complex to implement in KBM
My Recommendation for Your Case:
Option 3 (State Comparison) is probably best because:
- KBM macros are fast enough that running twice isn't a problem
- Your operations are naturally idempotent (checking "did this actually change?")
- No risk of lost information
- Simpler logic—no timing dependencies
Implementation approach:
Create a single "Update Window State" handler that both triggers call:
1. Get current Space name
2. Get current frontmost window (app, title, ID)
3. Compare to LastRecordedSpace and LastRecordedWindow
4. If Space changed: [Space change logic]
5. If Window changed: [Window change logic]
6. If both changed: [Combined logic]
7. Update LastRecordedSpace and LastRecordedWindow
The key is determining what changed by comparison, not by which trigger fired.
Does this match your intuition? Or do you see specific operations where you absolutely need to know which trigger fired first?
End Claude }
If you've read this far and have any experience with this kind of problem or if you follow the logic and have questions about any part, what do you think? Is the suggestion from Claude resonable?
One thing that the Claude outline does not mention is how to have the shared handler only run once when both triggers happen in close succession. Is this a job for Semaphores? I've never used them. How would that work?
Should I have one macro that is defined to be triggered by either trigger or should I have two separate macros that each simply respond to their own trigger by executing the handler? Would the first be faster? Would the second be more flexible, allowing thing to happen before and after the handler that are specific to that trigger-type and which are independent of what the shared handler is doing?
I'm still very much in the planning phase and I have no experience. And I don't trust to Claude to be more that reasonable-sounding.
Suggestions?
Solved
Solution by @_jims in Comment #5
and by @Nige_S in Comment #6
The actual problem turned out to have a different solution than the orginal question. The above posts provide the solution to the question. The actual KBM design problem was solved in Post #10:
triggers first, otherwise 
triggers (assuming the focused window title changes).
