Inspiration
Windows Snap is excellent until two or more applications occupy the same half or quarter of the screen. Switching then becomes a search through Alt+Tab or the taskbar. Window Swap keeps the user's spatial context: the corner of the region becomes the switch point for the windows already stacked there.
What it does
Window Swap is a tiny local Windows tray utility. It inspects visible top-level window geometry and, when the pointer reaches the bottom-right corner of a window region, shows a compact Swap control that brings the next window with matching bounds forward. It supports English and Portuguese, needs no account or administrator rights, and contains no telemetry, network client, or background service.
How we built it
The project combines Python, Win32 APIs, Tk, and a Windows tray integration. Pure geometry and ordering rules are separated from operating-system effects for deterministic testing. GitHub Actions validates Python 3.11, 3.12, and 3.13 on Windows and builds tagged one-file releases with a published SHA-256 digest.
During Build Week, Codex helped turn an earlier prototype into a testable public release: signed popup geometry for monitors left of or above the primary display, duplicate-instance protection, privacy-conscious diagnostics, expanded tests, release-workflow repairs, live Windows validation, and sanitized publication. I made the key product decisions: keep the utility local and focused, add no runtime AI or telemetry, preserve the deliberate corner interaction, and favor daily reliability over extra features.
Challenges
The hardest boundaries were foreground activation across desktop and UWP applications, physical-pixel geometry under Windows scaling, signed coordinates on monitors positioned left of the primary display, and ensuring a packaged executable never runs two competing tray instances. The release pipeline also exposed that the Windows Python launcher could ignore the interpreter installed by the CI matrix.
Accomplishments
- A working downloadable Windows utility, not only a prototype
- Fifteen passing deterministic and Windows integration tests
- Real visual testing with desktop and UWP applications at 150% scaling
- Correct negative-coordinate popup placement and duplicate-instance prevention
- Public MIT-licensed source, security guidance, secret scanning, and a digest-verified release
What we learned
For a tiny desktop utility, product quality is mostly boundary quality: monitor coordinates, DPI, foreground rules, process lifecycle, packaging, and privacy. Codex was most useful when paired with evidence from the real machine and CI logs.
What's next
Gather feedback from more physical multi-monitor arrangements and a second Windows machine, then consider an optional dwell delay and code signing without changing the local-first design.
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