Apply when facing a novel UI interaction or architectural decision with no precedent in the codebase. Build 2-3 competing prototypes and compare side by side before committing.
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What the file says
# Exhaust the Design Space
**The rule.** When the right answer is not obvious, build 2-3 competing prototypes or sketches. Compare them side by side. Only then commit. Building the wrong thing costs more than exploring three options; a second flavor of the first shape does not count.
**When it applies:**
- Novel UI interactions (no prior art in the codebase)
- Architectural choices with multiple viable approaches
- Product design decisions where user experience depends on feel, not logic
**When it doesn't:**
- Mechanical implementation where the pattern is established
- Bug fixes or refactors with a clear target state
- Changes where constraints dictate a single viable approach
The line at the top of this page pins the label git:20261014.daa0fc5, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.
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Source
GitHub
arjitj2/open-pstack · 14 stars · license MIT · pushed 2026-10-19 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_rgc7xw67lthz57bz
GET https://markdownregistry.com/api/v1/resolve?ref=arjitj2/open-pstack/principle-exhaust-the-design-space
GET https://markdownregistry.com/api/v1/blob/a554dd7395718f2e8d6bfe5b004bb589e330c169e51eb6defa003a58459c265e
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