Built the homepage prototype and the Bilateral Coordination Test prototype (session 7 is where BCT prototype 1 was created). Established the visual design language for the entire platform: dark navy blue (#1e40af), white, and light blue (#dbeafe). Split-card design with animated hover previews showing test mechanics.
Solved the camera mirroring bug after 5 iterations — the most technically significant debugging moment of the project.
Homepage design: Claude generated initial layout with emoji icons for test cards. Rejected emoji in favor of clean card design — emoji felt too casual against the professional/approachable tone from the Position Statement.
AI suggested emoji icons for the test cards — quick, recognizable, zero design work. I rejected them. The Position Statement says "professional + approachable." Emoji read as game-like, not clinical. Replaced with clean card hover mechanics that show a preview of what the test actually does — which is more informative and more on-brand than any icon could be.
Camera mirroring bug: This was a 5-iteration debugging process that began with AI's standard suggestion and ended with a solution AI hadn't proposed.
The bug: hand tracking dots appeared on the wrong side of the screen. AI suggested applying a canvas-level transform: ctx.scale(-1, 1). This made it worse — now it was double-mirrored. Four more iterations, each trying a different variation of the same approach. None worked. The breakthrough came when I stopped trying to fix the symptom and asked: why is there already a mirror? Answer: browsers mirror camera video by default. Fix: apply scaleX(-1) to the video element via CSS only, then use (1 - indexTip.x) * width in the coordinate math. No canvas transform needed. This pattern was reused in Session 17's Fine Motor Precision Test with zero debugging time.
Debugging requires diagnosing the cause, not just treating the symptom. Four of the five iterations failed because they were variations of the same wrong approach. The fifth worked because it started from a different question: "why is the mirror already happening before I do anything?"
Visual design decisions have measurement consequences. Rejecting emoji wasn't about aesthetics — it was about maintaining credibility with users who might use this data to understand something real about their bodies.
The camera mirroring fix is directly load-bearing: if the visual and the tracking don't match, users can't understand what the test is measuring. A broken mirror invalidates the assessment before it starts. Getting this right was a prerequisite for everything camera-based that followed.
Establish GAME_STANDARD.md — a universal architecture for all test pages. Fix the hard lesson about version control (no commits were made this session — work was almost lost). Finalize per-hand scoring and symmetry metric for Bilateral Coordination.