replica-diff

Two tools in this folder, both standard-library Python, no installs:

python3 parity.py replica/features.csv                         # feature parity + missing list
python3 imgdiff.py replica/screens/S07.png replica/clone-screens/S07.png --out diff-S07.png
python3 imgdiff.py a.png b.png --json > replica/diffs/S07.json # for parity.py --visual
python3 parity.py replica/features.csv --visual replica/diffs/*.json --markdown > replica/parity.md

What parity means here

Parity means it does the same job, not that it looks the same. The feature score is the number that matters: can a user do everything they could do in the original. The layout score checks structure (is the information in the same places, in the same hierarchy), because that is what makes a switcher feel at home. It deliberately ignores colour, because replica-brand changes every colour on purpose. Do not chase pixel parity with the original. Its exact look is its trade dress, and it changes before launch.

Step 1: feature parity

Make sure replica/features.csv is current: every row's clone column is yes, partial (with a note), no, or skip (with a reason). Then:

python3 parity.py replica/features.csv

It weights must 3, should 2, could 1, counts partial as half, leaves out skip rows and rows you added that the original does not have, and prints: the score, must-haves done of total, each area weakest first, and the missing list in build order. Must-haves not done means not shippable, and it says so.

Step 2: layout diff

For each key screen, take two screenshots at the same viewport (1440x900 desktop, 390x844 mobile) in the same state (same data shape, same tab open, logged in the same way). The original's come from public pages or the user's own account, saved in replica/screens/. The clone's go in replica/clone-screens/.