Wordle Extra Hard Mode

extra-hard-wordle.js

// Turn into a bookmarklet, or user-script or paste into your console. 
if (!wordle.extraHardMode) {
    wordle.extraHardMode = true;
    // toggle hardMode
    const state = JSON.parse(localStorage.gameState);
    state.hardMode = true;
    localStorage.gameState = JSON.stringify(state);

    const originalEvaluateRow = wordle.bundle.GameApp.prototype.evaluateRow;
    wordle.bundle.GameApp.prototype.evaluateRow = function extraHardMode() {
        // force hard extraHardMode
        this.hardMode = true;
        // the original code checks that no yellow/green letters are omitted, this code checks that no
        // known "missing" letters are _used_.
        const knownAbsentLetters = this.evaluations.flatMap((x,i)=>{
            return x ? x.map((y,j)=>{
                if (y === 'absent') {
                    return this.boardState[i][j];
                }
            }
            ).filter(Boolean) : [];
        }
        );
        if ([...(this.boardState[this.rowIndex]??"")].some(c=>knownAbsentLetters.indexOf(c) !== -1)) {
            return this.$board.querySelectorAll("game-row")[this.rowIndex].setAttribute("invalid", ""),
            void this.addToast("Must not use known absent letters");
        }
        return originalEvaluateRow.call(this);
    }
    document.querySelector("game-app").addToast("Extra Hard Mode Enabled.")
}
;

This adds a check to the hard mode to not only insist that you use the green/yellow letters you have discovered, but also forbids you from using any letters you have ruled out as absent.

The next step is to insist that you don't guess a "yellow" letter in the same spot you have already tried... but that's it little more complex.