It has been confirmed that the EU has threatened to use a technicality to ban food movement from GB to NI, to try to force the UK to capitulate to their demands for a trade agreement

I believe this breaks the WA in both spirit and letter in the following places

The WA starts off summarising the premise under which the WA is being agreed.

This threat is completely opposed to these previously agreed statements and as such surely breaks the spirit of the agreement.

Article 1 shows the objectives of the protocol. The EU using the protocol to prevent food going from GB to NI, through a technicality, would surely be contrary to point 2, which explains why the UK never saw the threat as viable

Annexing Northern Ireland in the way they are threatening is surely at least against the spirit of Article 4, if not the letter

Article 5 describes which goods going from GB to NI would be liable to tariffs etc.

This whole article surely goes out of the window if they unilaterally decide to use a technicality to ban all food

Paragraph 2 in Article 6 says this. Note the term 'best endeavours'.

That is a legal term defined as shown in the image.

The EU would surely be breaking this if they did what they're threatening

And this, in my opinion, is the deal-breaker. The EU using a technicality to prevent GB sending food to NI would surely come under paragraph 1 in 'Safeguards', meaning the UK was well within its rights to take unilateral action.

So is the UK 'breaking international law' by putting domestic legislation to mitigate this threat? Technically. But if they actually did it, surely they would be breaking the WA in both spirit and letter, meaning the UK would be free to do whatever it wished in response.