Before I started the project home work, I read the interview feedback from others here. but I would not believe a company would steal valuable work from external principle developers in such a way.
HR called for 20 mins to market the company and convince me they are eagerly hiring for this role. She tole me multiple hiring managers are very interested at you. I was asked to develop a mini project which is quite involved and time consuming. You put on your best effort to impress them. the project code you sent to their engineering team is worth $10k at least in market fair value. Then you were interviewed by the dev team to explain the advanced points in your project design and codes. After that, you were informed the hiring plan is changed and the role is closed. From the time marketing you the job role to the time informing you the hiring plan is changed, it was One and Half week apart!!! I got an determined conclusion that the company uses the tactics to steal external software engineer valuable design and codes for free. The job postings are used as phishing tool for external design and codes. The moment you sent them your project codes, your value is disposed. Just like the moment you transfer money to a online thief, your money are gone.
Lesson learned. If multiple principle developers interviewed all said the company stealing code using the fake job postings and interview process, it is true. Do not waste your time to develop the home work project if you are senior and your work sending to them is valued at $10k.
In order to convince you to develop a take home project for them for free, they will make it appear so real and true by giving out a list of their internal employees name and email address. Be alert. Trust your instinct when you feel doubt and uncomfortable about the time consuming take home project. No matter you do or not do it, you won't get the job. There is a big problem with the software engineering team in San Francisco, US, assuming the dev team in San Fransisco are legacy & incompetent thus having to resort to a phishing tactics to steal modern design and codes.
In the all process, the HR recruiter only saw my short Linkedin profile. She and hiring manager even forgot to ask me for my resume to make the phishing process looked flawless.