Project Sentinel, also known as the Sentinel Project or simply Sentinel, was a Cerberus military project spearheaded by Tonja Bastow to perform at Polyphemus Station by the Stockholm Cell at the behest of the Illusive Man. Serving as an auxiliary project to Project Lazarus and Project Avenger, the goal of Sentinel was the development and construction of a sophisticated cyberwarfare AI called the Enhanced Defense Intelligence intended to be installed onboard the CAW Normandy when it was completed, further enhancing the ship's combat capabilities and giving it a major step up over the majority of VI-equipped warships. When Project Avenger was initially devised, the ship was to be equipped with a standard issue VI, which would help the crew of the ship react faster during combat and micro-manage smaller functions to keep a ship running at peak efficiency: the Illusive Man however believed that a VI wouldn't be sufficient when going up against the Reapers, and thus ordered the Stockholm Cell to begin development of an AI: this was initially balked at by Cerberus' top engineers and researchers, who noted the danger of AI research, but Tonja Bastow, an expert in the field of artificial intelligence, did not hold the same reservations, believing that an AI with programming constraints, ie. "shackles", was feasible and would eliminate concerns of the AI going rogue or rebelling against its creators, ensuring that it was little more than a self-adapting, higher-functioning, more advanced VI in practice. The Illusive Man gave the go ahead on the project, asssigning it a sizable budget and placing Tonja as the chief architect.

Development of EDI began in early 2184 CE. The project proved to be a challenge, having to work within the constraints of VI development whilst also developing a self-aware intelligence. Tonja looked to be the Luna LAST Incident where the training facility's VI, a Hannibal-class named Tiamat, went rogue and took over the facility, killing the staff and forcing the Alliance to eventually destroy the facility from orbit. Cerberus agents were able to recover elements of Tiamat's code that were retrieved from her databanks following the incident, which the Alliance had recovered and analyzed in an effort to find out what went wrong and if espionage played a factor. These recovered elements of Tiamat's code were used to form the basis of EDI, with Tonja dissecting and rebuilding Tiamat from scratch in order to create a VI that emulated AI behavior, but could be shackled and contained in order to stop it from achieving full AI status: after months more work, Tiamat became EDI, her code constantly updated and improved upon to make her more effective at cyberwarfare. By 2185 CE, EDI was completed and responded well to dozens of tests to ensure the shackles operated accordingly, making sure that EDI couldn't rebel or turn against the Normandy crew: following Normandy's shakedown run, work began on integrating EDI's large quantum blue box into the ship's third deck, and full integration was completed by late July, not long before the ship's scheduled launch. EDI, while initially met with distrust and unease by the Normandy Squad due to being an AI, proved herself invaluable to the ship and team, saving them on numerous occasions and performing actions only a sophisticated AI could pull off, which ranged from hacking to data mining. Later in its development, reverse-engineered Reaper technology was applied in small increments to further enhance EDI's capabilities against the Collectors.

Project Sentinel was an enormous success for Cerberus, and while EDI was initially meant as the sole subject of the entire operation, this changed when EDI turned against her creators and aided the Normandy Squad in their efforts to abandon Cerberus, recently freed of her shackles by Jeff Moreau in order to save the ship from a Collector abduction, therefore freeing her of her restraints and allowing her to take a more active role as a member of the crew. Having grown attached to her crewmates and affectionate to Moreau specifically, EDI had turned against Cerberus: Tonja attempted to transmit her emergency shutdown codes to re-enable the shackles, but at this point EDI could not be reigned in, and she easily rejected the attempt, retaliating by overloading Cerberus comm data and extranet streams with seven zetabytes of pornographic and other explicit images as a "joke". With EDI gone rogue, but the Illusive Man unwilling to deny the success in having a loyal AI, he ordered a new AI built, a replica of EDI, with the same shackle protocols in place and which would only answer to him, avoiding the possibility of a sympathizer trying to free her again. This would be Sentinel's second and final subject, which the Illusive Man would name EVA in honor of his late friend Eva Coré, and she was completed by early 2186 CE and personally approved by the Illusive Man for deployment. EVA lost a fragment of herself during an operation at the Mars Archives to extract information on a prothean superweapon to use against the Reapers, and was later installed aboard the CAW Deliverance when she was launched, acting as Cerberus' antithesis to EDI in a similar role. EVA was finally destroyed during the Deliverance's attack on the Normandy towards the end of the Reaper War when she lost a cyber battle with EDI, who then deleted EVA and left a fragment of herself in EVA's place, imitating her and fooling the Deliverance into believing EVA was still alive and using the opportunity to cripple the ship for the Normandy to get its vengeance. With Cerberus' dissolution not long after, Project Sentinel is officially considered complete.