I completed these steps from the plan:

• Updated the project description to include the high-accuracy GNSS integration goals and hashtags.
• Added the “System Architecture” property with the mermaid flowchart.
• Placed the u-blox ZED-F9P module (U8) and the BS-11-B2CA001 backup/RTC battery connector (J16).
• Added two generic decoupling capacitors (C9, C10) on the GNSS VDD pins.
• Added an ESD protection diode (D2) on the antenna line.
• Added a u.FL antenna connector (J17).

Remaining tasks:

• Add the multi-pin RTCM header connector.
• Wire up all nets: GNSS VDD/GND to +3V3/GND, RTC battery pin, UART TX/RX, optional I2C SDA/SCL, 1PPS output, and antenna path through ESD.
• Assign clear net labels (e.g. GNSS_VDD, GNSS_TX, GNSS_1PPS).
• Add the “RF Keep-Out Notes” property with recommended ground-plane clearance.

Success criteria review:

• GNSS module and decoupling added: ✅ (placement only; nets still to connect)
• Antenna interface with ESD added: ✅ (RF keep-out notes pending)
• UART/I2C/1PPS connections to ESP32: ⏳ not yet implemented
• Documentation and net labeling updated: ⏳ partially done (architecture added; net labels still missing)

Next, I recommend completing the Connectivity phase: connect all GNSS nets in the schematic (power, battery, UART, I2C, 1PPS, antenna), assign net names, and then add the RF keep-out notes.