Information architecture

README.md
├── docs/                         Maintained navigation and validation records
├── A9_A9G/doc/                   Preserved historical notes
│   ├── AT-Command-Set.md         Selected Ai-Thinker AT extensions
│   ├── Change-History.md         Firmware change history
│   ├── 功能说明.md               Historical Chinese feature notes
│   ├── pay-attention.md          Historical Chinese hardware FAQ
│   └── TODO-List.md              Empty historical placeholder
├── GitHub Releases               Published historical firmware assets
└── external GPRS_C_SDK           Separate on-chip application-development path

Responsibility boundaries

Area	Authoritative location in this project	Boundary
Repository navigation	Root README and docs/	Maintained overview, not product certification
Selected AT extensions	A9_A9G/doc/AT-Command-Set.md	Not a complete AT reference
Version history	A9_A9G/doc/Change-History.md	Historical record only
Firmware downloads	GitHub Releases	Binary contents are not rebuilt here
Product electrical details	Linked official product PDFs	Check document revision and hardware revision
SoC application development	External GPRS_C_SDK repositories	Separate from AT firmware use

Operational flow

Identify hardware -> read product documents -> select AT or SDK development path -> match firmware version -> validate on the actual hardware and local mobile network.

The repository can support the first four decisions with documentation. Only a real device, suitable power supply, SIM, antenna, and available network can validate the final step.