feat(framework): Enable FastAPI to manage SuperLinkLifespan

framework/FASTAPI.md

@@ -2,21 +2,51 @@
 
 ## Install
 
+To run FastAPI, install `flwr` with all extras to ensure the `rest` extra is included:
+
 ```bash
-uv sync --all-extras
+uv sync --locked --all-extras
 ```
 
-## Run SuperLink
+## SuperLink Run Modes
+
+With the new HTTP API, there are now four different options to start and run the SuperLink:
+
+1. **Legacy Mode** `flower-superlink` (without `--enable-http-api`): This starts the SuperLink in "legacy mode" with only gRPC APIs, but no HTTP API.
+
+   ```bash
+   uv run flower-superlink --insecure
+   ```
+
+1. **Compatibility Mode** `flower-superlink --enable-http-api`: This starts the SuperLink in Compatibility Mode with both the HTTP API and the legacy gRPC APIs. **This is what we're running in prod until the gRPC-to-HTTP conversion is complete.** Note that in Compatibility Mode, FastAPI is limited to only 1 worker, which is a serious limitation during this transition.
+
+   ```bash
+   uv run flower-superlink --insecure --enable-http-api
+   ```
+
+1. **Next Mode** `flower-superlink --enable-http-api --disable-grpc-api`: This starts the SuperLink in "HTTP mode" with only the HTTP API, but not the legacy gRPC APIs.
+
+   ```bash
+   uv run flower-superlink --insecure --enable-http-api --disable-grpc-api
+   ```
+
+1. **Experimental Mode** `uvicorn flwr.superlink.main:app`: This starts the SuperLink in "experimental mode" via uvicorn, skipping the `flower-superlink` argument parsing. This mode is experimental because it needs to reach parity with `flower-superlink --enable-http-api --disable-grpc-api`.
+
+   ```bash
+   uv run uvicorn flwr.superlink.main:app
+   ```
+
+## Run SuperLink in Experimental Mode
 
-Start the SuperLink FastAPI server using uvicorn:
+Start the SuperLink's FastAPI server using uvicorn:
 
 ```bash
 uv run uvicorn flwr.superlink.main:app
 ```
 
-## Run SuperNode
+## Run SuperNode in Experimental Mode
 
-Start the SuperNode FastAPI server using uvicorn:
+Start the SuperNode's FastAPI server using uvicorn:
 
 ```bash
 uv run uvicorn flwr.supernode.main:app

framework/py/flwr/supercore/constant.py

@@ -67,6 +67,10 @@
 FLWR_UPDATE_CHECK_CACHE_FILENAME = "update-check.json"
 FLWR_UPDATE_CHECK_SHOW_INTERVAL_SECONDS = 12 * 60 * 60
 
+# Constants for Uvicorn-backed API servers
+UVICORN_DEFAULT_HOST = "127.0.0.1"
+UVICORN_DEFAULT_PORT = 8000
+
 # SuperGrid constants
 SUPERGRID_ADDRESS = "supergrid.flower.ai"