diff --git a/.github/workflows/circuitpython.yml b/.github/workflows/circuitpython.yml
index 7a459270..769d8c5c 100644
--- a/.github/workflows/circuitpython.yml
+++ b/.github/workflows/circuitpython.yml
@@ -181,3 +181,59 @@ jobs:
 
       - name: mdns - the API, and a service found by the process that advertised it
         run: timeout 300 ./builds/circuitpython/unix/coverage/micropython modules/mdns/tests/test_mdns.py
+
+  # The ESP32-P4 host engine on CircuitPython: usbhost's C compiled against
+  # CircuitPython's own ESP-IDF 6 and Espressif's usb component, for the
+  # DEV-KIT's board cell. Nothing else in CI compiles this path, since the
+  # unix port builds usbhost to nothing, and a change to the shared engine
+  # sources (modules/usbhost/src) can break it with every other check green.
+  esp32p4-usbhost:
+    runs-on: ubuntu-latest
+    timeout-minutes: 90
+    env:
+      CCACHE_DIR: /home/runner/.cache/ccache
+      CCACHE_MAXSIZE: 400M
+      CCACHE_COMPILERCHECK: content
+      CCACHE_BASEDIR: ${{ github.workspace }}
+      CMAKE_C_COMPILER_LAUNCHER: ccache
+      CMAKE_CXX_COMPILER_LAUNCHER: ccache
+      CMAKE_ASM_COMPILER_LAUNCHER: ccache
+      IDF_CCACHE_ENABLE: '1'
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Packages the build needs
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y ccache gettext cmake ninja-build pkg-config libffi-dev
+
+      - name: Cache the toolchains
+        uses: actions/cache@v6
+        with:
+          path: |
+            deps/circuitpython
+            deps/circuitpython-venv
+            ~/.espressif
+          key: deps-cp-esp32p4-${{ hashFiles('deps.lock', 'patches/circuitpython/**') }}
+
+      - name: Cache compiler output
+        uses: actions/cache@v6
+        with:
+          path: /home/runner/.cache/ccache
+          key: ccache-cp-esp32p4-usbhost-${{ hashFiles('UPSTREAM', 'modules.lock') }}-${{ github.run_id }}
+          restore-keys: |
+            ccache-cp-esp32p4-usbhost-${{ hashFiles('UPSTREAM', 'modules.lock') }}-
+            ccache-cp-esp32p4-usbhost-
+
+      - name: Build CircuitPython for the WIFI6 DEV-KIT with usbhost
+        run: |
+          python3 build_mp.py --interpreter circuitpython --port espressif \
+            --board waveshare_esp32p4_wifi6_dev_kit --modules usbhost
+
+      - name: The host engine is in the image
+        run: |
+          out=builds/circuitpython/espressif/waveshare_esp32p4_wifi6_dev_kit
+          test -s "$out/firmware.bin"
+          for o in mod_usbhost usbhost_host usbhost_host_xfer usbhost_host_stream; do
+            grep -q "/$o.o" "$out/firmware.objs" || { echo "$o.o was not linked"; exit 1; }
+          done
diff --git a/ROADMAP.md b/ROADMAP.md
index 393a3cb3..483dc026 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -13,9 +13,10 @@ More modules in CircuitPython-compatible builds
 - **castif casting on CircuitPython's ESP32-P4 builds.** castif and h264enc
   build there and h264enc encodes, but the port has no network until
   CircuitPython drives the boards' ESP32-C6 radio, so a cast can't start yet.
-- **usbhost on a CircuitPython ESP32-P4 board.** The host builds into
-  CircuitPython's ESP32-P4 firmware but hasn't run on a board yet: first a
-  device enumerated and read. Tethering waits for the port's network.
+- **More of usbhost on a CircuitPython ESP32-P4 board.** The host enumerates
+  and answers a wireless keyboard-and-mouse dongle on the WIFI6 DEV-KIT. Still
+  to try there: a drive, a webcam's stream and a phone. Tethering waits for the
+  port's network.
 - **The USB host drivers on CircuitPython's own `usb.core`**, on the RP2040
   and i.MX: planned in [pydevices](https://github.com/PyDevices/pydevices/blob/main/ROADMAP.md#usb).
 
diff --git a/docs/build-plan.md b/docs/build-plan.md
index 0bbfad32..9470ba34 100644
--- a/docs/build-plan.md
+++ b/docs/build-plan.md
@@ -420,7 +420,7 @@ five cells of [`release-firmware.yml`](../.github/workflows/release-firmware.yml
 | jpegio | yes | ESP32-P4 | adds only the encoder's C API: CircuitPython has its own `jpegio` decoder |
 | cameraif | yes (`available()` is False) | ESP32-P4 | |
 | mdns | yes (was left out) | no, on purpose | CircuitPython's boards have an `mdns` of their own; its unix port had none |
-| usbhost | yes, as `_usbhost`, with no host engine (was a build error) | ESP32-P4 | the host engine runs on ESP-IDF's USB host library, which from ESP-IDF 6 is Espressif's `usb` component: `build_mp.py` fetches it at the version `deps.lock` pins. The P4's boards leave its high-speed controller to us. Tethering is left out until the port has a network, and the host hasn't run on a CircuitPython board yet ([roadmap](../ROADMAP.md)). The S3's one controller is CircuitPython's drive and REPL, so it gets the module without the engine. On the RP2040 and i.MX, CircuitPython's own `usb.core` is the host, and pydevices' HID, CDC and MSC drivers are planned for it |
+| usbhost | yes, as `_usbhost`, with no host engine (was a build error) | ESP32-P4 | the host engine runs on ESP-IDF's USB host library, which from ESP-IDF 6 is Espressif's `usb` component: `build_mp.py` fetches it at the version `deps.lock` pins. The P4's boards leave its high-speed controller to us. Tethering is left out until the port has a network, and on the WIFI6 DEV-KIT the host has enumerated a webcam and a keyboard-and-mouse dongle, with drives and streams still to try ([roadmap](../ROADMAP.md)). The S3's one controller is CircuitPython's drive and REPL, so it gets the module without the engine. On the RP2040 and i.MX, CircuitPython's own `usb.core` is the host, and pydevices' HID, CDC and MSC drivers are planned for it |
 | audioif | no | no | links against audiodsp's audio pump and `cp_compat`, which audiodsp's CircuitPython glue doesn't build. CircuitPython's audio samples are fed only from C, so audio made in Python needs a stream sample, the pump's C side shaped as one ([roadmap](../ROADMAP.md)); boards have `audiobusio` of their own |
 | ulab | CircuitPython's own | CircuitPython's own | |
 | castif | no: it is the ESP32-P4's | ESP32-P4, with no network yet | talks to lwIP directly, the lwIP under CircuitPython's own `socketpool`. CircuitPython's P4 port has no network until it drives the boards' ESP32-C6, so castif is built without one and `start()` says so ([roadmap](../ROADMAP.md)). Name tsmux, h264enc and ppa with it |
diff --git a/modules/usbhost/README.md b/modules/usbhost/README.md
index f4ed23a5..2218c5f0 100644
--- a/modules/usbhost/README.md
+++ b/modules/usbhost/README.md
@@ -10,9 +10,11 @@ ESP-IDF's USB host library. Its CMake glue skips every other part, so a
 firmware for those still builds, without the host.
 
 On CircuitPython the host builds for the ESP32-P4, where the boards leave the
-high-speed controller free. It hasn't run on a CircuitPython board yet, so
-treat it as untried there. Phone tethering is left out there, because the
-port has no network yet. Every other CircuitPython build gets `_usbhost`
+high-speed controller free. On the Waveshare ESP32-P4-WIFI6-DEV-KIT it
+enumerates a webcam and a wireless keyboard-and-mouse dongle behind the
+board's hub (started with `full_speed=True`) and answers the dongle's HID
+requests; drives and streams haven't been tried there. Phone tethering is
+left out there, because the port has no network yet. Every other CircuitPython build gets `_usbhost`
 without the host.
 
 ## The packages are in pydevices