hermes-bot/CONTEXT.md

Current state

Last updated 2026-10-04. HANDOFF.md is the brief; this file tracks where the work stands.

Hardware on hand

Raspberry Pi 4 (8 GB), BrainCraft HAT, Arducam UC-346 camera, and nothing else: no servos, no fan, no speakers, no USB-C splitter, no printed enclosure (the camera hangs loose on its ribbon and is held by hand). The Pi runs at about 62 C open-air with everything on and no fan; an enclosure will be hotter, so fit the fan before enclosing it. Playback and the servos are untested. Work until those arrive is limited to what the Pi, HAT and camera can do.

The Pi (hermes-bot)

• Ubuntu 24.04.5 server, kernel 6.8.0-1065-raspi (fully upgraded), flashed from talos. User hermes (key-only; passwordless sudo), SSH keys for kyle@vade (talos) and kyle@straylight.
• On Wi-Fi at 192.168.88.152 (MAC d8:3a:dd:0d:66:f5); eth0 is not cabled. The owner says it has a static IP on the rack switch; that address is not recorded here yet. USB link: 10.55.0.2 (see package 0b below); ssh hermes@10.55.0.2 works from talos. avahi-daemon is installed, but mDNS is off in systemd-resolved on talos, so hermes-bot.local doesn't resolve there; use the IP.
• cloud-init applies network-config and user-data on the first boot only. To change Wi-Fi later, edit /etc/netplan/50-cloud-init.yaml on the Pi, or bump instance_id in meta-data on system-boot. pi/50-cloud-init.yaml is a template for the Wi-Fi block; it is gitignored because it holds credentials.
• Installed: ROS 2 Jazzy (ros-base, ros-dev-tools, colcon, robot_state_publisher, xacro, camera_ros); python3-numpy/pil/spidev/lgpio/rpi-lgpio; a venv ~/venv (system site packages visible) with adafruit-circuitpython-rgb-display and Blinka. Workspace: ~/ros_ws, source synced from ros/ with rsync -a --delete --exclude __pycache__ ros/ hermes@<ip>:~/ros_ws/src/, then colcon build --symlink-install.
• One unit runs the whole robot: robot.service runs ros2 launch hermes_bringup robot.launch.py as hermes (face, camera, face detection, audio levels), so everything is ROS and the face is up whenever the robot is powered; each node is its own process, respawned by the launch file. Install with pi/install-robot-service.sh. RuntimeDirectory=robot gives lgpio a writable working directory (it drops a pipe in its cwd; systemd's default / is not writable). The face starts first and the camera, vision and audio nodes follow start_delay (6 s) later, so the Python processes do not fight over the CPU. Parameters are in ros/hermes_bringup/config/robot.yaml. robot-cpu-performance.service holds the governor at performance (the face costs about half the CPU at full clock). pi/trim-boot.sh disables snapd and ModemManager (unused; ~9 s of boot CPU).
• Boot timing (reboot-tested, everything returns by itself): the face draws at about 28 s on the boot clock (kernel 6.9 s, robot.service at ~10 s into userspace, then ros2 launch takes ~10 s to start on a cold Pi, then the face ~3 s); camera, audio and vision are up by ~37 s. The owner is fine with up to a minute, and prefers everything in ROS to a faster non-ROS face; a split robot-face.service that skipped the launch framework only saved 3.7 s and was dropped.
• Steady-state CPU with everything running (4 cores): face ~76%, camera ~57% (15 fps, from 30 at ~40% alone), detector ~40% (was 131%), audio ~12%; about half the machine idle, 62 C, no throttling, no fan fitted. Camera FrameDurationLimits is the lever (15 fps ~20% alone, 10 fps ~14%); JPEG quality barely matters. OpenCV's DNN spins every core and burns 3-4x its elapsed time in CPU, so the detector node pins it to one thread (YuNet 86 ms, SFace 161 ms of CPU), decodes the JPEG at half size (IMREAD_REDUCED_COLOR_2, boxes scaled back to full-size pixels) and re-identifies a tracked face at most once a second (IdentityCache).
• ros2 node list with its default short discovery window often shows only some of the nodes; use ros2 node list --no-daemon --spin-time 6 (all four appear), or check topics.
• ROS never leaves the Pi (owner's decision): ROS_AUTOMATIC_DISCOVERY_RANGE=LOCALHOST (set in pi/robot-env.sh, which sources everything) and the firewall drops domain 42's DDS ports (17900-18149) on every interface but loopback. hermes_mcp is the only bridge to the outside; a host that wants data from the robot gets it through an MCP tool, not DDS. This supersedes HANDOFF.md's host/ros-shell talking to the robot. (ROS's setup script exports SUBNET, so the variable must be assigned, not defaulted.)
• PipeWire (1.0.5, WirePlumber 0.4.17) runs as hermes's user services (loginctl enable-linger). ~/.config/pipewire/pipewire-pulse.conf.d/50-network-server.conf (from pi/pipewire/) makes pipewire-pulse listen on TCP 4713 on all interfaces; the firewall is the protection. Defaults are the WM8960 source and sink (alsa_input/output.platform-soc_sound.stereo-fallback). Verified from talos: pactl -s tcp:10.55.0.2:4713 info works; the same on the Wi-Fi address times out.

Package 0a (platform proof on Ubuntu 24.04)

• Step 1 done: host/check-pi-platform.sh passes.
• Step 2 done: flashed, booted, upgraded; ROS installed; ros2 topic list works.
• Step 5 (display) done. ST7789 works on lgpio through Blinka (rpi-lgpio, no RPi.GPIO). Two gotchas: pass cs=None (the kernel drives CE0; claiming GPIO8 raises "GPIO busy"), and the 240x240 glass sits at y_offset=80 in the controller's RAM, for every rotation (the driver rotates in software and leaves the scan direction fixed). Mounted pose (microSD end up, USB-C edge on the left) needs content turned 90 degrees clockwise: rotation=270. Full-frame push is ~23 fps through the driver; the face pushes raw RGB565 with _block and reaches ~27-28 fps.
• Camera: works with the Raspberry Pi libcamera fork, not with the stock stacks. The OV5647 is detected (ov5647 10-0036) and Ubuntu's libcamera 0.2.0 lists it once libcamera-ipa is installed, but capture dies in the Pi IPA (assertion "it != buffers_.end()" in prepareIsp()), and ROS Jazzy's libcamera 0.7.2 dies with FATAL … A list of V4L2 controls requires a ControlInfoMap right after configure. Both are deterministic whatever the stream format or size. Fix: build the fork (github.com/raspberrypi/libcamera, commit 6c1dd9d, 2026-08-17) with -Dpipelines=rpi/vc4 -Dipas=rpi/vc4 -Dcam=enabled -Dv4l2=false … into /opt/libcamera-rpi; its cam then captures 1296x972 RGB888 at ~16 fps (dim room). pi/capture_still.py takes a still with it. camera_ros still has to be built against this fork (the apt one uses ROS's broken libcamera). Frames are padded (stride 3936) and B,G,R in memory.
• camera_ros 0.7.0 is built from source against the fork in ~/camera_ws (overlay on ROS; at runtime the fork must come first in LD_LIBRARY_PATH, which source ~/robot-env.sh does; copy from pi/robot-env.sh). Verified: ros2 run camera_ros camera_node --ros-args -p width:=1296 -p height:=972 -p format:=RGB888 publishes /camera/image_raw, /camera/image_raw/compressed (~26 Hz) and /camera/camera_info. It costs ~140% of a core with raw and compressed both on; lower the frame rate or size before running everything together. No calibration file yet.
• ros/hermes_vision: hermes_vision.detect (YuNet, Haar fallback; no ROS imports) and a node face_detector that subscribes to the compressed image and publishes /vision/faces (vision_msgs/Detection2DArray, bbox centre/size in pixels, class_id: face, score), at rate_hz (default 4, ~47% of a core on a Pi 4); publish_debug:=true adds an annotated image. CLI: python -m hermes_vision.detect_cli IMAGE. YuNet 2023mar needs OpenCV 4.8+, so ~/venv has opencv-python-headless==4.10.0.84 with numpy<2 (system NumPy stays 1.26.4 for ROS), and robot-env.sh puts the venv first on PYTHONPATH; YuNet also needs input sides that are multiples of 32. Tested on a sample image and on a live frame (one face found, upright, no flip needed).
• Audio capture works (verified 2026-10-04). The stock wm8960-soundcard overlay fails every stream with wm8960: No MCLK configured on Ubuntu 24.04: it puts the 12.288 MHz fixed clock on the sound card's codec link, but the codec driver reads mclk from its own node. pi/overlays/hermes-wm8960.dts is the stock overlay plus clocks/clock-names on the codec node; pi/install-audio-overlay.sh compiles it to /boot/firmware/overlays/hermes-wm8960.dtbo, sets dtparam=audio=off and dtoverlay=hermes-wm8960. Capture then opens at 8-48 kHz. Address the card by name (hw:CARD=wm8960soundcard,DEV=0): its index changes (it was card 1, then 0).
• The HAT's hardware Audio ON/OFF slide switch (right edge, by the "Audio" label) must be ON. With it off, the codec still answers on I2C and every software check looks right, but all recordings are exactly zero. That cost an hour of debugging; check it first.
• Mixer: Left/Right Input Mixer Boost Switch default to off and must be on. Settings in use: Capture 47/47 (+18 dB), Left/Right Input Boost Mixer LINPUT1/RINPUT1 volume 1, input mixer boost on. Singing at arm's length: RMS -34 to -49 dBFS, peaks -18 dBFS, no clipping, channels within 1-2 dB. Saved with alsactl store and exported as pi/wm8960_asound.state; restoring at boot is not yet verified. No speakers on hand, so playback is untested.
• Not done: PWM (waits for servos). Ask before rebooting the Pi.

Package 0b (USB link): Pi side and talos side working

• Pi: dtoverlay=dwc2,dr_mode=peripheral; robot-usb-gadget.service builds a configfs gadget (NCM usb0 + ACM ttyGS0, host MAC 02:68:65:72:6d:01, robot MAC 02:68:65:72:6d:02) before networking; serial-getty@ttyGS0 is enabled; /etc/netplan/60-usb0.yaml gives usb0 10.55.0.2/30 with no gateway, so the default route stays on Wi-Fi. Installed by pi/install-usb-gadget.sh (a backup of config.txt is config.txt.bak-usbgadget). NCM works on the Pi 4 with kernel 1065; ECM was not needed.
• netplan gotcha: match the gadget interface by name: usb0. A macaddress: match becomes PermanentMACAddress= in networkd, which a gadget interface lacks, so it stays unmanaged.
• talos (Omarchy, NetworkManager): host/omarchy/robot-usb-link.sh (needs sudo) adds profile hermes-robot-usb: 10.55.0.1/30 on the interface with MAC 02:68:65:72:6d:01, priority 100, never-default. Verified from talos: ping ~2.4 ms, SSH over the link.
• Firewall: robot-firewall.service loads pi/nftables-robot.nft before networking at every boot (pi/install-firewall.sh; it must be loaded before the PipeWire network server is enabled). It accepts 4713/8765/8766 only on usb0 from 10.55.0.1, drops them elsewhere, and drops DDS on every interface but loopback. Verified: from talos, 4713 connects over usb0 and times out over Wi-Fi, while an unused port on the Pi's Wi-Fi address refuses instantly (so only 4713 is blocked). SSH is deliberately left open on all interfaces (key-only), for V2; the owner's call.
• Not yet verified: serial login prompt (talos's /dev/ttyACM0 is root:uucp; use sudo screen /dev/ttyACM0 115200). The hermes account has no password, so the console shows a login prompt but cannot log in until the owner sets one; no autologin by design. Also not done: the Pi booting with Wi-Fi off, replug and second-host recovery, get_throttled after a servo sweep on the splitter, the NixOS snippet, and straylight/other-host testing. Currently the Pi is powered from talos's USB port (bench test, no servos).

Face (ros/hermes_face)

• render.py: numpy port of docs/face-prototype.html, flat face only (head and lowpoly not ported). Phosphor and vector styles. States: sleeping idle listening thinking looking speaking. sleeping (new) is the "no agent connected" pose: eyes closed to thin lines, mouth short, dim and slowly breathing. looking returns to the state it interrupted. Tone mapping is a lookup table (RGB and RGB565 tables), glow is computed at half resolution, rotation is a free np.rot90.
• display.py: ST7789 driver plus an async pusher (render overlaps the SPI transfer).
• face_node.py: node hermes_face; subscribes /hermes/state (std_msgs/String) and /joint_states (pan_joint, tilt_joint, radians); starts in initial_state (sleeping), so it runs with nothing else up. Parameters: rotation (270), x_offset (0), y_offset (80), baudrate, fps, output (st7789 or none), phosphor (P7), style, persistence_ms, focus, jitter, intensity, initial_state.
• demo.py: no ROS. python -m hermes_face.demo --sequence cycles the states on the panel; --png-dir DIR writes a PNG per state without hardware.
• Tests: python3 -m pytest test in ros/hermes_face (25 pass on the Pi). Renderer parameters (focus, persistence_ms, intensity, jitter) are clamped; fps is clamped to 1-60.
• Measured on the Pi 4: ~9 ms per frame in isolation. With the CPU at full clock: 24% of a core at 20 fps and 40% at 30 fps (target was under 40% at 20 fps or more). Under ondemand the same load reads 40% at 20 fps and ~67% at 30 fps. No C++ rewrite was needed.
• Gaze: the node subscribes to /vision/faces (and /camera/camera_info for the image size) and the eyes glance toward the best face: a recognised one first, then the biggest. Image x flips on the display (a person on the image's right is on the robot's right, the viewer's left); the glance is smoothed, held 2.5 s, then drifts back to centre. Sleeping ignores it. The pan sign in the renderer was wrong (carried over from the prototype) and is fixed: positive pan = the robot's left = the viewer's right, positive tilt = looks up, as the MCP turn_head tool documents. Confirmed by the owner on the real display (2026-10-04): the glance directions look right. An earlier run showed nothing because the one-off wake message was lost (volatile QoS drops a sample published before discovery matches); test publishers must republish, as hermes_mcp will. The node logs every state change (state: idle (agent=..., audio=...)), so behaviour can be checked from journalctl -u robot-face without watching the panel.
• Agent heartbeat: /hermes/state doubles as the agent's heartbeat. hermes_mcp must republish its state about once a second; after agent_timeout_s (default 10, 0 disables) with none, the face logs agent gone, sleeping and sleeps, so "sleeping" means "no agent connected". Verified: woke on messages, slept 10 s after the last.
• Not yet: audio levels for the mouth (/audio/levels), hermes_mcp publishing states, launch file in hermes_bringup, head/lowpoly shapes, DotStar LEDs, button mute.
• Open: IPS black level. The backlight is on at full brightness, so black reads dark gray on camera. Dimming it needs a software PWM on GPIO26 (not a hardware PWM pin).

Audio levels and the literal voice trace (ros/hermes_audio, face integration)

• hermes_audio node audio_state taps the default source and the default sink's monitor with parec (16 kHz mono) and publishes /audio/levels ([mic_dbfs, speaker_dbfs]), /audio/activity (speaking | listening | quiet) and trigger-locked waveform windows /audio/scope/{mic,speaker} (256 samples). Audio itself never goes through ROS. hermes_audio.levels.Activity debounces and keeps an adaptive noise floor: a 3 s start-up calibration, then it drops fast and rises slowly, and anything 'listening' without a gap for 8 s is absorbed as ambient noise. The microphone is ignored while speaking (it would hear the robot).
• The face arbitrates (hermes_face.arbiter): sleeping (agent side only) > speaking > listening > thinking > idle. Room sound never wakes a sleeping face: sleeping means "no agent connected". looking stays a timed event owned by the renderer. While fresh (< 0.35 s) scope data exists, the mouth draws the real waveform (speaker when speaking, mic when listening), auto-scaled.
• WirePlumber resets the codec's capture gain to 100% (+30 dB) when it takes the device, overriding alsactl's saved level. Fix: pactl set-source-volume @DEFAULT_SOURCE@ 63% (PipeWire's scale is cubic: 63% is -12 dB from the +30 dB maximum, so ALSA Capture lands at 46, about +17 dB). WirePlumber remembers it; recheck after a reboot. The quiet-room floor at this gain is about -43 dBFS (preamp and mic noise).
• Confirmed by the owner: the mouth draws their live voice and its size follows how close and loud they are (proportional). The activity detector was retuned after the log showed the face flickering between listening and idle about twice a second: margin 7 dB (quiet-room noise peaks sit at about +3 dB over the floor), hold 1.2 s so pauses between words do not drop it. The flicker fix is covered by unit tests but not yet re-confirmed live (the retest window was silent).
• Verified on the Pi: the speaking path (a tone played to the sink, with no speaker attached, shows on the monitor at -13.5 dBFS, speaking for its length, mic ignored); levels and scope publish; 49 face tests, 10 audio tests. Not yet verified: the audio node as a service (it was run as a transient unit).

The MCP bridge (ros/hermes_mcp)

The only way in or out of the ROS graph. Serves MCP (SDK 2.3, streamable HTTP) on http://10.55.0.2:8765/mcp, the USB address only (retrying the bind if the link is not up yet), with a bearer token. Tool names are the stable contract with Hermes: look(), and turn_head / head_position only when a head is fitted. With no servos only look is registered, by design (head: false; the node refuses head: true until hermes_head exists). look() waits for the next camera frame taken after the call (never a stale one) and passes the camera's JPEG through (1296x972, ~155 KB); it also publishes looking on /hermes/state so the face squints and flashes. While an authenticated client is connected (in flight, or heard within connected_grace_s = 30) it republishes idle on /hermes/state once a second: the agent heartbeat that wakes the face. Verified end to end from talos over the USB link with a real MCP client: connects, lists look, look() returns a JPEG in 0.08 s, a wrong token is refused, the Wi-Fi path is dropped by the firewall, and the face went looking -> idle on connect and agent gone, sleeping about 40 s after the client left. The token is in /etc/robot-mcp.env (root:hermes, mode 640), generated by pi/install-robot-service.sh and never printed; read it with sudo cat. The MCP SDK is in ~/venv (pip install "mcp>=2"). The old pi/robot_mcp_server.py, pi/robot-mcp.service and pi/install.sh are superseded (package 5 rewrites the installer). Not yet verified: a real Hermes client, and whether Hermes passes MCP image content to the model (HANDOFF package 6).

Face recognition (opt-in)

hermes_vision.recognize / people: SFace embeddings on YuNet's landmarks. Nothing is stored until someone is enrolled (python -m hermes_vision.people enroll NAME, live from the camera topic, or enroll-images); only 128-number embeddings are kept, in ~/.local/share/hermes/faces.json (mode 0600, directory 0700, written atomically), never images. list, forget NAME and check IMAGE manage and test it. The detector node puts a recognised name in Detection2D.id and picks up database changes without a restart; its log prints a count, not names. Checked with a throwaway database: 8 of 9 unenrolled frames of the same person were recognised, down to side profiles (similarity 0.52-0.66), the miss being a head tipped back (0.34 against the 0.363 threshold); an unrelated photo scored 0.16. Nobody is enrolled yet; the owner enrols themselves live.

Next

1. Finish package 0b: Wi-Fi-off boot test, replug recovery, serial login check, NixOS snippet in host/nixos/. A new Omarchy host with a GPU (runs the local model "ornith") arrives this week: it needs only host/omarchy/robot-usb-link.sh and its SSH key added to the Pi.
2. hermes_head and the servos when they arrive (then head: true), echo cancel and the robot_mic naming once speakers arrive, a fan before any enclosure, the Wi-Fi-off boot test, a real Hermes client against hermes_mcp, and the rest of HANDOFF.md.
3. Confirm the retuned listening detector live (the flicker fix is unit-tested only); a second person in frame for the recognition test (not possible on 2026-10-04).

Repository

Branch master. .gitignore covers .remember/, caches, .venv/, *.orig, *.rej and pi/50-cloud-init.yaml. tools/check-pi-platform.sh duplicates host/check-pi-platform.sh and can probably go.

Security review notes (parked until the USB link is up)

An automated review of the initial commit flagged three items. All stem from the code predating the USB-gadget design (HANDOFF.md package 0b); none is exposed until the Pi runs the services.

• pi/robot_mcp_server.py: plain HTTP, ROBOT_MCP_BIND defaults to 0.0.0.0. Plan: default to 10.55.0.2, start after usb0.
• pi/pipewire/50-network-server.conf: TCP 4713 on all interfaces, unrestricted. Plan: keep, comment that the firewall is the protection.
• pi/nftables-robot.nft: still the Pi Zero version (single host IP, any interface). Package 0b rewrites it to accept only on the USB interface from 10.55.0.1.
• pi/install.sh permissions looked fine (/etc/robot-mcp.env is root:$USER, 640).

The owner wants to confirm the real IPs on the link before changing any of this. If the USB link doesn't work, revisit: TLS or a Tailscale-only bind for MCP and audio.