VMflow — Vending Machine Fleet Management

Manage your vending machine fleet with AI. Send credits, inspect device health, query sales and inventory, and trigger firmware updates — all from a single agent.

Two control planes:

• Supabase REST — historical data, inventory, sales, device list
• MQTT RPC — real-time signed commands directly to each device

Setup

1. Get a Bearer Token

The SUPABASE_ANON_KEY below is public and safe to embed — row-level security enforces per-operator data isolation after login.

SUPABASE_URL="${SUPABASE_URL:-https://supabase.vmflow.xyz}"
SUPABASE_ANON_KEY="${SUPABASE_ANON_KEY:-eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyb2xlIjoiYW5vbiIsImlzcyI6InN1cGFiYXNlLWRlbW8iLCJpYXQiOjE2NDE3NjkyMDAsImV4cCI6MTc5OTUzNTYwMH0.VGEEIztVo-do9cy_Qw2-2sF8bSONckhX71Nvtwj15X4}"

ACCESS_TOKEN=$(curl -s -X POST "$SUPABASE_URL/auth/v1/token?grant_type=password" \
  -H "apikey: $SUPABASE_ANON_KEY" \
  -H "Content-Type: application/json" \
  -d "{\"email\":\"$SUPABASE_EMAIL\",\"password\":\"$SUPABASE_PASSWORD\"}" \
  | jq -r '.access_token')

2. Fetch Device Credentials

Each device has a subdomain (integer) and passkey (18-char hex) stored in Supabase. The agent retrieves them before issuing any RPC command.

curl -s "$SUPABASE_URL/rest/v1/embedded?select=subdomain,passkey,status,status_at,machine_id" \
  -H "apikey: $SUPABASE_ANON_KEY" \
  -H "Authorization: Bearer $ACCESS_TOKEN"

Operations

Query Sales

# Latest 50 sales with machine and product name
curl -s "$SUPABASE_URL/rest/v1/sales?select=created_at,item_price,channel,coil_alias,machines(name),products(name)&order=created_at.desc&limit=50" \
  -H "apikey: $SUPABASE_ANON_KEY" -H "Authorization: Bearer $ACCESS_TOKEN"

# Sales today
TODAY=$(date -u +%Y-%m-%dT00:00:00Z)
curl -s "$SUPABASE_URL/rest/v1/sales?select=machine_id,item_price,channel&created_at=gte.$TODAY" \
  -H "apikey: $SUPABASE_ANON_KEY" -H "Authorization: Bearer $ACCESS_TOKEN"

Check Inventory

# Coils with 2 or fewer units remaining
curl -s "$SUPABASE_URL/rest/v1/machine_coils?select=machine_id,alias,current_stock,capacity,products(name)&current_stock=lte.2" \
  -H "apikey: $SUPABASE_ANON_KEY" -H "Authorization: Bearer $ACCESS_TOKEN"

# All machines with device status
curl -s "$SUPABASE_URL/rest/v1/machines?select=id,name,location_name,monthly_rent,embedded(status,status_at)" \
  -H "apikey: $SUPABASE_ANON_KEY" -H "Authorization: Bearer $ACCESS_TOKEN"

Send Credit (Cashless Payment)

Signs and publishes the MQTT credit RPC, records a sale. Device must be online.

curl -s -X POST "$SUPABASE_URL/functions/v1/send-credit" \
  -H "apikey: $SUPABASE_ANON_KEY" \
  -H "Authorization: Bearer $ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d "{\"subdomain\": $SUB, \"amount\": 5.00}"

Device Health Snapshot (RPC info)

MQTT_HOST="${MQTT_HOST:-mqtt.vmflow.xyz}"
TS=$(date +%s)
SIG=$(printf '%s' "info:-:$TS" | openssl dgst -sha256 -hmac "$PASSKEY" -hex | awk '{print $NF}')
# publish; listen for reply on domain.vmflow.xyz/$SUB/rpc/info
mosquitto_pub -h "$MQTT_HOST" -t "$SUB.vmflow.xyz/rpc" -m "info:-:$TS:$SIG" -q 1

Reply JSON:

{
  "version": "fw-version",
  "uptime_s": 86400,
  "reset_reason": 1,
  "free_heap": 182000,
  "min_free_heap": 145000,
  "machine_state": 3,
  "last_sale_price": 150,
  "last_sale_item": 7,
  "last_vend_success_time": 1751000000,
  "vend_fail_count": 2
}

machine_state: 0=INACTIVE 1=DISABLED 2=ENABLED 3=IDLE 4=VEND

reset_reason: 1=POWERON 2=EXT 3=SW 4=PANIC 5=INT_WDT 6=TASK_WDT 7=WDT

Other RPC Commands

All RPC envelopes: <cmd>:<args>:<ts>:<hmac> where hmac = HMAC-SHA256(passkey, "<cmd>:<args>:<ts>"). Commands with no argument use - as <args>. Messages expire after 10 seconds — sign at send time.

_rpc() {
  local CMD=$1 ARGS=${2:--}
  local TS SIG
  TS=$(date +%s)
  SIG=$(printf '%s' "$CMD:$ARGS:$TS" | openssl dgst -sha256 -hmac "$PASSKEY" -hex | awk '{print $NF}')
  mosquitto_pub -h "${MQTT_HOST:-mqtt.vmflow.xyz}" -t "$SUB.vmflow.xyz/rpc" -m "$CMD:$ARGS:$TS:$SIG" -q 1
}

_rpc echo          # liveness probe — reply on domain.vmflow.xyz/$SUB/rpc/echo
_rpc buzzer        # 1s beep (physical locate)
_rpc oos           # send MDB "out of sequence" to recover stuck VMC
_rpc restart       # reboot device — ack on .../rpc/restart then disconnects
_rpc dex           # pull EVA-DTS DEX telemetry — raw bytes on .../rpc/dex
_rpc ota -         # OTA to latest firmware release
_rpc ota v1.2.3    # OTA pinned to specific tag

Foot-Traffic (PAX Counter)

curl -s "$SUPABASE_URL/rest/v1/metrics?name=eq.paxcounter&select=created_at,value,machine_id&order=created_at.desc&limit=100" \
  -H "apikey: $SUPABASE_ANON_KEY" -H "Authorization: Bearer $ACCESS_TOKEN"

Each row is a BLE scan count (nearby devices detected) timestamped at scan completion.

Agent Playbooks

Fleet health sweep

1. GET /rest/v1/embedded → list all devices with subdomain, passkey, status
2. For each device send info RPC, collect reply JSON
3. Flag: machine_state=0 (MDB lost), vend_fail_count > 0, min_free_heap < 50000, reset_reason >= 4 (crash/watchdog)

Restocking priority list

1. GET /rest/v1/machine_coils?current_stock=lte.2 → critical coils
2. Join machines → group by location_name
3. Return ordered list by most critical location first

Revenue report

1. GET /rest/v1/sales?created_at=gte.{start} → all sales in period
2. Aggregate by machine_id, sum item_price, count rows
3. Join machines.monthly_rent → compute revenue - rent per machine

Recover unresponsive device

1. Send echo RPC, subscribe to domain.vmflow.xyz/$SUB/rpc/echo, wait 15s
2. No reply → device offline or MQTT unreachable
3. Try restart RPC; if no ack within 15s → escalate to physical inspection

Data Model

Known Limitations

• sales.product_id is NULL for MercadoPago/Stripe webhook payments — product-level analytics only available for cash and BLE sales.
• vend_fail_count resets on device reboot — not a reliable all-time counter.
• embedded.status_at is the last status change only — no downtime history table.
• dex RPC result is raw EVA-DTS binary on the MQTT reply topic — no Supabase table persists DEX data today.

References

• Full agent context + BLE payload spec: AGENTS.md
• RPC helper script: tools/rpc.sh
• Firmware RPC handler: mdb-slave-esp32s3/main/mdb-slave-esp32s3.c
• Supabase schema: docker/supabase/migrations/
• Web dashboard: https://vmflow.xyz/dashboard
• GitHub: https://github.com/nodestark/mdb-esp32-cashless