diff --git a/src/__tests__/threshold-control.test.ts b/src/__tests__/threshold-control.test.ts
new file mode 100644
index 0000000..efdf843
--- /dev/null
+++ b/src/__tests__/threshold-control.test.ts
@@ -0,0 +1,242 @@
+import { EventEmitter } from 'events'
+
+let NodeConstructor: (this: any, config: any) => void
+
+const RED = {
+  nodes: {
+    createNode (node: any, _config: any): void {
+      const ee = new EventEmitter()
+      node.on = ee.on.bind(ee)
+      node.emit = ee.emit.bind(ee)
+      node.status = jest.fn()
+      node.send = jest.fn()
+      node.warn = jest.fn()
+    },
+    registerType (_name: string, ctor: (this: any, config: any) => void): void {
+      NodeConstructor = ctor
+    }
+  },
+  util: {
+    evaluateNodeProperty: jest.fn((value: unknown, type: string, _node: unknown, _msg: unknown, cb?: (err: null, val: unknown) => void) => {
+      const result = type === 'num' ? Number(value) : value
+      if (cb) cb(null, result)
+      return result
+    })
+  }
+}
+
+require('../threshold-control')(RED)
+
+const DEFAULT_CONFIG = {
+  onPayload: '1',
+  payloadOnType: 'num',
+  offPayload: '0',
+  payloadOffType: 'num',
+  onThreshold: '100',
+  onThresholdType: 'num',
+  offThreshold: '80',
+  offThresholdType: 'num',
+  onDelay: '0',
+  offDelay: '0'
+}
+
+function createNode (config: Record<string, unknown> = {}): any {
+  const node: any = {}
+  NodeConstructor.call(node, { ...DEFAULT_CONFIG, ...config })
+  return node
+}
+
+function input (node: any, payload: unknown, extras: Record<string, unknown> = {}): void {
+  node.emit('input', { payload, ...extras })
+}
+
+describe('threshold-control', () => {
+  beforeEach(() => {
+    jest.useFakeTimers()
+  })
+
+  afterEach(() => {
+    jest.useRealTimers()
+    jest.clearAllMocks()
+  })
+
+  describe('input validation', () => {
+    it('rejects non-numerical payload', () => {
+      const node = createNode()
+      input(node, 'hello')
+      expect(node.status).toHaveBeenCalledWith({ fill: 'red', shape: 'dot', text: 'Non-numerical input' })
+      expect(node.send).not.toHaveBeenCalled()
+    })
+
+    it('rejects invalid onThreshold', () => {
+      const node = createNode({ onThreshold: 'abc' })
+      input(node, 90)
+      expect(node.status).toHaveBeenCalledWith(
+        expect.objectContaining({ fill: 'red', text: expect.stringContaining('ON threshold') })
+      )
+    })
+
+    it('rejects invalid offThreshold', () => {
+      const node = createNode({ offThreshold: 'abc' })
+      input(node, 90)
+      expect(node.status).toHaveBeenCalledWith(
+        expect.objectContaining({ fill: 'red', text: expect.stringContaining('OFF threshold') })
+      )
+    })
+  })
+
+  describe('initial state', () => {
+    it('sets on immediately when first payload exceeds onThreshold', () => {
+      const node = createNode()
+      input(node, 110)
+      expect(node.status).toHaveBeenCalledWith({ fill: 'green', shape: 'dot', text: 'on' })
+      expect(node.send).not.toHaveBeenCalled()
+    })
+
+    it('sets off immediately when first payload is below offThreshold', () => {
+      const node = createNode()
+      input(node, 70)
+      expect(node.status).toHaveBeenCalledWith({ fill: 'red', shape: 'dot', text: 'off' })
+      expect(node.send).not.toHaveBeenCalled()
+    })
+
+    it('shows blue unknown status when first payload is between thresholds', () => {
+      const node = createNode()
+      input(node, 90)
+      expect(node.status).toHaveBeenCalledWith({ fill: 'blue', shape: 'dot', text: 'unknown' })
+    })
+
+    it('does not start a countdown for the initial state', () => {
+      const node = createNode({ onDelay: '10' })
+      input(node, 110)
+      jest.advanceTimersByTime(15000)
+      expect(node.send).not.toHaveBeenCalled()
+    })
+  })
+
+  describe('state transitions', () => {
+    it('starts yellow countdown when payload crosses onThreshold', () => {
+      const node = createNode({ onDelay: '5' })
+      input(node, 70)   // initial: off
+      input(node, 110)  // cross onThreshold; yellow status appears on first tick
+      jest.advanceTimersByTime(1000)
+      expect(node.status).toHaveBeenCalledWith(
+        expect.objectContaining({ fill: 'yellow', text: expect.stringContaining('on') })
+      )
+    })
+
+    it('sends on payload after onDelay expires', () => {
+      const node = createNode({ onDelay: '2' })
+      input(node, 70)   // initial: off
+      input(node, 110)  // trigger countdown (counter=2)
+      jest.advanceTimersByTime(3000) // 3 ticks: counter 2→1→0→fire
+      expect(node.send).toHaveBeenCalledWith({ payload: 1 })
+    })
+
+    it('sends off payload after offDelay expires', () => {
+      const node = createNode({ offDelay: '2' })
+      input(node, 110)  // initial: on
+      input(node, 70)   // trigger off countdown (counter=2)
+      jest.advanceTimersByTime(3000) // 3 ticks: counter 2→1→0→fire
+      expect(node.send).toHaveBeenCalledWith({ payload: 0 })
+    })
+
+    it('cancels on countdown when payload drops back below onThreshold', () => {
+      const node = createNode({ onDelay: '5' })
+      input(node, 70)   // initial: off
+      input(node, 110)  // start on countdown
+      jest.advanceTimersByTime(2000)
+      input(node, 90)   // drops below onThreshold → cancel
+      jest.advanceTimersByTime(5000)
+      expect(node.send).not.toHaveBeenCalledWith({ payload: 1 })
+    })
+
+    it('cancels off countdown when payload rises back above offThreshold', () => {
+      const node = createNode({ offDelay: '5' })
+      input(node, 110)  // initial: on
+      input(node, 70)   // start off countdown
+      jest.advanceTimersByTime(2000)
+      input(node, 90)   // rises above offThreshold → cancel
+      jest.advanceTimersByTime(5000)
+      expect(node.send).not.toHaveBeenCalledWith({ payload: 0 })
+    })
+
+    it('updates status to green after on transition completes', () => {
+      const node = createNode()
+      input(node, 70)   // initial: off
+      input(node, 110)  // trigger countdown (counter=0)
+      jest.advanceTimersByTime(1000) // 1 tick: counter=0 → fire
+      expect(node.status).toHaveBeenCalledWith({ fill: 'green', shape: 'dot', text: 'on' })
+    })
+
+    it('updates status to red after off transition completes', () => {
+      const node = createNode()
+      input(node, 110)  // initial: on
+      input(node, 70)   // trigger countdown (counter=0)
+      jest.advanceTimersByTime(1000) // 1 tick: counter=0 → fire
+      expect(node.status).toHaveBeenCalledWith({ fill: 'red', shape: 'dot', text: 'off' })
+    })
+
+    it('does not send output when payloadOnType is nul', () => {
+      const node = createNode({ payloadOnType: 'nul' })
+      input(node, 70)   // initial: off
+      input(node, 110)  // trigger countdown
+      jest.advanceTimersByTime(1000)
+      expect(node.send).not.toHaveBeenCalledWith({ payload: 1 })
+    })
+
+    it('does not send output when payloadOffType is nul', () => {
+      const node = createNode({ payloadOffType: 'nul' })
+      input(node, 110)  // initial: on
+      input(node, 70)   // trigger countdown
+      jest.advanceTimersByTime(1000)
+      expect(node.send).not.toHaveBeenCalledWith({ payload: 0 })
+    })
+  })
+
+  describe('overrides from message', () => {
+    it('uses onThreshold from message', () => {
+      const node = createNode()
+      input(node, 90, { onThreshold: 85 })  // 90 > 85 → initial on
+      expect(node.status).toHaveBeenCalledWith({ fill: 'green', shape: 'dot', text: 'on' })
+    })
+
+    it('uses offThreshold from message', () => {
+      const node = createNode()
+      input(node, 110)                          // initial: on
+      input(node, 110, { offThreshold: 115 })  // 110 <= 115 → off transition
+      jest.advanceTimersByTime(1000)
+      expect(node.send).toHaveBeenCalledWith({ payload: 0 })
+    })
+
+    it('uses onDelay from message', () => {
+      const node = createNode({ onDelay: '10' })
+      input(node, 70)
+      input(node, 110, { onDelay: 1 })  // override to 1, so 2 ticks needed
+      jest.advanceTimersByTime(2000)
+      expect(node.send).toHaveBeenCalledWith({ payload: 1 })
+    })
+
+    it('uses offDelay from message', () => {
+      const node = createNode({ offDelay: '10' })
+      input(node, 110)
+      input(node, 70, { offDelay: 1 })  // override to 1
+      jest.advanceTimersByTime(2000)
+      expect(node.send).toHaveBeenCalledWith({ payload: 0 })
+    })
+  })
+
+  describe('node lifecycle', () => {
+    it('clears the interval on close', () => {
+      const spy = jest.spyOn(global, 'clearInterval')
+      const node = createNode()
+      node.emit('close')
+      expect(spy).toHaveBeenCalled()
+    })
+
+    it('warns when verbose is enabled', () => {
+      const node = createNode({ verbose: true })
+      expect(node.warn).toHaveBeenCalledWith('verbose')
+    })
+  })
+})
diff --git a/src/threshold-control.ts b/src/threshold-control.ts
index d4459ad..82fb281 100644
--- a/src/threshold-control.ts
+++ b/src/threshold-control.ts
@@ -1,6 +1,6 @@
 import type NodeRed from 'node-red'
 import { type NodeDef, type Node, type NodeStatusFill, type NodeMessageInFlow } from '@node-red/registry'
-import { isValidThreshold, shouldCancelCountDown, getNextTransition, type DesiredState } from './threshold-logic'
+import { isValidThreshold, shouldCancelCountDown, getNextTransition, getInitialState, type DesiredState } from './threshold-logic'
 
 type NodeAPI = NodeRed.NodeAPI
 
@@ -148,6 +148,14 @@ module.exports = function (RED: NodeAPI) {
       }
 
       if (State === 'unknown') {
+        const initial = getInitialState(Number(msg.payload), Number(onThreshold), Number(offThreshold))
+        if (initial !== 'unknown') {
+          desiredState = initial
+          State = initial
+          fill = initial === 'on' ? 'green' : 'red'
+          node.status({ fill, shape: 'dot', text: `${desiredState}` })
+          return
+        }
         fill = 'blue'
       }