Stéphane Tailland
1ec9e308ba
The service's own supplier, simulated: a fixed lead time or a 15% chance of a stockout is the whole model, on purpose — this simulates that fulfilment can fail, not why a given supplier would. One service, two capacities: this workflow both raises reorder.requested (the periodic run) and answers its own request (this workflow), under the same Kafka account and Keycloak client, per the 2026-08-31 decision that réapprovisionnement stays one service. The delivery write goes through the front door — patch-product, under a new restocker role that may PATCH a product and nothing else — so the resulting product.stock_changed event is the only stock-update fact. No second, n8n-emitted event claims a delivery happened with nothing to certify it. Shipped with, and fixed, a bug where the delivery-application node spread the wrong upstream , silently dropping reorder_id/productcode/quantity two nodes before the failure surfaced. Verified separately: the write+event chain (a real bug, now fixed) and the state machine (persists correctly on a real trigger; a manual test run does not persist staticData, which is a testing limitation, not a production one). Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
460 lines
17 KiB
JSON
460 lines
17 KiB
JSON
{
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"name": "Supply \u2014 procurement",
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"nodes": [
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{
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"parameters": {
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"topic": "classic-models.procurement",
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"groupId": "supply-procurement",
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"resolveOffset": "onCompletion",
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"allowedStatuses": [
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"success"
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],
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"options": {
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"jsonParseMessage": true,
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"onlyMessage": true,
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"fromBeginning": false
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}
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},
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"type": "n8n-nodes-base.kafkaTrigger",
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"typeVersion": 2,
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"position": [
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0,
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0
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],
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"id": "procurement-events",
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"name": "Procurement events",
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"credentials": {
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"kafka": {
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"id": "8qNZXLzvdx5rWQ0V",
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"name": "kafka-classic-models"
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}
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}
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},
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{
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"parameters": {
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"jsCode": "// Every fact on this topic passes through here \u2014 requests, and this\n// service's own answers to them. Only a request is this node's job; an\n// answer re-arriving (a replay, or this consumer's own message) is not\n// something to decide on a second time.\nif ($json.type !== 'com.sttlab.classicmodels.reorder.requested.v1') return [];\nreturn [{ json: $json.data ?? {} }];"
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},
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"type": "n8n-nodes-base.code",
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"typeVersion": 2,
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"position": [
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220,
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0
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],
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"id": "filter-requested",
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"name": "Only requests"
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},
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{
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"parameters": {
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"jsCode": "// The supplier's answer to one request \u2014 decided once, here, never revisited.\n//\n// A random stockout is the honest way to simulate \"sometimes a supplier\n// cannot fulfil a request\" without pretending to model a real one: no lead\n// time table, no supplier entity, no negotiation. `STOCKOUT_CHANCE` is the\n// whole model.\nconst LEAD_TIME_DAYS = 7;\nconst STOCKOUT_CHANCE = 0.15;\n\nconst req = $json;\nif (!req.reorder_id || !req.productcode) {\n // Not our envelope, or unreadable. Every message on this topic is either a\n // request or an answer to one \u2014 this node only runs on requests (filtered\n // upstream), so a shape this far off the contract is not this run's job.\n return [];\n}\n\nconst rejected = Math.random() < STOCKOUT_CHANCE;\nconst now = new Date();\n\nif (rejected) {\n return [{ json: {\n outcome: 'rejected',\n reorder_id: req.reorder_id,\n productcode: req.productcode,\n quantity: req.quantity,\n decided_at: now.toISOString(),\n reason: 'supplier stockout',\n }}];\n}\n\nconst deliverOn = new Date(now);\ndeliverOn.setUTCDate(deliverOn.getUTCDate() + LEAD_TIME_DAYS);\n\nreturn [{ json: {\n outcome: 'confirmed',\n reorder_id: req.reorder_id,\n productcode: req.productcode,\n quantity: req.quantity,\n decided_at: now.toISOString(),\n deliver_on: deliverOn.toISOString().slice(0, 10),\n}}];\n"
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},
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"type": "n8n-nodes-base.code",
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"typeVersion": 2,
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"position": [
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440,
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0
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],
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"id": "decide-request",
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"name": "Decide the request"
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},
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{
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"parameters": {
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"jsCode": "// The envelope for whichever answer \"Decide the request\" produced. One node\n// covers both event types on purpose: they share every field except the ones\n// that differ (deliver_on vs reason), and a caller distinguishes them by\n// `type`, the way any consumer here already does.\nconst d = $json;\nconst type = d.outcome === 'confirmed'\n ? 'com.sttlab.classicmodels.reorder.confirmed.v1'\n : 'com.sttlab.classicmodels.reorder.rejected.v1';\n\nconst data = d.outcome === 'confirmed'\n ? { reorder_id: d.reorder_id, productcode: d.productcode, quantity: d.quantity, deliver_on: d.deliver_on }\n : { reorder_id: d.reorder_id, productcode: d.productcode, quantity: d.quantity, reason: d.reason };\n\nreturn [{ json: {\n envelope: JSON.stringify({\n specversion: '1.0',\n type,\n source: '/supply-agent/procurement',\n subject: d.reorder_id,\n id: `${d.reorder_id}-${d.outcome}`,\n time: d.decided_at,\n datacontenttype: 'application/json',\n data,\n }),\n reorder_id: d.reorder_id,\n}}];\n"
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},
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"type": "n8n-nodes-base.code",
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"typeVersion": 2,
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"position": [
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660,
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-100
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],
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"id": "build-answer",
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"name": "Build the answer"
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},
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{
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"parameters": {
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"topic": "classic-models.procurement",
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"sendInputData": false,
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"message": "={{ $json.envelope }}",
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"useKey": true,
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"key": "={{ $json.reorder_id }}",
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"options": {}
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},
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"type": "n8n-nodes-base.kafka",
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"typeVersion": 2,
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"position": [
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880,
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-100
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],
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"id": "publish-answer",
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"name": "Publish the answer",
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"credentials": {
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"kafka": {
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"id": "8qNZXLzvdx5rWQ0V",
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"name": "kafka-classic-models"
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}
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}
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},
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{
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"parameters": {
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"jsCode": "// Remembering what to deliver, and when \u2014 the same staticData pattern the\n// stock-watch workflow already uses for its own pending state, so this is not\n// a second mechanism to reason about, just a second use of one.\nif ($json.outcome !== 'confirmed') {\n // A rejection has nothing further to do: no delivery, nothing to schedule.\n return [];\n}\nconst store = $getWorkflowStaticData('global');\nstore.pendingDeliveries = store.pendingDeliveries ?? {};\nstore.pendingDeliveries[$json.reorder_id] = {\n productcode: $json.productcode,\n quantity: $json.quantity,\n deliver_on: $json.deliver_on,\n};\nreturn [{ json: { scheduled: true, reorder_id: $json.reorder_id } }];\n"
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},
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"type": "n8n-nodes-base.code",
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"typeVersion": 2,
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"position": [
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],
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"id": "schedule-delivery",
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"name": "Schedule the delivery"
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},
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{
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"parameters": {
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"rule": {
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"interval": [
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{
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"field": "days",
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"triggerAtHour": 6,
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"triggerAtMinute": 15
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}
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]
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}
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},
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"type": "n8n-nodes-base.scheduleTrigger",
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"typeVersion": 1.2,
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"position": [
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0,
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300
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],
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"id": "every-morning-delivery",
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"name": "Every morning (delivery)"
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},
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{
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"parameters": {
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"method": "POST",
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"url": "https://keycloak.sttlab.local/realms/classic-models/protocol/openid-connect/token",
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"sendBody": true,
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"contentType": "form-urlencoded",
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"bodyParameters": {
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"parameters": [
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{
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"name": "grant_type",
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"value": "client_credentials"
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},
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{
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"name": "client_id",
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"value": "classic-models-agent-supply"
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},
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{
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"name": "client_secret",
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"value": "={{ $env.SUPPLY_CLIENT_SECRET }}"
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},
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{
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"name": "scope",
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"value": "openid mcp-catalog-audience token-exchange-broker-audience"
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}
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]
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},
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"options": {}
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},
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"type": "n8n-nodes-base.httpRequest",
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"typeVersion": 4.2,
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"position": [
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220,
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300
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],
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"id": "machine-token-delivery",
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"name": "Machine token"
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},
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{
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"parameters": {
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"method": "POST",
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"url": "https://catalog-dev.sttlab.local/catalog-mcp",
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"sendHeaders": true,
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"headerParameters": {
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"parameters": [
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{
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"name": "Authorization",
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"value": "=Bearer {{ $json.access_token }}"
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},
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{
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"name": "Accept",
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"value": "application/json, text/event-stream"
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}
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]
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},
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"sendBody": true,
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"specifyBody": "json",
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"jsonBody": "{\"jsonrpc\": \"2.0\", \"id\": 1, \"method\": \"initialize\", \"params\": {\"protocolVersion\": \"2025-06-18\", \"capabilities\": {}, \"clientInfo\": {\"name\": \"supply-procurement\", \"version\": \"0.1.0\"}}}",
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"options": {
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"response": {
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"response": {
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"fullResponse": true
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}
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}
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}
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},
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"type": "n8n-nodes-base.httpRequest",
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"typeVersion": 4.2,
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"position": [
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440,
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300
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],
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"id": "mcp-initialize-delivery",
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"name": "MCP initialize"
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},
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{
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"parameters": {
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"jsCode": "// What is due today or earlier \u2014 anything scheduled for a date already past\n// is delivered on the next run rather than lost, since this only runs once a\n// day and a missed day must not mean a missed delivery.\nconst store = $getWorkflowStaticData('global');\nstore.pendingDeliveries = store.pendingDeliveries ?? {};\n\nconst today = new Date().toISOString().slice(0, 10);\nconst due = Object.entries(store.pendingDeliveries)\n .filter(([, d]) => d.deliver_on <= today)\n .map(([reorder_id, d]) => ({ json: { reorder_id, ...d } }));\n\nreturn due;\n"
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},
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"type": "n8n-nodes-base.code",
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"typeVersion": 2,
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"position": [
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660,
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300
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],
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"id": "due-deliveries",
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"name": "Due deliveries"
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},
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{
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"parameters": {
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"method": "POST",
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"url": "https://catalog-dev.sttlab.local/catalog-mcp",
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"sendHeaders": true,
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"headerParameters": {
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"parameters": [
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{
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"name": "Authorization",
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"value": "=Bearer {{ $('Machine token').item.json.access_token }}"
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},
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{
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"name": "Accept",
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"value": "application/json, text/event-stream"
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},
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{
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"name": "mcp-session-id",
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"value": "={{ $('MCP initialize').item.json.headers['mcp-session-id'] }}"
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}
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]
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},
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"sendBody": true,
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"specifyBody": "json",
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"jsonBody": "={{ JSON.stringify({ jsonrpc: '2.0', id: 2, method: 'tools/call', params: { name: 'get-product', arguments: { path_productcode: $json.productcode } } }) }}",
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"options": {
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"response": {
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"response": {
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"neverError": true
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}
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}
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}
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},
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"type": "n8n-nodes-base.httpRequest",
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"typeVersion": 4.2,
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"position": [
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880,
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300
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],
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"id": "read-current-stock",
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"name": "Read current stock",
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"alwaysOutputData": true
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},
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{
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"parameters": {
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"jsCode": "// The new stock figure, read fresh rather than trusted from whenever this was\n// scheduled \u2014 a delivery adds to whatever is on hand *now*, not to a number\n// that may be a week stale.\n//\n// Two upstream nodes matter here, not one: \"Due deliveries\" carries what this\n// delivery IS (reorder_id, productcode, quantity), \"Read current stock\" carries\n// what the catalog says right now. `$json` at this point is the LATTER \u2014 using\n// it for the former was the bug that shipped first: it silently dropped\n// reorder_id/productcode/quantity, and the write two nodes later failed on\n// \"path_productcode is a required property\" with no due-delivery context left\n// to explain why.\nconst due = $('Due deliveries').item.json;\n\nconst raw = $json ?? {};\nconst body = typeof raw === 'string' ? raw : (raw.data ?? JSON.stringify(raw));\nconst line = String(body).split('\\n').find((l) => l.startsWith('data:'));\nif (!line) return [{ json: { ...due, applied: false, why: 'unreadable catalog reply' } }];\n\nlet rpc;\ntry { rpc = JSON.parse(line.slice(5).trim()); }\ncatch (e) { return [{ json: { ...due, applied: false, why: 'unreadable catalog reply' } }]; }\nif (rpc.error || rpc.result?.isError) {\n return [{ json: { ...due, applied: false, why: 'read failed' } }];\n}\n\nconst product = JSON.parse(rpc.result.content[0].text);\nconst newQuantity = Number(product.quantityinstock) + Number(due.quantity);\n\nreturn [{ json: { ...due, new_quantity: newQuantity } }];\n"
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},
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"type": "n8n-nodes-base.code",
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"typeVersion": 2,
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"position": [
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1100,
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300
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],
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"id": "apply-delivery",
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"name": "Apply delivery"
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},
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{
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"parameters": {
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"method": "POST",
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"url": "https://catalog-dev.sttlab.local/catalog-mcp",
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"sendHeaders": true,
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"headerParameters": {
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"parameters": [
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{
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"name": "Authorization",
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"value": "=Bearer {{ $('Machine token').item.json.access_token }}"
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},
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{
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"name": "Accept",
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"value": "application/json, text/event-stream"
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},
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{
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"name": "mcp-session-id",
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"value": "={{ $('MCP initialize').item.json.headers['mcp-session-id'] }}"
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}
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]
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},
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"sendBody": true,
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"specifyBody": "json",
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"jsonBody": "={{ JSON.stringify({ jsonrpc: '2.0', id: 3, method: 'tools/call', params: { name: 'patch-product', arguments: { path_productcode: $json.productcode, ['header_X-Stock-Change-Reason']: 'delivery:' + $json.reorder_id, body: { quantityinstock: $json.new_quantity } } } }) }}",
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"options": {
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"response": {
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"response": {
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"neverError": true
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}
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}
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}
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},
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"type": "n8n-nodes-base.httpRequest",
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"typeVersion": 4.2,
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"position": [
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1320,
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300
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],
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"id": "update-stock",
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"name": "Update stock",
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"alwaysOutputData": true
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},
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{
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"parameters": {
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"jsCode": "// Only clear the pending entry once the write is actually confirmed \u2014 the\n// classic-models-api response is the proof, never an assumption. A failed\n// PATCH here must leave the entry in place so tomorrow's run retries it,\n// rather than silently losing a delivery nobody applied.\nconst raw = $json ?? {};\nconst body = typeof raw === 'string' ? raw : (raw.data ?? JSON.stringify(raw));\nconst line = String(body).split('\\n').find((l) => l.startsWith('data:'));\n\nlet ok = false;\ntry {\n const rpc = JSON.parse(line.slice(5).trim());\n ok = !rpc.error && !rpc.result?.isError;\n} catch (e) {\n ok = false;\n}\n\nconst pending = $('Apply delivery').item.json;\nif (!ok) {\n return [{ json: { delivered: false, reorder_id: pending.reorder_id, why: 'the write did not confirm; retrying tomorrow' } }];\n}\n\nconst store = $getWorkflowStaticData('global');\nif (store.pendingDeliveries) delete store.pendingDeliveries[pending.reorder_id];\nreturn [{ json: { delivered: true, reorder_id: pending.reorder_id, productcode: pending.productcode, new_quantity: pending.new_quantity } }];\n"
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},
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"type": "n8n-nodes-base.code",
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"typeVersion": 2,
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"position": [
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1540,
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300
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],
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"id": "clear-delivery",
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"name": "Confirm delivery"
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}
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],
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"connections": {
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"Procurement events": {
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"main": [
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[
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{
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"node": "Only requests",
|
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Only requests": {
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"main": [
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[
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{
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"node": "Decide the request",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Decide the request": {
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"main": [
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[
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{
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"node": "Build the answer",
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"type": "main",
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"index": 0
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},
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{
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"node": "Schedule the delivery",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Build the answer": {
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"main": [
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[
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{
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"node": "Publish the answer",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Every morning (delivery)": {
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"main": [
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[
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{
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"node": "Machine token",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Machine token": {
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"main": [
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[
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{
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"node": "MCP initialize",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"MCP initialize": {
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"main": [
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[
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{
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"node": "Due deliveries",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Due deliveries": {
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"main": [
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[
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{
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"node": "Read current stock",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Read current stock": {
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"main": [
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[
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{
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"node": "Apply delivery",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Apply delivery": {
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"main": [
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[
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{
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"node": "Update stock",
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"type": "main",
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"index": 0
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}
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]
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]
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},
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"Update stock": {
|
|
"main": [
|
|
[
|
|
{
|
|
"node": "Confirm delivery",
|
|
"type": "main",
|
|
"index": 0
|
|
}
|
|
]
|
|
]
|
|
}
|
|
},
|
|
"settings": {
|
|
"executionOrder": "v1"
|
|
}
|
|
}
|