Multi-plug toggle wiring with single button, avoid Node-RED mqtt-broker duplicate-delivery bug #1

New Issue

2026-07-01T05:12:46Z

david commented

2026-07-01 05:12:46 +00:00

Track the wiring that maps a single ThirdReality button (Door Button) to toggling three ThirdReality smart plugs (Squiggle, Sideboard Lamp, Bamboo Lights) via zigbee2mqtt.

Findings

Node-RED 5.0 + Dashboard 2.0 (v1.30.2) mqtt-broker has a duplicate-delivery bug when a single mqtt-in subscriber exists alongside a wildcard # subscriber on the same base topic. Source: /usr/src/node-red/node_modules/@node-red/nodes/core/network/10-mqtt.js line ~1091: node._clientOn('message', subscription.handler) is unconditional and re-adds the handler as an EventEmitter listener on every subscribe call.
Workaround: each mqtt-in must subscribe to a unique topic. Use specific topics (zigbee2mqtt/<device>) instead of wildcards (zigbee2mqtt/#).
zigbee2mqtt groups do not support TOGGLE — only ON/OFF. Use individual mqtt out nodes per plug.

Implemented

Three parallel mqtt out nodes, each publishes TOGGLE to its plug on button press
Three separate mqtt in nodes, one per plug, drive the corresponding ui-text widget
btn-filter function node drops non-action:single button events (battery reports, double press, etc.)

Reboot survival

All configs are bind-mounted to host paths:

/root/nodered/flows.json → nodered container /data/flows.json (volume)
/root/zigbee2mqtt/configuration.yaml → zigbee2mqtt container /app/data/configuration.yaml (volume)
/root/nodered/node_modules/@flowfuse/node-red-dashboard/dist/index.html (modified with <base href="/dashboard/"> to fix Vue Router 4 replace() error)

The <base href> patch is fragile: any npm install in the nodered container would overwrite it. Needs a proper upstream PR to FlowFuse/node-red-dashboard.

Next steps

Submit upstream PR for the <base href> issue (or document as manual fix)
Add Rego policy to catch wildcard-alongside-specific topic collisions
Add ui-template support for advanced widget rendering

Track the wiring that maps a single ThirdReality button (Door Button) to toggling three ThirdReality smart plugs (Squiggle, Sideboard Lamp, Bamboo Lights) via zigbee2mqtt. ## Findings - Node-RED 5.0 + Dashboard 2.0 (v1.30.2) mqtt-broker has a duplicate-delivery bug when a single mqtt-in subscriber exists alongside a wildcard `#` subscriber on the same base topic. Source: `/usr/src/node-red/node_modules/@node-red/nodes/core/network/10-mqtt.js` line ~1091: `node._clientOn('message', subscription.handler)` is unconditional and re-adds the handler as an EventEmitter listener on every subscribe call. - Workaround: each mqtt-in must subscribe to a unique topic. Use specific topics (`zigbee2mqtt/<device>`) instead of wildcards (`zigbee2mqtt/#`). - zigbee2mqtt groups do not support `TOGGLE` — only `ON`/`OFF`. Use individual `mqtt out` nodes per plug. ## Implemented - Three parallel `mqtt out` nodes, each publishes TOGGLE to its plug on button press - Three separate `mqtt in` nodes, one per plug, drive the corresponding `ui-text` widget - `btn-filter` function node drops non-`action:single` button events (battery reports, double press, etc.) ## Reboot survival All configs are bind-mounted to host paths: - `/root/nodered/flows.json` → nodered container `/data/flows.json` (volume) - `/root/zigbee2mqtt/configuration.yaml` → zigbee2mqtt container `/app/data/configuration.yaml` (volume) - `/root/nodered/node_modules/@flowfuse/node-red-dashboard/dist/index.html` (modified with `<base href="/dashboard/">` to fix Vue Router 4 `replace()` error) The `<base href>` patch is fragile: any `npm install` in the nodered container would overwrite it. Needs a proper upstream PR to FlowFuse/node-red-dashboard. ## Next steps - Submit upstream PR for the `<base href>` issue (or document as manual fix) - Add Rego policy to catch wildcard-alongside-specific topic collisions - Add ui-template support for advanced widget rendering

david commented

2026-07-01 06:16:10 +00:00

Update: the duplicate-delivery theory in this ticket was a red herring. The real bug in nodered 5.0 + mqtt-broker is that tabs containing an internal nodes: [...] array silently break the MQTT broker connection — no error, no log, just no Connected to broker line. Switching to a flat structure (all nodes at top level with z field referencing the tab id) restores the broker. Verified by bisection from a minimal flow (broker connects) to a wrapped-tab flow (broker never connects).

The wildcard-alongside-specific topic pattern also works fine once the structure is flat, so the subscribe-handler stacking theory from 10-mqtt.js:1091 is not the blocker. We still use specific topics for cleanliness.

Added deny_wrapped_tab to the Rego policy to catch this on validation. Implementing in the next commit (closes this issue).

Update: the duplicate-delivery theory in this ticket was a red herring. The real bug in nodered 5.0 + mqtt-broker is that **tabs containing an internal `nodes: [...]` array silently break the MQTT broker connection** — no error, no log, just no `Connected to broker` line. Switching to a flat structure (all nodes at top level with `z` field referencing the tab id) restores the broker. Verified by bisection from a minimal flow (broker connects) to a wrapped-tab flow (broker never connects). The wildcard-alongside-specific topic pattern also works fine once the structure is flat, so the subscribe-handler stacking theory from `10-mqtt.js:1091` is not the blocker. We still use specific topics for cleanliness. Added `deny_wrapped_tab` to the Rego policy to catch this on validation. Implementing in the next commit (closes this issue).

david referenced this issue from a commit

2026-07-01 06:16:21 +00:00

Flat-structure generator + Rego guards, rename Laser & Fog to DJ Booth

david closed this issue

2026-07-01 06:16:21 +00:00

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Reference: david/nr-flow-validator#1