diff --git a/src/commands/handlers.js b/src/commands/handlers.js
index cf7781e..f402351 100644
--- a/src/commands/handlers.js
+++ b/src/commands/handlers.js
@@ -5,8 +5,6 @@
 // handler (the legacy nodeClass did it inline) — anything else inbound
 // is passed straight through to source.handleInput.
 
-const { convert } = require('generalFunctions');
-
 exports.cmdStart = (source, msg) => {
   source.handleInput('i_start', Boolean(msg.payload));
 };
@@ -20,17 +18,15 @@ exports.setRain = (source, msg) => {
 };
 
 exports.dataFlow = (source, msg, ctx) => {
+  // The registry has already normalised any accepted shape (number, numeric
+  // string, or { value, unit }) to a number in m3/h and tagged msg.unit.
   const log = ctx?.logger || source.logger;
-  const value = Number(msg.payload?.value);
-  const unit = msg.payload?.unit;
-  if (!Number.isFinite(value) || !unit) {
-    log?.warn?.('data.flow payload must include numeric value and unit.');
+  const value = Number(msg.payload);
+  if (!Number.isFinite(value)) {
+    log?.warn?.(`data.flow payload must be numeric, got '${JSON.stringify(msg.payload)}'.`);
     return;
   }
-  let converted = value;
-  try { converted = convert(value).from(unit).to('m3/h'); }
-  catch (err) { log?.warn?.(`data.flow unit conversion failed: ${err.message}`); return; }
-  source.handleInput('input_q', { value: converted, unit: 'm3/h' });
+  source.handleInput('input_q', { value, unit: msg.unit || 'm3/h' });
 };
 
 exports.setMode = (source, msg) => {
diff --git a/src/commands/index.js b/src/commands/index.js
index f71a5a1..d70bc31 100644
--- a/src/commands/index.js
+++ b/src/commands/index.js
@@ -32,11 +32,11 @@ module.exports = [
   {
     topic: 'data.flow',
     aliases: ['input_q'],
-    payloadSchema: { type: 'object' },
-    // Compound payload `{value, unit}` — handler converts internally to m3/h.
-    // Registry-level normalisation is skipped (the handler reads payload.value /
-    // payload.unit directly; flattening would break it).
-    description: 'Push the upstream flow measurement (payload: {value, unit}).',
+    // any: number, numeric string, or { value, unit } — the registry normalises
+    // all of them to a number in `unit` (m3/h) before the handler runs.
+    payloadSchema: { type: 'any' },
+    unit: 'm3/h',
+    description: 'Push the upstream flow measurement (payload: number or {value, unit}).',
     handler: handlers.dataFlow,
   },
   {
diff --git a/wiki/Reference-Contracts.md b/wiki/Reference-Contracts.md
index 6870d5b..6032682 100644
--- a/wiki/Reference-Contracts.md
+++ b/wiki/Reference-Contracts.md
@@ -23,7 +23,7 @@ The registry lives in `src/commands/index.js`. Each descriptor maps a canonical
 | `cmd.start` | `i_start` | any | — | Trigger / release the sampler start gate. |
 | `set.schedule` | `monsternametijden` | any | — | Replace the sampling-times schedule. |
 | `set.rain` | `rain_data` | any | — | Push current rain-event data into the sampler logic. |
-| `data.flow` | `input_q` | `object` | — | Push the upstream flow measurement (payload: {value, unit}). |
+| `data.flow` | `input_q` | any | `volumeFlowRate` (default `m3/h`) | Push the upstream flow measurement (payload: number or {value, unit}). |
 | `set.mode` | `setMode` | any | — | Switch the monster between auto / manual modes. |
 | `set.model-prediction` | `model_prediction` | any | — | Push the upstream rain-prediction snapshot used by the sampler. |
 | `child.register` | `registerChild` | `string` | — | Register a child node (typically a measurement) with this monster. |