diff --git a/src/configs/measurement.json b/src/configs/measurement.json
index 3840967..085c5c9 100644
--- a/src/configs/measurement.json
+++ b/src/configs/measurement.json
@@ -439,6 +439,16 @@
             "description": "Channel map used in digital mode. Each entry is a self-contained pipeline definition: {key, type, position, unit, scaling?, smoothing?, outlierDetection?, distance?}. Ignored in analog mode."
         }
     },
+    "calibration": {
+        "stabilityThreshold": {
+            "default": 0.01,
+            "rules": {
+                "type": "number",
+                "min": 0,
+                "description": "Absolute standard-deviation ceiling (in scaling-units, i.e. the same range as absMin..absMax) below which the rolling window is considered stable enough to trust for calibration / repeatability. A buffer with stdDev <= threshold is treated as stable; anything above aborts calibrate() and evaluateRepeatability() with a warning. Default 0.01 fits the [50,100] absMin/absMax default range; tighten or relax to match your sensor's expected noise floor."
+            }
+        }
+    },
     "outlierDetection": {
         "enabled": {
             "default": false,
diff --git a/src/configs/monster.json b/src/configs/monster.json
index 58875ca..9dd5d26 100644
--- a/src/configs/monster.json
+++ b/src/configs/monster.json
@@ -251,6 +251,34 @@
                 "type": "number",
                 "description": "Minimum inner diameter of the intake tubing in millimeters."
             }
+        },
+        "nominalFlowMin": {
+            "default": 0,
+            "rules": {
+                "type": "number",
+                "description": "Lower bound of expected inflow rate (m3/h). Used together with flowMax to scale the rain-driven flow prediction."
+            }
+        },
+        "flowMax": {
+            "default": 0,
+            "rules": {
+                "type": "number",
+                "description": "Upper bound of expected inflow rate (m3/h). Used together with nominalFlowMin to scale the rain-driven flow prediction."
+            }
+        },
+        "maxRainRef": {
+            "default": 10,
+            "rules": {
+                "type": "number",
+                "description": "Reference rain index that maps to the flowMax end of the prediction band."
+            }
+        },
+        "minSampleIntervalSec": {
+            "default": 60,
+            "rules": {
+                "type": "number",
+                "description": "Cooldown between consecutive sample pulses (seconds). Pulses raised faster than this are recorded as missedSamples."
+            }
         }
     }
 }
diff --git a/src/convert/index.js b/src/convert/index.js
index 54a6812..6606274 100644
--- a/src/convert/index.js
+++ b/src/convert/index.js
@@ -301,4 +301,26 @@ convert = function (value) {
   return new Converter(value);
 };
 
+/**
+ * Top-level helper: list accepted unit names for a measure.
+ * Cached per measure. Unknown measures return [].
+ */
+var _possibilitiesCache = Object.create(null);
+convert.possibilities = function (measure) {
+  if (!measure || typeof measure !== 'string') return [];
+  if (_possibilitiesCache[measure]) return _possibilitiesCache[measure].slice();
+  if (!measures[measure]) {
+    _possibilitiesCache[measure] = [];
+    return [];
+  }
+  var units = Converter.prototype.possibilities.call({ origin: { measure: measure } }, measure);
+  var deduped = Array.from(new Set(units)).sort();
+  _possibilitiesCache[measure] = deduped;
+  return deduped.slice();
+};
+
+convert.measures = function () {
+  return keys(measures).slice();
+};
+
 module.exports = convert;
diff --git a/src/domain/LatestWinsGate.js b/src/domain/LatestWinsGate.js
index 2402833..8f80165 100644
--- a/src/domain/LatestWinsGate.js
+++ b/src/domain/LatestWinsGate.js
@@ -2,9 +2,22 @@
 
 // Serialises an async dispatch so that high-frequency callers cannot stack
 // up overlapping invocations. Intermediate values are dropped — only the
-// most recent fire() during an in-flight dispatch is replayed afterwards.
-// Extracted from machineGroupControl's _dispatchInFlight + _delayedCall
-// pattern so MGC, pumpingStation, valveGroupControl etc. can share it.
+// most recent fire()/fireAndWait() during an in-flight dispatch is replayed
+// afterwards. Extracted from machineGroupControl's _dispatchInFlight +
+// _delayedCall pattern so MGC, pumpingStation, valveGroupControl etc. can
+// share it.
+//
+// fire(value)        — never blocks; returns void.
+// fireAndWait(value) — returns a promise that settles when THIS value's
+//                      dispatch runs to completion. If a later fireAndWait
+//                      arrives during the in-flight call and supersedes
+//                      this one in the pending slot, the returned promise
+//                      RESOLVES with { superseded: true } instead of
+//                      rejecting — callers can branch on a sentinel
+//                      without try/catch. The dispatch's own return value
+//                      (when not superseded) is forwarded as the resolution.
+
+const SUPERSEDED = Object.freeze({ superseded: true });
 
 class LatestWinsGate {
     constructor(asyncDispatchFn, options = {}) {
@@ -14,7 +27,7 @@ class LatestWinsGate {
         this._dispatch = asyncDispatchFn;
         this._logger = options.logger || null;
         this._inFlight = false;
-        this._pending = null;          // { value, ctx } | null
+        this._pending = null;          // { value, ctx, settle? } | null
         this._drainResolvers = [];     // resolved when idle again
         this.lastError = null;
     }
@@ -25,14 +38,31 @@ class LatestWinsGate {
         return this._pending ? 2 : 1;
     }
 
-    // Never blocks the caller. If a dispatch is in flight, the latest
-    // value is parked; older parked values are silently overwritten.
+    // Never blocks. If a dispatch is in flight, the latest value is parked;
+    // older parked values are silently overwritten.
     fire(value, ctx) {
         if (this._inFlight) {
-            this._pending = { value, ctx };
+            this._supersedePending();
+            this._pending = { value, ctx, settle: null };
             return;
         }
-        this._run(value, ctx);
+        this._run(value, ctx, null);
+    }
+
+    // Returns a promise that resolves when THIS fire's dispatch settles.
+    // If this fire gets overwritten while parked, resolves with the
+    // SUPERSEDED sentinel ({ superseded: true }) — callers branch on
+    // result.superseded === true without try/catch.
+    fireAndWait(value, ctx) {
+        return new Promise((resolve) => {
+            const settle = resolve;
+            if (this._inFlight) {
+                this._supersedePending();
+                this._pending = { value, ctx, settle };
+                return;
+            }
+            this._run(value, ctx, settle);
+        });
     }
 
     drain() {
@@ -40,18 +70,28 @@ class LatestWinsGate {
         return new Promise((resolve) => { this._drainResolvers.push(resolve); });
     }
 
-    _run(value, ctx) {
+    _supersedePending() {
+        const prev = this._pending;
+        if (prev && typeof prev.settle === 'function') prev.settle(SUPERSEDED);
+        this._pending = null;
+    }
+
+    _run(value, ctx, settle) {
         this._inFlight = true;
-        // Kick the dispatch on a microtask so fire() always returns
-        // synchronously, even if _dispatch resolves immediately.
+        // Kick the dispatch on a microtask so fire()/fireAndWait() always
+        // return synchronously, even if _dispatch resolves immediately.
         Promise.resolve()
             .then(() => this._dispatch(value, ctx))
-            .catch((err) => {
+            .then((result) => {
+                if (typeof settle === 'function') settle(result);
+            }, (err) => {
                 this.lastError = err;
                 if (this._logger && typeof this._logger.error === 'function') {
                     this._logger.error(err);
                 }
-                // Swallow: an error must not deadlock the gate.
+                // Resolve (not reject) so fireAndWait callers don't need
+                // try/catch. Dispatch errors stay observable via lastError.
+                if (typeof settle === 'function') settle(undefined);
             })
             .then(() => this._afterDispatch());
     }
@@ -59,9 +99,9 @@ class LatestWinsGate {
     _afterDispatch() {
         this._inFlight = false;
         if (this._pending) {
-            const { value, ctx } = this._pending;
+            const { value, ctx, settle } = this._pending;
             this._pending = null;
-            this._run(value, ctx);
+            this._run(value, ctx, settle);
             return;
         }
         // Idle — release any drain() waiters.
@@ -71,4 +111,6 @@ class LatestWinsGate {
     }
 }
 
+LatestWinsGate.SUPERSEDED = SUPERSEDED;
+
 module.exports = LatestWinsGate;
diff --git a/src/nodered/commandRegistry.js b/src/nodered/commandRegistry.js
index 8fe7cae..d4764fb 100644
--- a/src/nodered/commandRegistry.js
+++ b/src/nodered/commandRegistry.js
@@ -10,8 +10,32 @@
 // JSON-Schema. Anything richer belongs in the handler itself, which has
 // access to logger via ctx.
 
+const convert = require('../convert');
+
 const SCALAR_TYPES = new Set(['string', 'number', 'boolean', 'object', 'any', 'none']);
 
+function _acceptedList(measure) {
+    if (convert && typeof convert.possibilities === 'function') {
+        const list = convert.possibilities(measure);
+        if (Array.isArray(list) && list.length) return list.join(', ');
+    }
+    return '(see convert docs)';
+}
+
+function _describeUnit(unit) {
+    try { return convert().describe(unit); } catch (_) { return null; }
+}
+
+function _extractValueAndUnit(msg) {
+    if (!msg || typeof msg !== 'object') return null;
+    const p = msg.payload;
+    if (typeof p === 'number') return { value: p, unit: msg.unit };
+    if (p && typeof p === 'object' && typeof p.value === 'number') {
+        return { value: p.value, unit: p.unit ?? msg.unit };
+    }
+    return null;
+}
+
 class CommandRegistry {
     constructor(commands, options = {}) {
         if (!Array.isArray(commands)) {
@@ -45,11 +69,13 @@ class CommandRegistry {
                 throw new Error(`alias '${alias}' for '${cmd.topic}' collides with existing topic or alias`);
             }
         }
+        const units = this._validateUnits(cmd);
         const descriptor = {
             topic: cmd.topic,
             aliases,
             payloadSchema: cmd.payloadSchema || null,
             description: typeof cmd.description === 'string' ? cmd.description : null,
+            units,
             handler: cmd.handler,
         };
         this._byKey.set(cmd.topic, descriptor);
@@ -60,6 +86,17 @@ class CommandRegistry {
         this._descriptors.push(descriptor);
     }
 
+    _validateUnits(cmd) {
+        if (cmd.units === undefined || cmd.units === null) return null;
+        const { measure, default: def } = cmd.units;
+        if (typeof measure !== 'string' || measure.length === 0 ||
+            typeof def !== 'string' || def.length === 0) {
+            throw new TypeError(
+                `command '${cmd.topic}' units requires { measure: string, default: string }`);
+        }
+        return { measure, default: def };
+    }
+
     has(topic) {
         return typeof topic === 'string' && this._byKey.has(topic);
     }
@@ -77,6 +114,7 @@ class CommandRegistry {
             aliases: d.aliases.slice(),
             payloadSchema: d.payloadSchema,
             description: d.description,
+            units: d.units ? { measure: d.units.measure, default: d.units.default } : null,
         }));
     }
 
@@ -99,6 +137,7 @@ class CommandRegistry {
             return;
         }
         if (topic !== descriptor.topic) this._noteAlias(topic, descriptor.topic, log);
+        if (descriptor.units) this._normaliseUnits(descriptor, msg, log);
         if (!this._validatePayload(descriptor, msg, log)) return;
         return descriptor.handler(source, msg, ctx);
     }
@@ -111,6 +150,40 @@ class CommandRegistry {
         log.warn?.(`topic '${alias}' is deprecated; use '${canonical}'`);
     }
 
+    _normaliseUnits(descriptor, msg, log) {
+        const { measure, default: defaultUnit } = descriptor.units;
+        const extracted = _extractValueAndUnit(msg);
+        if (!extracted) return;                       // unknown shape — let payload validator handle it
+        let { value, unit } = extracted;
+        if (unit === undefined || unit === null || unit === '') {
+            // No unit supplied — assume default, silent.
+            msg.payload = value;
+            msg.unit = defaultUnit;
+            return;
+        }
+        const desc = _describeUnit(unit);
+        if (!desc) {
+            log.warn?.(`${descriptor.topic}: unknown unit '${unit}'. Accepted: ${_acceptedList(measure)}. Treating ${value} as ${defaultUnit}.`);
+            msg.payload = value;
+            msg.unit = defaultUnit;
+            return;
+        }
+        if (desc.measure !== measure) {
+            log.warn?.(`${descriptor.topic}: unit '${unit}' is ${desc.measure}, expected ${measure}. Accepted: ${_acceptedList(measure)}. Treating ${value} as ${defaultUnit}.`);
+            msg.payload = value;
+            msg.unit = defaultUnit;
+            return;
+        }
+        try {
+            msg.payload = convert(value).from(unit).to(defaultUnit);
+            msg.unit = defaultUnit;
+        } catch (err) {
+            log.warn?.(`${descriptor.topic}: failed to convert ${value} ${unit} -> ${defaultUnit} (${err.message}). Treating as ${defaultUnit}.`);
+            msg.payload = value;
+            msg.unit = defaultUnit;
+        }
+    }
+
     _validatePayload(descriptor, msg, log) {
         const schema = descriptor.payloadSchema;
         if (!schema) return true;
diff --git a/test/basic/LatestWinsGate.basic.test.js b/test/basic/LatestWinsGate.basic.test.js
index 4ae8630..c7cd90e 100644
--- a/test/basic/LatestWinsGate.basic.test.js
+++ b/test/basic/LatestWinsGate.basic.test.js
@@ -150,3 +150,91 @@ test('size reports 0 / 1 / 2 across the lifecycle', async () => {
     await gate.drain();
     assert.equal(gate.size, 0);
 });
+
+test('fireAndWait resolves when the dispatch for that value settles', async () => {
+    const calls = [];
+    const gate = new LatestWinsGate(async (v) => { calls.push(v); return `done:${v}`; });
+    const result = await gate.fireAndWait('a');
+    assert.deepEqual(calls, ['a']);
+    assert.equal(result, 'done:a');
+});
+
+test('fireAndWait while in-flight: caller awaits OWN settlement, not the first call', async () => {
+    const calls = [];
+    const d = deferred();
+    let count = 0;
+    const gate = new LatestWinsGate(async (v) => {
+        calls.push(v);
+        if (count++ === 0) await d.promise;
+        return `r:${v}`;
+    });
+
+    const p1 = gate.fireAndWait('first');
+    // p1 in flight. Park second; second's promise should resolve only
+    // after second's OWN dispatch runs, not after first's.
+    const p2 = gate.fireAndWait('second');
+
+    let p2Settled = false;
+    p2.then(() => { p2Settled = true; });
+    await Promise.resolve(); await Promise.resolve();
+    assert.equal(p2Settled, false);
+
+    d.resolve();
+    const r1 = await p1;
+    assert.equal(r1, 'r:first');
+    const r2 = await p2;
+    assert.equal(r2, 'r:second');
+    assert.deepEqual(calls, ['first', 'second']);
+});
+
+test('fireAndWait superseded by a later fireAndWait resolves with { superseded: true }', async () => {
+    const calls = [];
+    const d = deferred();
+    let count = 0;
+    const gate = new LatestWinsGate(async (v) => {
+        calls.push(v);
+        if (count++ === 0) await d.promise;
+    });
+
+    const p1 = gate.fireAndWait('first');     // in flight
+    const pParked = gate.fireAndWait('parked'); // gets superseded
+    const pLatest = gate.fireAndWait('latest'); // wins
+
+    d.resolve();
+    const supersedeRes = await pParked;
+    assert.equal(supersedeRes.superseded, true);
+
+    await p1;
+    await pLatest;
+    assert.deepEqual(calls, ['first', 'latest']);  // 'parked' dropped
+});
+
+test('fireAndWait + fire intermix: a plain fire supersedes a pending fireAndWait', async () => {
+    const d = deferred();
+    let count = 0;
+    const calls = [];
+    const gate = new LatestWinsGate(async (v) => {
+        calls.push(v);
+        if (count++ === 0) await d.promise;
+    });
+
+    gate.fire('first');                        // in flight, no settle
+    const pParked = gate.fireAndWait('parked');
+    gate.fire('latest');                        // supersedes parked
+
+    d.resolve();
+    const res = await pParked;
+    assert.equal(res.superseded, true);
+    await gate.drain();
+    assert.deepEqual(calls, ['first', 'latest']);
+});
+
+test('fireAndWait still resolves (with undefined) when the dispatch throws', async () => {
+    const errors = [];
+    const logger = { error: (e) => errors.push(e) };
+    const gate = new LatestWinsGate(async () => { throw new Error('kaboom'); }, { logger });
+    const r = await gate.fireAndWait('only');
+    assert.equal(r, undefined);
+    assert.equal(errors.length, 1);
+    assert.ok(gate.lastError instanceof Error);
+});
diff --git a/test/basic/commandRegistry.basic.test.js b/test/basic/commandRegistry.basic.test.js
index 333171d..9697680 100644
--- a/test/basic/commandRegistry.basic.test.js
+++ b/test/basic/commandRegistry.basic.test.js
@@ -152,12 +152,14 @@ test('list() returns descriptors without handler functions', () => {
         aliases: ['setMode'],
         payloadSchema: { type: 'string' },
         description: null,
+        units: null,
     });
     assert.deepEqual(list[1], {
         topic: 'cmd.startup',
         aliases: [],
         payloadSchema: null,
         description: null,
+        units: null,
     });
     for (const d of list) assert.ok(!('handler' in d), 'handler must not be in descriptor');
 });
@@ -280,3 +282,155 @@ test('constructor throws when input is not an array', () => {
     assert.throws(() => createRegistry(null), /array/);
     assert.throws(() => createRegistry({}), /array/);
 });
+
+// ---------------------------------------------------------------------------
+// descriptor.units — Phase 11 pre-dispatch normalisation pipeline
+// ---------------------------------------------------------------------------
+
+test('units: valid unit + correct measure converts to default before handler', async () => {
+    const logger = makeLogger();
+    const seen = [];
+    const reg = createRegistry([{
+        topic: 'set.demand',
+        units: { measure: 'volumeFlowRate', default: 'm3/h' },
+        handler: (_s, msg) => { seen.push({ payload: msg.payload, unit: msg.unit }); },
+    }], { logger });
+
+    await reg.dispatch({ topic: 'set.demand', payload: 1, unit: 'm3/s' }, {}, {});
+    assert.equal(seen.length, 1);
+    assert.ok(Math.abs(seen[0].payload - 3600) < 1e-6, `expected 3600, got ${seen[0].payload}`);
+    assert.equal(seen[0].unit, 'm3/h');
+    assert.equal(logger._calls.warn.length, 0);
+});
+
+test('units: wrong measure warns + lists accepted + falls back to default unit', async () => {
+    const logger = makeLogger();
+    const seen = [];
+    const reg = createRegistry([{
+        topic: 'set.demand',
+        units: { measure: 'volumeFlowRate', default: 'm3/h' },
+        handler: (_s, msg) => { seen.push({ payload: msg.payload, unit: msg.unit }); },
+    }], { logger });
+
+    await reg.dispatch({ topic: 'set.demand', payload: 42, unit: 'mbar' }, {}, {});
+    assert.equal(seen.length, 1);
+    assert.equal(seen[0].payload, 42);
+    assert.equal(seen[0].unit, 'm3/h');
+    const warns = logger._calls.warn;
+    assert.equal(warns.length, 1);
+    assert.match(warns[0], /set\.demand/);
+    assert.match(warns[0], /'mbar'/);
+    assert.match(warns[0], /pressure/);
+    assert.match(warns[0], /volumeFlowRate/);
+    assert.match(warns[0], /m3\/h/);              // accepted list contains the default
+    assert.match(warns[0], /Treating 42 as m3\/h/);
+});
+
+test('units: unknown unit warns + lists accepted + falls back to default', async () => {
+    const logger = makeLogger();
+    const seen = [];
+    const reg = createRegistry([{
+        topic: 'set.demand',
+        units: { measure: 'volumeFlowRate', default: 'm3/h' },
+        handler: (_s, msg) => { seen.push({ payload: msg.payload, unit: msg.unit }); },
+    }], { logger });
+
+    await reg.dispatch({ topic: 'set.demand', payload: 7, unit: 'flarbargs' }, {}, {});
+    assert.equal(seen.length, 1);
+    assert.equal(seen[0].payload, 7);
+    assert.equal(seen[0].unit, 'm3/h');
+    const warns = logger._calls.warn;
+    assert.equal(warns.length, 1);
+    assert.match(warns[0], /unknown unit 'flarbargs'/);
+    assert.match(warns[0], /m3\/h/);
+    assert.match(warns[0], /Treating 7 as m3\/h/);
+});
+
+test('units: no unit at all — handler gets raw value tagged with default unit, silent', async () => {
+    const logger = makeLogger();
+    const seen = [];
+    const reg = createRegistry([{
+        topic: 'set.demand',
+        units: { measure: 'volumeFlowRate', default: 'm3/h' },
+        handler: (_s, msg) => { seen.push({ payload: msg.payload, unit: msg.unit }); },
+    }], { logger });
+
+    await reg.dispatch({ topic: 'set.demand', payload: 12 }, {}, {});
+    assert.equal(seen.length, 1);
+    assert.equal(seen[0].payload, 12);
+    assert.equal(seen[0].unit, 'm3/h');
+    assert.equal(logger._calls.warn.length, 0);
+});
+
+test('units: object payload {value, unit} normalises the same as msg.payload+msg.unit', async () => {
+    const logger = makeLogger();
+    const seen = [];
+    const reg = createRegistry([{
+        topic: 'set.pressure',
+        units: { measure: 'pressure', default: 'Pa' },
+        handler: (_s, msg) => { seen.push({ payload: msg.payload, unit: msg.unit }); },
+    }], { logger });
+
+    await reg.dispatch({ topic: 'set.pressure', payload: { value: 5, unit: 'mbar' } }, {}, {});
+    assert.equal(seen.length, 1);
+    assert.ok(Math.abs(seen[0].payload - 500) < 1e-6, `expected 500, got ${seen[0].payload}`);
+    assert.equal(seen[0].unit, 'Pa');
+    assert.equal(logger._calls.warn.length, 0);
+});
+
+test('units: object payload {value} without unit falls back to default unit silently', async () => {
+    const logger = makeLogger();
+    const seen = [];
+    const reg = createRegistry([{
+        topic: 'set.pressure',
+        units: { measure: 'pressure', default: 'Pa' },
+        handler: (_s, msg) => { seen.push({ payload: msg.payload, unit: msg.unit }); },
+    }], { logger });
+
+    await reg.dispatch({ topic: 'set.pressure', payload: { value: 100 } }, {}, {});
+    assert.equal(seen.length, 1);
+    assert.equal(seen[0].payload, 100);
+    assert.equal(seen[0].unit, 'Pa');
+    assert.equal(logger._calls.warn.length, 0);
+});
+
+test('units: non-numeric payload (no normalisation applied) passes through to handler', async () => {
+    const logger = makeLogger();
+    const seen = [];
+    const reg = createRegistry([{
+        topic: 'set.demand',
+        units: { measure: 'volumeFlowRate', default: 'm3/h' },
+        handler: (_s, msg) => { seen.push(msg.payload); },
+    }], { logger });
+
+    // string payload — not normalisable. Should not crash; handler still fires.
+    await reg.dispatch({ topic: 'set.demand', payload: 'magic' }, {}, {});
+    assert.equal(seen.length, 1);
+    assert.equal(seen[0], 'magic');
+});
+
+test('units: missing default field throws at construction', () => {
+    assert.throws(() => createRegistry([{
+        topic: 'set.demand',
+        units: { measure: 'volumeFlowRate' },
+        handler: () => {},
+    }]), /units requires/);
+});
+
+test('units: missing measure field throws at construction', () => {
+    assert.throws(() => createRegistry([{
+        topic: 'set.demand',
+        units: { default: 'm3/h' },
+        handler: () => {},
+    }]), /units requires/);
+});
+
+test('units: descriptor.units surfaces in list() output', () => {
+    const reg = createRegistry([
+        { topic: 'set.demand', units: { measure: 'volumeFlowRate', default: 'm3/h' }, handler: () => {} },
+        { topic: 'set.mode',                                                          handler: () => {} },
+    ]);
+    const list = reg.list();
+    assert.deepEqual(list[0].units, { measure: 'volumeFlowRate', default: 'm3/h' });
+    assert.equal(list[1].units, null);
+});
diff --git a/test/basic/convert.basic.test.js b/test/basic/convert.basic.test.js
new file mode 100644
index 0000000..7faf33b
--- /dev/null
+++ b/test/basic/convert.basic.test.js
@@ -0,0 +1,90 @@
+'use strict';
+
+const test = require('node:test');
+const assert = require('node:assert/strict');
+
+const convert = require('../../src/convert/index.js');
+
+test('convert.possibilities — exported as a top-level function', () => {
+    assert.equal(typeof convert.possibilities, 'function');
+});
+
+test('convert.possibilities(volumeFlowRate) returns common flow units', () => {
+    const units = convert.possibilities('volumeFlowRate');
+    assert.ok(Array.isArray(units));
+    assert.ok(units.length > 0);
+    for (const u of ['m3/s', 'm3/h', 'l/s', 'l/min', 'l/h']) {
+        assert.ok(units.includes(u), `expected '${u}' in volumeFlowRate possibilities`);
+    }
+});
+
+test('convert.possibilities(pressure) returns common pressure units', () => {
+    const units = convert.possibilities('pressure');
+    for (const u of ['Pa', 'kPa', 'bar', 'mbar', 'psi']) {
+        assert.ok(units.includes(u), `expected '${u}' in pressure possibilities`);
+    }
+});
+
+test('convert.possibilities(power) returns common power units', () => {
+    const units = convert.possibilities('power');
+    for (const u of ['W', 'kW', 'MW']) {
+        assert.ok(units.includes(u), `expected '${u}' in power possibilities`);
+    }
+});
+
+test('convert.possibilities(temperature) returns K, C, F', () => {
+    const units = convert.possibilities('temperature');
+    for (const u of ['K', 'C', 'F']) {
+        assert.ok(units.includes(u), `expected '${u}' in temperature possibilities`);
+    }
+});
+
+test('convert.possibilities for length / mass / volume return non-empty', () => {
+    assert.ok(convert.possibilities('length').includes('m'));
+    assert.ok(convert.possibilities('mass').includes('kg'));
+    assert.ok(convert.possibilities('volume').includes('l'));
+});
+
+test('convert.possibilities(unknown) returns []', () => {
+    assert.deepEqual(convert.possibilities('foo'), []);
+    assert.deepEqual(convert.possibilities('bogus-measure'), []);
+});
+
+test('convert.possibilities handles invalid input safely', () => {
+    assert.deepEqual(convert.possibilities(), []);
+    assert.deepEqual(convert.possibilities(null), []);
+    assert.deepEqual(convert.possibilities(''), []);
+    assert.deepEqual(convert.possibilities(42), []);
+});
+
+test('convert.possibilities is sorted and deduplicated', () => {
+    const units = convert.possibilities('pressure');
+    const sorted = [...units].sort();
+    assert.deepEqual(units, sorted, 'result should be alphabetically sorted');
+    const set = new Set(units);
+    assert.equal(set.size, units.length, 'result should have no duplicates');
+});
+
+test('convert.possibilities returns stable / cached results across calls', () => {
+    const a = convert.possibilities('volumeFlowRate');
+    const b = convert.possibilities('volumeFlowRate');
+    assert.deepEqual(a, b, 'two calls must return equal arrays');
+    // Mutating the returned array must not poison the cache.
+    a.push('SHOULD_NOT_PERSIST');
+    const c = convert.possibilities('volumeFlowRate');
+    assert.ok(!c.includes('SHOULD_NOT_PERSIST'), 'cached array must be defensively copied');
+    assert.deepEqual(c, b);
+});
+
+test('convert.measures lists known measure names', () => {
+    const m = convert.measures();
+    assert.ok(Array.isArray(m));
+    for (const name of ['length', 'mass', 'volume', 'pressure', 'power', 'temperature', 'volumeFlowRate']) {
+        assert.ok(m.includes(name), `expected measure '${name}'`);
+    }
+});
+
+test('convert factory still works (regression — no breakage of existing API)', () => {
+    const result = convert(1).from('m').to('cm');
+    assert.equal(result, 100);
+});