diff --git a/wiki/Home.md b/wiki/Home.md
index 54d75ec..4c61256 100644
--- a/wiki/Home.md
+++ b/wiki/Home.md
@@ -1,251 +1,134 @@
# settler
-> **Reflects code as of `94b6616` · regenerated `2026-05-11` via `npm run wiki:all`**
-> If this banner is stale, the page may be out of date. Treat as informative, not authoritative.
+  
-## 1. What this node is
+A `settler` models a secondary clarifier — the sludge-separation stage that sits downstream of a biological reactor. It receives the upstream reactor's effluent stream, performs a 13-species TSS mass balance, and splits the result into three Fluent envelopes: clarified effluent, surplus sludge, and return sludge. A downstream return pump (a `rotatingMachine` registered as `machine` / `downstream`) draws the return-sludge flow.
-**settler** is an S88 Unit that models a secondary clarifier. It takes the upstream reactor's effluent stream, performs a 13-species TSS mass balance, and splits it into three Fluent envelopes: clarified effluent, surplus sludge, and return sludge. A downstream return pump (rotatingMachine child) draws the return-sludge flow.
+> [!NOTE]
+> Pending full node review (2026-05). Content reflects `CONTRACT.md` and current source only. The shipped `examples/` folder ships stubs only — production-grade flows are still TODO. Treat this page as informative, not authoritative.
-## 2. Position in the platform
+---
+
+## At a glance
+
+| Thing | Value |
+|:---|:---|
+| What it represents | Secondary clarifier / sludge settler — the gravity-separation stage between a biological reactor and its downstream sludge handling |
+| S88 level | Unit |
+| Use it when | You have a reactor whose effluent must be split into clarified water + return / surplus sludge by a TSS mass balance |
+| Don't use it for | Primary sedimentation (species 7–12 zeroing is wrong), generic mass-balance transforms (the 13-species ASM3 vector is hard-coded), single-tank SBRs that don't need a 3-stream split |
+| Children it accepts | `measurement` (any, but `quantity (tss)` is the only one that mutates state), `reactor` (upstream), `machine` (downstream — the return pump) |
+| Parents it talks to | Typically a downstream `reactor` — the three Fluent streams are routed by `payload.inlet` |
+
+---
+
+## How it fits
```mermaid
flowchart LR
upstream[reactor
upstream
Unit]:::unit
settler[settler
Unit]:::unit
downstream[reactor
downstream
Unit]:::unit
- return[rotatingMachine
return pump
Equipment]:::equip
- tss[measurement
type=quantity (tss)
position=atequipment]:::ctrl
+ return_pump[rotatingMachine
return pump
Equipment]:::equip
+ tss[measurement
quantity tss
atequipment]:::ctrl
upstream -.stateChange.-> settler
- settler -->|Fluent inlet=0,1,2| downstream
- return -->|child.register downstream| settler
- settler -.F_sr.-> return
- tss -->|quantity (tss).measured.atequipment| settler
+ settler -->|Fluent inlet=0 effluent| downstream
+ settler -->|Fluent inlet=1 surplus| downstream
+ settler -->|Fluent inlet=2 return| return_pump
+ return_pump -->|child.register downstream| settler
+ tss -->|quantity tss.measured.atequipment| settler
classDef unit fill:#50a8d9,color:#000
classDef equip fill:#86bbdd,color:#000
classDef ctrl fill:#a9daee,color:#000
```
-S88 colours: Unit `#50a8d9`, Equipment `#86bbdd`, Control Module `#a9daee`. Source of truth: `.claude/rules/node-red-flow-layout.md`.
+S88 colours are anchored in `.claude/rules/node-red-flow-layout.md`. The settler editor colour is currently `#e4a363` (orange) — tracked as drift in §16 of that rule; diagrams in this wiki use the correct Unit blue (`#50a8d9`).
-## 3. Capability matrix
+---
-| Capability | Status | Notes |
-|---|---|---|
-| TSS mass-balance split (3 streams) | ✅ | Effluent / surplus / return derived from `F_in * Cs[12] / C_TS`. |
-| Particulate zeroing in effluent | ✅ | Species 7–12 set to 0 in effluent when `F_s > 0`. |
-| Particulate concentration in sludge | ✅ | Species 7–12 scaled by `F_in / F_s` in surplus + return. |
-| Return-pump flow draw | ✅ | `F_sr` = min(pump flow, F_s). Surplus = F_s − F_sr. |
-| F_s clamp to F_in | ✅ | Prevents negative effluent when X_TS_in > C_TS. |
-| Manual influent override | ✅ | `data.influent` lets ops supply `{ F, C }` directly. |
-| Multiple reactor upstreams | ❌ | Only one `upstreamReactor` slot; last registration wins. |
-| Stateful FSM | ❌ | Stateless transform — recomputes on every push. |
+## Try it — 1-minute demo
-## 4. Code map
+> [!IMPORTANT]
+> The shipped examples (`examples/basic.flow.json`, `integration.flow.json`, `edge.flow.json`) are skeleton stubs — they create a settler node and a debug tap, but do not exercise the reactor → settler → pump chain. A proper Tier-1 / Tier-2 / Tier-3 example set is on the TODO list; until then this section walks the minimum stimulus.
-```mermaid
-flowchart TB
- subgraph nodeRED["nodeClass.js — adapter (BaseNodeAdapter)"]
- nc["buildDomainConfig()
static DomainClass = Settler
static commands"]
- end
- subgraph domain["specificClass.js — orchestrator (BaseDomain)"]
- sc["Settler.configure()
ChildRouter rules
getEffluent — TSS split
_connectReactor (manual listener)"]
- end
- subgraph commands["src/commands/"]
- cmds["index.js + handlers.js
data.influent + aliases"]
- end
- nc --> sc
- nc --> cmds
+Import the basic stub, deploy, then drive influent manually:
+
+```bash
+curl -X POST -H 'Content-Type: application/json' \
+ --data @nodes/settler/examples/basic.flow.json \
+ http://localhost:1880/flow
```
-| Module | Owns | Read first if you're changing… |
-|---|---|---|
-| `specificClass.js` | All domain logic: getEffluent split, reactor + machine + measurement wiring, getOutput, getStatusBadge. | Mass-balance math, child wiring, telemetry shape. |
-| `commands/` | Single command (`data.influent`) + aliases + payload validation. | Manual-influent topic, new aliases. |
+After deploy, send one inject:
-Settler is small enough (~140 LOC) that no concern-split was needed (per P6.6).
+| Topic | Payload | What it does |
+|:---|:---|:---|
+| `data.influent` | `{ "F": 1000, "C": [0,0,0,0,0,0,0,0,0,0,0,0,3000] }` | Pushes 1000 m³/h influent with 3000 mg/L total solids (index 12 = `X_TS`). Three Fluent envelopes appear on Port 0 immediately. |
-## 5. Topic contract
+> [!NOTE]
+> Pending full node review (2026-05). Real flows (Tier-1 inject only, Tier-2 reactor + settler + pump, Tier-3 dashboard) are not yet shipped. See [Reference — Examples](Reference-Examples).
-> **Auto-generated** from `src/commands/index.js`. Do NOT hand-edit between the markers. Re-run `npm run wiki:contract`.
+---
-
+## The two things you'll send
-| Canonical topic | Aliases | Payload | Unit | Effect |
-|---|---|---|---|---|
-| `data.influent` | `influent`, `setInfluent` | `any` | — | Push the influent stream (payload: {F: flow m3/h, C: [concentrations mg/L]}). |
-| `child.register` | `registerChild` | `string` | — | Register a child node (typically a measurement) with this settler. |
+| Topic | Aliases | Payload | What it does |
+|:---|:---|:---|:---|
+| `data.influent` | `influent`, `setInfluent` | `{F: number, C: number[13]}` — either field optional | Override the influent stream directly. Triggers a recompute of all three Fluent envelopes. |
+| `child.register` | `registerChild` | `string` (child node id) | Register a `measurement`, `reactor`, or `machine` child. Port 2 wiring does this automatically in normal flows. |
-
+That is the entire input contract. Settler has no FSM, no setpoint, no startup sequence — it is a stateless transform on top of whatever the upstream reactor + measurement children push into it.
-## 6. Child registration
+---
-```mermaid
-flowchart LR
- subgraph kids["accepted children (softwareType)"]
- m["measurement"]:::ctrl
- r["reactor
upstream"]:::unit
- mach["machine
downstream"]:::equip
- end
- m -->|"<type>.measured.<position>"| h_m[_connectMeasurement]
- r -.stateChange.-> h_r[_connectReactor
manual listener]
- mach -->|registered| h_mach[_connectMachine
sets returnPump]
- h_r --> pull[upstreamReactor.getEffluent]
- pull --> emit[notifyOutputChanged]
- classDef ctrl fill:#a9daee,color:#000
- classDef unit fill:#50a8d9,color:#000
- classDef equip fill:#86bbdd,color:#000
-```
+## What you'll see come out
-| softwareType | filter | wired to | side-effect |
-|---|---|---|---|
-| `measurement` | any | `_connectMeasurement` | Re-emits on settler's measurements; `quantity (tss)` updates `C_TS`. |
-| `reactor` | `positionVsParent=upstream` (warns otherwise) | `_connectReactor` | Stores as `upstreamReactor`; subscribes to its **own** `emitter` (NOT `measurements.emitter`) for `'stateChange'`. |
-| `machine` | `positionVsParent=downstream` | `_connectMachine` | Stores as `returnPump`; sets `machine.upstreamSource = settler`. |
-
-### 6.1 Reactor ↔ settler wiring (the load-bearing bit)
-
-The reactor pushes its `stateChange` event on `reactor.emitter`, not `reactor.measurements.emitter`. The standard `router.onMeasurement` path can't subscribe — so settler attaches the listener manually inside `_connectReactor`. On each fire, settler **pulls** the upstream effluent via `reactor.getEffluent` and copies it into `this.F_in` + `this.Cs_in`.
-
-`reactor.getEffluent` historically returned either an array (3-stream) or a single envelope — the 2026-03-02 `_connectReactor` fix preserves both shapes:
-
-```js
-const raw = this.upstreamReactor.getEffluent;
-const effluent = Array.isArray(raw) ? raw[0] : raw;
-this.F_in = effluent.payload.F;
-this.Cs_in = effluent.payload.C;
-this.notifyOutputChanged();
-```
-
-If you change the reactor's effluent shape, this is the line to update.
-
-## 7. Lifecycle — what one stateChange does
-
-```mermaid
-sequenceDiagram
- participant reactor as upstream reactor
- participant settler as settler
- participant pump as return pump child
- participant downstream as downstream consumer
- participant out as Port-0 output
-
- reactor->>settler: emitter.emit('stateChange')
- settler->>reactor: pull getEffluent
- reactor-->>settler: { F, C[13] }
- settler->>settler: F_in = F, Cs_in = C
- settler->>pump: read measurements.flow.measured.atequipment
- pump-->>settler: returnFlow
- settler->>settler: getEffluent — split into 3 inlets
- settler->>out: [Fluent inlet=0, Fluent inlet=1, Fluent inlet=2]
- out->>downstream: 3 msgs on Port 0
-```
-
-The split runs lazily inside `getEffluent`: each call recomputes from current `F_in`, `Cs_in`, `C_TS`, and the pump's reported `flow.measured.atequipment`.
-
-## 8. Data model — `getOutput()`
-
-Port 0 carries the 3-envelope Fluent stream directly; Port 1 (this snapshot) is the scalar dashboard view.
-
-
-
-| Key | Type | Unit | Sample |
-|---|---|---|---|
-| `C_TS` | number | — | `2500` |
-| `F_eff` | number | — | `0` |
-| `F_in` | number | — | `0` |
-| `F_return` | number | — | `0` |
-| `F_surplus` | number | — | `0` |
-
-
-
-**Concrete sample** (typical operating point):
+Sample Port 0 messages (one push, three envelopes):
```json
-{
- "F_in": 1000,
- "C_TS": 2500,
- "F_eff": 850.0,
- "F_surplus": 50.0,
- "F_return": 100.0
-}
+[
+ { "topic": "Fluent", "payload": { "inlet": 0, "F": 850.0, "C": [/*7-12 zeroed*/] }, "timestamp": 1715000000000 },
+ { "topic": "Fluent", "payload": { "inlet": 1, "F": 50.0, "C": [/*7-12 concentrated*/] }, "timestamp": 1715000000000 },
+ { "topic": "Fluent", "payload": { "inlet": 2, "F": 100.0, "C": [/*7-12 concentrated*/] }, "timestamp": 1715000000000 }
+]
```
-`F_eff + F_surplus + F_return = F_in` always holds (modulo float). Particulates concentrate by `F_in / F_s` in the surplus + return streams.
+| `payload.inlet` | Meaning | Particulate species (indices 7–12) |
+|:---:|:---|:---|
+| `0` | Clarified effluent | zeroed when `F_s > 0` |
+| `1` | Surplus sludge (the fraction the return pump does not draw) | concentrated by `F_in / F_s` |
+| `2` | Return sludge (drawn by the downstream return pump, capped at `F_s`) | concentrated by `F_in / F_s` |
-## 9. Configuration — editor form ↔ config keys
+Mass balance invariant: `F_eff + F_surplus + F_return = F_in` (modulo float).
-```mermaid
-flowchart TB
- subgraph editor["Node-RED editor form"]
- f1[Name]
- f2[Process Output Format]
- f3[Database Output Format]
- f4[Logging level]
- f5[Position vs parent]
- end
- subgraph config["Domain config / nodeClass"]
- c1[general.name]
- c2[processOutputFormat → nodeClass]
- c3[dbaseOutputFormat → nodeClass]
- c4[general.logging.logLevel]
- c5[functionality.positionVsParent]
- end
- f1 --> c1
- f2 --> c2
- f3 --> c3
- f4 --> c4
- f5 --> c5
-```
+Port 1 (InfluxDB) is the scalar dashboard view — see [Reference — Contracts](Reference-Contracts#data-model--getoutput-shape). Port 2 carries the one-shot `child.register` upward at startup.
-| Form field | Config key | Default | Range | Where used |
-|---|---|---|---|---|
-| Name | `general.name` | `Settler` | string | display + Port-1 topic |
-| Process Output Format | `processOutputFormat` (nodeClass) | `process` | `process` / `json` / `csv` | Port-0 serialisation |
-| Database Output Format | `dbaseOutputFormat` (nodeClass) | `influxdb` | `influxdb` / `json` / `csv` | Port-1 serialisation |
-| Logging level | `general.logging.logLevel` | `info` | `debug` / `info` / `warn` / `error` | logger threshold |
-| Position vs parent | `functionality.positionVsParent` | `downstream` | `upstream` / `atEquipment` / `downstream` | parent-side routing |
-| Software type | `functionality.softwareType` | `settler` | string | parent-side router filter |
-| ID | `general.id` | `null` | nullable string | child registration key |
+---
-Settler has no operational process config of its own — all behaviour is driven by runtime state (`F_in`, `Cs_in`, `C_TS`). Tune behaviour by feeding it different reactor effluents or `C_TS` measurements.
+## Capability matrix
-## 10. State chart
+| Capability | Status | Notes |
+|:---|:---:|:---|
+| TSS mass-balance split (3 streams) | yes | `F_s = min(F_in * Cs[12] / C_TS, F_in)` — clamped to prevent negative effluent. |
+| Particulate zeroing in effluent | yes | Species 7–12 set to 0 in `inlet=0` when `F_s > 0`. |
+| Particulate concentration in sludge | yes | Species 7–12 scaled by `F_in / F_s` in `inlet=1` + `inlet=2`. |
+| Return-pump flow draw | yes | `F_sr = min(pump flow at equipment, F_s)`. Surplus = `F_s - F_sr`. |
+| `F_s` clamp to `F_in` | yes | Prevents negative effluent when `X_TS_in > C_TS`. |
+| Manual influent override | yes | `data.influent` lets ops supply `{F, C}` directly. |
+| Multiple reactor upstreams | no | Only one `upstreamReactor` slot; last registration wins. |
+| Stateful FSM | no | Stateless transform — recomputes on every trigger. |
+| Curve loading / drift / sequence-abort | n/a | Not applicable to a passive split. |
-Not applicable — settler is stateless. There is no FSM. Every trigger (`stateChange` from the reactor, `data.influent`, or a `quantity (tss)` update) causes a fresh recompute of the 3 Fluent streams from the current runtime state and the split immediately re-emits.
+---
-## 11. Examples
+## Need more?
-| Tier | File | What it shows | Status |
-|---|---|---|---|
-| Basic | `examples/basic.flow.json` | Inject `data.influent`, watch 3-stream split | ✅ in repo |
-| Integration | `examples/integration.flow.json` | reactor (upstream) + settler + return pump | ✅ in repo |
-| Edge | `examples/edge.flow.json` | F_s clamp + zero-influent fallback | ✅ in repo |
+| Page | What you'll find |
+|:---|:---|
+| [Reference — Contracts](Reference-Contracts) | Topic registry, config schema, child registration filters |
+| [Reference — Architecture](Reference-Architecture) | Three-tier code map, reactor ↔ settler wiring (the load-bearing bit), lifecycle, output ports |
+| [Reference — Examples](Reference-Examples) | Shipped example flows (currently stubs) + the TODO list for production-grade demos |
+| [Reference — Limitations](Reference-Limitations) | When not to use, known limitations, open questions |
-One screenshot per tier where helpful. PNG ≤ 200 KB under `wiki/_partial-screenshots/settler/`.
-
-## 12. Debug recipes
-
-| Symptom | First thing to check | Where to look |
-|---|---|---|
-| `F_eff` negative or NaN | `C_TS` zero or `Cs_in[12]` huge. F_s clamp should prevent — confirm clamp present. | `specificClass.js → getEffluent` |
-| Settler never updates after reactor changes | Reactor child not on `'upstream'` position, or listener attached to wrong emitter. | `_connectReactor` — listens on `reactor.emitter`, NOT `measurements.emitter`. |
-| Return-sludge flow = 0 | `returnPump.measurements.type('flow').variant('measured').position('atEquipment')` empty. Wire a flow measurement on the pump. | `_connectMachine`, pump measurement chain. |
-| 3 Fluent envelopes not arriving downstream | `payload.inlet` selector on the downstream reactor mismatches (0=eff, 1=surplus, 2=return). | downstream reactor's `data.fluent` handler. |
-| `quantity (tss)` updates don't change `C_TS` | Measurement child's `asset.type` not `quantity (tss)` exactly. | `_updateMeasurement` switch. |
-
-## 13. When you would NOT use this node
-
-- Use settler for **secondary clarification** downstream of a biological reactor. For primary sedimentation (raw sewage), the species-7-12 zeroing is wrong — model that as a separate process.
-- Don't use settler as a generic mass-balance node — the 13-species ASM3 vector is hard-coded.
-- Skip settler when the downstream reactor doesn't need a 3-stream split (e.g. single-tank SBR). A direct reactor → reactor wire is lighter.
-
-## 14. Known limitations / current issues
-
-| # | Issue | Tracked in |
-|---|---|---|
-| 1 | Only one `upstreamReactor` slot — multi-reactor settlers not supported (last registration wins). | `_connectReactor` |
-| 2 | TSS mass balance uses index 12 (`X_TS`) hard-coded — coupled tightly to ASM3 species ordering. | `getEffluent`, `_updateMeasurement` |
-| 3 | Settler depends on `mathjs` (~14 MB install) but only uses it transitively via reactor; no direct mathjs call in settler code. | `package.json` |
-| 4 | No flow-balance check at runtime — if particulate concentration drives F_s above F_in, the clamp masks an upstream bug rather than warning. | `getEffluent` |
-| 5 | Editor colour is `#e4a363` (orange) in `settler.html` but S88 Unit level requires `#50a8d9` (blue). Diagrams in this wiki use the correct `#50a8d9`. Colour cleanup tracked in `.claude/rules/node-red-flow-layout.md` §16. | `settler.html` |
+[EVOLV master wiki](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Home) · [Topology Patterns](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Topology-Patterns) · [Topic Conventions](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Topic-Conventions)
diff --git a/wiki/Reference-Architecture.md b/wiki/Reference-Architecture.md
new file mode 100644
index 0000000..0b5cb54
--- /dev/null
+++ b/wiki/Reference-Architecture.md
@@ -0,0 +1,291 @@
+# Reference — Architecture
+
+
+
+> [!NOTE]
+> Pending full node review (2026-05). Content reflects `CONTRACT.md` and current source only.
+
+Code structure for `settler`: the three-tier sandwich, the `src/` layout, the reactor ↔ settler wiring (the load-bearing bit), the lifecycle, and the output-port pipeline. For an intuitive overview, return to [Home](Home).
+
+---
+
+## Three-tier code layout
+
+```
+nodes/settler/
+|
++-- settler.js entry: RED.nodes.registerType('settler', ...) + /settler/menu.js admin route
++-- settler.html editor form (Name, output formats, logger, position) — currently colour-drifted to #e4a363
+|
++-- src/
+| nodeClass.js extends BaseNodeAdapter — domain wiring + Port 0/1 emit (~30 LOC)
+| specificClass.js extends BaseDomain — TSS split + child wiring (~140 LOC)
+| |
+| +-- commands/
+| index.js 2 topic descriptors: data.influent (+aliases), child.register
+| handlers.js pure handler functions
+```
+
+Settler is small enough (~140 LOC of domain code) that no concern-split was needed; per the platform's MODULE_SPLIT contract a node only fans out into `src//` modules when complexity demands it.
+
+### Tier responsibilities
+
+| Tier | File | What it owns | Touches `RED.*` |
+|:---|:---|:---|:---:|
+| entry | `settler.js` | Type registration + `/settler/menu.js` admin endpoint (proxies reactor's MenuManager). | yes |
+| nodeClass | `src/nodeClass.js` | `_emitOutputs()` only — calls `source.getEffluent` for the 3-msg Port-0 array and `source.getOutput()` for Port-1 InfluxDB telemetry. `tickInterval = null` (event-driven, no periodic loop). `statusInterval = 1000` for the badge. | yes |
+| specificClass | `src/specificClass.js` | `Settler.configure()` wires the `ChildRouter` for `measurement` / `reactor` / `machine` children. `getEffluent` is the mass-balance core. `getOutput` is the scalar Port-1 view. `getStatusBadge` renders the editor badge. | no |
+
+`specificClass` does the work directly; there is no orchestration / concern layer between it and the math.
+
+> [!NOTE]
+> Pending full node review (2026-05). The router-based registration uses `this.router.onRegister(...)` — verify against the latest BaseDomain contract when next touched.
+
+---
+
+## FSM
+
+Not applicable. Settler is **stateless**. There is no FSM, no `state.*` member, no `executeSequence`, no movement / setpoint. Every trigger (`stateChange` from the upstream reactor, `data.influent` from an operator, or a `quantity (tss)` update from a measurement child) causes a fresh recompute of the three Fluent envelopes from the current runtime state, and the split immediately re-emits.
+
+The status badge has two cosmetic branches only:
+
+| Condition | Badge |
+|:---|:---|
+| `F_in <= 0` | `statusBadge.idle('no influent')` |
+| else | green dot, label `F_in= eff= surplus=` |
+
+There are no "protected states", no abort tokens, no allow-lists. All of that belongs to FSM-bearing nodes (`rotatingMachine`, `pumpingStation`, `machineGroupControl`, …).
+
+---
+
+## Reactor ↔ settler wiring — the load-bearing bit
+
+This is the one piece of settler that needs care, because the reactor uses a different event channel than every other child type in EVOLV.
+
+```mermaid
+flowchart TB
+ reactor[upstream reactor]:::unit
+ rEmit{reactor.emitter}
+ rMeas{reactor.measurements.emitter}
+ settler[settler._connectReactor]:::unit
+ pull[upstreamReactor.getEffluent]
+ apply[F_in = ...
Cs_in = ...]
+ notify[notifyOutputChanged()]
+
+ reactor --> rEmit
+ reactor --> rMeas
+ rEmit -- stateChange --> settler
+ rMeas -. NOT used .- settler
+ settler --> pull
+ pull --> apply
+ apply --> notify
+ classDef unit fill:#50a8d9,color:#000
+```
+
+Mechanism:
+
+1. The reactor pushes its `stateChange` event on `reactor.emitter` — **not** on `reactor.measurements.emitter`. The standard `router.onMeasurement` subscription path therefore can't see it.
+2. `_connectReactor(reactorChild)` attaches the listener manually:
+
+ ```js
+ reactorChild.emitter.on('stateChange', () => {
+ const raw = this.upstreamReactor.getEffluent;
+ const effluent = Array.isArray(raw) ? raw[0] : raw;
+ this.F_in = effluent.payload.F;
+ this.Cs_in = effluent.payload.C;
+ this.notifyOutputChanged();
+ });
+ ```
+
+3. `reactor.getEffluent` historically returned either an **array** (a 3-stream Fluent envelope, same shape settler itself emits) or a **single envelope** — the 2026-03-02 `_connectReactor` fix preserves both shapes via `Array.isArray(raw) ? raw[0] : raw`. If you change the reactor's effluent shape, this is the line to update.
+4. Position check: settler warns `Reactor children of settlers should be upstream.` if `positionVsParent !== 'upstream'`, but still stores the reactor. The wiring is not blocked — it just becomes the operator's problem to confirm intent.
+
+> [!NOTE]
+> Pending full node review (2026-05). The settler-side pull-not-push semantics rely on `reactor.getEffluent` being a property getter (no arguments). Future reactor refactors that turn this into a parameterised method will need a coordinated change here.
+
+---
+
+## Return-pump wiring
+
+`_connectMachine(machineChild)` is the second non-trivial registration path:
+
+| Condition | Effect |
+|:---|:---|
+| `positionVsParent === 'downstream'` | Store as `this.returnPump`. Set `machineChild.upstreamSource = this` so the pump's own flow predictor can use settler's `inlet=2` envelope as its suction-side Fluent. |
+| else | Warn `Failed to register machine child.`, no storage. |
+
+At each call to `getEffluent`, settler reads the pump's current measured flow:
+
+```js
+F_sr = Math.min(
+ this.returnPump.measurements.type('flow').variant('measured').position(POSITIONS.AT_EQUIPMENT).getCurrentValue(),
+ F_s,
+);
+```
+
+If no return pump is registered or its flow measurement is zero, `F_sr = 0` — in that case all separated sludge becomes surplus (`inlet=1`) and the return stream (`inlet=2`) is zero-flow.
+
+---
+
+## Measurement-child wiring
+
+`_connectMeasurement(measurementChild)` is generic: it subscribes to `.measured.` on the child's `measurements.emitter` and:
+
+1. Re-emits the value on settler's own `this.measurements` container (lets settler's own parent subscribe).
+2. Calls `_updateMeasurement(type, value, position, eventData)`.
+
+`_updateMeasurement` currently recognises only one type:
+
+| `measurementType` | Side-effect |
+|:---|:---|
+| `quantity (tss)` | Set `this.C_TS = value`. Trigger `notifyOutputChanged()`. |
+| anything else | Log an `error` (`Type '' not recognized for measured update.`) — the re-emit still happened, just no settler-side state change. |
+
+The `quantity (tss)` value is the **settler's own setpoint** for the target return-sludge concentration. The default is `2500` mg/L. Higher `C_TS` → less return + surplus, more effluent. Lower `C_TS` → more return + surplus.
+
+---
+
+## Mass-balance math (`getEffluent`)
+
+```mermaid
+flowchart TB
+ F_in[F_in m³/h]:::input
+ Cs_in[Cs_in array 13
mg/L per species]:::input
+ C_TS[C_TS
target return mg/L]:::input
+ pumpFlow[returnPump.flow.measured.atequipment]:::input
+
+ F_in --> Fs[F_s = min(F_in × Cs_in[12] / C_TS, F_in)]
+ Cs_in --> Fs
+ C_TS --> Fs
+ Fs --> F_eff[F_eff = F_in − F_s]
+ Fs --> F_sr[F_sr = min(pumpFlow, F_s)]
+ pumpFlow --> F_sr
+ F_sr --> F_so[F_so = F_s − F_sr]
+
+ Cs_in --> CsEff[Cs_eff: copy then zero 7..12 if F_s > 0]
+ Cs_in --> CsS[Cs_s: copy then scale 7..12 by F_in / F_s if F_s > 0]
+
+ F_eff --> envEff[envelope inlet=0]
+ CsEff --> envEff
+ F_so --> envSur[envelope inlet=1]
+ CsS --> envSur
+ F_sr --> envRet[envelope inlet=2]
+ CsS --> envRet
+ classDef input fill:#a9daee,color:#000
+```
+
+Key facts:
+
+- `F_s` is the **total separated sludge stream**. Mass-balance derivation: at steady state, `F_in * Cs_in[12] = F_s * C_TS` → `F_s = F_in * Cs_in[12] / C_TS`.
+- The clamp `min(..., F_in)` prevents `F_eff` going negative when `Cs_in[12] > C_TS` (i.e. the influent is denser than the target sludge concentration). Sub-rosa: the clamp masks the **upstream** problem; settler does not warn when the clamp fires — see [Reference — Limitations](Reference-Limitations#no-flow-balance-warning).
+- Species indices 7–12 are the ASM3 particulate species (`X_*`). Index 12 specifically is `X_TS` — the lumped total-suspended-solids surrogate the split is keyed off.
+- Soluble species 0–6 pass through unchanged in all three streams.
+- All three envelopes share a single `timestamp = Date.now()` — downstream consumers can rely on them being a coherent triple.
+
+---
+
+## Lifecycle — what one trigger does
+
+```mermaid
+sequenceDiagram
+ autonumber
+ participant reactor as upstream reactor
+ participant settler as settler (specificClass)
+ participant nc as nodeClass
+ participant pump as return pump child
+ participant out as Port 0 / 1
+
+ reactor->>settler: emitter.emit('stateChange')
+ settler->>reactor: read getEffluent
+ reactor-->>settler: {F, C[13]} (or [{...}])
+ settler->>settler: F_in = F · Cs_in = C
+ settler->>settler: notifyOutputChanged()
+ nc->>settler: read getEffluent (recompute)
+ settler->>pump: read measurements.flow.measured.atequipment
+ pump-->>settler: returnFlow (m³/h)
+ settler->>settler: getEffluent — split into 3 envelopes
+ settler-->>nc: [Fluent inlet=0, inlet=1, inlet=2]
+ nc->>settler: read getOutput()
+ settler-->>nc: {F_in, C_TS, F_eff, F_surplus, F_return, ...measurements}
+ nc->>out: send([fluent, influxMsg, null])
+```
+
+The three triggers that route through this lifecycle are:
+
+| Trigger | Origin | Path |
+|:---|:---|:---|
+| Reactor `stateChange` | `reactor.emitter.emit('stateChange')` | `_connectReactor` listener → pull `getEffluent` → copy → `notifyOutputChanged` |
+| Operator `data.influent` | Inbound `msg.topic` | `commands/handlers.js#dataInfluent` → mutate `F_in` / `Cs_in` → `notifyOutputChanged` |
+| Measurement `quantity (tss)` | `measurementChild.measurements.emitter` | `_connectMeasurement` re-emit + `_updateMeasurement` → mutate `C_TS` → `notifyOutputChanged` |
+
+`notifyOutputChanged` is BaseDomain's standard `output-changed` event. `BaseNodeAdapter` listens, calls `_emitOutputs()`, which produces the Port 0 / Port 1 messages.
+
+---
+
+## Output ports
+
+| Port | Carries | Sample shape |
+|:---|:---|:---|
+| 0 (process) | **Array of three Node-RED messages**, each `{topic: 'Fluent', payload: {inlet, F, C}, timestamp}`. Re-emitted on every recompute. | See [Home — What you'll see come out](Home#what-youll-see-come-out). |
+| 1 (telemetry) | Single InfluxDB line-protocol payload built by `outputUtils.formatMsg(getOutput(), cfg, 'influxdb')`. Delta-compressed: only changed fields shipped. | `settler,id=settler_a F_in=1000,F_eff=850,F_surplus=50,F_return=100,C_TS=2500,...` |
+| 2 (register / control) | `null` from `_emitOutputs`. The one-shot `child.register` upward at startup goes through the BaseNodeAdapter init path, not `_emitOutputs`. | `{topic: 'child.register', payload: , positionVsParent, distance}` (init only) |
+
+Port-1 key shape from `getOutput()`:
+
+| Key | Type | Source | Notes |
+|:---|:---|:---|:---|
+| `F_in` | number | `host.F_in` | Influent flow (m³/h). |
+| `C_TS` | number | `host.C_TS` | Target return-sludge concentration (mg/L). Default 2500. |
+| `F_eff` | number | `streams[0].payload.F` | Clarified effluent flow. |
+| `F_surplus` | number | `streams[1].payload.F` | Surplus sludge flow. |
+| `F_return` | number | `streams[2].payload.F` | Return sludge flow. |
+| `...` | varies | `measurements.getFlattenedOutput()` | Flattened snapshot of every measurement settler has seen (re-emitted from children). |
+
+See [EVOLV — Telemetry](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Telemetry) for the full InfluxDB layout.
+
+> [!NOTE]
+> Pending full node review (2026-05). The `getOutput()` return shape has not been audited against an `_output-manifest.md` (the output-coverage rule). TODO: add the manifest and `test/basic/output-*.test.js` coverage in both populated and degraded states (no influent / no pump / no TSS measurement).
+
+---
+
+## Event sources
+
+| Source | Where it fires | What it triggers |
+|:---|:---|:---|
+| `reactor.emitter` `'stateChange'` | Upstream reactor on every internal state advance | `_connectReactor` listener → pull `getEffluent` → recompute |
+| `measurementChild.measurements.emitter` `'.measured.'` | Any registered measurement child on a new sample | `_connectMeasurement` re-emit + `_updateMeasurement` switch |
+| Inbound `msg.topic = data.influent` | Node-RED input wire | `commands/handlers.js#dataInfluent` |
+| Inbound `msg.topic = child.register` | Node-RED input wire (rare; usually Port 2 wiring) | `commands/handlers.js#childRegister` |
+| `BaseDomain` `'output-changed'` | `notifyOutputChanged()` in domain | `nodeClass._emitOutputs()` |
+| `setInterval(statusInterval = 1000)` | `BaseNodeAdapter` | Re-render the status badge |
+
+No per-second tick on the domain itself. `tickInterval = null` is explicit in `nodeClass`.
+
+---
+
+## Where to start reading
+
+| If you're changing… | Read first |
+|:---|:---|
+| The TSS mass-balance math | `src/specificClass.js#getEffluent` (lines 37–62) |
+| Reactor ↔ settler wiring (stateChange listener, both-shape envelope handling) | `src/specificClass.js#_connectReactor` |
+| Return-pump wiring (the `machine` / `downstream` registration) | `src/specificClass.js#_connectMachine` |
+| Measurement re-emit + `C_TS` setpoint | `src/specificClass.js#_connectMeasurement` + `#_updateMeasurement` |
+| Operator-side influent override | `src/commands/handlers.js#dataInfluent` |
+| Port 0 (3-msg array) + Port 1 (InfluxDB) emit pipeline | `src/nodeClass.js#_emitOutputs` |
+| Status-badge text | `src/specificClass.js#getStatusBadge` |
+| Editor form / colour drift | `settler.html` (currently `color: '#e4a363'`; should be `#50a8d9`) |
+
+---
+
+## Related pages
+
+| Page | Why |
+|:---|:---|
+| [Home](Home) | Intuitive overview |
+| [Reference — Contracts](Reference-Contracts) | Topic + config + child filters |
+| [Reference — Examples](Reference-Examples) | Shipped flows + debug recipes |
+| [Reference — Limitations](Reference-Limitations) | Known issues and open questions |
+| [reactor wiki](https://gitea.wbd-rd.nl/RnD/reactor/wiki/Home) | The upstream parent — emits `stateChange` and exposes `getEffluent` |
+| [rotatingMachine wiki](https://gitea.wbd-rd.nl/RnD/rotatingMachine/wiki/Home) | The return-pump child — consumes `inlet=2` via `upstreamSource` |
+| [EVOLV — Architecture](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Architecture) | Platform-wide three-tier pattern |
diff --git a/wiki/Reference-Contracts.md b/wiki/Reference-Contracts.md
new file mode 100644
index 0000000..aebdd6d
--- /dev/null
+++ b/wiki/Reference-Contracts.md
@@ -0,0 +1,176 @@
+# Reference — Contracts
+
+
+
+> [!NOTE]
+> Pending full node review (2026-05). Content reflects `CONTRACT.md`, `src/commands/index.js`, and `generalFunctions/src/configs/settler.json` only.
+
+Full topic contract, configuration schema, and child-registration filters for `settler`. Source of truth: `src/commands/index.js`, `src/specificClass.js` `configure()`, and the schema at `generalFunctions/src/configs/settler.json`. For an intuitive overview, return to the [Home](Home).
+
+---
+
+## Topic contract
+
+The registry lives in `src/commands/index.js`. Each descriptor maps a canonical `msg.topic` to its handler; aliases emit a one-time deprecation warning the first time they fire.
+
+
+
+| Canonical topic | Aliases | Payload | Unit | Effect |
+|:---|:---|:---|:---|:---|
+| `data.influent` | `influent`, `setInfluent` | `{F: number, C: number[13]}` — either field optional | `F` in m³/h, `C[*]` in mg/L | Replaces influent flow and/or the 13-species concentration vector on the domain (`source.F_in`, `source.Cs_in`). Triggers `notifyOutputChanged`, which re-emits the 3-stream Fluent envelope on Port 0. |
+| `child.register` | `registerChild` | `string` (child node id) | — | Register a child node (measurement / reactor / machine) with this settler. Port 2 wiring does this automatically in normal flows; the explicit handler exists because `BaseNodeAdapter` does not have an implicit registration path. |
+
+
+
+> [!NOTE]
+> Pending full node review (2026-05). The autogen markers above will be populated by a future `npm run wiki:contract` tool. Until then the table is hand-maintained against `src/commands/index.js`.
+
+### Mode / source / action allow-lists
+
+**Not applicable.** Settler has no operational mode, no source allow-list, no action allow-list. Both topics are accepted unconditionally; payload-shape validation lives in the handler itself.
+
+The `data.influent` handler validates:
+
+```js
+if (!p || typeof p !== 'object' || Array.isArray(p)) {
+ log?.warn?.(`data.influent expects an object {F, C}; got ${typeof p}`);
+ return;
+}
+if (typeof p.F === 'number' && Number.isFinite(p.F)) source.F_in = p.F;
+if (Array.isArray(p.C)) source.Cs_in = [...p.C];
+```
+
+Non-finite or non-numeric `F` is silently ignored. Non-array `C` is silently ignored. Either field may be omitted to update only the other. Negative `F` is **not** rejected — the downstream `getEffluent` math will produce nonsense but the node will not throw.
+
+---
+
+## Data model — `getOutput()` shape
+
+Composed each tick by `src/specificClass.js` `getOutput()`. Port 0 carries the 3-message Fluent stream **directly** (not via `getOutput`); Port 1 (this snapshot) is the scalar dashboard view.
+
+
+
+### Scalar keys
+
+| Key | Type | Unit | Source | Notes |
+|:---|:---|:---|:---|:---|
+| `F_in` | number | m³/h | `host.F_in` | Influent flow. Default 0. |
+| `C_TS` | number | mg/L | `host.C_TS` | Target return-sludge concentration. Default 2500. Updated by `quantity (tss)` measurement child. |
+| `F_eff` | number | m³/h | `streams[0].payload.F` | Clarified effluent flow. |
+| `F_surplus` | number | m³/h | `streams[1].payload.F` | Surplus sludge flow (`F_s - F_sr`). |
+| `F_return` | number | m³/h | `streams[2].payload.F` | Return sludge flow (`min(pumpFlow, F_s)`). |
+
+### Per-measurement keys
+
+For every `(type, variant, position)` stored in `this.measurements` MeasurementContainer, the flattened output emits:
+
+```
+...
+```
+
+Position labels are normalised to lowercase. The trailing `` is the registering measurement child's id. Settler does not write its own measurements directly — every key in this group came from a registered child (the `_connectMeasurement` re-emit).
+
+
+
+### Status badge
+
+`getStatusBadge()` in `src/specificClass.js`:
+
+| Condition | Badge |
+|:---|:---|
+| `F_in <= 0` | `statusBadge.idle('no influent')` (grey ring) |
+| else | green dot, label `F_in= eff= surplus=` (m³/h, 2 dp) |
+
+No state-symbol enumeration — settler has no FSM.
+
+---
+
+## Configuration schema — editor form to config keys
+
+Source of truth: `generalFunctions/src/configs/settler.json` plus `settler.html`.
+
+### General (`config.general`)
+
+| Form field | Config key | Default | Notes |
+|:---|:---|:---|:---|
+| Name | `general.name` | `"Settler"` | Human-readable name. |
+| (auto-assigned) | `general.id` | `null` | Node-RED node id. |
+| Default unit | `general.unit` | `null` | Default measurement unit. Currently unused by settler — child measurements carry their own units. |
+| Enable logging | `general.logging.enabled` | `true` | Master switch. |
+| Log level | `general.logging.logLevel` | `info` | `debug` / `info` / `warn` / `error`. |
+
+### Functionality (`config.functionality`)
+
+| Form field | Config key | Default | Notes |
+|:---|:---|:---|:---|
+| (hidden) | `functionality.softwareType` | `settler` | Constant. Used by the parent's router as a registration filter. |
+| (hidden) | `functionality.role` | `Secondary settler for sludge separation` | Documentation string. |
+| Position vs parent | `functionality.positionVsParent` | `downstream` | One of `upstream` / `atEquipment` / `downstream`. Settler typically registers as `downstream` against an upstream reactor. |
+
+### Node-RED-side (editor form, not domain config)
+
+| Form field | Stored on | Default | Notes |
+|:---|:---|:---|:---|
+| Process Output Format | `nodeClass.processOutputFormat` | `process` | `process` / `json` / `csv`. Port-0 serialisation. |
+| Database Output Format | `nodeClass.dbaseOutputFormat` | `influxdb` | `influxdb` / `json` / `csv`. Port-1 serialisation. |
+
+`buildDomainConfig()` returns `{}` — settler does not push any editor-derived values into the domain at start-up. All operational state is runtime (`F_in`, `Cs_in`, `C_TS`).
+
+> [!NOTE]
+> Pending full node review (2026-05). The editor form (`settler.html`) is currently colour-drifted to `#e4a363` (orange); should be `#50a8d9` (Unit blue) per `.claude/rules/node-red-flow-layout.md` §16.
+
+### Unit policy
+
+| Quantity | Canonical (internal) | Output (Port 1) | Notes |
+|:---|:---|:---|:---|
+| Flow (`F_in`, `F_eff`, `F_surplus`, `F_return`) | m³/h | m³/h | No conversion — settler is unit-agnostic above the storage layer. |
+| Concentration (`C_TS`, `Cs_in[*]`) | mg/L | mg/L | Same. |
+
+> [!NOTE]
+> Pending full node review (2026-05). Settler does **not** declare a `requireUnitForTypes` policy via MeasurementContainer; verify against the general unit policy before relying on internal canonicalisation.
+
+---
+
+## Child registration
+
+Source: `src/specificClass.js` `configure()` (the `this.router.onRegister(...)` chain) and the three `_connect*` methods.
+
+| Software type | Filter | Wired to | Side-effect |
+|:---|:---|:---|:---|
+| `measurement` | any (no asset-type / position filter at register time) | `_connectMeasurement(child)` | Subscribes to `.measured.` on the child's `measurements.emitter`. Re-emits on settler's own MeasurementContainer (lets settler's parent see the value). `quantity (tss)` updates `C_TS`; anything else logs an `error` from `_updateMeasurement` but the re-emit still happened. |
+| `reactor` | `positionVsParent === 'upstream'` (warns otherwise but still registers) | `_connectReactor(child)` | Stored as `this.upstreamReactor`. Listener attached **manually** to `reactor.emitter` (NOT `measurements.emitter`) for `'stateChange'`; on fire, settler pulls `reactor.getEffluent` and copies `F_in` + `Cs_in`. Handles both array and single-envelope `getEffluent` shapes. |
+| `machine` | `positionVsParent === 'downstream'` (warns + skips otherwise) | `_connectMachine(child)` | Stored as `this.returnPump`. Settler reads `returnPump.measurements.type('flow').variant('measured').position('atEquipment').getCurrentValue()` to determine `F_sr`. Sets `machineChild.upstreamSource = this` so the pump can use settler's `inlet=2` Fluent as its suction-side context. |
+
+> [!NOTE]
+> Pending full node review (2026-05). The `measurement` filter accepts any asset-type at register time; only the runtime `_updateMeasurement` switch acts on `quantity (tss)`. Other measurement types are silently re-emitted but not consumed. TODO: decide whether this is desired (pass-through telemetry) or a contract gap.
+
+### No virtual children
+
+Unlike `rotatingMachine`, settler does **not** auto-register any virtual measurement children. Every measurement must come from an explicitly wired child node.
+
+---
+
+## Parent relationship
+
+Settler typically registers as `softwareType: 'settler'` with `positionVsParent: 'downstream'` against a reactor (the reactor's downstream stage). The downstream reactor consumes the three Fluent streams via `payload.inlet`:
+
+| `inlet` | Consumer expectation |
+|:---|:---|
+| `0` (clarified effluent) | Routed onward to the next process unit. |
+| `1` (surplus sludge) | Typically routed to a sludge-handling process (digestion, thickening, dewatering). |
+| `2` (return sludge) | Drawn back to a reactor inlet or the head of the biological train. |
+
+Multi-reactor settlers are **not supported** — `this.upstreamReactor` is a single slot; the last `child.register` call wins.
+
+---
+
+## Related pages
+
+| Page | Why |
+|:---|:---|
+| [Home](Home) | Intuitive overview |
+| [Reference — Architecture](Reference-Architecture) | Code map, reactor ↔ settler wiring, mass-balance math |
+| [Reference — Examples](Reference-Examples) | Shipped flows + debug recipes |
+| [Reference — Limitations](Reference-Limitations) | Known issues and open questions |
+| [EVOLV — Topic Conventions](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Topic-Conventions) | Platform-wide topic rules |
+| [EVOLV — Telemetry](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Telemetry) | Port 0 / 1 / 2 InfluxDB layout |
diff --git a/wiki/Reference-Examples.md b/wiki/Reference-Examples.md
new file mode 100644
index 0000000..d97acfa
--- /dev/null
+++ b/wiki/Reference-Examples.md
@@ -0,0 +1,139 @@
+# Reference — Examples
+
+
+
+> [!NOTE]
+> Pending full node review (2026-05). The shipped example flows are **stub level**: each is a 4-node skeleton (tab + node + inject + debug) that proves the node loads in Node-RED but does **not** exercise the reactor → settler → return-pump chain or the TSS mass-balance math. Production-grade examples are TODO. See [Reference — Limitations — Example flows](Reference-Limitations#example-flows-are-stub-level).
+
+---
+
+## Shipped examples
+
+| File | Tier | Dependencies | What it shows |
+|:---|:---:|:---|:---|
+| `basic.flow.json` | 1 (stub) | EVOLV only | Loads a single settler node, wires a `ping` inject to its input, taps Port 0 (only) to a debug node. Inject payload is the string `"1"` — will be rejected by `data.influent`'s payload validator (warn logged). Useful only to verify the node type registers. |
+| `integration.flow.json` | 2 (stub) | EVOLV only | Same shape; inject sends `topic = registerChild`, payload `example-child-id`. The lookup will fail (no such node) and log a warn. Does **not** exercise reactor or pump wiring. |
+| `edge.flow.json` | 3 (stub) | EVOLV only | Same shape; inject sends `topic = doesNotExist`. Verifies the registry rejects unknown topics. |
+
+### Status
+
+| Aspect | State |
+|:---|:---|
+| Loads in Node-RED on deploy | yes |
+| Drives `data.influent` with a valid payload | no |
+| Drives the reactor → settler → return-pump chain | no |
+| Shows the 3-stream Fluent split on Port 0 | no |
+| Has a dashboard tier | no |
+| Validated against a live Node-RED instance | no |
+
+---
+
+## Loading a flow
+
+### Via the editor
+
+1. Open the Node-RED editor at `http://localhost:1880`.
+2. Menu → Import → drag the JSON file.
+3. Click Deploy.
+
+### Via the Admin API
+
+```bash
+curl -X POST -H 'Content-Type: application/json' \
+ --data @nodes/settler/examples/basic.flow.json \
+ http://localhost:1880/flows
+```
+
+---
+
+## TODO — production-grade example set
+
+The matching `rotatingMachine` repo ships three tiers; settler needs the same. Tracking placeholder:
+
+| Tier | Proposed filename | What it should show |
+|:---|:---|:---|
+| 1 | `01 - Basic Manual Influent.json` | Single settler + inject sending `data.influent` with a realistic `{F, C}` payload. Three debug taps (one per Port 0 stream by `payload.inlet`). Operator can vary F and watch the split rebalance. |
+| 2 | `02 - Reactor and Return Pump.json` | One `reactor` (upstream) + one `settler` + one `rotatingMachine` (return pump, downstream). Auto-registration via Port 2. Drive the reactor with an inject; settler should re-split on every reactor `stateChange`. |
+| 3 | `03 - Dashboard Visualization.json` | FlowFuse Dashboard 2.0 page: F_in / F_eff / F_surplus / F_return trend chart, C_TS gauge, status badges per stream. Required: `@flowfuse/node-red-dashboard` installed. |
+
+> [!IMPORTANT]
+> **Screenshots needed** once the production-grade examples land. Save as `wiki/_partial-screenshots/settler/01-basic-editor.png`, `02-reactor-pump-editor.png`, `03-dashboard-rendered.png`, ≤ 200 KB each.
+
+---
+
+## What the basic example would do (sketch — not yet shipped)
+
+Operator workflow once a real Tier-1 ships:
+
+1. Deploy the flow.
+2. Send `data.influent` with payload:
+
+ ```json
+ { "F": 1000, "C": [0,0,0,0,0,0,0,30,80,400,200,80,3000] }
+ ```
+
+ Twelve soluble species at low concentrations + index 12 `X_TS = 3000` mg/L.
+3. Observe three Port-0 messages arrive simultaneously, each with `topic = "Fluent"` and `payload.inlet` ∈ {0, 1, 2}.
+4. With default `C_TS = 2500` mg/L:
+ - `F_s = 1000 * 3000 / 2500 = 1200` — but clamped to `F_in = 1000`. **The clamp fires** — this is the input edge case [Reference — Limitations — no-flow-balance warning](Reference-Limitations#no-flow-balance-warning) refers to.
+ - `F_eff = 0`. The clarified-effluent envelope carries zero flow but still has its `C` vector (with species 7–12 zeroed).
+ - `F_sr` is 0 (no pump wired) → `F_surplus = 1000`, `F_return = 0`.
+5. Send `data.influent` with `X_TS = 1500` mg/L instead. Now `F_s = 600`, `F_eff = 400`, `F_surplus = 600`, `F_return = 0`. Realistic split.
+
+> [!NOTE]
+> Pending full node review (2026-05). The clamp-fires behaviour above is intended (per code comment in `getEffluent`) but produces no operator-visible warning. Tracked.
+
+---
+
+## Docker compose snippet
+
+To bring up Node-RED + InfluxDB with EVOLV nodes pre-loaded:
+
+```yaml
+# docker-compose.yml (extract)
+services:
+ nodered:
+ build: ./docker/nodered
+ ports: ['1880:1880']
+ volumes:
+ - ./docker/nodered/data:/data/evolv
+ influxdb:
+ image: influxdb:2.7
+ ports: ['8086:8086']
+```
+
+Full file: [EVOLV/docker-compose.yml](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/development/docker-compose.yml).
+
+---
+
+## Debug recipes
+
+> [!NOTE]
+> Pending full node review (2026-05). Recipes below are grounded in the source; the symptom-side has not been confirmed against a live deployment.
+
+| Symptom | First thing to check | Where to look |
+|:---|:---|:---|
+| `F_eff` negative or `NaN` | `C_TS` is zero or `Cs_in[12]` is huge. The `F_s` clamp should prevent negatives — confirm the clamp `min(..., F_in)` is present. Likely the clamp fires but masks a deeper input problem. | `src/specificClass.js#getEffluent` line `const F_s = Math.min(...)`. |
+| Settler never updates after reactor changes | Reactor child is not on `'upstream'` position (warn logged but registration proceeds), or the listener is attached to the wrong emitter. | `_connectReactor` — listens on `reactor.emitter`, **NOT** `reactor.measurements.emitter`. |
+| Return-sludge flow stays at 0 | `returnPump.measurements.type('flow').variant('measured').position('atEquipment')` has no current value. Wire a flow measurement child on the pump (with `asset.type='flow'`, `positionVsParent='atEquipment'`). | `_connectMachine`, pump's MeasurementContainer chain. |
+| Three Fluent envelopes do not arrive at the downstream consumer | `payload.inlet` selector on the downstream reactor / pump mismatches (0 = effluent, 1 = surplus, 2 = return). | The downstream consumer's inlet routing. |
+| `quantity (tss)` updates don't change `C_TS` | Measurement child's `asset.type` must be the literal string `"quantity (tss)"` (with the space + parenthesised "tss"). | `src/specificClass.js#_updateMeasurement` switch case. |
+| `data.influent` inject is silently dropped | Payload must be an object `{F, C}`. A string, number, or array logs a warn (`data.influent expects an object {F, C}; got `) and short-circuits. | `src/commands/handlers.js#dataInfluent`. |
+| Settler logs an `error` `Type '' not recognized for measured update.` | A measurement child has registered with an `asset.type` settler doesn't recognise. The re-emit still happened — the error is about the absence of a `_updateMeasurement` switch case. Currently only `quantity (tss)` mutates state. | `_updateMeasurement`. |
+| `child.register` topic logs `child.register skipped: missing child/source for id=` | The given node id doesn't resolve to a Node-RED node with a `.source` (i.e. an EVOLV domain). Verify the id is correct and the target node has already been deployed. | `src/commands/handlers.js#childRegister`. |
+| Status badge stuck on `idle: no influent` | `F_in <= 0`. Either no reactor has fired `stateChange` yet, or `data.influent` has not been sent with a positive `F`. | `src/specificClass.js#getStatusBadge`. |
+
+> Never ship `enableLog: 'debug'` in a demo — fills the container log within seconds and obscures real errors.
+
+---
+
+## Related pages
+
+| Page | Why |
+|:---|:---|
+| [Home](Home) | Intuitive overview |
+| [Reference — Contracts](Reference-Contracts) | Topic + config + child filters |
+| [Reference — Architecture](Reference-Architecture) | Code map, reactor ↔ settler wiring, mass-balance math |
+| [Reference — Limitations](Reference-Limitations) | Known issues and open questions |
+| [reactor — Examples](https://gitea.wbd-rd.nl/RnD/reactor/wiki/Reference-Examples) | The upstream parent — how to drive `stateChange` |
+| [EVOLV — Topology Patterns](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Topology-Patterns) | Where settler fits in a larger plant |
diff --git a/wiki/Reference-Limitations.md b/wiki/Reference-Limitations.md
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+++ b/wiki/Reference-Limitations.md
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+# Reference — Limitations
+
+
+
+> [!NOTE]
+> Pending full node review (2026-05). What `settler` does not do, current rough edges, and open questions. Open items live in `.agents/improvements/IMPROVEMENTS_BACKLOG.md` in the superproject.
+
+---
+
+## When you would not use this node
+
+| Scenario | Use instead |
+|:---|:---|
+| Primary sedimentation upstream of biological treatment | The species 7–12 zeroing in the effluent stream is wrong for primary sludge (the soluble / particulate split is different). Model as a separate node. |
+| Generic mass-balance transform | The 13-species ASM3 concentration vector is hard-coded; `Cs[12]` (`X_TS`) is the only species the split is keyed off. Not a fit for arbitrary stream-splitting. |
+| Single-tank SBR with no separation stage | The 3-stream output expects a downstream consumer that routes by `payload.inlet`. A direct reactor → reactor wire is lighter. |
+| A reactor — you want to model biological transformation, not separation | `reactor` (settler is a passive separator, not a biological process). |
+| A return-pump itself — you want to model the pump's behaviour | `rotatingMachine` (settler reads the pump's measured flow but does not control it). |
+
+---
+
+## Known limitations
+
+### Example flows are stub level
+
+The three shipped flows (`basic.flow.json`, `integration.flow.json`, `edge.flow.json`) are 4-node skeletons (tab + node + inject + debug). They prove the node loads in Node-RED but do not exercise the reactor → settler → pump chain, do not drive `data.influent` with a valid payload, and do not have a dashboard tier. Production-grade examples are TODO — see [Reference — Examples — TODO](Reference-Examples#todo--production-grade-example-set).
+
+### Editor colour drift
+
+`settler.html` declares `color: '#e4a363'` (orange). The S88 Unit level requires `#50a8d9` (blue). The placement-rule registry (`.claude/rules/node-red-flow-layout.md` §14) already maps `settler` to the `UN` lane regardless of editor colour, so demos lay out correctly; the cosmetic mismatch is tracked in §16 of the same rule and is on the colour-cleanup list. The wiki diagrams use the correct blue.
+
+### Single-reactor upstream slot
+
+`this.upstreamReactor` is a single slot. Registering a second `reactor` child with `positionVsParent='upstream'` silently overwrites the first — the listener on the previous reactor's `emitter` is not detached, so it keeps firing into a settler that will pull effluent from the new reactor instead. Tracked.
+
+### `X_TS` index is hard-coded
+
+The mass balance uses `Cs_in[12]` (the ASM3 `X_TS` lumped solids species) as the surrogate for total suspended solids. Any change to the species ordering in the upstream reactor breaks settler. The coupling is not documented in the schema — it lives only in the `getEffluent` math and the `_updateMeasurement` switch case for `quantity (tss)`. Tracked.
+
+### No flow-balance warning
+
+When influent solids exceed the target return concentration (`Cs_in[12] > C_TS`), `F_s` is clamped to `F_in` and clarified effluent drops to zero. This is mathematically correct but masks an upstream problem (overloaded reactor, miscalibrated `C_TS` setpoint). The clamp fires silently — no warn, no badge change beyond the eventual `F_in <= 0` idle state. Operator must monitor `F_eff` directly. Tracked.
+
+### `quantity (tss)` measurement passes through but doesn't validate
+
+`_connectMeasurement` re-emits every measurement type, but `_updateMeasurement` only acts on `quantity (tss)`. Other types log an `error` (`Type '' not recognized for measured update.`) but the re-emit already happened — the parent of settler still sees the value. Whether this is desired (settler acts as telemetry pass-through) or a contract gap is unresolved.
+
+> [!NOTE]
+> Pending full node review (2026-05). Open question: should `_connectMeasurement` filter by asset-type at register time and reject non-`quantity (tss)` children, or continue accepting everything as pass-through telemetry?
+
+### No output manifest / no degraded-state coverage
+
+Per the platform output-coverage rule (`.claude/rules/output-coverage.md`), every node needs a `test/_output-manifest.md` enumerating every Port 0 / 1 / 2 key and a `test/basic/output-*.test.js` exercising each one in both populated **and** degraded states. Settler has neither. The most likely degraded-state crash points:
+
+- Port 0 emitted before any reactor `stateChange` — `F_in = 0`, `Cs_in = [0...]`, the three envelopes carry zero flow but valid (zero) `C` arrays. Should not crash a downstream consumer, but un-tested.
+- Port 0 with `returnPump` registered but no flow measurement landed yet — `returnPump.measurements.type('flow').variant('measured').position('atEquipment').getCurrentValue()` returns `undefined` → `Math.min(undefined, F_s) = NaN`. `F_sr` becomes `NaN` → both `inlet=1` and `inlet=2` carry `NaN` flow.
+
+Tracked. TODO before trial-readiness: add the manifest, tests, and `null`-flow-measurement handling.
+
+### `reactor.getEffluent` shape coupling
+
+`_connectReactor` does `Array.isArray(raw) ? raw[0] : raw` to absorb both the older single-envelope shape and the newer 3-stream array shape of `reactor.getEffluent`. The 2026-03-02 fix is the only thing keeping the older shape alive in production. If `reactor.getEffluent` ever returns a 3-stream array and settler should consume `inlet=0` specifically, the current `raw[0]` selector works by accident — it picks the first envelope regardless of inlet number. Open question whether to make the selection inlet-aware.
+
+### Stateful telemetry — no decay / no TTL
+
+The MeasurementContainer holds the last-known value of every re-emitted measurement forever. If a child stops publishing, the stale value persists on Port 1 indefinitely. There is no TTL, no `data.clear-measurement` topic, and no health flag like `rotatingMachine`'s `predictionQuality`. Open question.
+
+---
+
+## Open questions (tracked)
+
+| Question | Where it lives |
+|:---|:---|
+| Filter `_connectMeasurement` by asset-type at register time? | Internal — not yet ticketed |
+| Multi-reactor upstream support — teardown ordering, listener detach | Internal |
+| Flow-balance warning when `F_s` clamp fires | Internal |
+| Inlet-aware selection in `_connectReactor` shape handling | Internal |
+| Measurement TTL / staleness flag | Internal |
+| Production-grade example flows (Tier 1 / 2 / 3) | `.agents/improvements/IMPROVEMENTS_BACKLOG.md` |
+| Output manifest + degraded-state tests | `.claude/rules/output-coverage.md` (platform-wide rule) |
+| Editor colour cleanup (`#e4a363` → `#50a8d9`) | `.claude/rules/node-red-flow-layout.md` §16 |
+
+---
+
+## Migration notes
+
+> [!NOTE]
+> Pending full node review (2026-05). No structural migrations have been performed on settler since the AssetResolver refactor of rotatingMachine; the notes below document the one historical fix on record.
+
+### From pre-2026-03-02 `_connectReactor`
+
+Before 2026-03-02 `_connectReactor` assumed `reactor.getEffluent` always returned an array, and indexed `[0]` unconditionally. After the reactor refactor, `getEffluent` returns a single envelope — pre-fix settler would crash with `Cannot read properties of undefined (reading 'payload')`. The fix:
+
+```js
+const raw = this.upstreamReactor.getEffluent;
+const effluent = Array.isArray(raw) ? raw[0] : raw;
+```
+
+If you maintain a fork of settler from before that date, port this guard.
+
+### From topic-aliased payloads
+
+Both `influent` and `setInfluent` are accepted as aliases for `data.influent`. A one-time deprecation warning fires the first time each alias is seen. Tracked for removal; use the canonical `data.influent` in new flows.
+
+---
+
+## Related pages
+
+| Page | Why |
+|:---|:---|
+| [Home](Home) | Intuitive overview |
+| [Reference — Contracts](Reference-Contracts) | Topic + config + child filters |
+| [Reference — Architecture](Reference-Architecture) | Code map, reactor ↔ settler wiring, mass-balance math |
+| [Reference — Examples](Reference-Examples) | Shipped flows + the TODO list for production-grade demos |
+| [reactor — Limitations](https://gitea.wbd-rd.nl/RnD/reactor/wiki/Reference-Limitations) | The upstream parent — effluent shape contract |
+| [EVOLV — output-coverage rule](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/development/.claude/rules/output-coverage.md) | Platform-wide output-coverage requirement |
diff --git a/wiki/_Sidebar.md b/wiki/_Sidebar.md
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+++ b/wiki/_Sidebar.md
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+### settler
+
+- [Home](Home)
+
+**Reference**
+
+- [Contracts](Reference-Contracts)
+- [Architecture](Reference-Architecture)
+- [Examples](Reference-Examples)
+- [Limitations](Reference-Limitations)
+
+**Related**
+
+- [EVOLV master wiki](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Home)
+- [reactor wiki](https://gitea.wbd-rd.nl/RnD/reactor/wiki/Home)
+- [rotatingMachine wiki](https://gitea.wbd-rd.nl/RnD/rotatingMachine/wiki/Home)
+- [Topology Patterns](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Topology-Patterns)
+- [Topic Conventions](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Topic-Conventions)
+- [Telemetry](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Telemetry)