test(mgc): cover fn_status_split output 17 (% of capacity); fix stale 17→18 count

The dashboard fan-out grew to 18 outputs (output 17 = '% of capacity' chart)
but dashboard-fanout.integration.test.js still asserted 17 and had no PORT
entry or coverage for output 17. Add chart_pctcap (17) with populated (State C,
flow/capMax×100) and degraded (State A → null-drop) assertions, fix the count
assertion, and add the fan-out enumeration table to _output-manifest.md per
.claude/rules/output-coverage.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/_output-manifest.md

@@ -112,6 +112,33 @@ Documented in `CONTRACT.md`; tested indirectly via `group-bep-cascade.integratio
 
 ---
 
+## Example flow fan-out — `examples/02-Dashboard.json :: fn_status_split` (outputs: 18)
+
+Delta-caches Port 0 then fans one msg per dashboard widget. Charts return the
+whole msg as `null` (drop the output) when their source is missing — never
+`{ payload: null }`. All ports covered by `test/integration/dashboard-fanout.integration.test.js`.
+
+| # | Target widget | Topic / payload | Populated | Degraded (missing source) |
+|---|---|---|---|---|
+| 0 | ui_txt_mode | string | ✔ State C | ✔ State A → mode string |
+| 1 | ui_txt_flow | `'… m³/h'` | ✔ | ✔ State A → `—` |
+| 2 | ui_txt_power | `'… kW'` | ✔ | ✔ → `—` |
+| 3 | ui_txt_capacity | `'min – max m³/h'` | ✔ State B | ✔ → `—` |
+| 4 | ui_txt_machines | `'nAct / nTot'` | ✔ | ✔ → `—` |
+| 5 | ui_txt_bep (rel%) | `'… %'` | ✔ | ✔ null/undefined → `—` |
+| 6 | ui_txt_eta | `'… %'` | ✔ | ✔ → `—` |
+| 7 | ui_txt_eta_peak | `'… %'` | ✔ | ✔ → `—` |
+| 8 | ui_txt_bep_abs | `'…'` (η pts, 3dp) | ✔ | ✔ → `—` |
+| 9 | ui_txt_ncog | `'… %'` (sum/nAct) | ✔ | ✔ nAct=0/missing → `—` |
+| 10 | ui_chart_flow | `{topic:'Flow', payload:number}` | ✔ | ✔ → null (drop) |
+| 11 | ui_chart_flow (capacity) | `{topic:'Capacity', …}` | ✔ | ✔ → null |
+| 12 | ui_chart_power | `{topic:'Power', …}` | ✔ | ✔ → null |
+| 13 | ui_chart_bep | `{topic:'BEP rel %', ×100}` | ✔ | ✔ → null |
+| 14 | ui_chart_eta | `{topic:'η (%)', ×100}` | ✔ | ✔ → null |
+| 15 | ui_tpl_raw | `[{key,value}]` rows | ✔ | ✔ |
+| 16 | ui_chart_qh (passthrough) | raw `msg.payload` | ✔ | ✔ |
+| 17 | ui_chart_mgc_pctcap | `{topic:'% of capacity', payload:flow/capMax×100}` | ✔ State C | ✔ State A → null (drop) |
+
 ## Coverage gaps (open items)
 
 These are known holes flagged during the 2026-05-14 governance review; not yet

test/integration/dashboard-fanout.integration.test.js

@@ -22,7 +22,7 @@ function runFn(msgs) {
   return msgs.map(msg => fn_body(msg, context));
 }
 
-// Indices into the 17-output return array. Kept here as the manifest contract
+// Indices into the 18-output return array. Kept here as the manifest contract
 // for this function — every test below references these names, never raw ints.
 const PORT = {
   text_mode: 0, text_flow: 1, text_power: 2, text_capacity: 3,
@@ -31,6 +31,7 @@ const PORT = {
   chart_flow: 10, chart_capacity: 11, chart_power: 12, chart_bep_rel: 13,
   chart_eta: 14,
   raw_rows: 15, raw_passthrough: 16,
+  chart_pctcap: 17,
 };
 
 const initialMsg = {
@@ -64,9 +65,9 @@ const postDemandMsg = {
   },
 };
 
-test('manifest: function has exactly 17 outputs and wires array matches', () => {
+test('manifest: function has exactly 18 outputs and wires array matches', () => {
-  assert.equal(fn.outputs, 17);
+  assert.equal(fn.outputs, 18);
-  assert.equal(fn.wires.length, 17);
+  assert.equal(fn.wires.length, 18);
 });
 
 test('State A (deploy-time): no AT_EQUIPMENT keys → flow/power text show em-dash', () => {
@@ -113,6 +114,16 @@ test('State C (post-demand): every text/chart output has real value', () => {
   assert.equal(out[PORT.chart_flow].payload, 200);
   assert.equal(out[PORT.chart_power].payload, 11.4);
   assert.equal(out[PORT.chart_eta].payload, 62);
+  // % of capacity = flow / flowCapacityMax × 100 = 200 / 450 × 100 ≈ 44.44.
+  assert.equal(out[PORT.chart_pctcap].topic, '% of capacity');
+  assert.ok(Math.abs(out[PORT.chart_pctcap].payload - (200 / 450) * 100) < 1e-6);
+});
+
+test('% of capacity chart: drops msg when flow or capacity missing (no payload:null)', () => {
+  // State A: no flow + flowCapacityMax=0 → pctCap undefined → chart() returns
+  // null so the function node skips the output, never { payload: null }.
+  const [out] = runFn([initialMsg]);
+  assert.equal(out[PORT.chart_pctcap], null, 'chart_pctcap must drop msg when source missing');
 });
 
 test('NCog formatter: SUM is normalized by machineCountActive before display', () => {