fix(core): track STATUS_TRANSITION_VIOLATION status per connector

The rule validated connector status transitions against a single previous
status shared across all connectors, so on a multi-connector station an
interleaved notification from a different connector (connector 1 going
Available while connector 2 goes Finishing) was reported as an invalid
transition.

Status is now tracked per connectorId (connectorId 0, the charge point as a
whole, forms its own series), and each transition is validated only within
one connector's series. Genuine per-connector violations are still detected,
so the scenario corpus and conformance contract are unchanged. Adds three
regression tests.

Reported by shiv3 from the ocpp-cp-simulator integration.

Author: sepehr-safari

.changeset/fix-status-transition-per-connector.md

@@ -0,0 +1,5 @@
+---
+'@ocpp-debugkit/toolkit': patch
+---
+
+Fix `STATUS_TRANSITION_VIOLATION` false positives (#128). The rule validated connector status transitions against a single previous status shared across all connectors, so on a multi-connector station an interleaved notification from a different connector (for example connector 1 going `Available` while connector 2 goes `Finishing`) was reported as an invalid transition. Status is now tracked per `connectorId` (connectorId 0, the charge point as a whole, forms its own series), and each transition is validated only within one connector's series. Reported by shiv3 from the ocpp-cp-simulator integration.

CURRENT_STATE.md

@@ -4,20 +4,21 @@
 
 ## Current Version
 
-`0.4.0`, Open OCPP Trace Interop (published 2026-07-17). A `0.4.1` patch is in
-progress (METER_VALUE_ANOMALY false-positive fix, #127).
+`0.4.1`, METER_VALUE_ANOMALY fix (published 2026-07-22). A `0.4.2` patch is in
+progress (STATUS_TRANSITION_VIOLATION per-connector fix, #128).
 
 ## Active Milestone
 
-**v0.4.1 - detection correctness patch, then v0.5.0 (OCPP 2.0.1)**
+**v0.4.x - detection correctness patches, then v0.5.0 (OCPP 2.0.1)**
 
 v0.4.0 shipped the Open OCPP Trace interop: the toolkit reads and writes the
 shared v1.1 interchange format (input adapter #121, exporter + `convert` CLI
-#122), checked against the specification's conformance fixtures. **0.4.1**
-fixes a false-positive bug shiv3 found from the simulator integration: the
-`METER_VALUE_ANOMALY` rule flattened all measurands and connectors into one
-series (#127). Next milestone is **v0.5.0 (OCPP 2.0.1)**, where the same
-per-connector/EVSE model this fix introduces is required across detection.
+#122), checked against the specification's conformance fixtures. Two
+false-positive bugs shiv3 found from the simulator integration are being
+fixed: `METER_VALUE_ANOMALY` measurand/connector flattening (#127, shipped in
+0.4.1) and `STATUS_TRANSITION_VIOLATION` global status tracking (#128, in
+0.4.2). Next milestone is **v0.5.0 (OCPP 2.0.1)**, where the per-connector /
+EVSE model these fixes introduce is required across detection.
 
 ## What's Done
 
@@ -30,8 +31,16 @@ per-connector/EVSE model this fix introduces is required across detection.
 - ✅ Eliminates false positives on multi-measurand samples and multi-connector
   stations; genuine energy-register anomalies still detected (meter-anomaly
   scenario and conformance contract unchanged); 3 regression tests added
-- Companion issue drafted for the same connector-blindness in
-  `STATUS_TRANSITION_VIOLATION` (rule 8)
+- Sibling connector-blindness in `STATUS_TRANSITION_VIOLATION` fixed under #128
+
+### STATUS_TRANSITION_VIOLATION per-connector fix (0.4.2, Issue #128)
+
+- ✅ Rule 8 now tracks the previous status per `connectorId` (connectorId 0,
+  the whole charge point, forms its own series) and validates transitions only
+  within one connector's series, instead of one global sequence
+- ✅ Eliminates false violations on multi-connector stations; genuine
+  per-connector violations still detected (status-transition-violation scenario
+  and conformance contract unchanged); 3 regression tests added
 
 ### GitHub Infrastructure
 

packages/toolkit/src/core/detection.test.ts

@@ -664,6 +664,46 @@ describe('detectFailures', () => {
       const failures = detectFailures(events, sessions);
       expect(failures.some((f) => f.code === 'STATUS_TRANSITION_VIOLATION')).toBe(false);
     });
+
+    // Regression tests for the per-connector tracking fix (#128).
+    const statusEvent = (id: string, connectorId: number, status: string, ts: number): Event =>
+      makeEvent(id, id, 'Call', 'StatusNotification', { connectorId, status }, ts);
+
+    it('does not flag across connectors when interleaved statuses only look invalid globally (#128)', () => {
+      const events = [
+        statusEvent('e1', 1, 'Charging', 0),
+        statusEvent('e2', 2, 'Available', 500),
+        statusEvent('e3', 1, 'Finishing', 1000),
+      ];
+      const failures = detectFailures(events, buildSessionTimeline(events));
+      expect(failures.some((f) => f.code === 'STATUS_TRANSITION_VIOLATION')).toBe(false);
+    });
+
+    it('still flags a genuine per-connector violation when another connector is interleaved', () => {
+      const events = [
+        statusEvent('e1', 1, 'Available', 0),
+        statusEvent('e2', 2, 'Charging', 500),
+        statusEvent('e3', 1, 'Finishing', 1000),
+      ];
+      const violations = detectFailures(events, buildSessionTimeline(events)).filter(
+        (f) => f.code === 'STATUS_TRANSITION_VIOLATION',
+      );
+      expect(violations).toHaveLength(1);
+      expect(violations[0]?.eventIds).toEqual(['e1', 'e3']);
+    });
+
+    it('tracks connectorId 0 (whole charge point) as its own series', () => {
+      const events = [
+        statusEvent('e1', 0, 'Available', 0),
+        statusEvent('e2', 1, 'Available', 500),
+        statusEvent('e3', 0, 'Finishing', 1000),
+      ];
+      const violations = detectFailures(events, buildSessionTimeline(events)).filter(
+        (f) => f.code === 'STATUS_TRANSITION_VIOLATION',
+      );
+      expect(violations).toHaveLength(1);
+      expect(violations[0]?.eventIds).toEqual(['e1', 'e3']);
+    });
   });
 
   describe('DIAGNOSTICS_FAILURE', () => {

packages/toolkit/src/core/detection.ts

@@ -613,35 +613,42 @@ const VALID_TRANSITIONS: Record<string, Set<string>> = {
 function detectStatusTransitionViolation(events: Event[]): Failure[] {
   const failures: Failure[] = [];
 
-  // Collect all StatusNotification statuses in order
   const statusEvents = events.filter(
     (e) => e.messageType === 'Call' && e.action === 'StatusNotification',
   );
 
-  let prevStatus: string | null = null;
-  let prevEvent: Event | null = null;
+  // Each connector has an independent status machine, so a transition is only
+  // valid or invalid relative to the same connector's previous status. Track
+  // the previous status per connectorId; connectorId 0 refers to the charge
+  // point as a whole (OCPP 1.6) and forms its own series, and a missing
+  // connectorId is bucketed under 'unknown'. Comparing statuses across
+  // connectors (the previous behavior) produced false violations on
+  // multi-connector stations.
+  const previousByConnector = new Map<number | string, { status: string; event: Event }>();
 
   for (const event of statusEvents) {
-    const payload = event.payload as { status?: unknown };
+    const payload = event.payload as { status?: unknown; connectorId?: unknown };
     const status = payload?.status;
 
     if (typeof status !== 'string' || !VALID_CONNECTOR_STATUSES.has(status)) continue;
 
-    if (prevStatus !== null && prevEvent !== null) {
-      const allowed: Set<string> | undefined = VALID_TRANSITIONS[prevStatus];
+    const connectorId = typeof payload?.connectorId === 'number' ? payload.connectorId : 'unknown';
+    const previous = previousByConnector.get(connectorId);
+
+    if (previous) {
+      const allowed: Set<string> | undefined = VALID_TRANSITIONS[previous.status];
       if (allowed && !allowed.has(status)) {
         failures.push({
           code: 'STATUS_TRANSITION_VIOLATION',
-          description: `Connector status transition from "${prevStatus}" to "${status}" is not a valid OCPP 1.6 transition (messageId: ${event.messageId})`,
+          description: `Connector status transition from "${previous.status}" to "${status}" is not a valid OCPP 1.6 transition (messageId: ${event.messageId})`,
           severity: SEVERITY.STATUS_TRANSITION_VIOLATION,
-          eventIds: [prevEvent.id, event.id],
+          eventIds: [previous.event.id, event.id],
           suggestedSteps: SUGGESTED_STEPS.STATUS_TRANSITION_VIOLATION,
         });
       }
     }
 
-    prevStatus = status;
-    prevEvent = event;
+    previousByConnector.set(connectorId, { status, event });
   }
 
   return failures;