feat(engine): session timeline correlation + close out S1

CURRENT_STATE.md

@@ -8,8 +8,8 @@
 
 ## Active milestone
 
-**S1 — Engine core (0.1.0): in progress.** S0 — Foundation is complete (see
-[ROADMAP.md](ROADMAP.md)).
+**S1 — Engine core (0.1.0): complete.** Next up: **S2 — Detection + conformance**
+(see [ROADMAP.md](ROADMAP.md)).
 
 ## What's done
 
@@ -32,24 +32,30 @@
 
 **Exit criteria met:** CI green on macOS + Linux; `native doctor --strict` clean.
 
+### S1 — Engine core ✅
+
+The pure-Zig, headless OCPP engine under `src/ocpp/`, mirroring the toolkit's
+conformance contract (behavior, not source) and tested via
+`native test -Dplatform=null`:
+
+- **Types & value boundary** (#11) — canonical `Event` / `Session` / trace /
+  parse-result types, the `Direction` / `MessageType` / `Status` enums, and the
+  `std.json.Value` payload boundary (ADR-0005).
+- **Event normalizer** (#12) — message classification, ISO 8601 / epoch
+  timestamp normalization, and two-pass direction inference.
+- **Trace parser** (#13) — JSON object / JSONL / bare-array formats, structural
+  validation, per-entry warnings, and untrusted-input limits (10 MB, 10 000
+  events), into a caller-owned arena.
+- **Session timeline** (#14) — transactionId correlation, connector / time-based
+  distribution of un-keyed events, and session status.
+
+**Exit criteria met:** the vendored `normal-session` fixture parses and
+correlates end to end (one completed session, transactionId 100001); engine
+tests green headlessly on macOS + Linux.
+
 ## What's in progress
 
-**S1 — Engine core (0.1.0).** Building the pure-Zig engine module by module:
-
-- **Engine types & value boundary** (#11) — the `src/ocpp/` foundation: canonical
-  `Event` / `Session` / trace / parse-result types, the `Direction` /
-  `MessageType` / `Status` enums, and the `std.json.Value` payload boundary
-  (ADR-0005). Headless, imports no UI/runtime modules, tested via
-  `native test -Dplatform=null`.
-- **Event normalizer** (#12) — message classification, ISO 8601 / epoch-second /
-  epoch-millisecond timestamp normalization, and two-pass direction inference
-  (the CS↔CSMS action tables), producing canonical `Event`s. The toolkit's
-  normalizer test cases are ported.
-- **Trace parser** (#13) — JSON object / JSONL / bare-array formats with format
-  detection, structural validation, per-entry warnings for malformed data, and
-  the untrusted-input limits (10 MB input, 10 000 events). Parses into a
-  caller-owned arena. The toolkit's parser test cases are ported.
-- Next: session timeline (#14).
+- Nothing in flight — S1 is closed; S2 is next.
 
 ## What's next
 
@@ -67,7 +73,7 @@ checks Studio's detected failures against locked goldens.
 | --- | --- |
 | `repo` (tooling, CI) | ✅ done for S0 |
 | `docs` (docs, ADRs) | ✅ done for S0 |
-| `ocpp` (engine) | 🚧 in progress (S1) |
+| `ocpp` (engine) | ✅ done for S1 |
 | `ui` (native views) | ⬜ placeholder (S3) |
 | `capture` (live proxy) | ⬜ not started (S5) |
 | `cli` (headless) | ⬜ not started (S4) |

ROADMAP.md

@@ -9,8 +9,8 @@ the stable part.
 | Milestone | Version | Theme | Status |
 | --- | --- | --- | --- |
 | **S0** | 0.0.x | Foundation | ✅ Complete |
-| **S1** | 0.1.0 | Engine core | Next up |
-| **S2** | 0.1.0 | Detection + conformance | Planned |
+| **S1** | 0.1.0 | Engine core | ✅ Complete |
+| **S2** | 0.1.0 | Detection + conformance | Next up |
 | **S3** | 0.2.0 | Inspector UI | Planned |
 | **S4** | 0.3.0 | Analysis parity+ | Planned |
 | **S5** | 0.4.0 | Live capture ⭐ | Planned |
@@ -22,12 +22,15 @@ Repo, tooling, and CI. A native window that opens, an automation-driven smoke
 test, founding docs, and architecture decision records. **Exit criteria met:**
 CI green on macOS + Linux; `native doctor --strict` clean.
 
-## S1 — Engine core (0.1.0)
+## S1 — Engine core (0.1.0) ✅
 
 The pure-Zig OCPP engine, headless and testable: canonical `Event` / `Session`
-/ `Failure` types, a parser for the three input formats (JSON object, JSONL,
-bare array), the normalizer (message-direction inference and timestamp
-normalization), and session correlation by transaction id.
+types and the `std.json.Value` value boundary (ADR-0005), a parser for the three
+input formats (JSON object, JSONL, bare array) with untrusted-input limits, the
+normalizer (message classification, timestamp normalization, and direction
+inference), and session correlation by transaction id. **Exit criteria met:** the
+vendored `normal-session` fixture parses and correlates end to end; engine tests
+run green headlessly (`native test -Dplatform=null`) on macOS + Linux.
 
 ## S2 — Detection + conformance (0.1.0)
 

src/ocpp/ocpp.zig

@@ -7,9 +7,11 @@
 pub const types = @import("types.zig");
 pub const normalizer = @import("normalizer.zig");
 pub const parser = @import("parser.zig");
+pub const timeline = @import("timeline.zig");
 
 test {
     _ = types;
     _ = normalizer;
     _ = parser;
+    _ = timeline;
 }

src/ocpp/testdata/normal-session.json

@@ -0,0 +1,33 @@
+{
+  "traceId": "fixture-normal-session",
+  "metadata": {
+    "stationId": "CS-SYNTHETIC-001",
+    "ocppVersion": "1.6",
+    "source": "synthetic-fixture",
+    "description": "Normal charging session: boot -> authorize -> start transaction -> meter values -> stop transaction. No failures expected."
+  },
+  "events": [
+    { "timestamp": "2024-01-15T10:00:00.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-001", "BootNotification", { "chargePointVendor": "SyntheticVendor", "chargePointModel": "SM-100", "chargePointSerialNumber": "CS-SYNTHETIC-001", "firmwareVersion": "1.0.0" }] },
+    { "timestamp": "2024-01-15T10:00:00.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-001", { "currentTime": "2024-01-15T10:00:00.500Z", "interval": 300, "status": "Accepted" }] },
+    { "timestamp": "2024-01-15T10:01:00.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-002", "StatusNotification", { "connectorId": 0, "status": "Available", "errorCode": "NoError" }] },
+    { "timestamp": "2024-01-15T10:01:00.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-002", {}] },
+    { "timestamp": "2024-01-15T10:02:00.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-003", "StatusNotification", { "connectorId": 1, "status": "Preparing", "errorCode": "NoError" }] },
+    { "timestamp": "2024-01-15T10:02:00.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-003", {}] },
+    { "timestamp": "2024-01-15T10:02:15.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-004", "Authorize", { "idTag": "SYNTHETIC-TAG-001" }] },
+    { "timestamp": "2024-01-15T10:02:15.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-004", { "idTagInfo": { "status": "Accepted", "expiryDate": "2024-12-31T23:59:59.000Z", "parentIdTag": "SYNTHETIC-PARENT-001" } }] },
+    { "timestamp": "2024-01-15T10:02:30.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-005", "StartTransaction", { "connectorId": 1, "idTag": "SYNTHETIC-TAG-001", "meterStart": 0, "timestamp": "2024-01-15T10:02:30.000Z" }] },
+    { "timestamp": "2024-01-15T10:02:30.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-005", { "transactionId": 100001, "idTagInfo": { "status": "Accepted" } }] },
+    { "timestamp": "2024-01-15T10:02:31.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-006", "StatusNotification", { "connectorId": 1, "status": "Charging", "errorCode": "NoError" }] },
+    { "timestamp": "2024-01-15T10:02:31.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-006", {}] },
+    { "timestamp": "2024-01-15T10:07:30.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-hb-1", "Heartbeat", {}] },
+    { "timestamp": "2024-01-15T10:07:30.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-hb-1", { "currentTime": "2024-01-15T10:07:30.500Z" }] },
+    { "timestamp": "2024-01-15T10:15:00.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-007", "MeterValues", { "connectorId": 1, "transactionId": 100001, "meterValue": [{ "timestamp": "2024-01-15T10:15:00.000Z", "sampledValue": [{ "value": "5000", "measurand": "Energy.Active.Import.Register", "unit": "Wh" }] }] }] },
+    { "timestamp": "2024-01-15T10:15:00.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-007", {}] },
+    { "timestamp": "2024-01-15T10:30:00.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-008", "MeterValues", { "connectorId": 1, "transactionId": 100001, "meterValue": [{ "timestamp": "2024-01-15T10:30:00.000Z", "sampledValue": [{ "value": "10000", "measurand": "Energy.Active.Import.Register", "unit": "Wh" }] }] }] },
+    { "timestamp": "2024-01-15T10:30:00.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-008", {}] },
+    { "timestamp": "2024-01-15T10:35:00.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-009", "StopTransaction", { "transactionId": 100001, "idTag": "SYNTHETIC-TAG-001", "meterStop": 10000, "timestamp": "2024-01-15T10:35:00.000Z", "reason": "EVDisconnected" }] },
+    { "timestamp": "2024-01-15T10:35:00.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-009", { "idTagInfo": { "status": "Accepted" } }] },
+    { "timestamp": "2024-01-15T10:35:01.000Z", "direction": "CS_TO_CSMS", "message": [2, "msg-010", "StatusNotification", { "connectorId": 1, "status": "Available", "errorCode": "NoError" }] },
+    { "timestamp": "2024-01-15T10:35:01.500Z", "direction": "CSMS_TO_CS", "message": [3, "msg-010", {}] }
+  ]
+}