etcd-io · Qian-Cheng-nju · Feb 3, 2026 · Feb 4, 2026
diff --git a/tla/extended_spec/harness/README.md b/tla/extended_spec/harness/README.md
@@ -0,0 +1,71 @@
+# Trace Validation Harness
+
+This harness generates execution traces from raft's datadriven test scenarios and validates them against the TLA+ specification.
+
+## Prerequisites
+
+- Go 1.23+
+- Java (for TLC model checker)
+- TLA+ tools: [tla2tools.jar](https://nightly.tlapl.us/dist/tla2tools.jar) and [CommunityModules-deps.jar](https://github.com/tlaplus/CommunityModules/releases/latest/download/CommunityModules-deps.jar)
+
+## Step 1: Apply Instrumentation Patch
+
+The patch adds trace logging hooks to the raft library, guarded by the `with_tla` build tag (zero overhead in production builds).
+
+```bash
+cd /path/to/raft
+git apply tla/extended_spec/harness/patch/instrumentation.patch
+```
+
+## Step 2: Generate Traces
+
+```bash
+cd tla/extended_spec/harness
+go build -tags=with_tla -o harness .
+
+# Run a single scenario
+./harness -scenario basic_election
+
+# Run all scenarios
+./harness -set all
+
+# List available scenarios
+./harness -list
+```
+
+Traces are written to `traces/<scenario>.ndjson`.
+
+## Step 3: Validate Traces Against TLA+ Spec
+
+Validate a single trace:
+
+```bash
+env JSON=traces/basic_election.ndjson \
+  java -XX:+UseParallelGC \
+    -cp tla2tools.jar:CommunityModules-deps.jar \
+    tlc2.TLC -config ../Traceetcdraft.cfg ../Traceetcdraft.tla \
+    -lncheck final
+```
+
+A successful validation ends with `Model checking completed. No error has been found.`
+
+Validate all traces in batch using `validate.sh`:
+
+```bash
+./validate.sh \
+  -s ../Traceetcdraft.tla \
+  -c ../Traceetcdraft.cfg \
+  traces/*.ndjson
+```
+
+`validate.sh` runs TLC in parallel (one process per trace) and reports PASS/FAIL for each trace. Usage:
+
+```
+validate.sh [-p <parallel>] -s <spec> -c <config> <trace files>
+```
+
+- `-s` — path to `Traceetcdraft.tla`
+- `-c` — path to `Traceetcdraft.cfg`
+- `-p` — number of parallel workers (default: `nproc`)
+
+The script downloads `tla2tools.jar` and `CommunityModules-deps.jar` automatically if not found in `$TOOLDIR`.
diff --git a/tla/extended_spec/harness/go.mod b/tla/extended_spec/harness/go.mod
@@ -0,0 +1,20 @@
+module specula-harness
+
+go 1.23
+
+require (
+	github.com/cockroachdb/datadriven v1.0.2
+	go.etcd.io/raft/v3 v3.0.0-00010101000000-000000000000
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/protobuf v1.5.4 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.11.1 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
+
+replace go.etcd.io/raft/v3 => ../raft
diff --git a/tla/extended_spec/harness/go.sum b/tla/extended_spec/harness/go.sum
@@ -0,0 +1,49 @@
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