slice-4½: rutster-sim seed + CI-regressed thresholds (S1-S8) (#18)

Co-authored-by: Aaron D. Lee <himself@adlee.work>
Co-committed-by: Aaron D. Lee <himself@adlee.work>

.github/workflows/ci.yml

@@ -87,6 +87,33 @@ jobs:
         with:
           command: check
 
+  # slice-4½ (ADR-0010): the CI-regressed threshold sweep. Default-off
+  # `sim-bench` feature; runs `cargo test --all --features=sim-bench`
+  # in a SEPARATE job per PR + nightly. A latency regression fails the
+  # build the same way a broken test does. `--test-threads=1` is
+  # load-bearing: concurrent sim-bench tests would contaminate each
+  # other's shared gauge (the TickLagStats reads the SHARED tokio
+  # runtime; concurrent sweeps across tests would all pollute the same
+  # gauge). See crates/rutster-sim/src/thresholds.rs's
+  # `bench_assertions` module docs + spec §5.4 + §6.5.
+  sim-bench:
+    name: sim-bench (stable)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - name: Install libopus (media crate FFI dep)
+        run: apt-get update && apt-get install -y libopus-dev
+      - uses: Swatinem/rust-cache@v2
+      - name: cargo fmt + clippy on sim-bench feature paths
+        run: |
+          cargo fmt --all --check
+          cargo clippy --all --all-targets --features=sim-bench -- -D warnings
+      - name: Run sim-bench threshold sweep
+        run: cargo test --all --features=sim-bench -- --test-threads=1
+
   # The live TwilioCallControlClient is feature-gated behind `twilio-live`
   # (reqwest + rustls-tls + tracing + serde_json pulled in only when the
   # feature is on). This job exercises it against REAL Twilio credentials.