Post-route timing feedback with RustSTA 0.3

The dual-PDK route/extract/timing harness now requires wire_model=spef_rc and delay_calculator=nldm_ceff_ramp. It checks the finite-ramp driver/effective load/slew model, with explicit propagated clocks, rather than the earlier first-moment-only timing scope. The OpenSTA endpoint tolerance stays 0.001 ns.

A fresh run re-synthesizes the pipeline RTL, checks CEC and 512 simulation vectors, imports and places real cells, builds CTS, routes all signals, exports DEF and mapped Verilog, and invokes the pinned external extractor with actual PDK rules. Original GDS/DEF geometry, supply/tap connectivity, clock skew and negative controls remain in the acceptance flow. Both full timing recomputation and no-op update consistency are checked; the latter is not a changed-ECO test. RustSTA separately validates real cell replacement/restoration on each library with fixed RC topology, independent transient circuits and CPU/CUDA propagation.

python3 scripts/verify_routing.py --workspace work/postroute --base-rev empty \
  --rusteda /path/to/rusteda-0.3 --ruststa /path/to/ruststa-0.3

Use the local pinned PDK profile and the usual process memory/time guards. The new top-level timing_accuracy_status separates endpoint parity from the existing functional_status and overall result. An absent tool never passes.

The flow remains partial while any hold or parity gate fails, even when the accuracy gates and the functional chain pass; no violation is clipped or hidden. A physical optimization must re-route and re-extract before the checks run again.

Scope: TT/f64, factor-one grounded coupling, primary propagated clocks and CPPR off; 19 signal nets, 46 terminals and eight timing endpoints per PDK. This fixture is not industrial-scale throughput evidence. Complete DRC/LVS and full RTL-to-GDS signoff remain unverified; the current native routing/geometry checks cover an explicit subset. Reference programs are black-box executables; no reference implementation source is read, compared or translated.