c5133401e0
Multi-session work bundle on a draft branch. Splits into a clean
sequence of commits later; pushed here so it isn't lost on a reboot.
Reach work
- code/scripts/reach/reach_scram_pj.jl: shutdown_margin halfspace
X_exit (replaces "n <= 1e-4 AND T_f bound" framing); per-step
envelope extraction added.
- code/scripts/reach/reach_scram_pj_fat.jl: per-step envelope
extraction added; shutdown_margin discharge logic mirrored from the
tight scram script. 3 probes (10/30/60s) all discharge from the
fat union polytope.
- code/scripts/reach/reach_scram_full_fat.jl (NEW): full nonlinear
PKE scram reach with fat entry. Hits the stiffness wall at
~1.5 s plant time as expected; saves NaN-tolerant per-step
envelopes. Demonstrates concretely why PJ is the right tool for
the longer-horizon proof.
- code/scripts/reach/reach_heatup_pj.jl: T_REF_START_C constant
(entry-conditioned ramp) replaces T_STANDBY-init that was making
the FL controller command cooling at t=0. Per-step extraction
already in place.
- code/configs/heatup/tight.toml: bumped maxsteps; probe horizon
parameterized.
Hot-standby SOS barrier
- code/scripts/barrier/barrier_sos_2d_shutdown.jl (NEW): mirrors the
operation SOS machinery on the hot-standby thermal projection.
Includes the eps-slack pattern (so feasibility doesn't silently
collapse to B == 0).
- code/scripts/barrier/barrier_sos_2d.jl: refactored to use the same
helper.
- code/src/sos_barrier.jl (NEW): solve_sos_barrier_2d helper module
factoring out the SOS construction; eps-slack with eps_cap=1.0 to
avoid unbounded primal.
Library
- code/src/pke_states.jl (NEW): single source of truth for canonical
initial-condition vectors per DRC mode (op, shutdown, heatup) keyed
off plant + predicates.
- code/scripts/sim/{main_mode_sweep,validate_pj}.jl, code/CLAUDE.md:
migrated to pke_states.
Predicates + invariants
- reachability/predicates.json: new shutdown_margin predicate (1%
dk/k tech-spec floor, expressed as alpha_f*T_f + alpha_c*T_c
halfspace). Used as scram X_exit.
Plot script
- code/scripts/plot/plot_reach_tubes.jl: plot_tubes_scram_pj() with
variant=:fat|:tight knob; plot_tubes_scram_full() for full-PKE
3-panel (T_c, T_f, rho); plot_tubes_heatup_pj() reads results/
not reachability/.
Journal + memory
- journal/entries/2026-04-27-shutdown-sos-and-scram-X_exit.tex (NEW):
long-form entry on the SOS hot-standby barrier and the scram X_exit
refactor.
- journal/journal.tex: input chain updated.
- claude_memory/ — three new session notes:
* 2026-04-27-scram-X_exit-shutdown-margin.md
* 2026-04-28-DICE-2026-conference-intel.md (people, sessions,
strategic notes for the May 12 talk)
* 2026-04-28-path1-sos-pj-sketch.md (sketch of nonlinear-SOS via
polynomial multiply-through; saved for an overnight session)
Docs
- docs/model_cheatsheet.md (NEW): one-page reference of state vector,
dynamics, constants, modes, predicates, sanity numbers — the talk
prep cheatsheet Dane asked for.
- docs/figures/reach_*_tubes.png: regenerated with the new mat data.
- presentations/prelim-presentation/outline.md: revised arc per the
April-28 review pass (cuts: Lyapunov-fails standalone slide,
operation-tube standalone slide, SOS standalone; adds: scopes-of-
control framing, scram on the headline result slide).
- app/predicate_explorer.jl: minor.
Hacker-Split: end-of-session scratch bundle
app — Predicate Explorer (Pluto.jl)
A local-server visual companion to reachability/predicates.json. Maps
the FRET-spec boolean predicates to their numerical halfspaces over the
10-state continuous vector, shows mode invariants as conjunctions of
named safety limits, and previews a UI for editing them.
v1: read-only. Sliders display in the edit panel but do not write back to the JSON. v2 will add live write-through. v3 (the dream) will derive halfspaces automatically from the FRET spec.
This is the FRET-adjacent piece — the "hybrid-systems group tab" we talked about. Stand-alone for now; integration into the upstream FRET UI is a later story.
Run
First time:
cd app
julia --project=. -e 'using Pkg; Pkg.instantiate()'
Subsequent:
julia --project=. -e 'using Pluto; Pluto.run()'
A browser window opens (default http://localhost:1234). Pick
predicate_explorer.jl from the file list. The notebook is reactive —
edit any cell, dependent cells re-run.
What you can do today (v1)
- Inspect every operational deadband, safety limit, mode invariant, and mode boundary.
- See the boolean ↔ continuous mapping for each predicate.
- View a 2D projection (T_avg × n) showing the operating polytope.
- Read the reach-status traceability table — which artifact has tried to discharge which obligation, with link.
- Move sliders to feel out the editing workflow.
What lands in v2
- Sliders write back to
predicates.jsonwith an "are you sure" gate. - Diff view: pending changes vs.\ the on-disk version.
- Re-run reach scripts in-place from the notebook.
What's the dream (v3)
- The FRET spec at
../fret-pipeline/pwr_hybrid_3.jsondeclares predicate names without numerical concretization. Could we use a structured ontology of physical bounds (fuel limits, trip setpoints, rate limits) plus the FRET text to derive the concretization? - Round-tripping changes back into the FRET model so the synthesis side stays consistent.
Caveats
- Pluto notebooks aren't great in version control — they're long files with cell UUIDs and order metadata. The notebook is committed because it's small and the cell order matters.
- Manifest.toml is gitignored; regenerate locally.