Dane Sabo 44cc193829 app: Pluto.jl predicate explorer v1 (read-only)

The hybrid-systems-group tab for FRET, as a stand-alone Pluto
notebook. Reads reachability/predicates.json and renders:

  - Plant-derived constants (T_c0, T_standby, etc.)
  - All operational deadbands with concretization
  - All safety limits as one-sided halfspaces with meanings
  - Mode invariants (inv1_holds, inv2_holds) as conjunctions
  - Per-mode entry/safe/exit/time tables
  - 2D projection of operating polytope (T_avg x n)
  - Reach-traceability table — what's covered, by which artifact
  - Edit-UX preview with sliders that don't actually write back

Run with:
  cd app
  julia --project=. -e 'using Pkg; Pkg.instantiate()'   # first time
  julia --project=. -e 'using Pluto; Pluto.run()'

V2 will add write-back to predicates.json. V3 (the dream) is FRET-spec
driven derivation of halfspaces from a structured vocabulary of
physical bounds.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-04-20 21:48:08 -04:00

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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.json with 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.json declares 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.

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