Journey 05 — Sessions and live what-if

solvjump sessions list
solvjump sessions show <session_id>
 
# Python what-if (requires calibrated session):
# session.propagate(params={...}, t_end=...)

Reload a calibrated operator — no new fit

-- Act 1 - The situation --
  -> Yesterday you ran a study. In today's review someone asks: 'what if this knob moves a little?' You reload the session — no recalibration. propagate() is Python-only; the CLI is sessions list / show.

-- Act 2 - Inventory --
  -> solvjump sessions list — every session under ~/.solvjump/sessions.
  _section: Sessions (3)
  id: 439c8ae64112...
  tier: calibrated
  model: brusselator_model.py:make_rhs
  id: 74465eb894b3...
  tier: calibrated
  model: brusselator_model.py:make_rhs
  id: 87957655899d...
  tier: calibrated
  model: brusselator_model.py:make_rhs
  -> Using most recent calibrated session: <session_id>
  _section: Model
  model_ref: <product-root>\python\examples\brusselator_model.py:make_rhs
  problem_id: 29c89c6449dd0461
  stiffness_nom: S1
  y0: [1.0, 3.0]
  t_span: [0.0, 10.0]
  parameters: a in [0.8, 1.2], b in [2.5, 3.5]
  _section: Routing
  tier: calibrated
  operator_id: <operator_id>
  calibration: <session-dir>\calibration_receipt.json
  sweep: <session-dir>\sweep_receipt.json

-- Act 3 - The what-if --
  -> Four steps of 0.25 s. Each step prints safety mode (nominal / guard / anchor / srk_fallback) and a micro-verify digit count.
  step: 1/4
  mode: nominal
  sim_time: 0.25 s
  state: [0.9588, 3.0465]
  micro_verify_scd: n/a
  step: 2/4
  mode: nominal
  sim_time: 0.50 s
  state: [0.9160, 3.1053]
  micro_verify_scd: n/a
  step: 3/4
  mode: nominal
  sim_time: 0.75 s
  state: [0.8757, 3.1720]
  micro_verify_scd: n/a
  step: 4/4
  mode: nominal
  sim_time: 1.00 s
  state: [0.8412, 3.2424]
  micro_verify_scd: n/a

-- Act 4 - Answer in the meeting --
  -> At params={'a': 1.0, 'b': 3.2}, state after 1.0 s is [np.float64(0.8411567983241416), np.float64(3.2423550195766753)]. Modes stayed in nominal/guard/anchor — operator still valid for this what-if.

-- Act 5 - After the meeting --
  -> Log the session id. Formal sign-off is Journey 11 golden, not propagate().
  _section: Why run SolvJump here?
  log: Answer live what-if questions in a review without recalibrating — reuse yesterday's operator from a saved session.
  log: Each propagate step shows safety mode and accuracy check so you can explain the answer, not just quote a number.
  log: Turn a hallway question into a receipted answer in seconds instead of scheduling another overnight sweep.

cd python
# Guided tour — narrated scenario walkthrough (recommended first run):
python examples/journeys/05_sessions_and_whatif.py
 
# Production one-liner — same API call you ship:
solvjump sessions list