Sourced from whest-starterkit @ 96e308c.

Stage 2: Validate the contract

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Stage 1 confirms your estimator runs and converges. Stage 2 confirms it satisfies the harness contract: right shapes, right types, finite values, and optional lifecycle hooks that behave.

🚀 Run it

uv run whest validate --estimator estimator.py

A passing run renders a Rich panel with four green OK rows:

Validating estimator estimator.py
╭───────────────────────────────── Validation ─────────────────────────────────╮
│ Command: validate                                                            │
│ Status: success                                                              │
│ ╭───────────────────────────────── Checks ─────────────────────────────────╮ │
│ │ ┏━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┓                   │ │
│ │ ┃ Status ┃ Check                    ┃ Detail         ┃                   │ │
│ │ ┡━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━┩                   │ │
│ │ │ OK     │ class resolved           │ Estimator      │                   │ │
│ │ │ OK     │ setup(context) completed │ 0.00s (cap 5s) │                   │ │
│ │ │ OK     │ predict() returned shape │ (2, 4)         │                   │ │
│ │ │ OK     │ values finite            │ all finite     │                   │ │
│ │ └────────┴──────────────────────────┴────────────────┘                   │ │
│ ╰──────────────────────────────────────────────────────────────────────────╯ │
╰──────────────────────────────────────────────────────────────────────────────╯
✓ Validation passed in 21ms
Next: `whest run --estimator estimator.py --split mini`

(The panel is drawn to your terminal width, and the trailing timing figure moves run to run: ~20-30 ms here.)

What each check does

• class resolved — the loader found class Estimator(BaseEstimator) in your file (override with --class CustomName).
• setup(context: SetupContext) — if you defined setup() (it's optional), the validator calls it with a probe SetupContext and confirms it returns without raising. See SetupContext fields. The 0.00s (cap 5s) detail is your setup() budget: it is the only limit whose breach fails the whole submission rather than one MLP. To rehearse against a tighter limit, run whest run --setup-timeout SECONDS.
• predict() returned shape — invoked on a probe MLP (width=4, depth=2 by default) and asserts the returned array has shape (mlp.depth, mlp.width).
• values finite — no NaN or Inf in the returned array.

A failing run halts at the first failed check and prints a structured error pointing at the contract clause that broke. See estimator-contract.md for the full contract.

✅ Expected outcome

Validate is a sub-second sanity check against a probe MLP. It doesn't score your estimator; it only checks that it returns the right shape of the right type with finite values. Most participants pass on the first try.

If a check fails, the panel prints the broken clause inline. For shape mismatches, the error includes expected_shape and got_shape so you can fix the bug without reading source.

✅ When you're ready

Move on to Stage 3: run the harness locally.