[nick-gorman]

The new-format custom constraints from the translator (#139) are scoped by
investment period and timeslice, e.g. a flow limit can only apply during QLD
peak demand from 2030 onwards. The existing _add_custom_constraints sums every term
over every snapshot, so it can't express that. This change adds
_add_custom_constraints_with_temporal_scope, which creates linopy constraint for each unique constraint_name, investment_period and timeslice combination.

It isn't wired into build_pypsa_network yet; that comes with the final
wiring PR.

src/ispypsa/
├── pypsa_build/custom_constraints.py        ← new temporal-scope path
├── translator/timeslices.py                 ← no-snapshot warning now per investment period
└── validation/schemas/
    ├── ispypsa_tables/                      ← existing schemas, moved
    └── pypsa_friendly_tables/               ← new: contracts for this step's inputs
tests/test_model/test_custom_constraints_with_temporal_scope.py
CLAUDE.md                                    ← "investment period", never bare "period"

Design choices worth a look:

• Blank timeslice is a fallback, per constraint. It covers the snapshots
  in its investment period that none of the same constraint's named
  timeslices cover.
• Blank investment_period matches only blank. An LHS term joins only the
  RHS rows with its exact investment_period, a blank investment period doesn't act as wildcard or default value. Because the translator resolves all dated inputs to explicit investment periods,
  blank only appears on the expansion limits which apply across the all investment periods at once.
• Load terms are data, not variables. coefficient × p_set is added as a
  per-snapshot constant, which linopy moves to the RHS.
• Storage p is net dispatch (p_dispatch − p_store), matching PLEXOS's
  paired battery Generation/Load coefficients.
• Missing components aren't skipped. Unsupported (component, attribute)
  terms and constraints with no variable terms raise, rather than silently
  weakening the constraint.
• Schema split. The schema folder is now ispypsa_tables (translator
  input) and pypsa_friendly_tables (pypsa_build input). Only the three
  tables this step reads are declared so far. Nothing loads the schemas yet,
  so the move is paths only.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
src/ispypsa/pypsa_build/custom_constraints.py	93.49% <100.00%> (+13.49%)	⬆️
src/ispypsa/templater/existing_planned.py	100.00% <ø> (ø)
src/ispypsa/templater/new_entrants.py	100.00% <ø> (ø)
src/ispypsa/translator/constraints.py	100.00% <ø> (ø)
src/ispypsa/translator/timeslices.py	100.00% <100.00%> (ø)

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