add-value-test-shape

name	add-value-test-shape
description	Extend typed generated value-test planning and rendering in tslc. Use when asked to support a new authored tests shape or signature, add a case kind or pattern, handle memory, mask, conversion, scalable, or differential cases, resolve authored_unplanned or backend_unsupported coverage, or add backend rendering for a planned case.

Add Value-Test Shape

Workflow

1. Read AGENTS.md, CHARTER.md, PLANS.md, tslc/AGENTS.md, tslc/CHARTER.md, the differential-value-test section of tslc/DESCRIPTION.md, the source primitive/tests, and the closest patterns, case planners, capabilities, renderers, and tests under tslc/src/tslc/value_tests/.
2. Define the authored contract and oracle first: signature/result kinds, parameter layout, fixed or scalable lanes, masks, memory/alignment/aliasing, immediates, representation changes, safety, and supported backends.
3. Reuse an existing case kind when its typed components express the contract. Add vocabulary only when the new case has distinct invariants or render requirements; do not create one case kind per primitive or signature.
4. Keep source data semantic. Do not embed C++/Rust harness code or renderer policy in .tsl tests.
5. Plan before rendering: the focused pattern owns acceptance and actionable unplanned reasons; case planners construct typed components; case_capabilities.py declares invariants; patterns.py owns deterministic registration. Do not let renderers rediscover source semantics.
6. Declare backend case-kind support through renderer capabilities and add focused backend rendering. Missing support must remain backend_unsupported, not fail through a late dispatch or template error.
7. Keep fixed, scalable, differential, memory, and conversion behavior explicit. A missing harness primitive or ambiguous oracle must produce authored_unplanned coverage or a structured diagnostic, not fabricated expected behavior.
8. Test accepted and nearby rejected forms, unplanned reasons, component invariants, backend capability validation, deterministic planning, and rendering. Run executable generated tests for every affected backend/profile that the available toolchains can verify.

Checks

• Every authored case is planned, explicitly unplanned, or backend-unsupported with a deterministic reason.
• Planning remains backend-neutral until declared renderer capabilities and target-specific formatting are needed.
• Generated tests exercise the real primitive contract rather than merely proving that a harness compiles.

Useful Commands

PYTHONPATH=tslc/src python -m pytest -q tslc/tests/test_value_test_planning.py
PYTHONPATH=tslc/src python -m pytest -q tslc/tests/test_backend_target_capability.py tslc/tests/test_value_tests.py
PYTHONPATH=tslc/src python -m pytest -q --run-generated-builds tslc/tests/test_value_tests.py
git diff --check