[dmccoystephenson]

Summary

• Stage B (unit-test expansion) for the directional move methods: Environment::moveEntityInDirection finds the starting location with Grid::getLocation(entity.getLocationId()), which runs before the try that turns an off-grid step into false. Neither behavior was tested or documented.
• Test 80 shows that a directional move starts from the location the entity's location id names, not from the location that actually stores it. The entity is stored in 0-1-1 with its location id set to 0-0-0, and moveEntityRight puts it in 0-1-0.
• Test 81 shows that moveEntityUp and moveEntityToRandomAdjacentLocation throw std::runtime_error when the location id names no grid location, and that the entity stays where it was.
• The README's "Grid Layout and Movement" and "Errors" sections now describe both behaviors.
• Production code is unchanged. These are characterization tests that record what the code currently does.

No tracking issue: the gap was found during triage. The issue tracker was empty at triage, so no issues were skipped.

Test plan

• CI Library tests (make + CMake) runs bash run_tests.sh and every test through Test 81 prints --- Success. Local runs of the test binary are denied in this environment, so CI is the anchor.
• The ASan and CMake steps in the same job pass.

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This PR description was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

🤖 Generated with Claude Code

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drafted by Claude on behalf of Daniel Stephenson

[dmccoystephenson]

Self-review rubric (anchor: CI run 42985819569, Library tests (make + CMake). Local execution of the test binary is denied in this environment.)

• Local test suite: PASS. bash run_tests.sh in CI printed --- Success for every test through Test 81. The ASan step also printed Test 81 --- Success, and ctest reported 100% tests passed. The Strata and web build jobs are also green.
• Scope: PASS. Only src/tests.cpp (+45) and README.md (+3/-1) change, and both are about how directional moves find their starting location.
• Tests-new: PASS (not applicable). No public method is added. Two characterization tests cover existing behavior.
• Tests-fix: not applicable. This is not a bug fix, and production code is unchanged.
• Sibling structure: PASS. The new functions follow the existing void test<Behavior>() / Test N - ... / --- Success pattern, and their try/catch shape matches Tests 51–52.
• Sibling renames: not applicable.
• Docs: PASS. The README statements were checked against src/environment.cpp: moveEntityInDirection calls getGrid()->getLocation(entity.getLocationId()) before its try, so the lookup's runtime_error propagates; removeEntity then goes through Grid::removeEntity, which removes the entity from every location whose stored entity matches by id. The class table is unchanged and still accurate.
• Issue resolution: not applicable. There is no Closes reference, because the gap was found during triage.
• Test registration: PASS. Both functions are called at the end of main(), and CI printed both lines.
• Header/definition parity, include guards: not applicable. No header changed.

Observations:

• src/tests.cpp Test 80: the check that 0-2-1 is empty is the meaningful sentinel. 0-2-1 is where a move starting from the actual storage location would land, so the test can tell the two starting points apart.
• src/tests.cpp Test 81: moveEntityToRandomAdjacentLocation throws whichever direction rand() picks, because the lookup happens before the direction is chosen. The assertion is therefore deterministic.
• Out of diff: moveEntityToNewLocation does not read the location id, so it is not affected. This was left unpinned to keep the PR small.

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This comment was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

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drafted by Claude on behalf of Daniel Stephenson