[dmccoystephenson]

Summary

A Stage B (unit-test expansion) cycle on RenderWindow. Six characterization tests are added to tests/test_render_window.py, covering behaviour of render_window.py that no existing test asserted. No production code is changed.

• should_continue() returns True when no events are pending.
• Registered handlers are called in registration order, once for each event, with events taken in poll order.
• Once a QUIT event is seen, the rest of the events in that poll are not passed to handlers (the loop returns early).
• After a QUIT, later should_continue() calls return False without polling pygame.event.get() again, and Pygame is not shut down until close() is called.
• A single pygame.time.Clock is created in __init__ and used by every tick().
• Each close() call runs pygame.quit() again. This is what the docstring's "Calling this more than once is harmless" currently means: the call is repeated, not skipped.

No tracking issue: the gap was found during triage. The README's description of the test suite (which modules mock Pygame) still holds, since tests/test_render_window.py already mocked it, so no documentation change is needed.

Test plan

• python -m py_compile main.py graphik.py __init__.py render_window.py headless_run.py usage_reporting.py trace_client.py runs without errors.
• python -m unittest tests.test_render_window ran 16 tests and all passed (10 before this PR).
• python -m unittest discover -s tests ran 156 tests and all passed (150 on main).
• Mutation check: changing the return False in the QUIT branch of should_continue() to continue makes test_events_after_quit_in_the_same_poll_are_not_dispatched fail. With the source restored, it passes again.
• The Tests workflow is green on this PR.

Deferred issues

• A failed environment creation leaves the window open and shows no error, unlike a failed load #42 needs an owner decision on whether a failed creation should be handled like a failed load.
• The Viron submodule is pinned before Viron required bearer tokens, so Patchwork cannot reach a current Viron #41 needs the Viron submodule re-pinned, and the loop does not change that without explicit authorization.
• Decide whether per-location colours should be stable across frames #24 needs an owner decision on stable versus animated colours.
• Add text-based UI support to library for users #11 and Support drawing environments with multiple grids #2 are feature work too large for one polish-sized PR.

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 (Stage B, characterization only):

• Scope: PASS — git diff --name-only origin/main...HEAD lists only tests/test_render_window.py; no production file is touched.
• Tests-new: PASS — no new public method is added; each of the six new tests covers a render_window.py behaviour no existing test asserted (empty poll, handler/event ordering, early return on QUIT, no re-poll after QUIT, single Clock, repeated close()).
• Tests-fix: not applicable — no bug fix. Mutation check done instead: changing the QUIT branch's return False to continue makes test_events_after_quit_in_the_same_poll_are_not_dispatched fail, and it passes again once the source is restored.
• Sibling structure: PASS — the new tests use the existing setUp patch of render_window.pygame, the same *_SENTINEL event types and the same arrange/act/assert layout as the tests around them.
• Sibling renames: not applicable — nothing is renamed.
• Docs: PASS — the README's test-suite paragraph already says the render_window.py tests mock Pygame, and that is still true. No documented behaviour changes.
• Issue resolution: not applicable — no Closes, since the gap was found during triage.
• Manual validation: PASS — locally, py_compile of all top-level modules succeeds and python -m unittest discover -s tests ran 156 tests, all OK. The Tests workflow passed on the PR head (run 41015336109). The live Viron anchor was not run (UNVERIFIED-not-applicable): no rendering or service-call code is changed.

Findings and judgment calls:

• tests/test_render_window.py:65 — test_one_clock_is_created_and_reused_by_every_tick overlaps with the existing test_tick_delegates_to_clock. It is kept because only the new test pins that a single Clock is constructed. Folding the older test into it was not done, so that no existing assertion is removed in a characterization cycle.
• tests/test_render_window.py:84 — test_closing_twice_quits_pygame_each_time pins that pygame.quit() runs again on every close(). The close() docstring's "harmless" depends on pygame.quit() being idempotent, not on any guard in RenderWindow. If a guard is added later, this test should be updated on purpose.
• Out of diff: the README's RenderWindow section does not say that events queued after a QUIT in the same poll never reach handlers. That is a candidate for a later documentation sweep, not this PR.

Verdict: ready to merge.

This review 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