test: pin five documented behaviors that no test covered

[dmccoystephenson]

Summary

Five behaviors are already promised by the docstrings, the README, or a source
comment, but were not exercised by any test. They are pinned here as
characterization tests. No production code is changed.

• Default display size. Graphik() is documented as falling back to a
  900x600 window; the existing test only asserted that some display was
  created. The size assertion was folded into that existing test rather than
  added as a second one, since it strictly subsumes it.
• Package __getattr__ miss path. Defining __getattr__ on
  preponderous.graphik takes over every failed attribute lookup, so the miss
  path has to keep raising AttributeError. Nothing covered that branch.
• Per-path image cache. Both drawImage caches are keyed on filePath
  alone. A second asset getting its own entry — rather than evicting the first
  or being served the first's surface — was untested.
• drawRectangle fill bounds. drawButton's hit test is written against
  xpos through xpos + width - 1 (see PR fix: make drawButton's clickable region match the box it draws #37), but the bounds were only
  pinned on the button, not on the fill they are anchored to.
• Font cache across a resize. The session check compares display surface
  objects, and set_mode returns the same object when only the size changes.
  That is what keeps a resize from discarding the font cache, and the existing
  invalidation tests pass either way.

Each addition was confirmed to bite: the source was temporarily mutated (default
size changed, the AttributeError replaced with return None, the image cache
key made constant, the rectangle fill narrowed by a pixel, the session check
forced to always invalidate) and every corresponding test failed, then passed
again once the source was restored. The working tree was verified clean
afterwards.

Deferred issues

The three open issues were all skipped this cycle, each for a reason recorded
here rather than as a comment on the issue:

• release: version tags are pushed without the 'v' prefix publish.yml requires, so no release has ever been published #34 (release tags missing the v prefix) — the fix is a maintainer
  decision between two directions, and touches .github/workflows/ and the
  release process.
• ci: test.yml's header comment claims it runs on every push, but pushes outside main are only covered via pull_request #39 (test.yml header comment overstates its triggers) — the fix is
  correct and small, but it edits .github/workflows/, which is excluded from
  autonomous change here.
• packaging: the empty preponderous/__init__.py ships a regular package, which will collide with any future preponderous.* distribution #40 (the empty preponderous/__init__.py) — the issue states its own
  prerequisite (which namespace-package convention the sibling
  Preponderous-Software projects follow) is not determinable from inside this
  repository.

Test plan

• python -m pytest — 41 passed (37 before; four tests added and one
  assertion folded into an existing test), headless via conftest.py.
• python -m py_compile src/main/python/preponderous/graphik/graphik.py
• Import smoke test: import preponderous.graphik prints 0.3.0.dev20260808.
• Mutation check per addition, described above.
• CI (test.yml) green across Python 3.9–3.13.

No tracking issue — this is a test-expansion cycle, so nothing is auto-closed.

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

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drafted by Claude on behalf of Daniel Stephenson

[dmccoystephenson]

Self-review rubric

• Scope: PASS — git diff --name-only origin/main...HEAD lists one file, src/test/python/preponderous/graphik/test_graphik.py. No production source, docs, or version file is touched.
• Tests-new: NOT APPLICABLE — no new public method is added; this is a characterization-only cycle.
• Tests-fix (empirical): PASS — no bug is fixed here, so the stash-and-run equivalent was run as a mutation check instead. Each addition was verified against a deliberately broken source: displayWidth = 900 → 800, the package __getattr__'s raise AttributeError → return None, drawImage's cache key forced to a constant, pygame.draw.rect's extent narrowed to width - 1/height - 1, and _getFont's if display is not self._fontDisplay forced to if True. Every corresponding test failed under its mutation and passed once the source was restored, and git status confirmed the source was left unmodified.
• Sibling structure: PASS — no new file is created; each addition sits beside the sibling that covers the same method, and follows the file's existing shape (module-level test_* function, leading _-prefixed helper reuse, a comment stating why the behavior is worth pinning).
• Sibling renames: NOT APPLICABLE — nothing is renamed.
• Docs: PASS — no behavior changed, so no row of the documentation sources-of-truth table is affected. The README's 900x600 and xpos + width - 1 claims and the _getFont comment are now asserted by tests rather than described only in prose.
• Issue resolution: NOT APPLICABLE — no Closes #N is claimed. The three open issues are deferred with reasons recorded in the PR body.
• CI: PASS — all five matrix jobs (Python 3.9 through 3.13) pass on the PR head; run 32700291260. Locally, python -m pytest reports 41 passed (37 on main).
• camelCase: PASS — no public member is added or renamed. Local variables in the new tests (redPath, bluePath, resized, constructed) follow the file's existing camelCase/lowercase mix.
• Backward-compat: PASS — the diff contains no production change, so no member of the public surface consumed by Roam, Apex, Ophidian, Patchwork or Tic-Tak-Toe can have moved.
• Headless: PASS — every addition reuses _make_graphik / pygame.display.set_mode under the SDL_VIDEODRIVER=dummy and SDL_AUDIODRIVER=dummy defaults set by src/test/python/conftest.py. No new test requires a real display, audio device, or network. Confirmed by the CI matrix, which runs on a headless runner.
• Version sync: NOT APPLICABLE — no version string changed.
• No new deps: PASS — the additions import nothing that the file did not already import (pygame, pytest, stdlib).

Findings

Two observations are recorded rather than fixed, both judgment calls:

src/test/python/preponderous/graphik/test_graphik.py:439 — the resize test opens with assert resized is graphik.getGameDisplay(), "resize returned a new surface". That assertion is about pygame's own behavior, not Graphik's, so if a future pygame returns a fresh surface from a resizing set_mode, the failure will be reported by a Graphik font-cache test rather than by something that names the real cause. The message was written to make that legible, and the precondition is kept because without it the test would silently degrade into asserting nothing.

src/test/python/preponderous/graphik/test_graphik.py:279 — test_draw_rectangle_fills_exactly_the_requested_region sits next to the pre-existing test_draw_rectangle_fills_expected_region_with_color and the two overlap: both draw the same 5x5 rectangle and both check a pixel outside it. They were deliberately left separate because neither subsumes the other — the older test checks an interior pixel (which a hollow outline would fail) and the new one checks the four corners and the four coordinates just past each far edge (which a one-pixel-short fill would fail). The analogous overlap on the constructor test was not left standing: that addition was a strict superset of its sibling, so it was folded into the existing test in 54f4b97 instead of landing as a second test.

One cross-cutting note that is out of this diff's scope: three of the five behaviors pinned here are asserted only by their own source comment or a README line, which is what made them easy to miss. A short convention that a documented invariant carries a test would prevent the next one, but that belongs in the repository's contributing guidance rather than in this PR.

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

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drafted by Claude on behalf of Daniel Stephenson