[huxiaoyi-ovo]

Fork-only validation for pgraph-python #79; not intended to be merged into the fork.

Change

• Graph.plot() and Graph.highlight_path() now default to block=None, leaving figure display to the environment. Explicit False and True retain their existing show semantics.
• Update docstrings, the README script example, and docs/llms_intro.md.
• Add Matplotlib Agg regression tests covering no implicit plt.show, explicit block=False/True, and same-axes highlighting.

Verification

• Based directly on upstream main at 74402d5.
• Four commits; exactly four files changed, independently of other pgraph PRs.
• All fork CI checks passed: all Python 3.9–3.14 tests, mypy and Codecov; docs deploy skipped by workflow policy.
• Python 3.12 test matrix: 774 passed including three new regressions.
• The default change is intentional. Scripts that want immediate display should use block=False or call plt.show() after drawing all overlays.

Upstream submission

Issue petercorke#79 has been claimed by huxiaoyi-ovo. No duplicate upstream PR found. Ready to submit upstream via GitHub website, because the integration lacks cross-repository PR creation permissions (GitHub API 403).

AI assistance: ChatGPT (OpenAI GPT-6) helped review, implement and test this change.

[huxiaoyi-ovo]

Fork-only validation complete: all required CI checks passed. The same head commit has been submitted upstream as petercorke#84. Closing this staging draft PR to keep the fork tidy; the upstream PR and source branch remain unchanged.