fix(graph): exclude archived pages from kb.neighbors

[kurosawareiji7007-hub]

Summary

• kb.neighbors / vouch neighbors no longer return archived pages.
• Matches context-pack graph expansion (_page_is_live); claims were already filtered.

Fixes #696

Test plan

• pytest tests/test_graph.py
• ruff check on touched files
• CI green + 100% diff coverage

Made with Cursor

[plind-junior]

the behaviour is right — neighbors was the one graph surface still serving archived pages while context expansion dropped them, and matching the two is correct.

but the new _neighbor_ok page branch is context._page_is_live copied out, not called. side by side:

# graph.py, this PR
try:
    return store.get_page(node_id).status is not PageStatus.ARCHIVED
except ArtifactNotFoundError:
    return False

# context.py:601-604, already on test
try:
    return store.get_page(page_id).status is not PageStatus.ARCHIVED
except ArtifactNotFoundError:
    return False

identical apart from the parameter name, and the comment you wrote — "match context._page_is_live" — says you knew where it lived. from .context import _page_is_live gets the same behaviour with nothing to drift.

that matters more than usual here, because _page_is_live's own docstring is about this exact failure: "keeping it in three places is what let kb.context keep serving archived pages after #581 fixed kb.search." this PR is one of five open right now adding a copy (#710, #709, #708, #697 are the others), so the predicate is about to exist in six places, which is how #581 got a sequel in the first place.

if the import direction is awkward (graph → context), the cleaner move is the one suggested on #708: promote a page_is_live(page) next to _page_is_live and have both call sites use it. either way, not a fresh copy.

one smaller thing: assert graph._neighbor_ok(store, "missing-page", "page") is False is a second, unrelated assertion riding inside test_find_neighbors_excludes_archived_pages. it covers a real branch (the ArtifactNotFoundError path), so it should be its own test rather than a tail assertion on a test named for something else — otherwise a failure there reports as "archived pages leak", which it is not.