`_is_config_json()` decides whether a `.json` file is worth AST-walking. It
matches by filename first, then falls back to a root-key probe. `$schema` was
in that probe's key set -- correctly, since configs legitimately carry it --
but it is also the *defining marker* of a JSON Schema, so every schema
document satisfied the probe and got walked in full. That re-opened the
keyword-node explosion #1224 closed for data JSON: one 160 KB contract
contributed 362 nodes labelled with bare schema keywords (`description` x113,
`type` x83, `$ref` x53, ...) plus ~12 schema-only communities, polluting
clustering, god-node analysis and GRAPH_REPORT.md.
Two changes, both ahead of the existing probe:
- Drop `$ref` from the probe keys. A root-level `$ref` is a schema construct
and never a config signal.
- Return False when the root object carries `$schema` *plus* a
schema-definition marker (`$defs`, `definitions`, or `$id`). This is what
separates "this file IS a schema" from "this config POINTS AT a schema":
the latter points `$schema` at its own tool's schema (biomejs.dev,
docs.renovatebot.com) and never carries these markers.
The blast radius is smaller than it looks. The filename branches run first, so
biome.json / renovate.json / package.json / tsconfig.json never depended on the
probe at all; only arbitrarily-named files did. I confirmed this against a
control matrix before and after -- every config shape keeps byte-identical node
counts.
The root keys are now collected once into a set so the schema check and the
config probe agree on the same read of the file, rather than walking the root
twice.
Documented boundary, pinned by a test: a hand-written schema carrying only
`$schema` + `properties` (no `$defs`/`definitions`/`$id`) is still walked.
Closing that gap needs a keyword-density heuristic, which would risk skipping a
real config whose keys overlap schema vocabulary -- the worse error, since it
drops structure silently. Left for a deliberate change rather than guessed at.
Verified:
- uv run pytest tests/test_json_schema_config.py -q (14 passed; 5 fail pre-fix)
- uv run pytest tests/ -q -> 28 failed, 6262 passed, 101 skipped
- baseline on a clean v0.9.75 checkout: 28 failed, 6248 passed, 101 skipped
The 28 failures are byte-identical between the two (missing tree-sitter
grammars for erlang/R/solidity/vbnet, plus ollama retry tests) and are diffed
test-id-by-test-id, not compared by count. Passing delta is exactly +14.
- uv run ruff check . -> clean
- uv run pyright -> 636 errors, identical to the clean v0.9.75 baseline
Co-Authored-By: Claude <noreply@anthropic.com>
