The onetaskgraph engine.

It drives the sources a configuration names and reports what it had to do to answer. Everything a plugin author needs lives in onetaskgraph-plugin-api instead, and no plugin crate may depend on this one: deny.toml permits this crate exactly one wrapper, the binary, failing the required deny job, and scripts/check-plugin-isolation.sh reads the real cargo metadata graph inside just check.

The invariant that shapes this crate

No work data may be stored, cached, indexed or mirrored outside a plugin. The engine compensates for a missing capability transiently: it holds at most one source page plus the caller's page and writes nothing down. Three mechanisms enforce that rather than asking for it: deny.toml refuses every embedded store, index and cache crate, so reaching for one fails the required deny job; a sandboxed journey plants sentinels, drives every verb, and fails if one reaches any file written during the run; and a re-ask test fails if one query asked twice reaches the source once. The latter two land with the verbs they drive.