feat: expose type-aware partial evaluation (TPE) as tpe_authorize

[h0rv]

Draft, stacked on #108. Read only the last commit, 409d6b6.

The branch carries #108's commit 02e359f underneath, because GitHub cannot base a pull request on a branch that lives on a fork. #108 merges first, then this rebases onto main and 02e359f drops out, leaving only the TPE change. Transitively includes and is blocked by #106.

What

Adds tpe_authorize, an entry point for type-aware partial evaluation (TPE). Use it when you know the type of the principal or resource but not which one, e.g. some User, not sure which, instead of a concrete User::"alice".

This is separate from is_authorized_partial. It does not call it, change it, or share its response shape. is_authorized_partial and residuals are untouched. The two partial-eval implementations in cedar-policy behave differently in a way that matters here. is_authorized_partial's residuals can contain untyped unknown(...) nodes that PST cannot represent, per #108 and #107. TPE's residuals are checked against the schema and do convert. Confirmed by calling to_pst() on real output from both paths.

principal and resource each accept Type::"id" (concrete) or a bare Type (known type, unknown id). TPE's PartialEntityUid needs a type even when the id is unknown, so is_authorized_partial's convention of None meaning wholly unknown does not carry enough information here. action must be concrete. schema is required, unlike is_authorized/is_authorized_partial where it is optional, because TPE builds its request and entity types against it. entities must be fully concrete; this does not expose TPE's on-demand entity loading.

The response is a TpeAuthzResult dataclass. permits and forbids stay separate, each a TpeClassification of residual_ids, true_ids, false_ids, error_ids. residual_policies maps policy id to a cedarpy.pst.Template, the same typed node #108 exposes, not JSON.

Every failure raises ValueError. Unlike is_authorized/is_authorized_partial, there is no decision to fall back to when the input itself cannot be resolved.

The tpe feature

Enables tpe alongside partial-eval in Cargo.toml. Checked the resolved lockfile before and after: no change. cedar-policy's tpe = ["cedar-policy-core/tpe"] and cedar-policy-core's tpe = [] both have no dependency edges. cedar-policy 4.12.0 puts partial-eval and tpe in the same experimental bucket, and cedarpy already ships partial-eval as its documented partial-authorization API.

Testing

Built with maturin develop --release on macOS arm64, Python 3.14.

Suite	Result
pytest tests/unit	255 passed, 2 subtests (242 through #108 + 13 new)
pytest tests/integration/test_cedar_integration_tests.py	74 passed
pytest tests/integration/test_cedar_corpus_tests.py	59696 passed
git diff Cargo.lock	empty
cargo clippy --release	10 warnings, all pre-existing on main, none in this diff

New tests cover a type-only resource, a concrete resource that resolves allow and deny, a satisfied forbid overriding a satisfied permit while the permit stays in true_ids, a residual forbid blocking an otherwise-true permit from becoming a decision, the residual as a typed node with a working pattern match on it, trivial residuals not repeated in residual_policies, is_authorized_partial behaving exactly as before, and error handling for a missing schema, an unparseable principal, a bare-type action, unparseable policies, and unparseable entities.

Not run: make benchmark-compare, same reason as #108.

Marked draft because it stacks on #108, which stacks on #106.