src/explicit_learning/certificates/build.py

"""Build content-addressed state certificates.

The certificate is deliberately derived only from immutable inputs: the source
and transformed worlds, typed program, deterministic executor results, and two
byte-identical renderer passes.  A model response is never accepted as a label.
"""

from __future__ import annotations

from collections.abc import Mapping, Sequence
from dataclasses import dataclass
from functools import lru_cache
from typing import Any, Literal

from ..dsl.ast import Program, ast_node_from_dict
from ..executors.base import ExecutionResult
from ..hashing import canonical_json_hash
from ..paths import repo_root
from ..renderers.base import RenderedAssets
from ..schema_io import load_schema, validate
from ..sources.base import World
from ..sources.world_ops import world_sha256

State = Literal["FULL", "A_SAME", "A_CHANGED", "U_MISSING", "U_INVALID"]


class CertificateError(ValueError):
    """A certificate cannot be proven from the supplied artifacts."""


@dataclass(frozen=True)
class MissingProofInputs:
    completion_a_world_sha256: str
    completion_b_world_sha256: str
    completion_a_answer: str | int | bool
    completion_b_answer: str | int | bool
    observed_render_a_sha256: str
    observed_render_b_sha256: str


def certificate_id(certificate: Mapping[str, Any]) -> str:
    """Recompute the content address, excluding the address field itself."""
    payload = dict(certificate)
    payload.pop("certificate_id", None)
    return canonical_json_hash(payload)


@lru_cache(maxsize=1)
def _certificate_schema() -> dict[str, Any]:
    return load_schema(repo_root() / "schemas" / "intervention_certificate.schema.json")


def program_from_dict(data: Mapping[str, Any]) -> Program:
    """Rebuild a :class:`Program` from its P2 envelope."""
    selector = data.get("referent_selector")
    return Program(
        dsl=str(data["dsl"]),  # type: ignore[arg-type]
        program=ast_node_from_dict(data["program"]),
        base_id=str(data["base_id"]),
        question_sha256=str(data["question_sha256"]),
        choices_sha256=str(data["choices_sha256"]),
        compile_status=str(data["compile_status"]),  # type: ignore[arg-type]
        referent_selector=ast_node_from_dict(selector) if isinstance(selector, Mapping) else None,
        required_referent_cardinality=data.get("required_referent_cardinality"),
        referenced_node_ids=tuple(str(v) for v in data.get("referenced_node_ids", [])),
        canonical_program_sha256=str(data.get("canonical_program_sha256") or ""),
        reason_code=str(data["reason_code"]) if data.get("reason_code") is not None else None,
        constraint_channels=tuple((str(k), str(v)) for k, v in data.get("constraint_channels", [])),
    )


def _status(value: str) -> str:
    mapping = {
        "UNIQUE": "unique_answer",
        "MISSING_INFORMATION": "missing_information",
        "INVALID_REFERENT": "invalid_referent",
    }
    try:
        return mapping[value]
    except KeyError:
        raise CertificateError(f"executor status {value!r} cannot certify a label") from None


def _assert_render_replay(first: RenderedAssets, replay: RenderedAssets) -> None:
    if first.rgba_png != replay.rgba_png:
        raise CertificateError("RGBA render replay differs")
    if first.node_map_png != replay.node_map_png:
        raise CertificateError("node-map render replay differs")
    if first.render_manifest != replay.render_manifest:
        raise CertificateError("render manifest replay differs")
    if first.text_manifest != replay.text_manifest:
        raise CertificateError("text manifest replay differs")


def _proof(
    state: State,
    before: ExecutionResult,
    after: ExecutionResult,
    *,
    missing: MissingProofInputs | None,
) -> dict[str, Any]:
    if state == "FULL":
        if not before.is_unique or after.answer_canonical != before.answer_canonical:
            raise CertificateError("FULL requires the same unique before/after answer")
        return {"state": state, "answer": before.answer_canonical}
    if state == "A_SAME":
        if not before.is_unique or not after.is_unique:
            raise CertificateError("A_SAME requires two unique answers")
        if after.answer_canonical != before.answer_canonical:
            raise CertificateError("A_SAME answers differ")
        return {
            "state": state,
            "before_answer": before.answer_canonical,
            "after_answer": after.answer_canonical,
            "equality_asserted": True,
        }
    if state == "A_CHANGED":
        if not before.is_unique or not after.is_unique:
            raise CertificateError("A_CHANGED requires two unique answers")
        if after.answer_canonical == before.answer_canonical:
            raise CertificateError("A_CHANGED answers are equal")
        return {
            "state": state,
            "before_answer": before.answer_canonical,
            "after_answer": after.answer_canonical,
            "inequality_asserted": True,
        }
    if state == "U_MISSING":
        if after.status != "MISSING_INFORMATION":
            raise CertificateError("U_MISSING requires MISSING_INFORMATION after execution")
        if missing is None:
            raise CertificateError("U_MISSING requires two completion witnesses")
        if missing.completion_a_answer == missing.completion_b_answer:
            raise CertificateError("U_MISSING completion answers must differ")
        if missing.observed_render_a_sha256 != missing.observed_render_b_sha256:
            raise CertificateError("U_MISSING completion observations must be identical")
        return {
            "state": state,
            "completion_a_world_sha256": missing.completion_a_world_sha256,
            "completion_b_world_sha256": missing.completion_b_world_sha256,
            "completion_a_answer": missing.completion_a_answer,
            "completion_b_answer": missing.completion_b_answer,
            "answers_differ": True,
            "observed_render_a_sha256": missing.observed_render_a_sha256,
            "observed_render_b_sha256": missing.observed_render_b_sha256,
            "observed_renders_identical": True,
        }
    if state == "U_INVALID":
        if after.status != "INVALID_REFERENT":
            raise CertificateError("U_INVALID requires INVALID_REFERENT after execution")
        if before.referent_cardinality != 1 or after.referent_cardinality == 1:
            raise CertificateError("U_INVALID selector cardinalities do not prove failure")
        return {
            "state": state,
            "selector_cardinality_before": 1,
            "selector_cardinality_after": int(after.referent_cardinality or 0),
            "required_cardinality": 1,
            "precondition_failed": True,
        }
    raise CertificateError(f"unknown state {state!r}")


def build_certificate(
    *,
    tier: Literal["C1_SOURCE_NATIVE", "C2_DUAL_COMPILED"],
    base_id: str,
    view_id: str,
    question_sha256: str,
    choices_sha256: str,
    world_before: World,
    world_after: World,
    program: Program,
    before_result: ExecutionResult,
    after_result: ExecutionResult,
    renderer_id: str,
    renderer_version: str,
    renderer_seed: int,
    first_render: RenderedAssets,
    replay_render: RenderedAssets,
    changed_node_ids: Sequence[str],
    diff_mask_sha256: str,
    state: State,
    missing_proof: MissingProofInputs | None = None,
    reference_result: ExecutionResult | None = None,
    c2_compilation: Mapping[str, Any] | None = None,
) -> dict[str, Any]:
    """Build and schema-validate one content-addressed certificate."""
    if program.compile_status != "compiled":
        raise CertificateError("an unsupported program cannot be certified")
    if program.base_id != base_id:
        raise CertificateError("program/base ID mismatch")
    if program.question_sha256 != question_sha256 or program.choices_sha256 != choices_sha256:
        raise CertificateError("program question/choices hash mismatch")
    if not before_result.is_unique:
        raise CertificateError("FULL execution is not unique")
    _assert_render_replay(first_render, replay_render)

    selector_sha = (
        canonical_json_hash(program.referent_selector.to_ast_node_dict())
        if program.referent_selector is not None
        else None
    )
    proof = _proof(state, before_result, after_result, missing=missing_proof)
    certificate: dict[str, Any] = {
        "schema_version": 1,
        "tier": tier,
        "base_id": base_id,
        "view_id": view_id,
        "question_sha256": question_sha256,
        "choices_sha256": choices_sha256,
        "world_before_sha256": world_sha256(world_before),
        "world_after_sha256": world_sha256(world_after),
        "program": {
            "language": program.dsl,
            "canonical_ast_sha256": program.canonical_program_sha256,
            "dependency_node_ids": list(before_result.dependency_node_ids),
            "referent_selector_sha256": selector_sha,
        },
        "executor": {
            "name": before_result.executor_name,
            "version": before_result.executor_version,
            "deterministic": True,
            "before_trace_sha256": before_result.trace_sha256,
            "after_trace_sha256": after_result.trace_sha256,
            "before_answer_canonical": before_result.answer_canonical,
            "after_answer_canonical": after_result.answer_canonical,
            "after_status": _status(after_result.status),
        },
        "reference_executor": None,
        "renderer": {
            "name": renderer_id,
            "version": renderer_version,
            "seed": renderer_seed,
            "render_manifest_sha256": canonical_json_hash(first_render.render_manifest),
            "first_render_sha256": first_render.rgba_sha256,
            "replay_render_sha256": replay_render.rgba_sha256,
            "replay_exact_match": True,
            "changed_node_ids": sorted(set(changed_node_ids)),
            "diff_mask_sha256": diff_mask_sha256,
        },
        "proof": proof,
        "c2_compilation": dict(c2_compilation) if c2_compilation is not None else None,
        "checks": {
            "question_choices_unchanged": True,
            "source_full_answer_reproduced": True,
            "fresh_structured_render": True,
            "pixel_scope_audit_passed": True,
            "choice_uniqueness_passed": True,
            "certificate_replayed": True,
        },
    }
    if reference_result is not None:
        agrees = (
            reference_result.status == after_result.status
            and reference_result.answer_canonical == after_result.answer_canonical
        )
        if not agrees:
            raise CertificateError("reference executor disagrees with primary")
        certificate["reference_executor"] = {
            "name": reference_result.executor_name,
            "version": reference_result.executor_version,
            "after_status": _status(reference_result.status),
            "after_answer_canonical": reference_result.answer_canonical,
            "trace_sha256": reference_result.trace_sha256,
            "agrees_with_primary": True,
        }
    certificate["certificate_id"] = certificate_id(certificate)
    errors = validate(certificate, _certificate_schema())
    if errors:
        raise CertificateError("certificate schema validation failed: " + "; ".join(errors))
    return certificate