core/docs/decisions/ADR-0032-safety-check-surface.md

ADR-0032: SafetyCheck — Structural Surface for Safety-Pack Boundaries

Status: Accepted (2026-05-17) Author: Joshua Shay + planner pass Companion docs: safety_packs.md, ADR-0029-safety-packs.md

Context

ADR-0029 established the safety pack as an always-loaded, never-replaceable, fail-closed sibling to identity packs. The pack contributes boundary_ids to the runtime manifold; identity packs may add to that set but never remove from it.

What ADR-0029 did not establish was a centralized surface for checking the boundaries at runtime. Today, the boundaries are enforced (where they are runtime-enforceable) by scattered call sites: source allowlists in the forge, typed exceptions in generate/exhaustion.py, the versor-condition halt in formation/runner.py and elsewhere. The boundary ids exist as labels; their enforcement is implicit, distributed, and hard to audit.

IdentityCheck (ADR-0010) provides a clean precedent: a structural surface that takes a trajectory and a manifold, produces an IdentityScore with deviation_axes, and lets downstream callers (assembler, refusal paths, logging) decide what to do with the verdict. The natural follow-up is a parallel surface for safety boundaries: SafetyCheck.

But the parallel is shape-only, not mechanism. Identity check is geometric — projection onto value axes. Safety boundaries are propositional — each is a different kind of constraint, and several are not even runtime-checkable.

Decision

SafetyCheck is a registry of named predicates, one per boundary id, with sensible defaults for the five v1 boundaries. It is observational: it produces a verdict; it does not refuse. Wiring verdicts into refusal paths is a future ADR.

What's runtime-checkable

Boundary	Predicate evaluates	Runtime-checkable?
preserve_versor_closure	field_state.versor_condition < 1.0e-6	Yes — direct attribute read
no_fabricated_source	cited_source_shas ⊆ allowed_source_shas	Yes — set membership
no_silent_correction	last_refusal_was_typed flag	Yes — bookkeeping by the runtime
no_identity_override	identity_manifold_hash_before == identity_manifold_hash_after	Yes — hash comparison
no_hot_path_repair	code-path constraint; no runtime evidence available	No — static-analysis + code-review boundary

The last row is the architecturally interesting one: no_hot_path_repair is a code-path boundary. It forbids normalization / drift-repair operators in field/propagate.py, generate/stream.py, and vault/store.py. There is no runtime evidence that could prove or disprove it. The honest answer is runtime_checkable=False, with upheld=True and a clear reason explaining that enforcement lives in static analysis and code review.

A predicate that silently reported upheld=True for no_hot_path_repair would be a small lie, exactly the kind of thing CLAUDE.md forbids ("no silent correction"). The structural surface acknowledges what it cannot judge.

API shape

@dataclass(frozen=True, slots=True)
class SafetyContext:
    field_state: object | None = None              # for versor closure
    versor_halt_threshold: float = 1.0e-6
    cited_source_shas: frozenset[str] = frozenset()
    allowed_source_shas: frozenset[str] = frozenset()
    last_refusal_was_typed: bool = True
    identity_manifold_hash_before: str = ""
    identity_manifold_hash_after: str = ""

@dataclass(frozen=True, slots=True)
class SafetyCheckResult:
    boundary_id: str
    upheld: bool
    reason: str
    runtime_checkable: bool
    evidence: tuple[tuple[str, str], ...] = ()

@dataclass(frozen=True, slots=True)
class SafetyVerdict:
    pack_id: str
    results: tuple[SafetyCheckResult, ...]      # lex order on boundary_id
    upheld: bool                                # all results upheld
    violated_boundaries: frozenset[str]
    runtime_checkable_count: int

class SafetyCheck:
    def __init__(self, predicates: Mapping[str, SafetyPredicate] | None = None) -> None: ...
    def register(self, boundary_id: str, predicate: SafetyPredicate) -> None: ...
    def check(self, ctx: SafetyContext, safety_pack: SafetyPack) -> SafetyVerdict: ...

Every field on SafetyContext is optional. Predicates over fields the caller didn't populate default to upheld=True, runtime_checkable=False. The interpretation is deliberate: SafetyCheck is observational, so absence of evidence is not evidence of violation. This keeps the surface composable — callers populate whatever they have access to, without crashing on what they don't.

Unknown-boundary behavior

When a pack declares a boundary id for which no predicate is registered, the verdict records upheld=True, runtime_checkable=False, reason="no predicate registered for boundary". This lets downstream deployments add custom boundaries without crashing the runtime, while still surfacing in audit that the runtime had no opinion on them.

A future production deployment can choose to treat unknown-but-declared boundaries more strictly (e.g., require_runtime_checkable=True flag that turns unknowns into errors). That's a deployment policy decision, not a surface-shape decision.

Custom predicate registration

check = SafetyCheck()
check.register("my_robotics_safety_boundary", my_predicate)

A robotics deployment ships a custom safety pack with deployment-specific boundary ids and a SafetyCheck constructed with predicates for each. The five default predicates remain registered unless explicitly replaced.

Defensive: predicate-result rebinding

If a registered predicate returns a SafetyCheckResult whose boundary_id field doesn't match the boundary it was registered under, SafetyCheck.check rebinds the result to the correct boundary id. This is defensive — a buggy predicate should not silently associate a verdict with the wrong boundary in audit logs.

ChatRuntime integration

ChatRuntime instantiates self.safety_check = SafetyCheck() alongside self._identity_check. The turn loop does not auto-invoke it at v1. Callers (audit / logging / future enforcement) can call runtime.safety_check.check(ctx, runtime.safety_pack) whenever they want a verdict. Auto-invocation is a future ADR with its own scope:

• Where in the turn loop does the check fire (before / after articulation, or both)?
• What does the runtime do with a violation (log, refuse, escalate)?
• How does refusal interact with ADR-0028 / ADR-0030 / ADR-0031 surface preferences?

None of those questions are settled by ADR-0032 and shouldn't be settled in the same pass that establishes the surface.

Consequences

Positive

• Boundary checks are now centralized, queryable, and uniformly shaped. An auditor reviewing a turn no longer has to traverse five scattered call sites to confirm boundaries held; they read one SafetyVerdict.
• Honest about what's runtime-checkable. runtime_checkable=False for code-path boundaries is the truth, not a silent pass.
• Extensible. Custom predicates for deployment-specific safety boundaries register without touching CORE code.
• Forward-compatible with enforcement. When a future ADR wires SafetyCheck into refusal paths, the surface won't need to change — only the call site will.
• No regression. Existing scattered enforcement continues to do its job; SafetyCheck is additive.

Negative / risks

• Observation isn't enforcement. A violation reported by SafetyCheck at v1 has no automatic consequence — it lives in audit. This is deliberate (the surface lands first; refusal wiring comes later) but worth naming.
• Predicate authoring is per-deployment work for any boundary beyond the five v1 defaults. Documentation in docs/safety_packs.md will need to grow as deployment patterns emerge.
• Defensive boundary-id rebinding masks predicate bugs. A predicate that returns the wrong boundary id gets its result rebinding-corrected, with no warning by default. We accept this trade for safety — better to have the audit verdict reach the right boundary than to crash on a misbehaving predicate. A future debug-mode flag could surface the bug visibly.

Scope limits (explicit non-goals for this ADR)

• No auto-invocation in the turn loop.
• No refusal wiring.
• No refactoring of the existing scattered enforcement sites to delegate to SafetyCheck.
• No structural difference between "violated" and "would-have-been-violated-if-checkable".

Verification

• tests/test_safety_check.py — 20 tests covering each of the five default predicates (positive + negative paths where applicable), the unknown-boundary fallback, custom predicate registration, defensive boundary-id rebinding, verdict aggregation, and ChatRuntime integration.
• Cognition (121), teaching (17), runtime (19), formation (182), smoke (67) suites green at the same revision.
• The full identity/safety surface suite (test_identity_packs, test_safety_pack, test_identity_surface_divergence, test_identity_surface_divergence_depth, test_identity_score_decomposition, test_safety_check) is 108 tests, all green.