FLEX-WP-0031-T03: durable decision outbox and the FLEX-DEC-2026-018 release rule

internal/emission commits one audit-core-shaped event per decision with
fsync before release (one sync per batch), random event ids with the
decision id as correlation_id, torn-tail and failed-commit truncation, and
per-class committed/released_uncommitted counts at GET /v1/emission.
The engine releases restrictions whose record failed to commit and
withholds allow/audit_only (503). api.DecisionEffects() is pinned by a
source-parsing test and cadence.yaml must classify exactly it.

T03 split under the task budget: heartbeat+drain is T05, reconciliation,
profile check and PVC are T06. Nothing deployed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 307130@bnt-lap001
Assistant-Session: 270c79f7-0823-4b0d-990d-aad5af9935ce

internal/decision/engine.go

@@ -6,6 +6,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"reflect"
 	"slices"
@@ -36,6 +37,22 @@ type DecisionRecorder interface {
 	Append(api.DecisionEnvelope) error
 }
 
+// BatchRecorder commits several decisions in one durable write.
+type BatchRecorder interface {
+	AppendBatch([]api.DecisionEnvelope) error
+}
+
+// UncommittedNoter counts restrictions released after their record failed to
+// commit (FLEX-DEC-2026-018).
+type UncommittedNoter interface {
+	NoteReleasedUncommitted(api.DecisionEffect)
+}
+
+// ErrRecordNotCommitted means a permissive decision was withheld because its
+// record did not commit. The service answers 503, and the consumer's declared
+// stance applies (FLEX-DEC-2026-018).
+var ErrRecordNotCommitted = errors.New("decision withheld: record not committed")
+
 // ListAllowedRequest describes a deterministic list_allowed call.
 type ListAllowedRequest struct {
 	Subject       api.SubjectRef `json:"subject"`
@@ -104,8 +121,8 @@ func (e *Engine) now() time.Time {
 	return time.Now().UTC()
 }
 
-// Check evaluates one subject/action/resource request.
-func (e *Engine) Check(ctx context.Context, request api.CheckRequest) (api.DecisionEnvelope, error) {
+// decide evaluates one request without recording it.
+func (e *Engine) decide(ctx context.Context, request api.CheckRequest) (api.DecisionEnvelope, error) {
 	normalized, facts := e.normalizeRequest(request)
 
 	expectation, err := e.policy.Evaluate(ctx, normalized)
@@ -113,19 +130,29 @@ func (e *Engine) Check(ctx context.Context, request api.CheckRequest) (api.Decis
 		return api.DecisionEnvelope{}, err
 	}
 
-	decision := e.envelope(ctx, normalized, request, expectation, facts)
-	if err := e.recordDecision(decision); err != nil {
+	return e.envelope(ctx, normalized, request, expectation, facts), nil
+}
+
+// Check evaluates one subject/action/resource request. The decision is
+// released only after its record commits, except that a restriction is never
+// withheld (FLEX-DEC-2026-018).
+func (e *Engine) Check(ctx context.Context, request api.CheckRequest) (api.DecisionEnvelope, error) {
+	decision, err := e.decide(ctx, request)
+	if err != nil {
+		return api.DecisionEnvelope{}, err
+	}
+	if err := e.recordDecisions([]api.DecisionEnvelope{decision}); err != nil {
 		return api.DecisionEnvelope{}, err
 	}
 	return decision, nil
 }
 
 // BatchCheck evaluates one subject/action/context tuple against resources in
-// request order.
+// request order, and commits the whole batch in one durable write.
 func (e *Engine) BatchCheck(ctx context.Context, request api.BatchCheckRequest) ([]api.DecisionEnvelope, error) {
 	decisions := make([]api.DecisionEnvelope, 0, len(request.Resources))
 	for _, resource := range request.Resources {
-		decision, err := e.Check(ctx, api.CheckRequest{
+		decision, err := e.decide(ctx, api.CheckRequest{
 			ID:            request.ID,
 			Tenant:        request.Tenant,
 			Subject:       request.Subject,
@@ -139,18 +166,21 @@ func (e *Engine) BatchCheck(ctx context.Context, request api.BatchCheckRequest)
 		}
 		decisions = append(decisions, decision)
 	}
+	if err := e.recordDecisions(decisions); err != nil {
+		return nil, err
+	}
 	return decisions, nil
 }
 
 // ListAllowed evaluates candidate resources and returns only allow decisions.
 func (e *Engine) ListAllowed(ctx context.Context, request ListAllowedRequest) ([]api.DecisionEnvelope, error) {
 	candidates := e.store.ResourceRefs(request.System, request.ResourceType)
-	allowed := make([]api.DecisionEnvelope, 0, len(candidates))
+	decisions := make([]api.DecisionEnvelope, 0, len(candidates))
 	for _, resource := range candidates {
 		if !resourceMatchesFilters(resource, request.Filters) {
 			continue
 		}
-		decision, err := e.Check(ctx, api.CheckRequest{
+		decision, err := e.decide(ctx, api.CheckRequest{
 			Subject:       request.Subject,
 			Action:        request.Action,
 			Resource:      resource,
@@ -160,6 +190,13 @@ func (e *Engine) ListAllowed(ctx context.Context, request ListAllowedRequest) ([
 		if err != nil {
 			return nil, err
 		}
+		decisions = append(decisions, decision)
+	}
+	if err := e.recordDecisions(decisions); err != nil {
+		return nil, err
+	}
+	allowed := make([]api.DecisionEnvelope, 0, len(decisions))
+	for _, decision := range decisions {
 		if decision.Effect == api.DecisionEffectAllow {
 			allowed = append(allowed, decision)
 		}
@@ -404,12 +441,46 @@ func callerProvenance(ctx context.Context) *api.CallerProvenance {
 	return out
 }
 
-func (e *Engine) recordDecision(decision api.DecisionEnvelope) error {
+// recordDecisions commits decisions and applies FLEX-DEC-2026-018 when the
+// commit fails: restrictions are released and counted, and any permissive
+// decision withholds the call. In a batch that withholds the batch's
+// restrictions too; no live consumer calls batch_check (user-engine loops
+// /v1/check), and the residual is stated in the ruling.
+func (e *Engine) recordDecisions(decisions []api.DecisionEnvelope) error {
 	e.mu.Lock()
-	defer e.mu.Unlock()
-	e.history[decision.ID] = decision
-	if e.log != nil {
-		return e.log.Append(decision)
+	for _, decision := range decisions {
+		e.history[decision.ID] = decision
+	}
+	log := e.log
+	e.mu.Unlock()
+	if log == nil || len(decisions) == 0 {
+		return nil
+	}
+	err := appendAll(log, decisions)
+	if err == nil {
+		return nil
+	}
+	for _, decision := range decisions {
+		if !decision.Effect.Restricts() {
+			return fmt.Errorf("%w: %v", ErrRecordNotCommitted, err)
+		}
+	}
+	if noter, ok := log.(UncommittedNoter); ok {
+		for _, decision := range decisions {
+			noter.NoteReleasedUncommitted(decision.Effect)
+		}
+	}
+	return nil
+}
+
+func appendAll(log DecisionRecorder, decisions []api.DecisionEnvelope) error {
+	if batch, ok := log.(BatchRecorder); ok {
+		return batch.AppendBatch(decisions)
+	}
+	for _, decision := range decisions {
+		if err := log.Append(decision); err != nil {
+			return err
+		}
 	}
 	return nil
 }