v0.18.0: MCP entity-graph CRUD, lifecycle validation, curl -o /dev/null fix

- create_entity, set_entity_state, end_relationship MCP tools
- update_entity_attributes now triggers check derivation via EnsureEntityChecks
- shared db.EnsureEntityChecks + db.ValidateTransition hooks (HTTP + MCP parity)
- curl -o /dev/null now classified read_only (was config_mutation)
- db.ErrTransitionInvalid sentinel for HTTP error-type accuracy
- SOUL.md: capability escalation, self-grounding, exploration budget rules
- Runbook: oikos check lifecycle for agent self-knowledge

internal/db/checks.go

@@ -0,0 +1,34 @@
+package db
+
+import (
+	"context"
+
+	"github.com/dtoro/oikos/internal/checkdefaults"
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5"
+)
+
+// EnsureEntityChecks derives an entity's default check_defs from the
+// monitoring spec of its type (resolving per-entity `monitoring` overrides).
+//
+// This is the single shared hook that keeps the check graph in sync with
+// entity mutations. Both the HTTP create/patch handlers and the MCP
+// entity-mutation tools (create_entity, update_entity_attributes) call it so
+// that flipping an entity's `monitoring` attribute regenerates checks
+// regardless of which surface made the change — previously only the HTTP
+// path ran check derivation, so entities mutated via MCP silently produced no
+// checks (see plans/2026-08-03-session-review-haos-monitoring-capability-gaps.md, A2).
+func EnsureEntityChecks(ctx context.Context, tx pgx.Tx, id uuid.UUID, slug, entityType, name string, attrs []byte) (checkdefaults.Result, error) {
+	tree, err := LoadTypeTree(ctx, tx)
+	if err != nil {
+		return checkdefaults.Result{}, err
+	}
+	res, err := checkdefaults.Ensure(ctx, tx, tree, checkdefaults.Target{
+		ID: id, Slug: slug, Type: entityType, Name: name, Attrs: attrs,
+	})
+	if err != nil {
+		return res, err
+	}
+	checkdefaults.LogResult(slug, entityType, res)
+	return res, nil
+}