phase 1: Go foundation — module, migrations, domain, seed ingest

Core deliverables:
- Go module github.com/dtoro/oikos (Go 1.26.3)
- cmd/oikos: single binary with role subcommands (migrate, seed, export)
- 6 SQL migrations: ontology meta-schema, entity instances (UUID+slug,
  blast_radius recursive function), operations (signals/checks/approvals),
  cognition (classifications/executions/feedback/patterns/skills), policy,
  observability (TimescaleDB hypertables + CAGGs + retention)
- Domain layer: entity, signal, execution, classification, pattern, skill,
  approval, check types + 11 sentinel errors + lifecycle state machines
- DB layer: pgx pool, SQL splitter (handles 94436 and -- comments), migration
  runner, seed ingest (ontology+inventory+policy) with content-hash dedup
- Config: env-based with defaults, secrets redaction
- Observability: slog JSON logger with debug mode
- Infrastructure: Makefile, docker-compose.yml, multi-stage Dockerfile
  (distroless, CGO_ENABLED=0)

Verified end-to-end against timescale/timescaledb:2.17.2-pg16:
- 6 migrations applied (65 SQL statements)
- Seeds ingested: 6 lifecycles, 59 entity types, 46 relationship types,
  111 entities, 144 relationships, 4 risk classes, 27 approval rules,
  9 autonomy settings
- Idempotent: second seed run is a no-op (content hash matches)

Bugs fixed during implementation:
- TimescaleDB CAGGs can't run in a transaction -> splitSQL() executes
  statements individually
- Semicolons in -- comments treated as separators -> comment handling
- YAML keys source/target didn't match code's source_type/target_type
- yaml.Marshal produced YAML for JSONB columns -> json.Marshal

internal/domain/approval.go

@@ -0,0 +1,110 @@
+package domain
+
+import "time"
+
+// Approval is a short-TTL signed grant for a gated action.
+type Approval struct {
+	EntityID         UUID
+	SubjectEntityID  UUID
+	Action           string
+	RiskClass        string
+	Kind             string
+	Payload          map[string]any
+	Status           string
+	TokenHash        string
+	ExpiresAt        time.Time
+	DecidedAt        *time.Time
+	DecidedBy        UUID
+	CreatedAt        time.Time
+}
+
+// Approval statuses.
+const (
+	ApprovalPending  = "pending"
+	ApprovalApproved = "approved"
+	ApprovalDenied   = "denied"
+	ApprovalExpired  = "expired"
+	ApprovalRevoked  = "revoked"
+)
+
+// Approval kinds.
+const (
+	ApprovalKindExecution        = "execution"
+	ApprovalKindPolicyChange     = "policy-change"
+	ApprovalKindPatternActivation = "pattern-activation"
+)
+
+// CheckDef defines a probe (R3-7: probes as data, not code).
+type CheckDef struct {
+	EntityID   UUID
+	TargetID   UUID
+	TargetType string
+	Kind       string
+	Config     map[string]any
+	IntervalS  int
+	TimeoutS   int
+	Zone       string
+	Enabled    bool
+	UpdatedAt  time.Time
+}
+
+// Check kinds.
+const (
+	CheckHTTP      = "http"
+	CheckTCP       = "tcp"
+	CheckDisk      = "disk"
+	CheckCertExpiry = "cert-expiry"
+	CheckDrift     = "drift"
+	CheckSSHScript = "ssh-script"
+)
+
+// EntityStatus is the current health of an entity (R3-6: replaces state_snapshots).
+type EntityStatus struct {
+	EntityID    UUID
+	Health      string
+	LastCheckAt *time.Time
+	Details     map[string]any
+	UpdatedAt   time.Time
+}
+
+// Health values.
+const (
+	HealthHealthy  = "healthy"
+	HealthDegraded = "degraded"
+	HealthDown     = "down"
+	HealthUnknown  = "unknown"
+)
+
+// RiskClass is the four-level safety model.
+type RiskClass struct {
+	Name              string
+	Description       string
+	ApprovalRequired  string
+	AutonomyAllowed   bool
+}
+
+// Risk class names.
+const (
+	RiskReadOnly       = "read_only"
+	RiskReversibleLow  = "reversible_low"
+	RiskConfigMutation = "config_mutation"
+	RiskDestructive    = "destructive"
+)
+
+// ApprovalRule maps (entity_type, action) → risk_class + autonomy.
+type ApprovalRule struct {
+	ID           UUID
+	EntityType   string
+	Action       string
+	RiskClass    string
+	AutonomyLevel string
+	ScopeEntity  UUID
+	Version      int
+}
+
+// Autonomy levels.
+const (
+	AutonomyAuto     = "auto"
+	AutonomyEscalate = "escalate"
+	AutonomyNever    = "never"
+)