Phase 15: snapshots, forks, export/import, cognitive replay, experiments

- snapshots: checksummed JSON archive of every mind-scoped state table plus
  identity/personality/config and the event position; stored, downloadable
- fork: restore into a new mind with all ids remapped; event references are
  kept so history before the fork is shared by reference
- export/import: same archive; import is hostile-input validated (size,
  allow-listed tables, row caps, column names, checksum, forced mind_id)
- compare: deterministic counts, belief diffs by proposition, personality
  and config diffs, event mix
- replay: Runtime.Step for synchronous drivers; sandbox fork driven one
  stimulus at a time under a forbidden capability context; recorded model
  responses via a replaying router; steps labelled exact / approximate /
  diverged with recorded-vs-replayed digests
- experiments: definition (overrides, stimuli, expectations, seed, duration),
  background run in a disabled subject mind, stored and exportable results
- migration 0015, API, UI (Snapshots and Replay tabs, Experiments section,
  compare page), noemactl snapshots/compare/replay/experiments, docs

internal/replay/replaytest/harness.go

@@ -0,0 +1,60 @@
+// Package replaytest wires a deterministic cognitive stack for replay and
+// experiment tests.
+package replaytest
+
+import (
+	"context"
+	"log/slog"
+	"testing"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/andydixon/noema/internal/beliefs"
+	"github.com/andydixon/noema/internal/brain"
+	"github.com/andydixon/noema/internal/capabilities"
+	"github.com/andydixon/noema/internal/cognition"
+	"github.com/andydixon/noema/internal/conversation"
+	evstore "github.com/andydixon/noema/internal/events"
+	"github.com/andydixon/noema/internal/goals"
+	"github.com/andydixon/noema/internal/graph"
+	"github.com/andydixon/noema/internal/memory"
+	"github.com/andydixon/noema/internal/minds"
+	"github.com/andydixon/noema/internal/motivation"
+	"github.com/andydixon/noema/internal/observability"
+	"github.com/andydixon/noema/internal/predictions"
+	"github.com/andydixon/noema/internal/scheduler"
+	"github.com/andydixon/noema/internal/snapshots"
+	"github.com/andydixon/noema/internal/storage"
+	"github.com/andydixon/noema/migrations"
+)
+
+// Harness wires the deterministic cognitive registry without a model.
+type Harness struct {
+	Pool   *pgxpool.Pool
+	Events *evstore.Store
+	Minds  *minds.Store
+	Snaps  *snapshots.Store
+	Brain  brain.Config
+}
+
+// NewHarness is shared with the experiments tests.
+func NewHarness(t *testing.T) *Harness {
+	t.Helper()
+	pool := storage.TestPool(t, migrations.FS)
+	ctx := context.Background()
+	log := slog.New(slog.DiscardHandler)
+	es := evstore.NewStore(pool, evstore.NewBus(64), nil)
+	ms := minds.NewStore(pool)
+	mem := memory.NewStore(ctx, pool, nil)
+	bs := beliefs.NewStore(pool)
+	caps := &capabilities.Service{Registry: capabilities.NewRegistry(), DB: pool, Events: es, Log: log}
+	for _, c := range capabilities.Builtins() {
+		caps.Registry.Add(c)
+	}
+	reg := brain.NewRegistry().AddProcess(cognition.Attend{}).AddProcess(cognition.Retrieve{}).AddProcess(cognition.Associate{}).AddProcess(cognition.Perceive{}).
+		AddProcess(cognition.GoalMonitor{}).AddProcess(cognition.Curiosity{}).AddProcess(cognition.Metacognition{}).AddProcess(cognition.Act{})
+	cognition.Handlers{Memory: mem, Beliefs: bs, Conversations: conversation.NewStore(pool), Graph: graph.NewStore(pool)}.Register(reg)
+	cfg := brain.Config{DB: pool, Events: es, Minds: ms, Registry: reg, Pool: scheduler.NewPool(2), Log: log, Metrics: observability.NewMetrics(),
+		Services: brain.Services{Events: es, Memory: mem, Beliefs: bs, Goals: goals.NewStore(pool), Motivation: motivation.NewStore(pool), Predictions: predictions.NewStore(pool), Capabilities: caps}}
+	return &Harness{Pool: pool, Events: es, Minds: ms, Snaps: &snapshots.Store{DB: pool, Events: es, Minds: ms}, Brain: cfg}
+}