docs: Added alt text for illustrations

README.md

@@ -17,7 +17,7 @@
 The <b>world state lives outside the model</b>, characters act through <b>intents that get validated</b> and applied by engine code. Each character's knowledge, memory, and emotional state are subjective and partial by construction.
 
 <p align="center">
-  <img src="./web/docs/src/assets/img/puppet.webp" />
+  <img src="./web/docs/src/assets/img/puppet.webp" alt="This pixel-art style image, set against a black background with the title 'The Puppet Master Paradox' at the top, depicts two identical, stylized puppets with white, round heads and orange patterned bodies facing each other. Between them hovers a small, glowing, four-pointed star, while each puppet has an orange-outlined speech bubble above it: the left one states, 'Good evening. Welcome to my humble bakery!', and the right one replies, 'Nice to meet you Assassin Bob. Wait... wha-', concluding with a small white 'X' icon in the bottom right corner." />
 </p>
 
 Single-agent or single-context systems (AI Dungeon and its descendants) prompt one model to _be_ the world and everyone in it. That breaks in predictable ways over long sessions:
@@ -41,7 +41,7 @@ Omnia answers every one of these failures with the same move: **pull the thing t
 ## What this buys you
 
 <p align="center">
-  <img src="./web/docs/src/assets/img/features.webp" />
+  <img src="./web/docs/src/assets/img/features.webp" alt="This pixel-art image features a grid of six distinct panels, each with an orange-outlined, jagged border, illustrating different concepts: 'Emergent Deceit' shows a person hiding a sword behind their back while offering a rose to another person; 'Divergent Perceptions' depicts two figures sitting at a table with speech bubbles labeled 'A' and 'B'; 'Player Agnostic' shows three figures engaged in different activities—watering a plant, standing still, and juggling—under the plumbob symbol from the sims; 'State Validated Agency' displays a stylized symbol of a person partially inside a portal crossed out by a large red 'X'; 'Deterministic Time' shows four circular panels representing a day-night cycle connected by arrows and clock icons; and 'Bring Your Own Model' features a large, central omnia icon surrounded by various LLM model logos including chatgpt, mistral, deepseek, claude, etc****" />
 </p>
 
 The payoff is scenario complexity that **uni-agent systems structurally cannot represent, no matter how good the model gets**.

apps/gui/next-env.d.ts

@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-import "./.next/dev/types/routes.d.ts";
+import "./.next/types/routes.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.

apps/gui/src/app/builder/page.tsx

@@ -1,18 +1,5 @@
-"use client";
+import { BuilderView } from "@/components/builder/BuilderView";
 
 export default function BuilderPage() {
-  return (
-    <div className="flex-1 overflow-y-auto w-full">
-      <div className="mx-auto max-w-[800px] px-10 py-12">
-        <h1 className="mb-6 text-headline-lg text-primary animate-fade-in">
-          Scenario Builder
-        </h1>
-        <div className="border border-border/30 bg-card p-6 shadow-[2px_2px_0_0_var(--border)] min-h-[300px] flex flex-col items-center justify-center">
-          <p className="text-body-md text-muted-foreground font-mono text-center">
-            Scenario builder interface coming soon...
-          </p>
-        </div>
-      </div>
-    </div>
-  );
+  return <BuilderView />;
 }

apps/gui/src/app/page.tsx

@@ -1,5 +1,5 @@
-import { DashboardView } from "@/components/play/DashboardView";
+import { HomeView } from "@/components/home/HomeView";
 
 export default function Home() {
-  return <DashboardView />;
+  return <HomeView />;
 }

apps/gui/src/components/builder/BuilderView.tsx

@@ -0,0 +1,18 @@
+"use client";
+
+export function BuilderView() {
+  return (
+    <div className="flex-1 overflow-y-auto w-full">
+      <div className="mx-auto max-w-[800px] px-10 py-12">
+        <h1 className="mb-6 text-headline-lg text-primary animate-fade-in">
+          Scenario Builder
+        </h1>
+        <div className="border border-border/30 bg-card p-6 shadow-[2px_2px_0_0_var(--border)] min-h-[300px] flex flex-col items-center justify-center">
+          <p className="text-body-md text-muted-foreground font-mono text-center">
+            Scenario builder interface coming soon...
+          </p>
+        </div>
+      </div>
+    </div>
+  );
+}

apps/gui/src/components/home/HomeView.tsx

@@ -34,7 +34,7 @@ import {
   SelectValue,
 } from "@/components/ui/select";
 
-export function DashboardView() {
+export function HomeView() {
   const router = useRouter();
   const [loading, setLoading] = useState(false);
   const [loadingData, setLoadingData] = useState(true);

apps/gui/src/lib/simulation/alias-handoff.ts

@@ -0,0 +1,71 @@
+import { HandoffEngine, checkHandoffTrigger } from "@omnia/memory";
+import type { SimSession } from "./types";
+
+/**
+ * Runs the HandoffEngine for every agent entity that has accumulated enough
+ * buffer entries to warrant a handoff (compression to long-term memory).
+ */
+export async function runHandoffResolution(session: SimSession): Promise<void> {
+  const worldState = session.coreRepo.loadWorldState(session.worldInstanceId);
+  if (!worldState) throw new Error("World state lost");
+
+  const handoffEngine = new HandoffEngine(
+    session.handoffProvider,
+    session.embeddingProvider,
+    session.bufferRepo,
+    session.ledgerRepo,
+  );
+
+  const entities = Array.from(worldState.entities.values());
+  for (const entity of entities) {
+    if (!entity.isAgent) continue;
+
+    const bufferEntries = session.bufferRepo.listForOwner(entity.id);
+    const maxContext =
+      session.handoffProvider.maxContext !== undefined
+        ? session.handoffProvider.maxContext
+        : 32768;
+
+    const trigger = checkHandoffTrigger(
+      entity,
+      bufferEntries,
+      worldState.clock.get(),
+      maxContext,
+    );
+    if (trigger !== "none") {
+      await handoffEngine.runHandoff(
+        entity,
+        bufferEntries,
+        worldState.clock.get(),
+      );
+    }
+  }
+}
+
+/**
+ * For every agent that shares a location with another entity they haven't
+ * previously encountered, generates a first-person alias description and
+ * persists it on the viewing entity.
+ */
+export async function runAliasResolution(session: SimSession): Promise<void> {
+  const worldState = session.coreRepo.loadWorldState(session.worldInstanceId);
+  if (!worldState) throw new Error("World state lost");
+
+  const entities = Array.from(worldState.entities.values());
+  for (const viewer of entities) {
+    if (!viewer.isAgent) continue;
+    if (!viewer.locationId) continue;
+
+    for (const target of entities) {
+      if (viewer.id === target.id) continue;
+      if (
+        target.locationId === viewer.locationId &&
+        !viewer.aliases.has(target.id)
+      ) {
+        const alias = await session.aliasGenerator.generate(viewer, target);
+        viewer.aliases.set(target.id, alias);
+        session.coreRepo.saveEntity(viewer, worldState.id);
+      }
+    }
+  }
+}

apps/gui/src/lib/simulation/env.ts

@@ -0,0 +1,16 @@
+import dotenv from "dotenv";
+import path from "path";
+import fs from "fs";
+
+// Load .env from monorepo root or apps/gui/
+const cwd = process.cwd();
+const envCandidates = [
+  path.resolve(cwd, ".env"),
+  path.resolve(cwd, "../../.env"),
+];
+for (const c of envCandidates) {
+  if (fs.existsSync(c) && fs.statSync(c).isFile()) {
+    dotenv.config({ path: c });
+    break;
+  }
+}

apps/gui/src/lib/simulation/index.ts

@@ -0,0 +1,17 @@
+/**
+ * Barrel entry point for the simulation module.
+ *
+ * Consumers import from "@/lib/simulation" exactly as before — no import
+ * paths need to change anywhere in the codebase.
+ */
+import { SimulationManager } from "./simulation-manager";
+
+export const simulationManager = new SimulationManager();
+
+export type {
+  SimSnapshot,
+  EntityInfo,
+  LogEntry,
+  IntentInfo,
+  WaitingContext,
+} from "../simulation-types";

apps/gui/src/lib/simulation/provider-resolver.ts

@@ -0,0 +1,175 @@
+import {
+  GeminiProvider,
+  MockLLMProvider,
+  ProviderManager,
+  OpenRouterProvider,
+  GeminiEmbeddingProvider,
+  MockEmbeddingProvider,
+} from "@omnia/llm";
+import type {
+  ILLMProvider,
+  IEmbeddingProvider,
+  ModelProviderInstance,
+} from "@omnia/llm";
+
+// ---------------------------------------------------------------------------
+// Public types
+// ---------------------------------------------------------------------------
+
+export interface ResolvedProviders {
+  actorProvider: ILLMProvider;
+  validatorProvider: ILLMProvider;
+  decoderProvider: ILLMProvider;
+  timedeltaProvider: ILLMProvider;
+  handoffProvider: ILLMProvider;
+  embeddingProvider: IEmbeddingProvider;
+}
+
+export interface ProviderResolverOptions {
+  /**
+   * Pre-resolved generative instance to fall back to when ProviderManager has
+   * no active generative provider (e.g. when the caller already validated a
+   * specific provider during session creation).
+   */
+  fallbackInstance?: ModelProviderInstance | null;
+  /**
+   * When true, throws an Error if no provider can be resolved for a task.
+   * When false (default), falls back silently to MockLLMProvider / MockEmbeddingProvider.
+   */
+  required?: boolean;
+}
+
+// ---------------------------------------------------------------------------
+// Private builders
+// ---------------------------------------------------------------------------
+
+function buildLLMProvider(inst: ModelProviderInstance): ILLMProvider {
+  if (inst.providerName === "google-genai") {
+    return new GeminiProvider(
+      inst.apiKey,
+      inst.modelName,
+      inst.name,
+      inst.maxContext,
+    );
+  } else if (inst.providerName === "openrouter") {
+    return new OpenRouterProvider(
+      inst.apiKey,
+      inst.modelName,
+      inst.name,
+      inst.maxContext,
+    );
+  }
+  return new MockLLMProvider([]);
+}
+
+function buildEmbeddingProvider(
+  inst: ModelProviderInstance,
+): IEmbeddingProvider {
+  if (inst.providerName === "google-genai") {
+    return new GeminiEmbeddingProvider(inst.apiKey, inst.modelName);
+  }
+  return new MockEmbeddingProvider(inst.modelName);
+}
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+/**
+ * Resolves all six LLM + embedding providers needed for a simulation session.
+ *
+ * Resolution order for each generative task:
+ *  1. Task-specific mapping from ProviderManager (via `mappings[task]`)
+ *  2. ProviderManager active generative instance
+ *  3. `fallbackInstance` (if supplied)
+ *  4. GOOGLE_API_KEY env var → auto-creates a temporary GeminiProvider
+ *  5. Throws (if `required`) or returns MockLLMProvider
+ */
+export function resolveProviders(
+  mappings: Record<string, string>,
+  options: ProviderResolverOptions = {},
+): ResolvedProviders {
+  const { fallbackInstance = null, required = false } = options;
+  const list = ProviderManager.list();
+  const activeGenerative =
+    ProviderManager.getActive("generative") ?? fallbackInstance ?? null;
+
+  const resolveGenerative = (task: string): ILLMProvider => {
+    const mappedId = mappings[task];
+    let inst: ModelProviderInstance | null = mappedId
+      ? (list.find((p) => p.id === mappedId) ?? null)
+      : null;
+
+    if (!inst || inst.type !== "generative") {
+      inst = activeGenerative;
+    }
+
+    if (!inst) {
+      const envKey = process.env.GOOGLE_API_KEY;
+      if (envKey) {
+        inst = ProviderManager.create(
+          "Default (Env)",
+          "google-genai",
+          envKey,
+          undefined,
+          "generative",
+        );
+      }
+    }
+
+    if (!inst) {
+      if (required) {
+        throw new Error(
+          `No active LLM Provider Instance found for task "${task}". Please configure a key in Settings first.`,
+        );
+      }
+      return new MockLLMProvider([]);
+    }
+
+    return buildLLMProvider(inst);
+  };
+
+  const resolveEmbedding = (): IEmbeddingProvider => {
+    const mappedId = mappings["embeddings"];
+    let inst: ModelProviderInstance | null = mappedId
+      ? (list.find((p) => p.id === mappedId) ?? null)
+      : null;
+
+    if (!inst || inst.type !== "embedding") {
+      inst = ProviderManager.getActive("embedding");
+    }
+
+    if (!inst) {
+      const envKey = process.env.GOOGLE_API_KEY;
+      if (envKey) {
+        inst = ProviderManager.create(
+          "Default Embed (Env)",
+          "google-genai",
+          envKey,
+          "gemini-embedding-001",
+          "embedding",
+        );
+      }
+    }
+
+    if (!inst) {
+      if (required) {
+        throw new Error(
+          `No active Embedding Provider Instance found. Please configure an embedding key in Settings first.`,
+        );
+      }
+      return new MockEmbeddingProvider(undefined);
+    }
+
+    return buildEmbeddingProvider(inst);
+  };
+
+  return {
+    actorProvider: resolveGenerative("actor-prose"),
+    validatorProvider: resolveGenerative("llm-validator"),
+    decoderProvider: resolveGenerative("intent-decoder"),
+    timedeltaProvider: resolveGenerative("timedelta"),
+    handoffProvider: resolveGenerative("handoff"),
+    embeddingProvider: resolveEmbedding(),
+  };
+}

apps/gui/src/lib/simulation/session-store.ts

@@ -0,0 +1,139 @@
+import Database from "better-sqlite3";
+import path from "path";
+import fs from "fs";
+import type { SimSession, SavedState } from "./types";
+import type { SimSnapshot } from "../simulation-types";
+
+export const DATA_DIR = path.resolve(process.cwd(), "data");
+
+// ---------------------------------------------------------------------------
+// Low-level read/write helpers
+// ---------------------------------------------------------------------------
+
+export function loadSessionState(
+  db: Database.Database,
+  id: string,
+): SavedState | null {
+  try {
+    db.prepare(
+      `CREATE TABLE IF NOT EXISTS gui_meta (
+        id TEXT PRIMARY KEY,
+        state_json TEXT
+      )`,
+    ).run();
+    const row = db
+      .prepare(`SELECT state_json FROM gui_meta WHERE id = ?`)
+      .get(id) as { state_json: string } | undefined;
+    return row ? (JSON.parse(row.state_json) as SavedState) : null;
+  } catch {
+    return null;
+  }
+}
+
+export function saveSession(session: SimSession): void {
+  const state: SavedState = {
+    scenarioName: session.scenarioName,
+    scenarioDescription: session.scenarioDescription,
+    turn: session.turn,
+    maxTurns: session.maxTurns,
+    entities: session.entities,
+    playerEntityId: session.playerEntityId,
+    entityIndex: session.entityIndex,
+    status: session.status,
+    error: session.error,
+    waitingEntity: session.waitingEntity,
+    aliasDoneForTurn: session.aliasDoneForTurn,
+    log: session.log,
+    providerMappings: session.providerMappings,
+  };
+
+  session.db
+    .prepare(
+      `CREATE TABLE IF NOT EXISTS gui_meta (
+        id TEXT PRIMARY KEY,
+        state_json TEXT
+      )`,
+    )
+    .run();
+
+  session.db
+    .prepare(
+      `INSERT INTO gui_meta (id, state_json)
+       VALUES (?, ?)
+       ON CONFLICT(id) DO UPDATE SET state_json = excluded.state_json`,
+    )
+    .run(session.worldInstanceId, JSON.stringify(state));
+}
+
+// ---------------------------------------------------------------------------
+// Session file management
+// ---------------------------------------------------------------------------
+
+export function deleteSessionFile(id: string): void {
+  const dbPath = path.join(DATA_DIR, `${id}.db`);
+  if (fs.existsSync(dbPath)) {
+    try {
+      fs.unlinkSync(dbPath);
+    } catch (err) {
+      console.error(`Failed to delete session file ${dbPath}:`, err);
+    }
+  }
+}
+
+/**
+ * Lists all saved simulation snapshots by scanning the data directory.
+ * Active in-memory sessions are snapshotted via the provided callback;
+ * inactive ones are read directly from their `.db` files.
+ */
+export function listSavedSessions(
+  activeSessions: Map<string, SimSession>,
+  snapshotFn: (session: SimSession) => SimSnapshot,
+): SimSnapshot[] {
+  if (!fs.existsSync(DATA_DIR)) return [];
+
+  const snapshots: SimSnapshot[] = [];
+  const files = fs
+    .readdirSync(DATA_DIR)
+    .filter((f) => f.startsWith("sim-") && f.endsWith(".db"));
+
+  for (const file of files) {
+    const id = file.replace(".db", "");
+    const dbPath = path.join(DATA_DIR, file);
+
+    const active = activeSessions.get(id);
+    if (active) {
+      snapshots.push(snapshotFn(active));
+      continue;
+    }
+
+    try {
+      const db = new Database(dbPath);
+      const state = loadSessionState(db, id);
+      db.close();
+
+      if (state) {
+        snapshots.push({
+          id,
+          status: state.status,
+          turn: state.turn,
+          maxTurns: state.maxTurns,
+          scenarioName: state.scenarioName,
+          scenarioDescription: state.scenarioDescription,
+          entities: state.entities || [],
+          log: state.log || [],
+          entityIndex: state.entityIndex,
+          waitingEntity: state.waitingEntity,
+          error: state.error,
+        });
+      }
+    } catch {
+      /* skip corrupt / in-use db files */
+    }
+  }
+
+  return snapshots.sort((a, b) => {
+    const tsA = parseInt(a.id.replace("sim-", ""), 10) || 0;
+    const tsB = parseInt(b.id.replace("sim-", ""), 10) || 0;
+    return tsB - tsA;
+  });
+}

apps/gui/src/lib/simulation/simulation-manager.ts

@@ -0,0 +1,455 @@
+import "./env"; // Must be first — loads .env before any code reads process.env
+import Database from "better-sqlite3";
+import path from "path";
+import fs from "fs";
+import { SQLiteRepository } from "@omnia/core";
+import { BufferRepository, LedgerRepository } from "@omnia/memory";
+import { Architect, AliasDeltaGenerator } from "@omnia/architect";
+import {
+  ProviderManager,
+  GeminiEmbeddingProvider,
+  MockEmbeddingProvider,
+} from "@omnia/llm";
+import type { ModelProviderInstance, IEmbeddingProvider } from "@omnia/llm";
+import { ScenarioLoader } from "@omnia/scenario";
+import type { SimSnapshot } from "../simulation-types";
+import type { SimSession, EntityInfo } from "./types";
+import { resolveProviders } from "./provider-resolver";
+import {
+  DATA_DIR,
+  loadSessionState,
+  saveSession,
+  listSavedSessions,
+  deleteSessionFile,
+} from "./session-store";
+import {
+  preparePlayerTurn,
+  processNpcTurn,
+  executePlayerAction,
+} from "./turn-executor";
+import { runAliasResolution, runHandoffResolution } from "./alias-handoff";
+
+export class SimulationManager {
+  private sessions = new Map<string, SimSession>();
+
+  // ---------------------------------------------------------------------------
+  // Session lifecycle
+  // ---------------------------------------------------------------------------
+
+  async create(
+    scenarioPath: string,
+    playEntityName?: string,
+    providerInstanceId?: string,
+  ): Promise<SimSnapshot> {
+    // Resolve or validate the active generative provider upfront so we can
+    // return a clean error snapshot before touching the filesystem.
+    let activeInstance: ModelProviderInstance | null = providerInstanceId
+      ? ProviderManager.list().find((p) => p.id === providerInstanceId) || null
+      : ProviderManager.getActive("generative");
+
+    if (!activeInstance) {
+      const envKey = process.env.GOOGLE_API_KEY;
+      if (envKey) {
+        activeInstance = ProviderManager.create(
+          "Default (Env)",
+          "google-genai",
+          envKey,
+          undefined,
+          "generative",
+        );
+      }
+    }
+    if (!activeInstance) {
+      return {
+        id: "",
+        status: "error",
+        turn: 0,
+        maxTurns: 20,
+        scenarioName: "",
+        scenarioDescription: "",
+        entities: [],
+        log: [],
+        entityIndex: 0,
+        error:
+          "No active LLM Provider Instance found. Please configure a key in Settings first.",
+      };
+    }
+
+    const scenarioJson = JSON.parse(fs.readFileSync(scenarioPath, "utf-8"));
+    const id = `sim-${Date.now()}`;
+
+    fs.mkdirSync(DATA_DIR, { recursive: true });
+    const dbPath = path.join(DATA_DIR, `${id}.db`);
+    const db = new Database(dbPath);
+    const coreRepo = new SQLiteRepository(db);
+    const bufferRepo = new BufferRepository(db);
+    const ledgerRepo = new LedgerRepository(db);
+    const loader = new ScenarioLoader(coreRepo, bufferRepo);
+
+    const worldInstanceId = id;
+    await loader.initializeWorld(scenarioJson, worldInstanceId);
+
+    const worldState = coreRepo.loadWorldState(worldInstanceId);
+    if (!worldState) {
+      db.close();
+      return {
+        id: "",
+        status: "error",
+        turn: 0,
+        maxTurns: 20,
+        scenarioName: "",
+        scenarioDescription: "",
+        entities: [],
+        log: [],
+        entityIndex: 0,
+        error: "Failed to load world state after initialization.",
+      };
+    }
+
+    // Build entity list
+    const rawEntities = Array.from(worldState.entities.values());
+    const entityInfos: EntityInfo[] = rawEntities.map((e) => ({
+      id: e.id,
+      name: (e.attributes.get("name")?.getValue() as string) || e.id,
+      isPlayer: false,
+      isAgent: e.isAgent,
+    }));
+
+    // Resolve player entity (exact match → name match → fuzzy)
+    let playerEntityId: string | undefined;
+    if (playEntityName) {
+      let matched = worldState.getEntity(playEntityName);
+      if (!matched) {
+        for (const ent of rawEntities) {
+          const nameAttr = ent.attributes.get("name")?.getValue() as
+            string | undefined;
+          if (nameAttr?.toLowerCase() === playEntityName.toLowerCase()) {
+            matched = ent;
+            break;
+          }
+        }
+      }
+      if (!matched) {
+        for (const ent of rawEntities) {
+          const nameAttr = ent.attributes.get("name")?.getValue() as
+            string | undefined;
+          if (
+            nameAttr?.toLowerCase().includes(playEntityName.toLowerCase()) ||
+            ent.id.toLowerCase().includes(playEntityName.toLowerCase())
+          ) {
+            matched = ent;
+            break;
+          }
+        }
+      }
+      if (matched) {
+        playerEntityId = matched.id;
+        const info = entityInfos.find((e) => e.id === matched!.id);
+        if (info) info.isPlayer = true;
+      }
+    }
+
+    const mappings = ProviderManager.getMappings();
+    const {
+      actorProvider,
+      validatorProvider,
+      decoderProvider,
+      timedeltaProvider,
+      handoffProvider,
+      embeddingProvider,
+    } = resolveProviders(mappings, { fallbackInstance: activeInstance });
+
+    const architect = new Architect(
+      { validator: validatorProvider, timedelta: timedeltaProvider },
+      coreRepo,
+    );
+    const aliasGenerator = new AliasDeltaGenerator(actorProvider);
+
+    const session: SimSession = {
+      db,
+      dbPath,
+      coreRepo,
+      bufferRepo,
+      ledgerRepo,
+      worldInstanceId,
+      scenarioName: scenarioJson.name,
+      scenarioDescription: scenarioJson.description || "",
+      turn: 1,
+      maxTurns: 20,
+      entities: entityInfos,
+      playerEntityId,
+      entityIndex: 0,
+      actorProvider,
+      validatorProvider,
+      decoderProvider,
+      timedeltaProvider,
+      handoffProvider,
+      embeddingProvider,
+      architect,
+      aliasGenerator,
+      log: [],
+      status: "running",
+      aliasDoneForTurn: false,
+      providerMappings: mappings,
+    };
+
+    this.sessions.set(id, session);
+    return this.snapshot(session);
+  }
+
+  async load(id: string): Promise<SimSnapshot | null> {
+    const active = this.sessions.get(id);
+    if (active) return this.snapshot(active);
+
+    const dbPath = path.join(DATA_DIR, `${id}.db`);
+    if (!fs.existsSync(dbPath)) return null;
+
+    try {
+      const db = new Database(dbPath);
+      const state = loadSessionState(db, id);
+      if (!state) {
+        db.close();
+        return null;
+      }
+
+      const mappings = state.providerMappings || {};
+      const {
+        actorProvider,
+        validatorProvider,
+        decoderProvider,
+        timedeltaProvider,
+        handoffProvider,
+        embeddingProvider,
+      } = resolveProviders(mappings, { required: true });
+
+      const coreRepo = new SQLiteRepository(db);
+      const bufferRepo = new BufferRepository(db);
+      const ledgerRepo = new LedgerRepository(db);
+      const architect = new Architect(
+        { validator: validatorProvider, timedelta: timedeltaProvider },
+        coreRepo,
+      );
+      const aliasGenerator = new AliasDeltaGenerator(actorProvider);
+
+      const session: SimSession = {
+        db,
+        dbPath,
+        coreRepo,
+        bufferRepo,
+        ledgerRepo,
+        worldInstanceId: id,
+        scenarioName: state.scenarioName,
+        scenarioDescription: state.scenarioDescription,
+        turn: state.turn,
+        maxTurns: state.maxTurns,
+        entities: state.entities || [],
+        playerEntityId: state.playerEntityId,
+        entityIndex: state.entityIndex,
+        actorProvider,
+        validatorProvider,
+        decoderProvider,
+        timedeltaProvider,
+        handoffProvider,
+        embeddingProvider,
+        architect,
+        aliasGenerator,
+        log: state.log || [],
+        status: state.status,
+        error: state.error,
+        waitingEntity: state.waitingEntity,
+        aliasDoneForTurn: state.aliasDoneForTurn || false,
+        providerMappings: mappings,
+      };
+
+      this.sessions.set(id, session);
+      return this.snapshot(session);
+    } catch (err) {
+      console.error(`Failed to load session ${id}:`, err);
+      return null;
+    }
+  }
+
+  close(id: string): void {
+    const session = this.sessions.get(id);
+    if (session) {
+      session.db.close();
+      this.sessions.delete(id);
+    }
+  }
+
+  deleteSession(id: string): void {
+    const session = this.sessions.get(id);
+    if (session) {
+      session.db.close();
+      this.sessions.delete(id);
+    }
+    deleteSessionFile(id);
+  }
+
+  listSavedSessions(): SimSnapshot[] {
+    return listSavedSessions(this.sessions, (s) => this.snapshot(s));
+  }
+
+  getSnapshot(id: string): SimSnapshot | null {
+    const session = this.sessions.get(id);
+    return session ? this.snapshot(session) : null;
+  }
+
+  // ---------------------------------------------------------------------------
+  // Simulation stepping
+  // ---------------------------------------------------------------------------
+
+  async step(id: string): Promise<SimSnapshot | null> {
+    const session = this.sessions.get(id);
+    if (!session) return null;
+    if (session.status !== "running") return this.snapshot(session);
+
+    try {
+      if (session.turn > session.maxTurns) {
+        session.status = "done";
+        saveSession(session);
+        return this.snapshot(session);
+      }
+
+      // Start of turn: alias + handoff resolution before any entity acts
+      if (!session.aliasDoneForTurn && session.entityIndex === 0) {
+        await runAliasResolution(session);
+        await runHandoffResolution(session);
+        session.aliasDoneForTurn = true;
+        saveSession(session);
+        return this.snapshot(session);
+      }
+
+      // End of turn: advance to next turn
+      if (session.entityIndex >= session.entities.length) {
+        session.turn++;
+        session.entityIndex = 0;
+        session.aliasDoneForTurn = false;
+        saveSession(session);
+        return this.snapshot(session);
+      }
+
+      const info = session.entities[session.entityIndex];
+
+      if (!info.isAgent) {
+        session.entityIndex++;
+        saveSession(session);
+        return this.snapshot(session);
+      }
+
+      if (info.isPlayer) {
+        await preparePlayerTurn(session, info);
+        saveSession(session);
+        return this.snapshot(session);
+      }
+
+      await processNpcTurn(session, info);
+      session.entityIndex++;
+    } catch (err) {
+      session.status = "error";
+      session.error = err instanceof Error ? err.message : String(err);
+    }
+
+    saveSession(session);
+    return this.snapshot(session);
+  }
+
+  async submitPlayerAction(
+    id: string,
+    prose: string,
+  ): Promise<SimSnapshot | null> {
+    const session = this.sessions.get(id);
+    if (!session) return null;
+    if (session.status !== "waiting_player") return this.snapshot(session);
+    if (!session.waitingEntity) return this.snapshot(session);
+
+    const ctx = session.waitingEntity;
+    session.waitingEntity = undefined;
+    session.status = "running";
+
+    try {
+      await executePlayerAction(session, ctx, prose);
+      session.entityIndex++;
+    } catch (err) {
+      session.status = "error";
+      session.error = err instanceof Error ? err.message : String(err);
+    }
+
+    saveSession(session);
+    return this.snapshot(session);
+  }
+
+  // ---------------------------------------------------------------------------
+  // Utility
+  // ---------------------------------------------------------------------------
+
+  async regenerateAllEmbeddings(newProviderInstanceId?: string): Promise<void> {
+    if (!fs.existsSync(DATA_DIR)) return;
+
+    const files = fs
+      .readdirSync(DATA_DIR)
+      .filter((f) => f.startsWith("sim-") && f.endsWith(".db"));
+
+    const list = ProviderManager.list();
+    let inst = newProviderInstanceId
+      ? (list.find((p) => p.id === newProviderInstanceId) ?? null)
+      : null;
+    if (!inst || inst.type !== "embedding") {
+      inst = ProviderManager.getActive("embedding");
+    }
+
+    const key = inst ? inst.apiKey : process.env.GOOGLE_API_KEY || "";
+    const providerName = inst ? inst.providerName : "google-genai";
+    const modelName = inst ? inst.modelName : undefined;
+
+    const embeddingProvider: IEmbeddingProvider =
+      providerName === "google-genai"
+        ? new GeminiEmbeddingProvider(key, modelName)
+        : new MockEmbeddingProvider(modelName);
+
+    for (const file of files) {
+      const dbPath = path.join(DATA_DIR, file);
+      const fileId = file.replace(".db", "");
+      const activeSession = this.sessions.get(fileId);
+      const db = activeSession ? activeSession.db : new Database(dbPath);
+
+      try {
+        const rows = db
+          .prepare(`SELECT id, content FROM ledger_entries`)
+          .all() as { id: string; content: string }[];
+
+        for (const row of rows) {
+          const vector = await embeddingProvider.embed(row.content);
+          const buffer = Buffer.from(new Float32Array(vector).buffer);
+          db.prepare(
+            `UPDATE ledger_entries SET embedding = ? WHERE id = ?`,
+          ).run(buffer, row.id);
+        }
+      } catch (err) {
+        console.error(`Failed to regenerate embeddings for ${file}:`, err);
+      } finally {
+        if (!activeSession) db.close();
+      }
+    }
+  }
+
+  // ---------------------------------------------------------------------------
+  // Private
+  // ---------------------------------------------------------------------------
+
+  private snapshot(session: SimSession): SimSnapshot {
+    return {
+      id: session.worldInstanceId,
+      status: session.status,
+      turn: session.turn,
+      maxTurns: session.maxTurns,
+      scenarioName: session.scenarioName,
+      scenarioDescription: session.scenarioDescription,
+      entities: session.entities,
+      log: session.log,
+      entityIndex: session.entityIndex,
+      waitingEntity: session.waitingEntity,
+      error: session.error,
+    };
+  }
+}

apps/gui/src/lib/simulation/turn-executor.ts

@@ -0,0 +1,277 @@
+import {
+  ActorAgent,
+  ActorPromptBuilder,
+  buildBufferEntryForIntent,
+} from "@omnia/actor";
+import type { IActorProseGenerator } from "@omnia/actor";
+import type { SimSession } from "./types";
+import type {
+  EntityInfo,
+  IntentInfo,
+  LogEntry,
+  WaitingContext,
+} from "../simulation-types";
+
+// ---------------------------------------------------------------------------
+// Internal helpers
+// ---------------------------------------------------------------------------
+
+/** Prose generator that returns a fixed player-supplied string verbatim. */
+class FixedProseGenerator implements IActorProseGenerator {
+  constructor(private prose: string) {}
+
+  async generate(
+    entityId: string,
+    systemPrompt: string,
+    userContext: string,
+  ): Promise<string> {
+    void entityId;
+    void systemPrompt;
+    void userContext;
+    return this.prose;
+  }
+}
+
+/**
+ * Processes every intent produced by an actor turn:
+ * - Validates via Architect
+ * - Appends to actor's own buffer
+ * - Fan-outs to co-located observers for dialogue/action intents
+ *
+ * Extracted to eliminate verbatim duplication between NPC and player paths.
+ */
+async function processIntents(
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  intents: any[],
+  actorEntityId: string,
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  entity: any,
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  worldState: any,
+  session: SimSession,
+): Promise<IntentInfo[]> {
+  const intentInfos: IntentInfo[] = [];
+
+  for (const intent of intents) {
+    const outcome = await session.architect.processIntent(worldState, intent);
+    const ts = worldState.clock.get().toISOString();
+
+    intentInfos.push({
+      type: intent.type,
+      description: intent.description,
+      selfDescription: intent.selfDescription,
+      modifiers: intent.modifiers || [],
+      targetIds: intent.targetIds,
+      isValid: outcome.isValid,
+      reason: outcome.reason,
+      minutesToAdvance: outcome.timeDelta?.minutesToAdvance,
+    });
+
+    const actorEntry = buildBufferEntryForIntent(intent, ts, entity.locationId);
+    if (intent.type === "action") {
+      actorEntry.outcome = { isValid: outcome.isValid, reason: outcome.reason };
+    }
+    session.bufferRepo.save(actorEntry);
+
+    // Fan-out observable events to co-located entities
+    if (
+      entity.locationId &&
+      (intent.type === "dialogue" || intent.type === "action")
+    ) {
+      for (const [, other] of worldState.entities) {
+        if (
+          other.id !== actorEntityId &&
+          other.locationId === entity.locationId
+        ) {
+          const observerEntry = buildBufferEntryForIntent(
+            intent,
+            ts,
+            entity.locationId,
+          );
+          if (intent.type === "action") {
+            observerEntry.outcome = {
+              isValid: outcome.isValid,
+              reason: outcome.reason,
+            };
+          }
+          session.bufferRepo.save({ ...observerEntry, ownerId: other.id });
+        }
+      }
+    }
+  }
+
+  return intentInfos;
+}
+
+// ---------------------------------------------------------------------------
+// Exported turn functions
+// ---------------------------------------------------------------------------
+
+/**
+ * Builds the prompt for the player entity and sets the session to
+ * `waiting_player` so the next client call can supply the prose.
+ */
+export async function preparePlayerTurn(
+  session: SimSession,
+  info: EntityInfo,
+): Promise<void> {
+  const worldState = session.coreRepo.loadWorldState(session.worldInstanceId);
+  if (!worldState) throw new Error("World state lost");
+
+  const entity = worldState.getEntity(info.id);
+  if (!entity) throw new Error(`Entity "${info.id}" not found`);
+
+  const promptBuilder = new ActorPromptBuilder(
+    session.bufferRepo,
+    session.ledgerRepo,
+    20,
+  );
+  const { systemPrompt, userContext } = promptBuilder.build(worldState, entity);
+
+  session.waitingEntity = {
+    entityId: info.id,
+    name: info.name,
+    systemPrompt,
+    userContext,
+  };
+  session.status = "waiting_player";
+}
+
+/**
+ * Runs an autonomous NPC turn: generates prose via ActorAgent, validates
+ * and persists all intents, and appends a LogEntry to the session.
+ */
+export async function processNpcTurn(
+  session: SimSession,
+  info: EntityInfo,
+): Promise<void> {
+  const worldState = session.coreRepo.loadWorldState(session.worldInstanceId);
+  if (!worldState) throw new Error("World state lost");
+
+  const entity = worldState.getEntity(info.id);
+  if (!entity) throw new Error(`Entity "${info.id}" not found`);
+
+  const actor = new ActorAgent(
+    { actor: session.actorProvider, decoder: session.decoderProvider },
+    session.bufferRepo,
+    session.ledgerRepo,
+    20,
+  );
+  const result = await actor.act(worldState, entity);
+
+  const entry: LogEntry = {
+    turn: session.turn,
+    entityId: info.id,
+    entityName: info.name,
+    narrativeProse: result.narrativeProse,
+    intents: [],
+    timestamp: worldState.clock.get().toISOString(),
+  };
+
+  if (
+    session.actorProvider.lastCalls &&
+    session.actorProvider.lastCalls.length > 0
+  ) {
+    const actorCall =
+      session.actorProvider.lastCalls[
+        session.actorProvider.lastCalls.length - 1
+      ];
+    entry.rawPrompt = {
+      systemPrompt: actorCall.systemPrompt,
+      userContext: actorCall.userContext,
+    };
+    entry.usage = actorCall.usage;
+  }
+
+  if (
+    session.decoderProvider.lastCalls &&
+    session.decoderProvider.lastCalls.length > 0
+  ) {
+    const decoderCall =
+      session.decoderProvider.lastCalls[
+        session.decoderProvider.lastCalls.length - 1
+      ];
+    entry.decoderPrompt = {
+      systemPrompt: decoderCall.systemPrompt,
+      userContext: decoderCall.userContext,
+    };
+    entry.decoderUsage = decoderCall.usage;
+  }
+
+  entry.intents = await processIntents(
+    result.intents.intents,
+    info.id,
+    entity,
+    worldState,
+    session,
+  );
+
+  session.log.push(entry);
+  session.coreRepo.saveWorldState(worldState);
+}
+
+/**
+ * Executes the player's turn using the prose they supplied.
+ * Uses a `FixedProseGenerator` so the ActorAgent bypasses its LLM call and
+ * returns the player's text directly.
+ */
+export async function executePlayerAction(
+  session: SimSession,
+  ctx: WaitingContext,
+  prose: string,
+): Promise<void> {
+  const worldState = session.coreRepo.loadWorldState(session.worldInstanceId);
+  if (!worldState) throw new Error("World state lost");
+
+  const entity = worldState.getEntity(ctx.entityId);
+  if (!entity) throw new Error(`Player entity "${ctx.entityId}" not found`);
+
+  const playerActor = new ActorAgent(
+    { actor: session.actorProvider, decoder: session.decoderProvider },
+    session.bufferRepo,
+    session.ledgerRepo,
+    20,
+    new FixedProseGenerator(prose),
+  );
+
+  const result = await playerActor.act(worldState, entity);
+
+  const entry: LogEntry = {
+    turn: session.turn,
+    entityId: ctx.entityId,
+    entityName: ctx.name,
+    narrativeProse: result.narrativeProse,
+    intents: [],
+    timestamp: worldState.clock.get().toISOString(),
+    rawPrompt: {
+      systemPrompt: ctx.systemPrompt,
+      userContext: ctx.userContext,
+    },
+  };
+
+  if (
+    session.decoderProvider.lastCalls &&
+    session.decoderProvider.lastCalls.length > 0
+  ) {
+    const call =
+      session.decoderProvider.lastCalls[
+        session.decoderProvider.lastCalls.length - 1
+      ];
+    entry.decoderPrompt = {
+      systemPrompt: call.systemPrompt,
+      userContext: call.userContext,
+    };
+    entry.decoderUsage = call.usage;
+  }
+
+  entry.intents = await processIntents(
+    result.intents.intents,
+    ctx.entityId,
+    entity,
+    worldState,
+    session,
+  );
+
+  session.log.push(entry);
+  session.coreRepo.saveWorldState(worldState);
+}

apps/gui/src/lib/simulation/types.ts

@@ -0,0 +1,68 @@
+import type Database from "better-sqlite3";
+import type { SQLiteRepository } from "@omnia/core";
+import type { BufferRepository, LedgerRepository } from "@omnia/memory";
+import type { Architect, AliasDeltaGenerator } from "@omnia/architect";
+import type { ILLMProvider, IEmbeddingProvider } from "@omnia/llm";
+import type { EntityInfo, LogEntry, WaitingContext } from "../simulation-types";
+
+export type {
+  EntityInfo,
+  IntentInfo,
+  LogEntry,
+  SimSnapshot,
+  WaitingContext,
+} from "../simulation-types";
+
+// ---------------------------------------------------------------------------
+// Persisted state (written to sqlite gui_meta table as JSON)
+// ---------------------------------------------------------------------------
+
+export interface SavedState {
+  scenarioName: string;
+  scenarioDescription: string;
+  turn: number;
+  maxTurns: number;
+  entities: EntityInfo[];
+  playerEntityId: string | undefined;
+  entityIndex: number;
+  status: "running" | "waiting_player" | "done" | "error";
+  error?: string;
+  waitingEntity?: WaitingContext;
+  aliasDoneForTurn: boolean;
+  log: LogEntry[];
+  providerMappings: Record<string, string>;
+}
+
+// ---------------------------------------------------------------------------
+// In-memory session (held in SimulationManager.sessions Map)
+// ---------------------------------------------------------------------------
+
+export interface SimSession {
+  db: Database.Database;
+  dbPath: string;
+  coreRepo: SQLiteRepository;
+  bufferRepo: BufferRepository;
+  ledgerRepo: LedgerRepository;
+  worldInstanceId: string;
+  scenarioName: string;
+  scenarioDescription: string;
+  turn: number;
+  maxTurns: number;
+  entities: EntityInfo[];
+  playerEntityId: string | undefined;
+  entityIndex: number;
+  actorProvider: ILLMProvider;
+  validatorProvider: ILLMProvider;
+  decoderProvider: ILLMProvider;
+  timedeltaProvider: ILLMProvider;
+  handoffProvider: ILLMProvider;
+  embeddingProvider: IEmbeddingProvider;
+  architect: Architect;
+  aliasGenerator: AliasDeltaGenerator;
+  log: LogEntry[];
+  status: "running" | "waiting_player" | "done" | "error";
+  error?: string;
+  waitingEntity?: WaitingContext;
+  aliasDoneForTurn: boolean;
+  providerMappings: Record<string, string>;
+}