diff --git a/README.md b/README.md
index 05aad33..3e070d7 100644
--- a/README.md
+++ b/README.md
@@ -34,6 +34,21 @@ bun run check
 bun run build
 ```
 
+## Source layout
+
+The library is now grouped by domain under `src/`:
+
+- `src/core/` — shared adapter, type, and IdentityDB helper contracts
+- `src/persona/` — persona initialization service
+- `src/schedule/` — schedule generation and pruning service
+- `src/availability/` — availability state service
+- `src/conversation/` — DM turn orchestration service
+- `src/memory/` — fact-draft persistence service
+- `src/timing/` — typing/reply timing profile helpers
+- `src/providers/grok/` — Grok API client and adapter bundle
+
+Each domain now exposes a class-based service API in addition to the existing functional helpers so consumers can organize stateful integrations more cleanly.
+
 ## Release
 
 Tagging `vX.Y.Z` or `X.Y.Z` triggers the Gitea npm release workflow under `.gitea/workflows/npm-release.yml`.
diff --git a/src/availability.ts b/src/availability/index.ts
similarity index 87%
rename from src/availability.ts
rename to src/availability/index.ts
index adbb7f7..a885a29 100644
--- a/src/availability.ts
+++ b/src/availability/index.ts
@@ -1,13 +1,13 @@
 import { randomUUID } from 'node:crypto';
 import type { Fact, IdentityDB, JsonValue } from 'identitydb';
-import { dateOnly, getFactDomain, getJsonObject, jsonObject, listFactsInSpace } from './facts';
-import { persistFactDrafts } from './memory';
+import { dateOnly, getFactDomain, getJsonObject, jsonObject, listFactsInSpace } from '../core/facts';
+import { persistFactDrafts } from '../memory';
 import type {
   BoxBrainAvailabilityEntry,
   BoxBrainAvailabilityMode,
   BoxBrainAvailabilitySnapshot,
   BoxBrainAvailabilitySourceType,
-} from './types';
+} from '../core/types';
 
 export interface SetAvailabilityStatusInput {
   spaceName: string;
@@ -35,7 +35,27 @@ const EXPLICIT_SOURCE_PRIORITY: Record<Exclude<BoxBrainAvailabilitySourceType, '
   tool: 3,
 };
 
+export class AvailabilityService {
+  constructor(private readonly db: IdentityDB) {}
+
+  async setStatus(input: SetAvailabilityStatusInput): Promise<BoxBrainAvailabilityEntry> {
+    return setAvailabilityStatusWithDb(this.db, input);
+  }
+
+  async listEntries(input: ListAvailabilityEntriesInput): Promise<BoxBrainAvailabilityEntry[]> {
+    return listAvailabilityEntriesWithDb(this.db, input);
+  }
+
+  async getSnapshot(input: GetAvailabilitySnapshotInput): Promise<BoxBrainAvailabilitySnapshot> {
+    return getAvailabilitySnapshotWithDb(this.db, input);
+  }
+}
+
 export async function setAvailabilityStatus(db: IdentityDB, input: SetAvailabilityStatusInput): Promise<BoxBrainAvailabilityEntry> {
+  return new AvailabilityService(db).setStatus(input);
+}
+
+async function setAvailabilityStatusWithDb(db: IdentityDB, input: SetAvailabilityStatusInput): Promise<BoxBrainAvailabilityEntry> {
   assertAvailabilityMode(input.mode);
   assertChronology(input.effectiveFrom, input.until);
 
@@ -80,6 +100,13 @@ export async function setAvailabilityStatus(db: IdentityDB, input: SetAvailabili
 export async function listAvailabilityEntries(
   db: IdentityDB,
   input: ListAvailabilityEntriesInput,
+): Promise<BoxBrainAvailabilityEntry[]> {
+  return new AvailabilityService(db).listEntries(input);
+}
+
+async function listAvailabilityEntriesWithDb(
+  db: IdentityDB,
+  input: ListAvailabilityEntriesInput,
 ): Promise<BoxBrainAvailabilityEntry[]> {
   const facts = await listFactsInSpace(db, input.spaceName);
   const deletedScheduleEventIds = collectDeletedScheduleEventIds(facts);
@@ -94,6 +121,13 @@ export async function listAvailabilityEntries(
 export async function getAvailabilitySnapshot(
   db: IdentityDB,
   input: GetAvailabilitySnapshotInput,
+): Promise<BoxBrainAvailabilitySnapshot> {
+  return new AvailabilityService(db).getSnapshot(input);
+}
+
+async function getAvailabilitySnapshotWithDb(
+  db: IdentityDB,
+  input: GetAvailabilitySnapshotInput,
 ): Promise<BoxBrainAvailabilitySnapshot> {
   const entries = await listAvailabilityEntries(db, { spaceName: input.spaceName });
   const current = selectAvailabilityAt(entries, input.at) ?? createDefaultOnlineAvailability(input.at);
diff --git a/src/conversation.ts b/src/conversation/index.ts
similarity index 93%
rename from src/conversation.ts
rename to src/conversation/index.ts
index 825f263..82da346 100644
--- a/src/conversation.ts
+++ b/src/conversation/index.ts
@@ -1,10 +1,10 @@
 import { randomUUID } from 'node:crypto';
 import type { Fact, IdentityDB, JsonValue } from 'identitydb';
-import type { StructuredModelAdapter } from './adapters';
-import { getAvailabilitySnapshot, setAvailabilityStatus } from './availability';
-import { dateOnly, getFactDomain, getJsonObject, jsonObject, listFactsInSpace, resolvePersonaProfile, shiftIsoDate } from './facts';
-import { persistFactDrafts } from './memory';
-import { createReplyDelay, createTypingDelay } from './timing';
+import type { StructuredModelAdapter } from '../core/adapters';
+import { getAvailabilitySnapshot, setAvailabilityStatus } from '../availability';
+import { dateOnly, getFactDomain, getJsonObject, jsonObject, listFactsInSpace, resolvePersonaProfile, shiftIsoDate } from '../core/facts';
+import { persistFactDrafts } from '../memory';
+import { createReplyDelay, createTypingDelay } from '../timing';
 import type {
   BoxBrainAvailabilityMode,
   BoxBrainConversationDirection,
@@ -12,7 +12,7 @@ import type {
   BoxBrainMemoryReference,
   BoxBrainMessage,
   BoxBrainToolCall,
-} from './types';
+} from '../core/types';
 
 export interface ConversationMemorySelectionResult {
   memoryIds: string[];
@@ -70,7 +70,27 @@ export interface ListConversationEntriesInput {
   until?: string | undefined;
 }
 
+export class ConversationService {
+  constructor(private readonly db: IdentityDB) {}
+
+  async reply(input: ReplyToConversationInput): Promise<ConversationTurnResult> {
+    return replyToConversationWithDb(this.db, input);
+  }
+
+  async start(input: StartConversationInput): Promise<ConversationTurnResult> {
+    return startConversationWithDb(this.db, input);
+  }
+
+  async listEntries(input: ListConversationEntriesInput): Promise<BoxBrainConversationEntry[]> {
+    return listConversationEntriesWithDb(this.db, input);
+  }
+}
+
 export async function replyToConversation(db: IdentityDB, input: ReplyToConversationInput): Promise<ConversationTurnResult> {
+  return new ConversationService(db).reply(input);
+}
+
+async function replyToConversationWithDb(db: IdentityDB, input: ReplyToConversationInput): Promise<ConversationTurnResult> {
   const turnId = randomUUID();
   await persistConversationEntry(db, {
     spaceName: input.spaceName,
@@ -93,6 +113,10 @@ export async function replyToConversation(db: IdentityDB, input: ReplyToConversa
 }
 
 export async function startConversation(db: IdentityDB, input: StartConversationInput): Promise<ConversationTurnResult> {
+  return new ConversationService(db).start(input);
+}
+
+async function startConversationWithDb(db: IdentityDB, input: StartConversationInput): Promise<ConversationTurnResult> {
   return generateConversationTurn(db, {
     ...input,
     proactive: true,
@@ -103,6 +127,13 @@ export async function startConversation(db: IdentityDB, input: StartConversation
 export async function listConversationEntries(
   db: IdentityDB,
   input: ListConversationEntriesInput,
+): Promise<BoxBrainConversationEntry[]> {
+  return new ConversationService(db).listEntries(input);
+}
+
+async function listConversationEntriesWithDb(
+  db: IdentityDB,
+  input: ListConversationEntriesInput,
 ): Promise<BoxBrainConversationEntry[]> {
   const facts = await listFactsInSpace(db, input.spaceName);
   return facts
diff --git a/src/adapters.ts b/src/core/adapters.ts
similarity index 100%
rename from src/adapters.ts
rename to src/core/adapters.ts
diff --git a/src/facts.ts b/src/core/facts.ts
similarity index 100%
rename from src/facts.ts
rename to src/core/facts.ts
diff --git a/src/types.ts b/src/core/types.ts
similarity index 100%
rename from src/types.ts
rename to src/core/types.ts
diff --git a/src/index.ts b/src/index.ts
index 9ca629b..6818985 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,9 +1,9 @@
-export * from './adapters';
+export * from './core/adapters';
+export * from './core/types';
 export * from './availability';
 export * from './conversation';
-export * from './grok';
 export * from './memory';
 export * from './persona';
+export * from './providers/grok';
 export * from './schedule';
 export * from './timing';
-export * from './types';
diff --git a/src/memory.ts b/src/memory/index.ts
similarity index 81%
rename from src/memory.ts
rename to src/memory/index.ts
index 4d109f3..be81200 100644
--- a/src/memory.ts
+++ b/src/memory/index.ts
@@ -1,5 +1,5 @@
 import type { AddFactInput, Fact, IdentityDB, JsonValue, TopicCategory } from 'identitydb';
-import type { BoxBrainFactDomain, BoxBrainFactDraft, BoxBrainTopicDraft } from './types';
+import type { BoxBrainFactDomain, BoxBrainFactDraft, BoxBrainTopicDraft } from '../core/types';
 
 export interface PersistFactDraftsInput {
   spaceName: string;
@@ -10,19 +10,27 @@ export interface PersistFactDraftsInput {
 
 const IDENTITYDB_TOPIC_CATEGORIES = new Set<TopicCategory>(['entity', 'concept', 'temporal', 'custom']);
 
+export class FactDraftMemoryStore {
+  constructor(private readonly db: IdentityDB) {}
+
+  async persist(input: PersistFactDraftsInput): Promise<Fact[]> {
+    if (input.facts.length === 0) {
+      return [];
+    }
+
+    await this.db.upsertSpace({ name: input.spaceName });
+
+    const persisted: Fact[] = [];
+    for (const draft of input.facts) {
+      persisted.push(await this.db.addFact(toAddFactInput(draft, input)));
+    }
+
+    return persisted;
+  }
+}
+
 export async function persistFactDrafts(db: IdentityDB, input: PersistFactDraftsInput): Promise<Fact[]> {
-  if (input.facts.length === 0) {
-    return [];
-  }
-
-  await db.upsertSpace({ name: input.spaceName });
-
-  const persisted: Fact[] = [];
-  for (const draft of input.facts) {
-    persisted.push(await db.addFact(toAddFactInput(draft, input)));
-  }
-
-  return persisted;
+  return new FactDraftMemoryStore(db).persist(input);
 }
 
 function toAddFactInput(draft: BoxBrainFactDraft, input: PersistFactDraftsInput): AddFactInput {
diff --git a/src/persona.ts b/src/persona/index.ts
similarity index 95%
rename from src/persona.ts
rename to src/persona/index.ts
index 596b2ee..46c72dd 100644
--- a/src/persona.ts
+++ b/src/persona/index.ts
@@ -1,8 +1,8 @@
 import { randomUUID } from 'node:crypto';
 import type { IdentityDB } from 'identitydb';
-import type { ImageModelAdapter, StructuredModelAdapter } from './adapters';
-import { persistFactDrafts } from './memory';
-import type { BoxBrainFactDraft, BoxBrainPersonaProfile } from './types';
+import type { ImageModelAdapter, StructuredModelAdapter } from '../core/adapters';
+import { persistFactDrafts } from '../memory';
+import type { BoxBrainFactDraft, BoxBrainPersonaProfile } from '../core/types';
 
 export interface PersonaRelationshipInput {
   name: string;
@@ -74,7 +74,19 @@ const PERSONA_FACT_EXTRACTION_SCHEMA = {
   },
 } as const;
 
+export class PersonaService {
+  constructor(private readonly db: IdentityDB) {}
+
+  async initialize(input: InitializePersonaInput): Promise<InitializedPersona> {
+    return initializePersonaWithDb(this.db, input);
+  }
+}
+
 export async function initializePersona(db: IdentityDB, input: InitializePersonaInput): Promise<InitializedPersona> {
+  return new PersonaService(db).initialize(input);
+}
+
+async function initializePersonaWithDb(db: IdentityDB, input: InitializePersonaInput): Promise<InitializedPersona> {
   assertPersonaInitializationInput(input);
 
   const id = input.id ?? createPersonaId(input.displayName);
diff --git a/src/grok.ts b/src/providers/grok/index.ts
similarity index 83%
rename from src/grok.ts
rename to src/providers/grok/index.ts
index 7661744..003649c 100644
--- a/src/grok.ts
+++ b/src/providers/grok/index.ts
@@ -5,7 +5,7 @@ import type {
   StructuredModelAdapter,
   TextGenerationRequest,
   TextModelAdapter,
-} from './adapters';
+} from '../../core/adapters';
 
 type GrokFetch = typeof fetch;
 
@@ -32,6 +32,43 @@ export interface GrokAdapterBundleOptions {
 const DEFAULT_BASE_URL = 'https://api.x.ai/v1';
 const GROK_PROVIDER = 'xai-grok';
 
+export class GrokApiClient {
+  private readonly baseUrl: string;
+  private readonly fetchImpl: GrokFetch;
+
+  constructor(private readonly options: Pick<GrokAdapterOptions, 'apiKey' | 'baseUrl' | 'fetch' | 'extraHeaders'>) {
+    this.baseUrl = (options.baseUrl ?? DEFAULT_BASE_URL).replace(/\/$/, '');
+    const fetchImpl = options.fetch ?? globalThis.fetch;
+    if (!fetchImpl) {
+      throw new Error('Grok adapter requires a fetch implementation.');
+    }
+    this.fetchImpl = fetchImpl;
+  }
+
+  async postJson(path: string, body: JsonObject): Promise<JsonObject> {
+    const response = await this.fetchImpl(`${this.baseUrl}${path}`, {
+      method: 'POST',
+      headers: {
+        authorization: `Bearer ${this.options.apiKey}`,
+        'content-type': 'application/json',
+        ...(this.options.extraHeaders ?? {}),
+      },
+      body: JSON.stringify(removeUndefined(body)),
+    });
+
+    const text = await response.text();
+    const parsed = text.length > 0 ? tryParseJson(text) : {};
+    if (!response.ok) {
+      throw new Error(`Grok API request failed (${response.status}): ${text}`);
+    }
+    if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
+      throw new Error('Grok API response must be a JSON object.');
+    }
+
+    return parsed;
+  }
+}
+
 export function createGrokTextModelAdapter(options: GrokAdapterOptions): TextModelAdapter {
   const runtime = createRuntime(options);
 
@@ -132,39 +169,8 @@ export function createGrokAdapters(options: GrokAdapterBundleOptions): {
   };
 }
 
-function createRuntime(options: Pick<GrokAdapterOptions, 'apiKey' | 'baseUrl' | 'fetch' | 'extraHeaders'>): {
-  postJson: (path: string, body: JsonObject) => Promise<JsonObject>;
-} {
-  const baseUrl = (options.baseUrl ?? DEFAULT_BASE_URL).replace(/\/$/, '');
-  const fetchImpl = options.fetch ?? globalThis.fetch;
-  if (!fetchImpl) {
-    throw new Error('Grok adapter requires a fetch implementation.');
-  }
-
-  return {
-    async postJson(path, body) {
-      const response = await fetchImpl(`${baseUrl}${path}`, {
-        method: 'POST',
-        headers: {
-          authorization: `Bearer ${options.apiKey}`,
-          'content-type': 'application/json',
-          ...(options.extraHeaders ?? {}),
-        },
-        body: JSON.stringify(removeUndefined(body)),
-      });
-
-      const text = await response.text();
-      const parsed = text.length > 0 ? tryParseJson(text) : {};
-      if (!response.ok) {
-        throw new Error(`Grok API request failed (${response.status}): ${text}`);
-      }
-      if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
-        throw new Error('Grok API response must be a JSON object.');
-      }
-
-      return parsed;
-    },
-  };
+function createRuntime(options: Pick<GrokAdapterOptions, 'apiKey' | 'baseUrl' | 'fetch' | 'extraHeaders'>): GrokApiClient {
+  return new GrokApiClient(options);
 }
 
 function buildMessages(system: string | undefined, prompt: string): Array<{ role: 'system' | 'user'; content: string }> {
diff --git a/src/schedule.ts b/src/schedule/index.ts
similarity index 89%
rename from src/schedule.ts
rename to src/schedule/index.ts
index d903a2f..ffa1aa4 100644
--- a/src/schedule.ts
+++ b/src/schedule/index.ts
@@ -1,9 +1,9 @@
 import { randomUUID } from 'node:crypto';
 import type { Fact, IdentityDB, JsonValue } from 'identitydb';
-import type { SpecialDateProvider, StructuredModelAdapter } from './adapters';
-import { setAvailabilityStatus } from './availability';
-import { dateOnly, getFactDomain, getJsonObject, jsonObject, listFactsInSpace, uniqueStrings } from './facts';
-import { persistFactDrafts } from './memory';
+import type { SpecialDateProvider, StructuredModelAdapter } from '../core/adapters';
+import { setAvailabilityStatus } from '../availability';
+import { dateOnly, getFactDomain, getJsonObject, jsonObject, listFactsInSpace, uniqueStrings } from '../core/facts';
+import { persistFactDrafts } from '../memory';
 import type {
   BoxBrainAvailabilityMode,
   BoxBrainAvailabilityEntry,
@@ -11,7 +11,7 @@ import type {
   BoxBrainScheduleEventKind,
   BoxBrainScheduleScope,
   BoxBrainTopicDraft,
-} from './types';
+} from '../core/types';
 
 export interface ScheduleEventDraft {
   title: string;
@@ -60,9 +60,36 @@ export interface SchedulePruneResult {
   deletedEventIds: string[];
 }
 
+export class ScheduleService {
+  constructor(private readonly db: IdentityDB) {}
+
+  async generate(input: GenerateScheduleInput): Promise<{ events: BoxBrainScheduleEvent[]; availabilityEntries: BoxBrainAvailabilityEntry[] }> {
+    return generateScheduleWithDb(this.db, input);
+  }
+
+  async listEvents(input: ListScheduleEventsInput): Promise<BoxBrainScheduleEvent[]> {
+    return listScheduleEventsWithDb(this.db, input);
+  }
+
+  async pruneExpired(input: PruneExpiredScheduleInput): Promise<SchedulePruneResult> {
+    return pruneExpiredScheduleWithDb(this.db, input);
+  }
+
+  async pruneBefore(input: PruneScheduleBeforeInput): Promise<SchedulePruneResult> {
+    return pruneScheduleBeforeWithDb(this.db, input);
+  }
+}
+
 export async function generateSchedule(
   db: IdentityDB,
   input: GenerateScheduleInput,
+): Promise<{ events: BoxBrainScheduleEvent[]; availabilityEntries: BoxBrainAvailabilityEntry[] }> {
+  return new ScheduleService(db).generate(input);
+}
+
+async function generateScheduleWithDb(
+  db: IdentityDB,
+  input: GenerateScheduleInput,
 ): Promise<{ events: BoxBrainScheduleEvent[]; availabilityEntries: BoxBrainAvailabilityEntry[] }> {
   await ensurePersonaSpace(db, input.spaceName, input.displayName);
 
@@ -134,6 +161,10 @@ export async function generateSchedule(
 }
 
 export async function listScheduleEvents(db: IdentityDB, input: ListScheduleEventsInput): Promise<BoxBrainScheduleEvent[]> {
+  return new ScheduleService(db).listEvents(input);
+}
+
+async function listScheduleEventsWithDb(db: IdentityDB, input: ListScheduleEventsInput): Promise<BoxBrainScheduleEvent[]> {
   const facts = await listFactsInSpace(db, input.spaceName);
   const deletedIds = new Set(
     facts
@@ -156,6 +187,10 @@ export async function listScheduleEvents(db: IdentityDB, input: ListScheduleEven
 }
 
 export async function pruneExpiredSchedule(db: IdentityDB, input: PruneExpiredScheduleInput): Promise<SchedulePruneResult> {
+  return new ScheduleService(db).pruneExpired(input);
+}
+
+async function pruneExpiredScheduleWithDb(db: IdentityDB, input: PruneExpiredScheduleInput): Promise<SchedulePruneResult> {
   const graceMs = (input.graceSeconds ?? 0) * 1000;
   const cutoffMs = Date.parse(input.referenceTime) - graceMs;
   const events = await listScheduleEvents(db, { spaceName: input.spaceName });
@@ -166,6 +201,10 @@ export async function pruneExpiredSchedule(db: IdentityDB, input: PruneExpiredSc
 }
 
 export async function pruneScheduleBefore(db: IdentityDB, input: PruneScheduleBeforeInput): Promise<SchedulePruneResult> {
+  return new ScheduleService(db).pruneBefore(input);
+}
+
+async function pruneScheduleBeforeWithDb(db: IdentityDB, input: PruneScheduleBeforeInput): Promise<SchedulePruneResult> {
   const cutoffMs = Date.parse(input.before);
   const events = await listScheduleEvents(db, { spaceName: input.spaceName });
   const toDelete = events.filter((event) => Date.parse(event.startAt) < cutoffMs);
diff --git a/src/timing.ts b/src/timing.ts
deleted file mode 100644
index 14ef531..0000000
--- a/src/timing.ts
+++ /dev/null
@@ -1,78 +0,0 @@
-import type { BoxBrainAvailability } from './types';
-
-export type RandomSource = () => number;
-
-export interface TypingDelayOptions {
-  rng?: RandomSource | undefined;
-  minSecondsPerCharacter?: number | undefined;
-  maxSecondsPerCharacter?: number | undefined;
-}
-
-export interface ReplyDelayOptions {
-  isFirstReplyInExchange: boolean;
-  rng?: RandomSource | undefined;
-  onlineMinSeconds?: number | undefined;
-  onlineMaxSeconds?: number | undefined;
-  dndReplyProbability?: number | undefined;
-  dndMinSeconds?: number | undefined;
-  dndMaxSeconds?: number | undefined;
-}
-
-export const ONLINE_AVAILABILITY: BoxBrainAvailability = { mode: 'online' };
-export const DND_AVAILABILITY: BoxBrainAvailability = { mode: 'do_not_disturb' };
-export const OFFLINE_AVAILABILITY: BoxBrainAvailability = { mode: 'offline' };
-
-export function createTypingDelay(message: string, options: TypingDelayOptions = {}): number {
-  if (message.length === 0) {
-    return 0;
-  }
-
-  const rng = options.rng ?? Math.random;
-  const min = options.minSecondsPerCharacter ?? 0.05;
-  const max = options.maxSecondsPerCharacter ?? 0.08;
-  const secondsPerCharacter = interpolate(min, max, clampUnit(rng()));
-
-  return roundSeconds(message.length * secondsPerCharacter);
-}
-
-export function createReplyDelay(
-  availability: BoxBrainAvailability,
-  options: ReplyDelayOptions,
-): number | null {
-  if (availability.mode === 'offline') {
-    return null;
-  }
-
-  if (!options.isFirstReplyInExchange) {
-    return 0;
-  }
-
-  const rng = options.rng ?? Math.random;
-
-  if (availability.mode === 'do_not_disturb') {
-    const probability = options.dndReplyProbability ?? 0.2;
-    if (clampUnit(rng()) > probability) {
-      return null;
-    }
-
-    return roundSeconds(interpolate(options.dndMinSeconds ?? 60, options.dndMaxSeconds ?? 600, clampUnit(rng())));
-  }
-
-  return roundSeconds(interpolate(options.onlineMinSeconds ?? 1, options.onlineMaxSeconds ?? 12, clampUnit(rng())));
-}
-
-function interpolate(min: number, max: number, ratio: number): number {
-  return min + (max - min) * ratio;
-}
-
-function clampUnit(value: number): number {
-  if (Number.isNaN(value)) {
-    return 0;
-  }
-
-  return Math.min(1, Math.max(0, value));
-}
-
-function roundSeconds(value: number): number {
-  return Math.round(value * 1_000_000) / 1_000_000;
-}
diff --git a/src/timing/index.ts b/src/timing/index.ts
new file mode 100644
index 0000000..e58dbab
--- /dev/null
+++ b/src/timing/index.ts
@@ -0,0 +1,87 @@
+import type { BoxBrainAvailability } from '../core/types';
+
+export type RandomSource = () => number;
+
+export interface TypingDelayOptions {
+  rng?: RandomSource | undefined;
+  minSecondsPerCharacter?: number | undefined;
+  maxSecondsPerCharacter?: number | undefined;
+}
+
+export interface ReplyDelayOptions {
+  isFirstReplyInExchange: boolean;
+  rng?: RandomSource | undefined;
+  onlineMinSeconds?: number | undefined;
+  onlineMaxSeconds?: number | undefined;
+  dndReplyProbability?: number | undefined;
+  dndMinSeconds?: number | undefined;
+  dndMaxSeconds?: number | undefined;
+}
+
+export const ONLINE_AVAILABILITY: BoxBrainAvailability = { mode: 'online' };
+export const DND_AVAILABILITY: BoxBrainAvailability = { mode: 'do_not_disturb' };
+export const OFFLINE_AVAILABILITY: BoxBrainAvailability = { mode: 'offline' };
+
+export class TimingProfile {
+  createTypingDelay(message: string, options: TypingDelayOptions = {}): number {
+    if (message.length === 0) {
+      return 0;
+    }
+
+    const rng = options.rng ?? Math.random;
+    const min = options.minSecondsPerCharacter ?? 0.05;
+    const max = options.maxSecondsPerCharacter ?? 0.08;
+    const secondsPerCharacter = interpolate(min, max, clampUnit(rng()));
+
+    return roundSeconds(message.length * secondsPerCharacter);
+  }
+
+  createReplyDelay(availability: BoxBrainAvailability, options: ReplyDelayOptions): number | null {
+    if (availability.mode === 'offline') {
+      return null;
+    }
+
+    if (!options.isFirstReplyInExchange) {
+      return 0;
+    }
+
+    const rng = options.rng ?? Math.random;
+
+    if (availability.mode === 'do_not_disturb') {
+      const probability = options.dndReplyProbability ?? 0.2;
+      if (clampUnit(rng()) > probability) {
+        return null;
+      }
+
+      return roundSeconds(interpolate(options.dndMinSeconds ?? 60, options.dndMaxSeconds ?? 600, clampUnit(rng())));
+    }
+
+    return roundSeconds(interpolate(options.onlineMinSeconds ?? 1, options.onlineMaxSeconds ?? 12, clampUnit(rng())));
+  }
+}
+
+const DEFAULT_TIMING_PROFILE = new TimingProfile();
+
+export function createTypingDelay(message: string, options: TypingDelayOptions = {}): number {
+  return DEFAULT_TIMING_PROFILE.createTypingDelay(message, options);
+}
+
+export function createReplyDelay(availability: BoxBrainAvailability, options: ReplyDelayOptions): number | null {
+  return DEFAULT_TIMING_PROFILE.createReplyDelay(availability, options);
+}
+
+function interpolate(min: number, max: number, ratio: number): number {
+  return min + (max - min) * ratio;
+}
+
+function clampUnit(value: number): number {
+  if (Number.isNaN(value)) {
+    return 0;
+  }
+
+  return Math.min(1, Math.max(0, value));
+}
+
+function roundSeconds(value: number): number {
+  return Math.round(value * 1_000_000) / 1_000_000;
+}
diff --git a/tests/public-api.test.ts b/tests/public-api.test.ts
index 4403d50..c2a2ea6 100644
--- a/tests/public-api.test.ts
+++ b/tests/public-api.test.ts
@@ -10,6 +10,13 @@ import {
   type SpecialDateProvider,
   type TextModelAdapter,
 } from '../src';
+import { AvailabilityService } from '../src/availability';
+import { ConversationService } from '../src/conversation';
+import { FactDraftMemoryStore } from '../src/memory';
+import { PersonaService } from '../src/persona';
+import { GrokApiClient } from '../src/providers/grok';
+import { ScheduleService } from '../src/schedule';
+import { TimingProfile } from '../src/timing';
 
 describe('public API', () => {
   it('exports timing helpers and runtime availability constants', () => {
@@ -39,7 +46,7 @@ describe('public API', () => {
     expect(fact.topics.map((topic) => topic.name)).toEqual(['Mina', 'quiet cafés']);
   });
 
-  it('exports schedule, conversation, Grok, and external special-date adapter contracts', () => {
+  it('exports grouped service classes and provider runtime helpers', () => {
     const specialDateProvider: SpecialDateProvider = {
       async listSpecialDates() {
         return [{ date: '2026-05-08', title: 'Parents Day' }];
@@ -50,5 +57,13 @@ describe('public API', () => {
     expect(typeof replyToConversation).toBe('function');
     expect(typeof createGrokAdapters).toBe('function');
     expect(specialDateProvider.listSpecialDates).toBeTypeOf('function');
+
+    expect(AvailabilityService).toBeTypeOf('function');
+    expect(ConversationService).toBeTypeOf('function');
+    expect(FactDraftMemoryStore).toBeTypeOf('function');
+    expect(PersonaService).toBeTypeOf('function');
+    expect(GrokApiClient).toBeTypeOf('function');
+    expect(ScheduleService).toBeTypeOf('function');
+    expect(TimingProfile).toBeTypeOf('function');
   });
 });