refactor(gateway): drop shared barrel, migrate to granular imports + shared error helpers

- delete src/shared/index.ts fat barrel; point 10 importers at the exact
  module they use (redis-channels, moderation-types, utils/pagination)
- message-capture/types.ts re-exports from shared/moderation-types directly
- shared/errors: add errorMessage() + isTransientStreamError() helpers,
  replacing the repeated err-message and transient-code checks
- drop unused imports flagged by biome

No behavior change. typecheck + lint + 138 tests green.

services/discord-gateway/src/app/retention.ts

@@ -1,8 +1,5 @@
 import { inArray, lt } from "drizzle-orm";
-import type {
-  NodePgDatabase,
-  NodePgQueryResultHKT,
-} from "drizzle-orm/node-postgres";
+import type { NodePgDatabase } from "drizzle-orm/node-postgres";
 import { createChildLogger } from "@/shared/logger/index";
 import { config } from "../shared/config/index.js";
 import { getDatabase } from "../shared/database/drizzle.js";

services/discord-gateway/src/modules/command-handler/commandHandler.ts

@@ -1,12 +1,12 @@
 import type { Client } from "discord.js-selfbot-v13";
 import Redis from "ioredis";
 import { config } from "../../shared/config/index.js";
+import { createChildLogger } from "../../shared/logger/index.js";
 import {
   BACKEND_COMMAND,
   type CommandMessage,
   type CommandReply,
-} from "../../shared/index.js";
-import { createChildLogger } from "../../shared/logger/index.js";
+} from "../../shared/redis-channels.js";
 import { GuildHandler } from "./guild.handler.js";
 import {
   type CommandHandlerFn,

services/discord-gateway/src/modules/command-handler/guild.handler.ts

@@ -1,6 +1,9 @@
 import type { Client } from "discord.js-selfbot-v13";
-import type { CommandMessage, CommandReply } from "../../shared/index.js";
 import { createChildLogger } from "../../shared/logger/index.js";
+import type {
+  CommandMessage,
+  CommandReply,
+} from "../../shared/redis-channels.js";
 
 // ---------------------------------------------------------------------------
 // GuildHandler

services/discord-gateway/src/modules/command-handler/handler-registry.ts

@@ -4,7 +4,7 @@ import {
   COMMAND_MODERATION_ACTION,
   type CommandMessage,
   type CommandReply,
-} from "../../shared/index.js";
+} from "../../shared/redis-channels.js";
 import type { GuildHandler } from "./guild.handler.js";
 import type { ModerationHandler } from "./moderation.handler.js";
 

services/discord-gateway/src/modules/command-handler/moderation.handler.ts

@@ -1,6 +1,9 @@
 import type { Client } from "discord.js-selfbot-v13";
-import type { CommandMessage, CommandReply } from "../../shared/index.js";
 import { createChildLogger } from "../../shared/logger/index.js";
+import type {
+  CommandMessage,
+  CommandReply,
+} from "../../shared/redis-channels.js";
 import { messageStore } from "../message-capture/messageStore.js";
 
 // ---------------------------------------------------------------------------

services/discord-gateway/src/modules/event-broadcaster/eventBroadcaster.ts

@@ -1,9 +1,12 @@
 import Redis from "ioredis";
-import type { AttachmentRecord, MessageRecord } from "../../shared/index.js";
 import {
   type CustomLogger,
   createChildLogger,
 } from "../../shared/logger/index.js";
+import type {
+  AttachmentRecord,
+  MessageRecord,
+} from "../../shared/moderation-types.js";
 import { type DiscordGatewayEvent, EventChannels } from "./eventTypes.js";
 
 export class RedisEventPublisher {

services/discord-gateway/src/modules/event-broadcaster/eventTypes.ts

@@ -17,7 +17,7 @@ import {
   DISCORD_THREAD_DELETED,
   DISCORD_THREAD_UPDATED,
   type DiscordGatewayEvent,
-} from "../../shared/index.js";
+} from "../../shared/redis-channels.js";
 
 export type { DiscordGatewayEvent };
 

services/discord-gateway/src/modules/message-capture/messagesPagination.ts

@@ -2,8 +2,11 @@ import { and, desc, eq, inArray, type SQL, sql } from "drizzle-orm";
 import type { NodePgDatabase } from "drizzle-orm/node-postgres";
 import type * as schema from "../../shared/database/schema.js";
 import { messagesTable } from "../../shared/database/schema.js";
-import { buildCursorCondition, pageResult } from "../../shared/index.js";
 import { createChildLogger, type Logger } from "../../shared/logger/index.js";
+import {
+  buildCursorCondition,
+  pageResult,
+} from "../../shared/utils/pagination.js";
 import type {
   MessageQuery,
   MessageRecord,

services/discord-gateway/src/modules/message-capture/moderationActionsDb.ts

@@ -2,8 +2,11 @@ import { and, desc, eq, inArray, type SQL } from "drizzle-orm";
 import type { NodePgDatabase } from "drizzle-orm/node-postgres";
 import type * as schema from "../../shared/database/schema.js";
 import { moderationActionsTable } from "../../shared/database/schema.js";
-import { buildCursorCondition, pageResult } from "../../shared/index.js";
 import { createChildLogger, type Logger } from "../../shared/logger/index.js";
+import {
+  buildCursorCondition,
+  pageResult,
+} from "../../shared/utils/pagination.js";
 import type { EventBroadcaster } from "../event-broadcaster/eventBroadcaster.js";
 import type { ModerationAction, PageResult } from "../message-capture/types.js";
 

services/discord-gateway/src/modules/message-capture/reviewsDb.ts

@@ -2,8 +2,11 @@ import { and, desc, eq, inArray, type SQL } from "drizzle-orm";
 import type { NodePgDatabase } from "drizzle-orm/node-postgres";
 import type * as schema from "../../shared/database/schema.js";
 import { messageReviewsTable } from "../../shared/database/schema.js";
-import { buildCursorCondition, pageResult } from "../../shared/index.js";
 import { createChildLogger, type Logger } from "../../shared/logger/index.js";
+import {
+  buildCursorCondition,
+  pageResult,
+} from "../../shared/utils/pagination.js";
 import type { MessageReview, PageResult } from "../message-capture/types.js";
 
 // ─── ReviewsDb Class ────────────────────────────────────────────────────────

services/discord-gateway/src/modules/message-capture/types.ts

@@ -2,8 +2,7 @@ import type {
   AnalysisQueueStatus,
   AttachmentRecord,
   MessageRecord,
-  UserMetadata,
-} from "../../shared/index.js";
+} from "../../shared/moderation-types.js";
 
 // Re-export all shared types for backward compatibility
 export type {
@@ -26,7 +25,7 @@ export type {
   ReviewStatus,
   RoleMetadata,
   UserMetadata,
-} from "../../shared/index.js";
+} from "../../shared/moderation-types.js";
 
 // Local-only types (not shared across services)
 export type ModerationWsEvent =

services/discord-gateway/src/shared/errors/index.ts

@@ -46,3 +46,32 @@ export class ConfigError extends AppError {
     this.name = "ConfigError";
   }
 }
+
+// ---------------------------------------------------------------------------
+// Generic error helpers (shared by every module — avoids the repeated
+// `err instanceof Error ? err.message : String(err)` pattern, 18+ sites)
+// ---------------------------------------------------------------------------
+
+/** Normalize an unknown thrown value to a readable message. */
+export function errorMessage(err: unknown): string {
+  return err instanceof Error ? err.message : String(err);
+}
+
+/**
+ * True when an error code is a transient stream-teardown failure
+ * (EPIPE / stream destroyed / write-after-end / socket reset).
+ *
+ * These are NOT fatal: crashing the gateway on them (e.g. voice stop races,
+ * ffmpeg stdin closed while we still write) takes the whole bot offline
+ * mid-operation. Callers that install process-level handlers use this to
+ * log-and-continue instead of shutting down.
+ */
+export function isTransientStreamError(err: unknown): boolean {
+  const code = (err as NodeJS.ErrnoException)?.code ?? "";
+  return (
+    code === "EPIPE" ||
+    code === "ERR_STREAM_DESTROYED" ||
+    code === "ERR_STREAM_WRITE_AFTER_END" ||
+    code === "ECONNRESET"
+  );
+}

services/discord-gateway/src/shared/index.ts

@@ -1,9 +0,0 @@
-export * from "./config/index.js";
-export * from "./database/init.js";
-export * from "./database/pool.js";
-export * from "./database/schema.js";
-export * from "./errors/index.js";
-export * from "./logger/index.js";
-export * from "./moderation-types.js";
-export * from "./redis-channels.js";
-export * from "./utils/index.js";