diff --git a/src/db/database.ts b/src/db/database.ts
index 37bb4c9..2b49ddb 100644
--- a/src/db/database.ts
+++ b/src/db/database.ts
@@ -2,29 +2,7 @@ import Database from "better-sqlite3";
 import * as fs from "fs";
 import * as path from "path";
 
-const SCHEMA_SQL = `
-CREATE TABLE IF NOT EXISTS workspaces (
-    id              INTEGER PRIMARY KEY AUTOINCREMENT,
-    channel_id      TEXT NOT NULL UNIQUE,
-    guild_id        TEXT NOT NULL,
-    agent_name      TEXT NOT NULL UNIQUE,
-    workspace_path  TEXT NOT NULL,
-    created_at      TEXT NOT NULL DEFAULT (datetime('now'))
-);
-
-CREATE TABLE IF NOT EXISTS conversations (
-    id              INTEGER PRIMARY KEY AUTOINCREMENT,
-    workspace_id    INTEGER NOT NULL REFERENCES workspaces(id),
-    discord_msg_id  TEXT NOT NULL UNIQUE,
-    role            TEXT NOT NULL,
-    content         TEXT NOT NULL,
-    author_name     TEXT,
-    created_at      TEXT NOT NULL DEFAULT (datetime('now'))
-);
-
-CREATE INDEX IF NOT EXISTS idx_conversations_workspace
-    ON conversations(workspace_id, created_at);
-`;
+const schema = fs.readFileSync(path.join(__dirname, "schema.sql"), "utf-8");
 
 export interface Workspace {
   id: number;
@@ -61,7 +39,7 @@ export class DisclawDatabase {
   }
 
   private runMigrations(): void {
-    this.db.exec(SCHEMA_SQL);
+    this.db.exec(schema);
   }
 
   // --- Workspace queries ---
diff --git a/src/db/schema.sql b/src/db/schema.sql
index 5e58204..4836d79 100644
--- a/src/db/schema.sql
+++ b/src/db/schema.sql
@@ -1,3 +1,7 @@
+-- DisClaw SQLite schema (SSOT)
+-- All statements use IF NOT EXISTS for idempotent initialization.
+
+-- Workspaces: maps a Discord channel to a local agent workspace directory.
 CREATE TABLE IF NOT EXISTS workspaces (
     id              INTEGER PRIMARY KEY AUTOINCREMENT,
     channel_id      TEXT NOT NULL UNIQUE,
@@ -7,6 +11,7 @@ CREATE TABLE IF NOT EXISTS workspaces (
     created_at      TEXT NOT NULL DEFAULT (datetime('now'))
 );
 
+-- Conversations: stores per-message history for each workspace.
 CREATE TABLE IF NOT EXISTS conversations (
     id              INTEGER PRIMARY KEY AUTOINCREMENT,
     workspace_id    INTEGER NOT NULL REFERENCES workspaces(id),
@@ -17,5 +22,6 @@ CREATE TABLE IF NOT EXISTS conversations (
     created_at      TEXT NOT NULL DEFAULT (datetime('now'))
 );
 
+-- Index for efficient conversation history retrieval ordered by time.
 CREATE INDEX IF NOT EXISTS idx_conversations_workspace
     ON conversations(workspace_id, created_at);
diff --git a/tests/integration/db-init.test.ts b/tests/integration/db-init.test.ts
new file mode 100644
index 0000000..6a35b70
--- /dev/null
+++ b/tests/integration/db-init.test.ts
@@ -0,0 +1,97 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import * as fs from "fs";
+import * as os from "os";
+import * as path from "path";
+import { DisclawDatabase } from "../../src/db/database";
+
+/**
+ * Integration tests for DisclawDatabase schema initialization.
+ *
+ * Each test uses a fresh SQLite file in os.tmpdir() to ensure full isolation.
+ * The DB file is cleaned up after each test.
+ */
+
+function makeTmpDbPath(): string {
+  return path.join(os.tmpdir(), `disclaw-test-${Date.now()}-${Math.random().toString(36).slice(2)}.db`);
+}
+
+describe("db-init: schema initialization", () => {
+  let dbPath: string;
+  let db: DisclawDatabase;
+
+  beforeEach(() => {
+    dbPath = makeTmpDbPath();
+  });
+
+  afterEach(() => {
+    try {
+      db.close();
+    } catch {
+      // ignore if already closed
+    }
+    try {
+      fs.unlinkSync(dbPath);
+    } catch {
+      // best-effort cleanup
+    }
+  });
+
+  // (a) All expected tables exist after initialization
+  it("creates all expected tables on first init", () => {
+    db = new DisclawDatabase(dbPath);
+
+    // Query sqlite_master for user-created tables
+    const rawDb = (db as unknown as { db: import("better-sqlite3").Database }).db;
+    const tables = rawDb
+      .prepare("SELECT name FROM sqlite_master WHERE type = 'table' ORDER BY name")
+      .all() as { name: string }[];
+
+    const tableNames = tables.map((t) => t.name);
+    expect(tableNames).toContain("workspaces");
+    expect(tableNames).toContain("conversations");
+  });
+
+  // (b) Initializing the same DB path twice is idempotent (IF NOT EXISTS)
+  it("is idempotent when initialized twice (IF NOT EXISTS)", () => {
+    db = new DisclawDatabase(dbPath);
+    db.close();
+
+    // Second initialization must not throw
+    expect(() => {
+      db = new DisclawDatabase(dbPath);
+    }).not.toThrow();
+
+    const rawDb = (db as unknown as { db: import("better-sqlite3").Database }).db;
+    const tables = rawDb
+      .prepare("SELECT name FROM sqlite_master WHERE type = 'table' ORDER BY name")
+      .all() as { name: string }[];
+
+    const tableNames = tables.map((t) => t.name);
+    expect(tableNames).toContain("workspaces");
+    expect(tableNames).toContain("conversations");
+  });
+
+  // (c) Basic CRUD: create a workspace and retrieve it by channel_id
+  it("supports basic workspace CRUD", () => {
+    db = new DisclawDatabase(dbPath);
+
+    const created = db.createWorkspace(
+      "channel-001",
+      "guild-001",
+      "test-agent",
+      "/tmp/test-agent"
+    );
+
+    expect(created.id).toBeGreaterThan(0);
+    expect(created.channel_id).toBe("channel-001");
+    expect(created.guild_id).toBe("guild-001");
+    expect(created.agent_name).toBe("test-agent");
+    expect(created.workspace_path).toBe("/tmp/test-agent");
+    expect(created.created_at).toBeTruthy();
+
+    const fetched = db.getWorkspaceByChannelId("channel-001");
+    expect(fetched).toBeDefined();
+    expect(fetched!.id).toBe(created.id);
+    expect(fetched!.agent_name).toBe("test-agent");
+  });
+});