diff --git a/src/db/bootstrap.test.ts b/src/db/bootstrap.test.ts
index 402e3b8..3cbfb21 100644
--- a/src/db/bootstrap.test.ts
+++ b/src/db/bootstrap.test.ts
@@ -20,6 +20,20 @@ function getAppliedSchemaMigrations(
     .all() as Array<{ version: number; name: string }>;
 }
 
+function getExpectedSchemaMigrations(): Array<{
+  version: number;
+  name: string;
+}> {
+  return [
+    { version: 1, name: 'legacy_schema_bundle' },
+    { version: 2, name: 'scheduled_task_columns' },
+    { version: 3, name: 'room_registration_canonical_columns' },
+    { version: 4, name: 'message_seq_and_work_item_indexes' },
+    { version: 5, name: 'sessions_composite_key' },
+    { version: 6, name: 'chat_channel_metadata' },
+  ];
+}
+
 describe('initializeDatabaseSchema', () => {
   const tempDirs: string[] = [];
 
@@ -35,12 +49,9 @@ describe('initializeDatabaseSchema', () => {
     try {
       initializeDatabaseSchema(database);
 
-      expect(getAppliedSchemaMigrations(database)).toEqual([
-        {
-          version: 1,
-          name: 'legacy_schema_bundle',
-        },
-      ]);
+      expect(getAppliedSchemaMigrations(database)).toEqual(
+        getExpectedSchemaMigrations(),
+      );
     } finally {
       database.close();
     }
@@ -53,12 +64,9 @@ describe('initializeDatabaseSchema', () => {
       initializeDatabaseSchema(database);
       initializeDatabaseSchema(database);
 
-      expect(getAppliedSchemaMigrations(database)).toEqual([
-        {
-          version: 1,
-          name: 'legacy_schema_bundle',
-        },
-      ]);
+      expect(getAppliedSchemaMigrations(database)).toEqual(
+        getExpectedSchemaMigrations(),
+      );
     } finally {
       database.close();
     }
@@ -86,12 +94,9 @@ describe('initializeDatabaseSchema', () => {
     try {
       initializeDatabaseSchema(reopened);
 
-      expect(getAppliedSchemaMigrations(reopened)).toEqual([
-        {
-          version: 1,
-          name: 'legacy_schema_bundle',
-        },
-      ]);
+      expect(getAppliedSchemaMigrations(reopened)).toEqual(
+        getExpectedSchemaMigrations(),
+      );
     } finally {
       reopened.close();
     }
diff --git a/src/db/migrations/002_scheduled-task-columns.ts b/src/db/migrations/002_scheduled-task-columns.ts
new file mode 100644
index 0000000..fe18641
--- /dev/null
+++ b/src/db/migrations/002_scheduled-task-columns.ts
@@ -0,0 +1,41 @@
+import type { SchemaMigrationDefinition } from './types.js';
+import { tryExecMigration } from './helpers.js';
+
+export const SCHEDULED_TASK_COLUMNS_MIGRATION = {
+  version: 2,
+  name: 'scheduled_task_columns',
+  apply(database) {
+    tryExecMigration(
+      database,
+      `ALTER TABLE scheduled_tasks ADD COLUMN context_mode TEXT DEFAULT 'isolated'`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE scheduled_tasks ADD COLUMN agent_type TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE scheduled_tasks ADD COLUMN ci_provider TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE scheduled_tasks ADD COLUMN ci_metadata TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE scheduled_tasks ADD COLUMN max_duration_ms INTEGER`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE scheduled_tasks ADD COLUMN status_message_id TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE scheduled_tasks ADD COLUMN status_started_at TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE scheduled_tasks ADD COLUMN suspended_until TEXT`,
+    );
+  },
+} satisfies SchemaMigrationDefinition;
diff --git a/src/db/migrations/003_room-registration-canonical-columns.ts b/src/db/migrations/003_room-registration-canonical-columns.ts
new file mode 100644
index 0000000..200026b
--- /dev/null
+++ b/src/db/migrations/003_room-registration-canonical-columns.ts
@@ -0,0 +1,72 @@
+import type { SchemaMigrationDefinition } from './types.js';
+import { tableHasColumn, tryExecMigration } from './helpers.js';
+
+export const ROOM_REGISTRATION_CANONICAL_COLUMNS_MIGRATION = {
+  version: 3,
+  name: 'room_registration_canonical_columns',
+  apply(database) {
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN mode_source TEXT NOT NULL DEFAULT 'explicit'`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN name TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN folder TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN trigger_pattern TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN requires_trigger INTEGER DEFAULT 1`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN is_main INTEGER DEFAULT 0`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN owner_agent_type TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN work_dir TEXT`,
+    );
+    tryExecMigration(
+      database,
+      `ALTER TABLE room_settings ADD COLUMN created_at TEXT`,
+    );
+
+    if (tableHasColumn(database, 'room_settings', 'created_at')) {
+      database.exec(`
+        UPDATE room_settings
+           SET created_at = COALESCE(created_at, updated_at, CURRENT_TIMESTAMP)
+      `);
+    }
+
+    database.exec(`
+      CREATE TABLE IF NOT EXISTS room_role_overrides (
+        chat_jid TEXT NOT NULL,
+        role TEXT NOT NULL,
+        agent_type TEXT NOT NULL,
+        agent_config_json TEXT,
+        created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
+        updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
+        PRIMARY KEY (chat_jid, role),
+        CHECK (role IN ('owner', 'reviewer', 'arbiter')),
+        CHECK (agent_type IN ('claude-code', 'codex'))
+      )
+    `);
+
+    database.exec(
+      `UPDATE room_settings
+       SET mode_source = 'explicit'
+       WHERE COALESCE(mode_source, '') NOT IN ('explicit', 'inferred')`,
+    );
+  },
+} satisfies SchemaMigrationDefinition;
diff --git a/src/db/migrations/004_message-seq-and-work-item-indexes.ts b/src/db/migrations/004_message-seq-and-work-item-indexes.ts
new file mode 100644
index 0000000..c842f3a
--- /dev/null
+++ b/src/db/migrations/004_message-seq-and-work-item-indexes.ts
@@ -0,0 +1,36 @@
+import type { SchemaMigrationDefinition } from './types.js';
+import { backfillMessageSeq, tryExecMigration } from './helpers.js';
+
+export const MESSAGE_SEQ_AND_WORK_ITEM_INDEXES_MIGRATION = {
+  version: 4,
+  name: 'message_seq_and_work_item_indexes',
+  apply(database, args) {
+    try {
+      database.exec(
+        `ALTER TABLE messages ADD COLUMN is_bot_message INTEGER DEFAULT 0`,
+      );
+      database
+        .prepare(`UPDATE messages SET is_bot_message = 1 WHERE content LIKE ?`)
+        .run(`${args.assistantName}:%`);
+    } catch {
+      /* column already exists */
+    }
+
+    tryExecMigration(database, `ALTER TABLE messages ADD COLUMN seq INTEGER`);
+    backfillMessageSeq(database);
+
+    database.exec(`
+      CREATE UNIQUE INDEX IF NOT EXISTS idx_messages_seq ON messages(seq);
+      CREATE INDEX IF NOT EXISTS idx_messages_chat_jid_seq ON messages(chat_jid, seq);
+    `);
+    database.exec(`DROP INDEX IF EXISTS idx_work_items_group_agent;`);
+    database.exec(`DROP INDEX IF EXISTS idx_work_items_open;`);
+    database.exec(`
+      CREATE INDEX IF NOT EXISTS idx_work_items_group_agent
+        ON work_items(chat_jid, agent_type, service_id, delivery_role, status);
+      CREATE UNIQUE INDEX IF NOT EXISTS idx_work_items_open
+        ON work_items(chat_jid, agent_type, IFNULL(service_id, ''), IFNULL(delivery_role, ''))
+        WHERE status IN ('produced', 'delivery_retry');
+    `);
+  },
+} satisfies SchemaMigrationDefinition;
diff --git a/src/db/migrations/005_sessions-composite-key.ts b/src/db/migrations/005_sessions-composite-key.ts
new file mode 100644
index 0000000..97c6d25
--- /dev/null
+++ b/src/db/migrations/005_sessions-composite-key.ts
@@ -0,0 +1,17 @@
+import { inferAgentTypeFromServiceShadow } from '../../role-service-shadow.js';
+import {
+  backfillLegacyServiceSessions,
+  dropLegacyServiceSessionsTable,
+  migrateSessionsTableToCompositePk,
+} from '../sessions.js';
+import type { SchemaMigrationDefinition } from './types.js';
+
+export const SESSIONS_COMPOSITE_KEY_MIGRATION = {
+  version: 5,
+  name: 'sessions_composite_key',
+  apply(database) {
+    migrateSessionsTableToCompositePk(database, 'claude-code');
+    backfillLegacyServiceSessions(database, inferAgentTypeFromServiceShadow);
+    dropLegacyServiceSessionsTable(database);
+  },
+} satisfies SchemaMigrationDefinition;
diff --git a/src/db/migrations/006_chat-channel-metadata.ts b/src/db/migrations/006_chat-channel-metadata.ts
new file mode 100644
index 0000000..5bfadf6
--- /dev/null
+++ b/src/db/migrations/006_chat-channel-metadata.ts
@@ -0,0 +1,26 @@
+import type { SchemaMigrationDefinition } from './types.js';
+
+export const CHAT_CHANNEL_METADATA_MIGRATION = {
+  version: 6,
+  name: 'chat_channel_metadata',
+  apply(database) {
+    try {
+      database.exec(`ALTER TABLE chats ADD COLUMN channel TEXT`);
+      database.exec(`ALTER TABLE chats ADD COLUMN is_group INTEGER DEFAULT 0`);
+      database.exec(
+        `UPDATE chats SET channel = 'whatsapp', is_group = 1 WHERE jid LIKE '%@g.us'`,
+      );
+      database.exec(
+        `UPDATE chats SET channel = 'whatsapp', is_group = 0 WHERE jid LIKE '%@s.whatsapp.net'`,
+      );
+      database.exec(
+        `UPDATE chats SET channel = 'discord', is_group = 1 WHERE jid LIKE 'dc:%'`,
+      );
+      database.exec(
+        `UPDATE chats SET channel = 'telegram', is_group = 1 WHERE jid LIKE 'tg:%'`,
+      );
+    } catch {
+      /* columns already exist */
+    }
+  },
+} satisfies SchemaMigrationDefinition;
diff --git a/src/db/migrations/helpers.ts b/src/db/migrations/helpers.ts
new file mode 100644
index 0000000..92d368b
--- /dev/null
+++ b/src/db/migrations/helpers.ts
@@ -0,0 +1,64 @@
+import { Database } from 'bun:sqlite';
+
+function getTableColumns(database: Database, tableName: string): string[] {
+  return (
+    database.prepare(`PRAGMA table_info(${tableName})`).all() as Array<{
+      name: string;
+    }>
+  ).map((column) => column.name);
+}
+
+export function tableHasColumn(
+  database: Database,
+  tableName: string,
+  columnName: string,
+): boolean {
+  return getTableColumns(database, tableName).includes(columnName);
+}
+
+export function tryExecMigration(database: Database, sql: string): void {
+  try {
+    database.exec(sql);
+  } catch {
+    /* column already exists */
+  }
+}
+
+export function backfillMessageSeq(database: Database): void {
+  const rows = database
+    .prepare(
+      `SELECT rowid, seq
+       FROM messages
+       ORDER BY CASE WHEN seq IS NULL THEN 1 ELSE 0 END, seq, timestamp, rowid`,
+    )
+    .all() as Array<{ rowid: number; seq: number | null }>;
+  if (rows.length === 0) {
+    return;
+  }
+
+  let nextSeq = 1;
+  const assignSeq = database.prepare(
+    'UPDATE messages SET seq = ? WHERE rowid = ? AND seq IS NULL',
+  );
+  const tx = database.transaction(() => {
+    for (const row of rows) {
+      if (row.seq === null) {
+        assignSeq.run(nextSeq, row.rowid);
+      }
+      nextSeq = Math.max(nextSeq, (row.seq ?? nextSeq) + 1);
+    }
+  });
+  tx();
+
+  const maxSeqRow = database
+    .prepare('SELECT MAX(seq) AS maxSeq FROM messages')
+    .get() as { maxSeq: number | null };
+  const maxSeq = maxSeqRow.maxSeq ?? 0;
+  if (maxSeq > 0) {
+    database
+      .prepare('INSERT OR IGNORE INTO message_sequence (id) VALUES (?)')
+      .run(maxSeq);
+  }
+}
+
+export { getTableColumns };
diff --git a/src/db/migrations/index.ts b/src/db/migrations/index.ts
index 1dc69f9..44fd457 100644
--- a/src/db/migrations/index.ts
+++ b/src/db/migrations/index.ts
@@ -1,6 +1,11 @@
 import type { Database } from 'bun:sqlite';
 
 import { LEGACY_SCHEMA_BUNDLE_MIGRATION } from './001_legacy-schema-bundle.js';
+import { SCHEDULED_TASK_COLUMNS_MIGRATION } from './002_scheduled-task-columns.js';
+import { ROOM_REGISTRATION_CANONICAL_COLUMNS_MIGRATION } from './003_room-registration-canonical-columns.js';
+import { MESSAGE_SEQ_AND_WORK_ITEM_INDEXES_MIGRATION } from './004_message-seq-and-work-item-indexes.js';
+import { SESSIONS_COMPOSITE_KEY_MIGRATION } from './005_sessions-composite-key.js';
+import { CHAT_CHANNEL_METADATA_MIGRATION } from './006_chat-channel-metadata.js';
 import type {
   SchemaMigrationArgs,
   SchemaMigrationDefinition,
@@ -10,6 +15,11 @@ const SCHEMA_MIGRATIONS_TABLE = 'schema_migrations';
 
 const ORDERED_SCHEMA_MIGRATIONS: readonly SchemaMigrationDefinition[] = [
   LEGACY_SCHEMA_BUNDLE_MIGRATION,
+  SCHEDULED_TASK_COLUMNS_MIGRATION,
+  ROOM_REGISTRATION_CANONICAL_COLUMNS_MIGRATION,
+  MESSAGE_SEQ_AND_WORK_ITEM_INDEXES_MIGRATION,
+  SESSIONS_COMPOSITE_KEY_MIGRATION,
+  CHAT_CHANNEL_METADATA_MIGRATION,
 ];
 
 function ensureSchemaMigrationsTable(database: Database): void {
diff --git a/src/db/schema.ts b/src/db/schema.ts
index 3100af6..90d5880 100644
--- a/src/db/schema.ts
+++ b/src/db/schema.ts
@@ -1,10 +1,7 @@
 import { Database } from 'bun:sqlite';
 
 import { SERVICE_SESSION_SCOPE, normalizeServiceId } from '../config.js';
-import {
-  inferAgentTypeFromServiceShadow,
-  resolveRoleServiceShadow,
-} from '../role-service-shadow.js';
+import { resolveRoleServiceShadow } from '../role-service-shadow.js';
 import {
   fillCanonicalChannelOwnerLeaseMetadata,
   fillCanonicalPairedTaskMetadata,
@@ -15,33 +12,17 @@ import {
   backfillPairedTurnAttemptsFromTurns,
   buildPairedTurnAttemptId,
 } from './paired-turn-attempts.js';
-import { normalizeStoredAgentType } from './room-registration.js';
 import {
-  backfillLegacyServiceSessions,
-  dropLegacyServiceSessionsTable,
-  migrateSessionsTableToCompositePk,
-} from './sessions.js';
+  getTableColumns,
+  tableHasColumn,
+  tryExecMigration,
+} from './migrations/helpers.js';
+import { normalizeStoredAgentType } from './room-registration.js';
 
 // Legacy monolithic migration bundle kept for compatibility with databases
 // that predate ordered schema migration tracking. New schema changes belong in
 // src/db/migrations/*.
 
-function getTableColumns(database: Database, tableName: string): string[] {
-  return (
-    database.prepare(`PRAGMA table_info(${tableName})`).all() as Array<{
-      name: string;
-    }>
-  ).map((column) => column.name);
-}
-
-export function tableHasColumn(
-  database: Database,
-  tableName: string,
-  columnName: string,
-): boolean {
-  return getTableColumns(database, tableName).includes(columnName);
-}
-
 function getTableSql(database: Database, tableName: string): string | null {
   const row = database
     .prepare(
@@ -56,14 +37,6 @@ function getTableSql(database: Database, tableName: string): string | null {
   return row?.sql ?? null;
 }
 
-function tryExecMigration(database: Database, sql: string): void {
-  try {
-    database.exec(sql);
-  } catch {
-    /* column already exists */
-  }
-}
-
 function buildPairedTurnAttemptIdSql(
   turnIdExpr: string,
   attemptNoExpr: string,
@@ -183,43 +156,6 @@ function tableHasForeignKey(
   return false;
 }
 
-function backfillMessageSeq(database: Database): void {
-  const rows = database
-    .prepare(
-      `SELECT rowid, seq
-       FROM messages
-       ORDER BY CASE WHEN seq IS NULL THEN 1 ELSE 0 END, seq, timestamp, rowid`,
-    )
-    .all() as Array<{ rowid: number; seq: number | null }>;
-  if (rows.length === 0) {
-    return;
-  }
-
-  let nextSeq = 1;
-  const assignSeq = database.prepare(
-    'UPDATE messages SET seq = ? WHERE rowid = ? AND seq IS NULL',
-  );
-  const tx = database.transaction(() => {
-    for (const row of rows) {
-      if (row.seq === null) {
-        assignSeq.run(nextSeq, row.rowid);
-      }
-      nextSeq = Math.max(nextSeq, (row.seq ?? nextSeq) + 1);
-    }
-  });
-  tx();
-
-  const maxSeqRow = database
-    .prepare('SELECT MAX(seq) AS maxSeq FROM messages')
-    .get() as { maxSeq: number | null };
-  const maxSeq = maxSeqRow.maxSeq ?? 0;
-  if (maxSeq > 0) {
-    database
-      .prepare('INSERT OR IGNORE INTO message_sequence (id) VALUES (?)')
-      .run(maxSeq);
-  }
-}
-
 interface LegacyExecutionLeaseServiceRow {
   rowid: number;
   role: string;
@@ -2574,98 +2510,10 @@ function backfillCanonicalWorkItemServiceIds(database: Database): void {
 
 export function applyLegacySchemaMigrations(
   database: Database,
-  args: {
+  _args: {
     assistantName: string;
   },
 ): void {
-  const { assistantName } = args;
-
-  tryExecMigration(
-    database,
-    `ALTER TABLE scheduled_tasks ADD COLUMN context_mode TEXT DEFAULT 'isolated'`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE scheduled_tasks ADD COLUMN agent_type TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE scheduled_tasks ADD COLUMN ci_provider TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE scheduled_tasks ADD COLUMN ci_metadata TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE scheduled_tasks ADD COLUMN max_duration_ms INTEGER`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE scheduled_tasks ADD COLUMN status_message_id TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE scheduled_tasks ADD COLUMN status_started_at TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE scheduled_tasks ADD COLUMN suspended_until TEXT`,
-  );
-
-  tryExecMigration(
-    database,
-    `ALTER TABLE room_settings ADD COLUMN mode_source TEXT NOT NULL DEFAULT 'explicit'`,
-  );
-  tryExecMigration(database, `ALTER TABLE room_settings ADD COLUMN name TEXT`);
-  tryExecMigration(
-    database,
-    `ALTER TABLE room_settings ADD COLUMN folder TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE room_settings ADD COLUMN trigger_pattern TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE room_settings ADD COLUMN requires_trigger INTEGER DEFAULT 1`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE room_settings ADD COLUMN is_main INTEGER DEFAULT 0`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE room_settings ADD COLUMN owner_agent_type TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE room_settings ADD COLUMN work_dir TEXT`,
-  );
-  tryExecMigration(
-    database,
-    `ALTER TABLE room_settings ADD COLUMN created_at TEXT`,
-  );
-  if (tableHasColumn(database, 'room_settings', 'created_at')) {
-    database.exec(`
-      UPDATE room_settings
-         SET created_at = COALESCE(created_at, updated_at, CURRENT_TIMESTAMP)
-    `);
-  }
-  database.exec(`
-    CREATE TABLE IF NOT EXISTS room_role_overrides (
-      chat_jid TEXT NOT NULL,
-      role TEXT NOT NULL,
-      agent_type TEXT NOT NULL,
-      agent_config_json TEXT,
-      created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
-      updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
-      PRIMARY KEY (chat_jid, role),
-      CHECK (role IN ('owner', 'reviewer', 'arbiter')),
-      CHECK (agent_type IN ('claude-code', 'codex'))
-    )
-  `);
-
   tryExecMigration(
     database,
     `ALTER TABLE service_handoffs ADD COLUMN intended_role TEXT`,
@@ -2935,41 +2783,6 @@ export function applyLegacySchemaMigrations(
   backfillCanonicalServiceHandoffServiceIds(database);
   backfillCanonicalWorkItemServiceIds(database);
 
-  database.exec(
-    `UPDATE room_settings
-     SET mode_source = 'explicit'
-     WHERE COALESCE(mode_source, '') NOT IN ('explicit', 'inferred')`,
-  );
-
-  try {
-    database.exec(
-      `ALTER TABLE messages ADD COLUMN is_bot_message INTEGER DEFAULT 0`,
-    );
-    database
-      .prepare(`UPDATE messages SET is_bot_message = 1 WHERE content LIKE ?`)
-      .run(`${assistantName}:%`);
-  } catch {
-    /* column already exists */
-  }
-
-  tryExecMigration(database, `ALTER TABLE messages ADD COLUMN seq INTEGER`);
-
-  backfillMessageSeq(database);
-
-  database.exec(`
-    CREATE UNIQUE INDEX IF NOT EXISTS idx_messages_seq ON messages(seq);
-    CREATE INDEX IF NOT EXISTS idx_messages_chat_jid_seq ON messages(chat_jid, seq);
-  `);
-  database.exec(`DROP INDEX IF EXISTS idx_work_items_group_agent;`);
-  database.exec(`DROP INDEX IF EXISTS idx_work_items_open;`);
-  database.exec(`
-    CREATE INDEX IF NOT EXISTS idx_work_items_group_agent
-      ON work_items(chat_jid, agent_type, service_id, delivery_role, status);
-    CREATE UNIQUE INDEX IF NOT EXISTS idx_work_items_open
-      ON work_items(chat_jid, agent_type, IFNULL(service_id, ''), IFNULL(delivery_role, ''))
-      WHERE status IN ('produced', 'delivery_retry');
-  `);
-
   const pairedTasksSqlRow = database
     .prepare(
       `SELECT sql FROM sqlite_master WHERE type = 'table' AND name = 'paired_tasks'`,
@@ -3134,29 +2947,6 @@ export function applyLegacySchemaMigrations(
       );
     `);
   }
-
-  migrateSessionsTableToCompositePk(database, 'claude-code');
-  backfillLegacyServiceSessions(database, inferAgentTypeFromServiceShadow);
-  dropLegacyServiceSessionsTable(database);
-
-  try {
-    database.exec(`ALTER TABLE chats ADD COLUMN channel TEXT`);
-    database.exec(`ALTER TABLE chats ADD COLUMN is_group INTEGER DEFAULT 0`);
-    database.exec(
-      `UPDATE chats SET channel = 'whatsapp', is_group = 1 WHERE jid LIKE '%@g.us'`,
-    );
-    database.exec(
-      `UPDATE chats SET channel = 'whatsapp', is_group = 0 WHERE jid LIKE '%@s.whatsapp.net'`,
-    );
-    database.exec(
-      `UPDATE chats SET channel = 'discord', is_group = 1 WHERE jid LIKE 'dc:%'`,
-    );
-    database.exec(
-      `UPDATE chats SET channel = 'telegram', is_group = 1 WHERE jid LIKE 'tg:%'`,
-    );
-  } catch {
-    /* columns already exist */
-  }
 }
 
 /** @deprecated New schema changes should be added under src/db/migrations/*. */