diff --git a/backend/internal/database/captain_skill_migration_test.go b/backend/internal/database/captain_skill_migration_test.go
index 806bf04c..b07c534e 100644
--- a/backend/internal/database/captain_skill_migration_test.go
+++ b/backend/internal/database/captain_skill_migration_test.go
@@ -1,6 +1,8 @@
 package database
 
 import (
+	"fmt"
+	"net/url"
 	"os"
 	"path/filepath"
 	"testing"
@@ -12,69 +14,155 @@ import (
 	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
 	"gorm.io/gorm/logger"
-
-	"github.com/gochat/gochat/internal/model"
 )
 
-func TestCaptainSkillSchemaSQLiteRoundTrip(t *testing.T) {
-	db, err := gorm.Open(sqlite.Open("file:"+t.Name()+"?mode=memory&cache=shared"), &gorm.Config{Logger: logger.Default.LogMode(logger.Silent)})
-	require.NoError(t, err)
-	require.NoError(t, db.AutoMigrate(&model.CaptainAssistant{}, &model.CaptainSkill{}, &model.CaptainSkillReference{}, &model.CaptainAssistantSkill{}))
-	for _, table := range []string{"captain_skills", "captain_skill_references", "captain_assistant_skills"} {
-		assert.True(t, db.Migrator().HasTable(table), table)
-		require.NoError(t, db.Migrator().DropTable(table))
-		assert.False(t, db.Migrator().HasTable(table), table)
+const captainSkillMigrationBaseline = `
+CREATE TABLE accounts (id INTEGER PRIMARY KEY);
+CREATE TABLE captain_assistants (id INTEGER PRIMARY KEY, account_id INTEGER NOT NULL);
+CREATE TABLE captain_skills (id INTEGER PRIMARY KEY, account_id INTEGER NOT NULL);
+CREATE TABLE captain_assistant_skills (
+  id INTEGER PRIMARY KEY,
+  account_id INTEGER NOT NULL REFERENCES accounts(id) ON DELETE CASCADE,
+  assistant_id INTEGER NOT NULL REFERENCES captain_assistants(id) ON DELETE CASCADE,
+  skill_id INTEGER NOT NULL REFERENCES captain_skills(id) ON DELETE CASCADE,
+  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  UNIQUE (assistant_id, skill_id)
+);
+CREATE INDEX idx_captain_assistant_skills_account ON captain_assistant_skills(account_id);
+CREATE INDEX idx_captain_assistant_skills_skill ON captain_assistant_skills(skill_id);
+`
+
+func captainSkillMigrationDir(t *testing.T, dialect string) string {
+	t.Helper()
+	dir := t.TempDir()
+	for _, direction := range []string{"up", "down"} {
+		require.NoError(t, os.WriteFile(filepath.Join(dir, "000080_baseline."+direction+".sql"), []byte("SELECT 1;"), 0o600))
 	}
+	for _, direction := range []string{"up", "down"} {
+		name := "000081_enforce_captain_skill_tenant_consistency." + direction + ".sql"
+		parts := []string{"..", "..", "migrations"}
+		if dialect != "" {
+			parts = append(parts, dialect)
+		}
+		data, err := os.ReadFile(filepath.Join(append(parts, name)...))
+		require.NoError(t, err)
+		require.NoError(t, os.WriteFile(filepath.Join(dir, name), data, 0o600))
+	}
+	return dir
 }
 
-func openCaptainMigrationPostgres(t *testing.T) *gorm.DB {
-	t.Helper()
-	dsn := os.Getenv("GOCHAT_TEST_DB_URL")
-	if dsn == "" {
-		dsn = "host=localhost port=5432 user=postgres password=postgres dbname=gochat_test sslmode=disable"
-	}
-	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{Logger: logger.Default.LogMode(logger.Silent)})
+func TestCaptainSkillSQLiteMigrationRoundTrip(t *testing.T) {
+	dbPath := filepath.Join(t.TempDir(), "captain-skill.db")
+	dbURL := "sqlite3://" + dbPath + "?_foreign_keys=on"
+	db, err := gorm.Open(sqlite.Open(dbPath+"?_foreign_keys=on"), &gorm.Config{Logger: logger.Default.LogMode(logger.Silent)})
 	require.NoError(t, err)
 	sqlDB, err := db.DB()
 	require.NoError(t, err)
 	sqlDB.SetMaxOpenConns(1)
 	t.Cleanup(func() { _ = sqlDB.Close() })
-	schema := "captain_skill_migration_" + time.Now().Format("20060102150405000000000")
-	require.NoError(t, db.Exec("CREATE SCHEMA "+schema).Error)
-	t.Cleanup(func() { _ = db.Exec("DROP SCHEMA " + schema + " CASCADE").Error })
-	require.NoError(t, db.Exec("SET search_path TO "+schema).Error)
-	return db
+	require.NoError(t, db.Exec(captainSkillMigrationBaseline).Error)
+	require.NoError(t, db.Exec("INSERT INTO accounts VALUES (1), (2); INSERT INTO captain_assistants VALUES (1, 1), (2, 2); INSERT INTO captain_skills VALUES (1, 1), (2, 2)").Error)
+
+	migrations := captainSkillMigrationDir(t, "sqlite")
+	require.NoError(t, ForceVersion(dbURL, migrations, 80))
+	require.NoError(t, MigrateSteps(dbURL, migrations, 1))
+	version, dirty, err := CurrentVersion(dbURL, migrations)
+	require.NoError(t, err)
+	assert.Equal(t, uint(81), version)
+	assert.False(t, dirty)
+
+	require.NoError(t, db.Exec("INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (1, 1, 1, 1)").Error)
+	assert.Error(t, db.Exec("INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (2, 1, 2, 1)").Error)
+	assert.Error(t, db.Exec("INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (3, 1, 1, 2)").Error)
+
+	require.NoError(t, MigrateSteps(dbURL, migrations, -1))
+	version, dirty, err = CurrentVersion(dbURL, migrations)
+	require.NoError(t, err)
+	assert.Equal(t, uint(80), version)
+	assert.False(t, dirty)
+	require.NoError(t, db.Exec("INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (2, 1, 2, 1), (3, 1, 1, 2)").Error)
+	assert.False(t, db.Migrator().HasIndex("captain_assistants", "idx_captain_assistants_account_id_id"))
+	assert.False(t, db.Migrator().HasIndex("captain_skills", "idx_captain_skills_account_id_id"))
+}
+
+func openCaptainMigrationPostgres(t *testing.T) (*gorm.DB, string) {
+	t.Helper()
+	dsn := os.Getenv("GOCHAT_TEST_DB_URL")
+	if dsn == "" {
+		dsn = "postgres://postgres:postgres@localhost:5432/gochat_test?sslmode=disable"
+	}
+	admin, err := gorm.Open(postgres.Open(dsn), &gorm.Config{Logger: logger.Default.LogMode(logger.Silent)})
+	require.NoError(t, err)
+	adminDB, err := admin.DB()
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = adminDB.Close() })
+
+	schema := fmt.Sprintf("captain_skill_migration_%d", time.Now().UnixNano())
+	require.NoError(t, admin.Exec("CREATE SCHEMA "+schema).Error)
+	t.Cleanup(func() { _ = admin.Exec("DROP SCHEMA " + schema + " CASCADE").Error })
+	migrationURL, err := url.Parse(dsn)
+	require.NoError(t, err)
+	require.NotEmpty(t, migrationURL.Scheme, "GOCHAT_TEST_DB_URL must be a PostgreSQL URL")
+	query := migrationURL.Query()
+	query.Set("search_path", schema)
+	migrationURL.RawQuery = query.Encode()
+
+	db, err := gorm.Open(postgres.Open(migrationURL.String()), &gorm.Config{Logger: logger.Default.LogMode(logger.Silent)})
+	require.NoError(t, err)
+	sqlDB, err := db.DB()
+	require.NoError(t, err)
+	sqlDB.SetMaxOpenConns(1)
+	t.Cleanup(func() { _ = sqlDB.Close() })
+	require.NoError(t, db.Exec(captainSkillMigrationBaseline).Error)
+	return db, migrationURL.String()
+}
+
+func runCaptainSkillMigration(t *testing.T, fn func() error) {
+	t.Helper()
+	require.NoError(t, withSanitizedPQEnvironment(fn))
 }
 
 func TestCaptainSkillPostgresMigrationRoundTrip(t *testing.T) {
 	if os.Getenv("GOCHAT_TEST_DB") == "sqlite" {
 		t.Skip("PostgreSQL migration test")
 	}
-	db := openCaptainMigrationPostgres(t)
-	require.NoError(t, db.Exec("CREATE TABLE accounts (id SERIAL PRIMARY KEY); CREATE TABLE captain_assistants (id SERIAL PRIMARY KEY, account_id INTEGER NOT NULL);").Error)
+	db, dbURL := openCaptainMigrationPostgres(t)
+	require.NoError(t, db.Exec("INSERT INTO accounts VALUES (1), (2); INSERT INTO captain_assistants VALUES (1, 1), (2, 2); INSERT INTO captain_skills VALUES (1, 1), (2, 2)").Error)
+	migrations := captainSkillMigrationDir(t, "")
+	runCaptainSkillMigration(t, func() error { return ForceVersion(dbURL, migrations, 80) })
+	runCaptainSkillMigration(t, func() error { return MigrateSteps(dbURL, migrations, 1) })
 
-	up, err := os.ReadFile(filepath.Join("..", "..", "migrations", "000080_add_captain_skills.up.sql"))
-	require.NoError(t, err)
-	require.NoError(t, db.Exec(string(up)).Error)
-	for _, table := range []string{"captain_skills", "captain_skill_references", "captain_assistant_skills"} {
-		assert.True(t, db.Migrator().HasTable(table), table)
-	}
-	require.NoError(t, db.Exec("INSERT INTO accounts(id) VALUES (1); INSERT INTO captain_assistants(id, account_id) VALUES (1, 1);").Error)
-	require.NoError(t, db.Exec("INSERT INTO captain_skills(id, account_id, name, description, instructions_md, status) VALUES (1, 1, 'policy', 'Policy', 'Use it', 'active')").Error)
-	require.NoError(t, db.Exec("INSERT INTO captain_skill_references(skill_id, reference_key, content_md, position) VALUES (1, 'standard', 'Terms', 0)").Error)
-	require.NoError(t, db.Exec("INSERT INTO captain_assistant_skills(account_id, assistant_id, skill_id) VALUES (1, 1, 1)").Error)
-	assert.Error(t, db.Exec("INSERT INTO captain_skill_references(skill_id, reference_key, content_md, position) VALUES (1, 'standard', 'Duplicate', 1)").Error)
-	require.NoError(t, db.Exec("DELETE FROM captain_skills WHERE id = 1").Error)
-	for _, table := range []string{"captain_skill_references", "captain_assistant_skills"} {
-		var count int64
-		require.NoError(t, db.Table(table).Count(&count).Error)
-		assert.Zero(t, count, table)
-	}
+	require.NoError(t, db.Exec("INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (1, 1, 1, 1)").Error)
+	assert.Error(t, db.Exec("INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (2, 1, 2, 1)").Error)
+	assert.Error(t, db.Exec("INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (3, 1, 1, 2)").Error)
 
-	down, err := os.ReadFile(filepath.Join("..", "..", "migrations", "000080_add_captain_skills.down.sql"))
-	require.NoError(t, err)
-	require.NoError(t, db.Exec(string(down)).Error)
-	for _, table := range []string{"captain_skills", "captain_skill_references", "captain_assistant_skills"} {
-		assert.False(t, db.Migrator().HasTable(table), table)
+	runCaptainSkillMigration(t, func() error { return MigrateSteps(dbURL, migrations, -1) })
+	require.NoError(t, db.Exec("INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (2, 1, 2, 1), (3, 1, 1, 2)").Error)
+	var count int64
+	require.NoError(t, db.Raw("SELECT count(*) FROM pg_indexes WHERE schemaname = current_schema() AND indexname IN ('idx_captain_assistants_account_id_id', 'idx_captain_skills_account_id_id')").Scan(&count).Error)
+	assert.Zero(t, count)
+}
+
+func TestCaptainSkillPostgresMigrationRejectsDirtyBindingsAtomically(t *testing.T) {
+	if os.Getenv("GOCHAT_TEST_DB") == "sqlite" {
+		t.Skip("PostgreSQL migration test")
 	}
+	db, dbURL := openCaptainMigrationPostgres(t)
+	require.NoError(t, db.Exec("INSERT INTO accounts VALUES (1), (2); INSERT INTO captain_assistants VALUES (1, 1), (2, 2); INSERT INTO captain_skills VALUES (1, 1), (2, 2); INSERT INTO captain_assistant_skills(id, account_id, assistant_id, skill_id) VALUES (1, 1, 2, 1)").Error)
+	migrations := captainSkillMigrationDir(t, "")
+	runCaptainSkillMigration(t, func() error { return ForceVersion(dbURL, migrations, 80) })
+	err := withSanitizedPQEnvironment(func() error { return MigrateSteps(dbURL, migrations, 1) })
+	require.Error(t, err)
+
+	var count int64
+	require.NoError(t, db.Table("captain_assistant_skills").Count(&count).Error)
+	assert.Equal(t, int64(1), count)
+	require.NoError(t, db.Raw("SELECT count(*) FROM pg_indexes WHERE schemaname = current_schema() AND indexname IN ('idx_captain_assistants_account_id_id', 'idx_captain_skills_account_id_id')").Scan(&count).Error)
+	assert.Zero(t, count)
+	require.NoError(t, db.Raw("SELECT count(*) FROM pg_constraint WHERE connamespace = current_schema()::regnamespace AND conname IN ('fk_captain_assistant_skills_assistant_tenant', 'fk_captain_assistant_skills_skill_tenant')").Scan(&count).Error)
+	assert.Zero(t, count)
+	version, dirty, versionErr := CurrentVersion(dbURL, migrations)
+	require.NoError(t, versionErr)
+	assert.Equal(t, uint(81), version)
+	assert.True(t, dirty)
 }
diff --git a/backend/migrations/000081_enforce_captain_skill_tenant_consistency.down.sql b/backend/migrations/000081_enforce_captain_skill_tenant_consistency.down.sql
new file mode 100644
index 00000000..fb328d93
--- /dev/null
+++ b/backend/migrations/000081_enforce_captain_skill_tenant_consistency.down.sql
@@ -0,0 +1,6 @@
+ALTER TABLE captain_assistant_skills
+  DROP CONSTRAINT IF EXISTS fk_captain_assistant_skills_assistant_tenant,
+  DROP CONSTRAINT IF EXISTS fk_captain_assistant_skills_skill_tenant;
+
+DROP INDEX IF EXISTS idx_captain_assistants_account_id_id;
+DROP INDEX IF EXISTS idx_captain_skills_account_id_id;
diff --git a/backend/migrations/000081_enforce_captain_skill_tenant_consistency.up.sql b/backend/migrations/000081_enforce_captain_skill_tenant_consistency.up.sql
new file mode 100644
index 00000000..0bcef8d6
--- /dev/null
+++ b/backend/migrations/000081_enforce_captain_skill_tenant_consistency.up.sql
@@ -0,0 +1,12 @@
+CREATE UNIQUE INDEX idx_captain_assistants_account_id_id
+  ON captain_assistants(account_id, id);
+CREATE UNIQUE INDEX idx_captain_skills_account_id_id
+  ON captain_skills(account_id, id);
+
+ALTER TABLE captain_assistant_skills
+  ADD CONSTRAINT fk_captain_assistant_skills_assistant_tenant
+    FOREIGN KEY (account_id, assistant_id)
+    REFERENCES captain_assistants(account_id, id) ON DELETE CASCADE,
+  ADD CONSTRAINT fk_captain_assistant_skills_skill_tenant
+    FOREIGN KEY (account_id, skill_id)
+    REFERENCES captain_skills(account_id, id) ON DELETE CASCADE;
diff --git a/backend/migrations/sqlite/000081_enforce_captain_skill_tenant_consistency.down.sql b/backend/migrations/sqlite/000081_enforce_captain_skill_tenant_consistency.down.sql
new file mode 100644
index 00000000..d5d22e75
--- /dev/null
+++ b/backend/migrations/sqlite/000081_enforce_captain_skill_tenant_consistency.down.sql
@@ -0,0 +1,21 @@
+CREATE TABLE captain_assistant_skills_000081 (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  account_id INTEGER NOT NULL REFERENCES accounts(id) ON DELETE CASCADE,
+  assistant_id INTEGER NOT NULL REFERENCES captain_assistants(id) ON DELETE CASCADE,
+  skill_id INTEGER NOT NULL REFERENCES captain_skills(id) ON DELETE CASCADE,
+  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  UNIQUE (assistant_id, skill_id)
+);
+
+INSERT INTO captain_assistant_skills_000081
+  (id, account_id, assistant_id, skill_id, created_at)
+SELECT id, account_id, assistant_id, skill_id, created_at
+FROM captain_assistant_skills;
+
+DROP TABLE captain_assistant_skills;
+ALTER TABLE captain_assistant_skills_000081 RENAME TO captain_assistant_skills;
+CREATE INDEX idx_captain_assistant_skills_account ON captain_assistant_skills(account_id);
+CREATE INDEX idx_captain_assistant_skills_skill ON captain_assistant_skills(skill_id);
+
+DROP INDEX idx_captain_assistants_account_id_id;
+DROP INDEX idx_captain_skills_account_id_id;
diff --git a/backend/migrations/sqlite/000081_enforce_captain_skill_tenant_consistency.up.sql b/backend/migrations/sqlite/000081_enforce_captain_skill_tenant_consistency.up.sql
new file mode 100644
index 00000000..7a44152b
--- /dev/null
+++ b/backend/migrations/sqlite/000081_enforce_captain_skill_tenant_consistency.up.sql
@@ -0,0 +1,29 @@
+CREATE UNIQUE INDEX idx_captain_assistants_account_id_id
+  ON captain_assistants(account_id, id);
+CREATE UNIQUE INDEX idx_captain_skills_account_id_id
+  ON captain_skills(account_id, id);
+
+CREATE TABLE captain_assistant_skills_000081 (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  account_id INTEGER NOT NULL REFERENCES accounts(id) ON DELETE CASCADE,
+  assistant_id INTEGER NOT NULL,
+  skill_id INTEGER NOT NULL,
+  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  UNIQUE (assistant_id, skill_id),
+  CONSTRAINT fk_captain_assistant_skills_assistant_tenant
+    FOREIGN KEY (account_id, assistant_id)
+    REFERENCES captain_assistants(account_id, id) ON DELETE CASCADE,
+  CONSTRAINT fk_captain_assistant_skills_skill_tenant
+    FOREIGN KEY (account_id, skill_id)
+    REFERENCES captain_skills(account_id, id) ON DELETE CASCADE
+);
+
+INSERT INTO captain_assistant_skills_000081
+  (id, account_id, assistant_id, skill_id, created_at)
+SELECT id, account_id, assistant_id, skill_id, created_at
+FROM captain_assistant_skills;
+
+DROP TABLE captain_assistant_skills;
+ALTER TABLE captain_assistant_skills_000081 RENAME TO captain_assistant_skills;
+CREATE INDEX idx_captain_assistant_skills_account ON captain_assistant_skills(account_id);
+CREATE INDEX idx_captain_assistant_skills_skill ON captain_assistant_skills(skill_id);