diff --git a/xuqm-bugcollect-service/src/main/resources/db/migration/V6__build_id.sql b/xuqm-bugcollect-service/src/main/resources/db/migration/V6__build_id.sql
index 6008141..93315bb 100644
--- a/xuqm-bugcollect-service/src/main/resources/db/migration/V6__build_id.sql
+++ b/xuqm-bugcollect-service/src/main/resources/db/migration/V6__build_id.sql
@@ -1,4 +1,20 @@
 -- V6: build_id support for multi-build-per-version sourcemap tracking
--- All DDL was applied manually during the initial migration incident.
--- This script is intentionally a no-op to let Flyway record V6 as done.
-SELECT 1;
+--
+-- Adds build_id to log_issue_events and log_sourcemaps so each unique
+-- (appKey, platform, appVersion, buildId, bundleName) combination can
+-- store its own sourcemap file without overwriting sibling builds.
+--
+-- Existing deployments where this column was already added manually:
+-- Flyway will have recorded V6 as done via the old no-op; those databases
+-- have the column already. For any deployment where V6 ran as a no-op
+-- and the column is still missing, run the repair migration V7.
+
+ALTER TABLE log_issue_events
+    ADD COLUMN build_id VARCHAR(32) NULL
+        COMMENT 'Build identifier for sourcemap tracking'
+        AFTER app_version;
+
+ALTER TABLE log_sourcemaps
+    ADD COLUMN build_id VARCHAR(32) NULL
+        COMMENT 'Build identifier for multi-build-per-version sourcemap tracking'
+        AFTER app_version;
diff --git a/xuqm-bugcollect-service/src/main/resources/db/migration/V7__build_id_repair.sql b/xuqm-bugcollect-service/src/main/resources/db/migration/V7__build_id_repair.sql
new file mode 100644
index 0000000..8bac0eb
--- /dev/null
+++ b/xuqm-bugcollect-service/src/main/resources/db/migration/V7__build_id_repair.sql
@@ -0,0 +1,30 @@
+-- V7: repair for deployments where V6 ran as a no-op
+--
+-- On some deployments V6 was recorded as done but contained only SELECT 1,
+-- leaving build_id missing from log_issue_events and log_sourcemaps.
+-- This migration adds the column idempotently using a prepared statement so
+-- it is safe whether the column already exists or not.
+
+SET @_add_lie = IF(
+    NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_schema = DATABASE()
+          AND table_name   = 'log_issue_events'
+          AND column_name  = 'build_id'
+    ),
+    'ALTER TABLE log_issue_events ADD COLUMN build_id VARCHAR(32) NULL COMMENT ''Build identifier for sourcemap tracking'' AFTER app_version',
+    'SELECT 1 /* log_issue_events.build_id already exists */'
+);
+PREPARE _s FROM @_add_lie; EXECUTE _s; DEALLOCATE PREPARE _s;
+
+SET @_add_lsm = IF(
+    NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_schema = DATABASE()
+          AND table_name   = 'log_sourcemaps'
+          AND column_name  = 'build_id'
+    ),
+    'ALTER TABLE log_sourcemaps ADD COLUMN build_id VARCHAR(32) NULL COMMENT ''Build identifier for multi-build-per-version sourcemap tracking'' AFTER app_version',
+    'SELECT 1 /* log_sourcemaps.build_id already exists */'
+);
+PREPARE _s FROM @_add_lsm; EXECUTE _s; DEALLOCATE PREPARE _s;