diff --git a/backend/src/db/migrations/057_exam_task_textbook.sql b/backend/src/db/migrations/057_exam_task_textbook.sql
new file mode 100644
index 0000000..43d4012
--- /dev/null
+++ b/backend/src/db/migrations/057_exam_task_textbook.sql
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+-- ═══════════════════════════════════════════════════════════════
+-- 057: Per-task textbook link for exam_tasks
+--
+-- Adds two columns to exam_tasks:
+--   textbook_slug      — textbook chapter slug (e.g. 'algebra-8-ch2')
+--   textbook_paragraph — paragraph number inside that chapter (pN → N as integer)
+--
+-- These are populated by backend/scripts/tag-exam-textbook.js.
+-- The controller (exam-prep.js) prefers these task-level values
+-- over the subtopic-level fallback from exam_topics.
+-- ═══════════════════════════════════════════════════════════════
+
+ALTER TABLE exam_tasks ADD COLUMN textbook_slug TEXT;
+ALTER TABLE exam_tasks ADD COLUMN textbook_paragraph INTEGER;