2026-05-10: Fix Docker prod re-seeds database on every startup

Problem

Running npm run docker:prod showed both user-created assets and seeded demo assets. Same issue occurred after deleting a demo asset — the next docker:prod restart re-created it.

Root cause: backend/Dockerfile CMD ran npx prisma db seed unconditionally on every container startup:

CMD ["sh", "-c", "npx prisma migrate deploy && npx prisma db seed && node dist/main.js"]

The seed script uses findFirst({ where: { name } }) guards — if a demo asset was deleted by the user, the guard returns null → seed re-creates it. This is identical to the Tauri startup bug fixed in 2026-05-09-fix-tauri-reseed-on-startup.md.

AGENTS.md Compliance

#	Convention	Check
1	Documentation	✅ backend.md, dev-setup.md updated
2	All 4 test gates	n/a — Dockerfile-only change
3	Self-review	✅ Check DB path before migrate, seed only if fresh
5	Bug-to-Test	n/a — infra-level, verified manually per Conv #9
8	Plan history	✅ This doc
9	Infra test gate	✅ Run npm run docker:reset to verify
12	Execution summary	✅ Below
13	Doc Grep Rule	✅ Grepped docs; updated backend.md + dev-setup.md

Fix

Create backend/docker-start.sh — checks if DB file exists before prisma migrate deploy (which creates the file on fresh install). Seed runs only when IS_FRESH=1.

DB_PATH=$(echo "$DATABASE_URL" | sed 's|^file:||')
if [ ! -f "$DB_PATH" ]; then
  npx prisma migrate deploy
  npx prisma db seed        # Fresh install only
else
  npx prisma migrate deploy # Schema updates; no seed
fi
exec node dist/main.js

Dockerfile CMD changed from:

CMD ["sh", "-c", "npx prisma migrate deploy && npx prisma db seed && node dist/main.js"]

to:

CMD ["./docker-start.sh"]

Files Changed

File	Change
backend/docker-start.sh	New startup script with conditional seed
backend/Dockerfile	COPY + exec docker-start.sh; chmod in same RUN
docs/src/content/docs/backend.md	Clarify seed runs only on first start
docs/src/content/docs/dev-setup.md	Note: seed is automatic on first Docker start

Execution Summary

Commit: TBD

Actual changes

Matches plan exactly.

Deviations from plan

None.

Test results

Gate	Result
Backend unit	⏭ not affected
Backend e2e	⏭ not affected
Frontend unit	⏭ not affected
Frontend e2e	⏭ not affected
Infra (docker:reset)	✅ verified — fresh DB seeds; existing DB skips seed

Key discoveries

• The Tauri lib.rs fix (2026-05-09) and this Docker fix are the same pattern: check DB existence before calling seed.
• ensure_data_dir() in Rust only creates the directory (not the file), so checking db_filename.exists() before it correctly detects fresh install. In Docker, prisma migrate deploy creates the DB file — so checking before migrate is the right guard.