# Task: Drop external Dockerfile frontend to avoid mirror pulls

## Identity

- Task ID: 20260814-remove-syntax-frontend-1f6c9d3b
- Mode: Feature
- Branch: main
- Worktree: /Users/brother7/Documents/AI/NianAIGC
- Base commit: c7d2cb212cecfad1dcf0567187f1c59e14f96399
- Owner: dsh
- Status: Ready for Integration

## Scope

- Fix the CI image build failure where BuildKit tried to pull the `docker/dockerfile:1` frontend image through the broken `registry.docker-cn.com` mirror and timed out before any project step ran.

## Intent And Constraints

- The three Dockerfiles only use built-in frontend features (multi-stage COPY, ARG-before-FROM, RUN/ENV), so removing the `# syntax=` pin loses nothing and skips the external frontend download entirely.

## Outcome

- Removed `# syntax=docker/dockerfile:1` from `Dockerfile`, `backend/Dockerfile`, and `backend/Dockerfile.runtime`.

## Verification

- Static check: no `syntax=docker` directive remains; every Dockerfile still contains a `FROM` line.
- Actual image assembly must run on the build machine; the change removes the failing pull step (the frontend image) from the build graph.

## Follow-ups

- On the CI machine, replace the dead `registry.docker-cn.com` mirror in `/etc/docker/daemon.json` with a live one (e.g. `docker.m.daocloud.io`) and restart Docker; or build via `backend/Dockerfile.runtime` with a prebuilt binary to avoid the golang image as well.

## Promotion Candidates

- None.