feat(git): read files from accepted trees

[zhiiw]

Summary

• add a bounded Gitoxide helper operation that reads one regular UTF-8 blob from an exact accepted commit tree
• bind repository, commit, and tree identity to the existing owner-issued managed repository capability
• reject non-canonical paths, symlinks/non-blob entries, non-UTF-8 content, and files above 8 MiB without projection or filesystem fallback
• document the immutable dependency-manifest input boundary for the upcoming managed dependency product composition

Primary invariant

Dependency manifests and lockfiles are read from the exact immutable accepted Git tree. A caller cannot substitute a repository, commit, tree, or mutable projection path.

Owner: Gitoxide managed-repository admission authority.

Atomicity boundary: one read-only helper invocation against one accepted commit/tree identity; no durable mutation or T1 is involved.

Failure state: any malformed path, missing object, identity mismatch, unsupported entry, encoding violation, or resource-limit violation fails closed.

Rollback: none required because this slice writes no durable state.

Verification

• npm --workspace @maka/runtime-host run build
• npx biome check ... for the changed Runtime Host files
• npm run check:asf-headers
• git diff --check
• Rust compile/fmt and real-helper tests are delegated to the three-platform Gitoxide CI because the local Windows checkout has no Rust toolchain

This is a stacked Draft based on codex/gitoxide-projection-data-plane. It has no standalone production consumer; the next M1.3 composition PR consumes it together with the packaged helper and dependency authorities.

中文说明

概要

• 新增有界的 Gitoxide helper 操作，只从 exact accepted commit tree 读取一个普通 UTF-8 blob；
• repository、commit、tree 身份全部绑定现有 owner-issued managed repository capability；
• 非规范路径、symlink/非 blob、非 UTF-8、超过 8 MiB 的文件全部 fail closed，不回退 projection 或文件系统读取；
• 为后续 M1.3 managed dependency 产品接线明确 immutable manifest/lockfile 输入边界。

主要不变量

依赖 manifest 与 lockfile 必须来自 exact immutable accepted Git tree。caller 不能替换 repository、commit、tree，也不能把 mutable projection 路径冒充权威输入。

Owner：Gitoxide managed-repository admission authority。

原子边界：单次只读 helper invocation 对应唯一 accepted commit/tree；没有 durable mutation，也没有 T1。

失败状态：路径、object、identity、entry kind、编码或资源上限任一不合法都 fail closed。

回滚：本切片不写 durable state，无需回滚。

这是基于 codex/gitoxide-projection-data-plane 的 stacked Draft；它不单独声明生产能力，下一步 M1.3 composition 会把它与 packaged helper、dependency authority 一起接入真实产品入口。

[zhiiw]

Closed as an obsolete extraction/integration slice. The current delivery path is the merged Gitoxide foundation followed by #40 -> #41 -> #42. This PR remains available as design and implementation history.

中文说明

该 PR 属于旧 extraction/integration 栈，现已失去独立合并价值。当前交付路径是已合并的 Gitoxide 基础，然后依次审查 #40 → #41 → #42。这里继续保留设计、实现与审查历史。