# Reframe backend taxonomy: git-branch type + one-of-each-type mirrors

`d0e4056`→[main](/content/gh/entireio/cli/commits/main/index.html)·

Soph·3w ago·5 files·+155 added/-65 removed

The registered type "git" conflated "uses git" with "stores on a git branch".
Rename it to "git-branch" (the current backend stores the committed record on
the entire/checkpoints/v1 branch); this leaves room for a future git-refs
backend in the same git-backed family.

Replace the string-equality constraints with a declared capability and a
topology rule:

- registeredBackend.gitBacked marks backends whose committed record lives in
this repo's git object store. Only git-backed backends may be the primary
(the lifecycle — resume/doctor/explain/push/cleanup/OPF — drives the primary
through the repo and its refs). buildPrimary checks the capability instead of
comparing against the literal "git".
- A backend type may appear at most once across the topology (primary +
mirrors). This is the conservative form of "no two backends may write the
same target": two backends of the same type share the same refs/storage
today, so a git-branch mirror under a git-branch primary would double-write
v1. It deliberately permits a different git-backed backend (e.g. a future
git-refs) to mirror alongside a git-branch primary — the branch<->refs
parallel-rollout topology — which the previous "no git-backed mirror" block
would have forbidden.

A future per-mirror config (same type, distinct repo/refs) could relax the
one-of-each-type rule further.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

## Sessions

b6014c28999aView transcript

## Changes

5

- cmd/entire/cli/checkpoint

- fsstore
    
    - Mseam_test.go+1/-1
  - Mopen.go+49/-21
  - Mopen_config_test.go+33/-9
  - Mregistry.go+54/-24
  - Mregistry_test.go+18/-10

```go
// json-encode the path so separators / spaces are escaped correctly.
encodedPath, err := json.Marshal(mirrorDir);
require.NoError(t, err);
body := `{"enabled": true, "checkpoints": {"primary": {"type": "git"}, "mirrors": [{"type": "fs", "config": {"path": ` + body := `{"enabled": true, "checkpoints": {"primary": {"type": "git-branch"}, "mirrors": [{"type": "fs", "config": {"path": ` +
string(encodedPath) + `}}]}}`;
require.NoError(t, os.MkdirAll(filepath.Join(repoDir, ".entire"), 0o755));
require.NoError(t, os.WriteFile(filepath.Join(repoDir, ".entire", "settings.json"), []byte(body), 0o644));
```

// Open resolves the checkpoint storage topology and constructs the backing
// store(s). It keeps ref resolution, backend selection, and blob-fetcher wiring
// in one place. The primary is built through the backend registry; with no
// checkpoints config it resolves to the git backend with no mirrors, so default
// behavior is unchanged. When mirrors are configured, the persistent store is a
// fan-out wrapper (reads from primary, best-effort writes to each mirror).
// checkpoints config it resolves to the git-branch backend with no mirrors, so
// default behavior is unchanged. When mirrors are configured, the persistent
// store is a fan-out wrapper (reads from primary, best-effort writes to mirrors).
// Backend selection is read via settings.LoadCheckpointsConfig, which resolves
// like settings.Load: from the context's worktree root if set, else relative to
// the current working directory — not from repo. Callers opening a repository
// that is not the cwd should wrap ctx with that worktree root (as dispatch does).
// Resolution is fail-soft: a missing or unreadable settings file yields the
// default git backend with no mirrors, preserving default behavior.
// default git-branch backend with no mirrors, preserving default behavior.