feat(workspace): clone-based Workspace adapter

backend/internal/adapters/workspace/clone/commands.go

@@ -0,0 +1,55 @@
+package clone
+
+// remoteGetURLArgs returns the args to read the configured origin URL of a
+// repository at dir. Used by Create to discover what URL to clone from and by
+// Restore to verify an existing clone points at the expected source.
+func remoteGetURLArgs(dir string) []string {
+	return []string{"-C", dir, "remote", "get-url", "origin"}
+}
+
+// cloneArgs returns the args to perform a full clone of source into dest.
+// Plain `git clone` (no --reference, no --shared) is used deliberately: each
+// destination gets an independent object database, so concurrent clones from
+// the same source touch only the source's read-only pack files and never
+// contend on .git/index.lock or alternates. See package doc for the full
+// concurrency model.
+func cloneArgs(source, dest string) []string {
+	return []string{"clone", source, dest}
+}
+
+// checkoutNewBranchArgs creates a new local branch starting from HEAD.
+func checkoutNewBranchArgs(dir, branch string) []string {
+	return []string{"-C", dir, "checkout", "-b", branch}
+}
+
+// checkoutBranchArgs checks out an existing branch (used as fallback when
+// checkoutNewBranchArgs reports the branch already exists).
+func checkoutBranchArgs(dir, branch string) []string {
+	return []string{"-C", dir, "checkout", branch}
+}
+
+// showCurrentBranchArgs returns the short name of the currently checked-out
+// branch (empty for detached HEAD).
+func showCurrentBranchArgs(dir string) []string {
+	return []string{"-C", dir, "branch", "--show-current"}
+}
+
+// statusPorcelainArgs returns the args used by Destroy to detect uncommitted
+// changes. Any non-empty output means the working tree has work the agent has
+// not committed; Destroy refuses to delete it.
+//
+// This is the clone-adapter analogue of gitworktree's intentional omission of
+// `--force` from `git worktree remove`: we never blindly delete a session
+// directory that may contain unsaved agent work (review item RA on PR #23).
+// There is no Force escape hatch on the port or on this adapter — the
+// safety check is unconditional.
+func statusPorcelainArgs(dir string) []string {
+	return []string{"-C", dir, "status", "--porcelain"}
+}
+
+// revParseInsideWorkTreeArgs returns the args used to confirm a directory is
+// a valid git working tree (used by List to skip corrupt clones and by
+// Restore to validate a recovered directory before reusing it).
+func revParseInsideWorkTreeArgs(dir string) []string {
+	return []string{"-C", dir, "rev-parse", "--is-inside-work-tree"}
+}