diff --git a/AGENTS.md b/AGENTS.md
index d4edaa0..5809688 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -39,7 +39,7 @@ git-stack is a CLI (`git stack <cmd>`) and stdio MCP server for GitHub's native
 - Read and write git config via `git config`, never by editing files as text.
 - Never edit `~/.claude.json` or `~/.codex/config.toml` directly; use `claude mcp` / `codex mcp`.
 - `install` must never clobber existing user aliases or config without confirmation, and `--uninstall` removes only what we recorded as managed.
-- Only `pkg/backend/ghstack` writes gh-stack's `<git-dir>/gh-stack` file, through its `Update` under `gh-stack.lock`, editing the JSON in place; nothing else writes it, and `gh stack` commands do every other mutation.
+- Only `pkg/backend/ghstack` writes gh-stack's `<git-dir>/gh-stack` file, through its `Update` (or, before running `gh stack` on a stack kept in another worktree's file, `adopt`, which moves that record into the current worktree's) under `gh-stack.lock`, editing the JSON in place; nothing else writes it, and `gh stack` commands do every other mutation.
 
 ## Testing
 - Tests must never touch the real user environment. Use `gittest.Isolate(t)` (sets `HOME`, `XDG_CONFIG_HOME`, `GIT_CONFIG_GLOBAL`, `GIT_CONFIG_NOSYSTEM`) in any test that runs git or installers.
diff --git a/docs/architecture.md b/docs/architecture.md
index d0c9fbd..b8345f8 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -117,6 +117,11 @@ no git config keys. The shape is roughly;
   stacks are strictly linear.
 - Trunk is per stack and several stacks can share one. A branch is in at most one stack.
 - `<git-dir>` is per worktree, so a linked worktree doesn't see the main checkout's stacks.
+  git-stack reads every worktree's file, but `gh stack submit` and `gh stack add` only find
+  a stack in the file of the worktree they run in. So before either, the backend moves the
+  current branch's stack record, untouched, into this worktree's file when it lives in another
+  (a stack started in the main checkout and then checked out in a worktree, say), and moves
+  it back the same way when the branch is next submitted from somewhere else.
 - `gh stack view --json` exists but only covers the current stack, calls the GitHub API,
   and writes the stack file as a side effect. Useless for completion or for listing every
   stack.
diff --git a/pkg/backend/ghstack/backend.go b/pkg/backend/ghstack/backend.go
index 7e635e5..ec3f886 100644
--- a/pkg/backend/ghstack/backend.go
+++ b/pkg/backend/ghstack/backend.go
@@ -158,31 +158,11 @@ func (b *Backend) Load(_ context.Context, repo git.Repo) (*stack.Graph, error) {
 // record). It must not remove or reorder existing stacks; a stack left with
 // no branches is removed.
 func (b *Backend) Update(ctx context.Context, repo git.Repo, fn func(*stack.Graph) error) error {
-	var dirs []string
-	for _, src := range sources(repo) {
-		if _, err := os.Stat(filepath.Join(src.gitDir, FileName)); err == nil {
-			dirs = append(dirs, src.gitDir)
-		}
-	}
-	// The current git dir is always locked, even with no file yet: Update
-	// may create its file for a new stack and two writers must not race it.
-	if !slices.Contains(dirs, repo.GitDir) {
-		dirs = append(dirs, repo.GitDir)
-	}
-	slices.Sort(dirs)
-	var unlocks []func()
-	defer func() {
-		for _, u := range unlocks {
-			u()
-		}
-	}()
-	for _, dir := range dirs {
-		unlock, err := lock(ctx, filepath.Join(dir, LockName), lockWait)
-		if err != nil {
-			return err
-		}
-		unlocks = append(unlocks, unlock)
+	unlock, err := lockAll(ctx, repo)
+	if err != nil {
+		return err
 	}
+	defer unlock()
 	r, err := b.read(repo)
 	if err != nil {
 		return err
@@ -220,6 +200,92 @@ func (b *Backend) Update(ctx context.Context, repo git.Repo, fn func(*stack.Grap
 	return nil
 }
 
+// lockAll takes gh stack's lock in every git dir that has a metadata file,
+// and in the current one even without a file yet, since a new stack may
+// create its file there and two writers must not race it. Dirs are locked
+// in sorted order so two of us never deadlock.
+func lockAll(ctx context.Context, repo git.Repo) (func(), error) {
+	var dirs []string
+	for _, src := range sources(repo) {
+		if _, err := os.Stat(filepath.Join(src.gitDir, FileName)); err == nil {
+			dirs = append(dirs, src.gitDir)
+		}
+	}
+	if !slices.Contains(dirs, repo.GitDir) {
+		dirs = append(dirs, repo.GitDir)
+	}
+	slices.Sort(dirs)
+	var unlocks []func()
+	unlockAll := func() {
+		for _, u := range slices.Backward(unlocks) {
+			u()
+		}
+	}
+	for _, dir := range dirs {
+		unlock, err := lock(ctx, filepath.Join(dir, LockName), lockWait)
+		if err != nil {
+			unlockAll()
+			return nil, err
+		}
+		unlocks = append(unlocks, unlock)
+	}
+	return unlockAll, nil
+}
+
+// adopt moves the record of the stack holding branch into the current
+// worktree's file when it is kept in another worktree's (it was started
+// there, or put in the main checkout's file by an older git-stack). gh
+// stack only reads the file in the git dir it runs in, so without this it
+// says the branch is not in a stack. The record moves as it is, pull
+// request records and members we don't model included. A branch in no
+// stack is left alone for gh stack to report.
+func (b *Backend) adopt(ctx context.Context, repo git.Repo, branch string) error {
+	if branch == "" {
+		return nil
+	}
+	unlock, err := lockAll(ctx, repo)
+	if err != nil {
+		return err
+	}
+	defer unlock()
+	r, err := b.read(repo)
+	if err != nil {
+		return err
+	}
+	gi := slices.IndexFunc(r.graph.Stacks, func(s stack.Stack) bool { return s.Index(branch) >= 0 })
+	if gi < 0 {
+		return nil
+	}
+	from := r.where[gi]
+	if r.files[from.file].src.gitDir == repo.GitDir {
+		return nil
+	}
+	to := r.fileFor(repo)
+	src, err := parseTree(r.files[from.file].data)
+	if err != nil {
+		return err
+	}
+	dst, err := parseTree(r.files[to].data)
+	if err != nil {
+		return err
+	}
+	srcStacks := src.get("stacks")
+	rec := srcStacks.items[from.rec]
+	srcStacks.items = slices.Delete(srcStacks.items, from.rec, from.rec+1)
+	dstStacks := dst.get("stacks")
+	if dstStacks == nil || dstStacks.kind != '[' {
+		dstStacks = arrayNode()
+		dst.set("stacks", dstStacks)
+	}
+	dstStacks.items = append(dstStacks.items, rec)
+	// The new home first: should the second write fail, the stack is in
+	// both files and the current worktree's copy is the one read first.
+	if err := writeFile(r.files[to].src.gitDir, dst); err != nil {
+		return err
+	}
+	return writeFile(r.files[from.file].src.gitDir, src)
+}
+
 // parseAll parses every loaded file and collects the node of every branch
 // in a record the graph came from, by name. Branch names are unique across
 // stacks, so a branch fn moved to another record, or to another file, takes
@@ -344,11 +410,17 @@ func (b *Backend) writeBack(r *reading, fi int, root *node, pool map[string]*nod
 		return nil
 	}
 	stacksNode.items = keep
+	return writeFile(r.files[fi].src.gitDir, root)
+}
+
+// writeFile replaces the metadata file in gitDir with root, atomically and
+// keeping the old file's permissions.
+func writeFile(gitDir string, root *node) error {
 	out, err := root.encode()
 	if err != nil {
 		return err
 	}
-	path := filepath.Join(r.files[fi].src.gitDir, FileName)
+	path := filepath.Join(gitDir, FileName)
 	tmp, err := os.CreateTemp(filepath.Dir(path), FileName+".*")
 	if err != nil {
 		return err
diff --git a/pkg/backend/ghstack/submitter.go b/pkg/backend/ghstack/submitter.go
index d654ab6..bb396aa 100644
--- a/pkg/backend/ghstack/submitter.go
+++ b/pkg/backend/ghstack/submitter.go
@@ -17,11 +17,15 @@ var (
 
 // Submit runs `gh stack submit`. Non-interactive runs use --auto and are
 // captured; interactive runs hand gh-stack the real terminal so its own
-// PR editor can open.
+// PR editor can open. The current branch's stack is moved into this
+// worktree's file first, as that is the only one gh stack reads here.
 func (b *Backend) Submit(ctx context.Context, repo git.Repo, o stack.SubmitOptions) (stack.SubmitResult, error) {
 	if err := b.Preflight(ctx); err != nil {
 		return stack.SubmitResult{}, err
 	}
+	if err := b.adoptCurrent(ctx, repo); err != nil {
+		return stack.SubmitResult{}, err
+	}
 	args := []string{"submit"}
 	if o.Publish {
 		args = append(args, "--open")
diff --git a/pkg/backend/ghstack/tracker.go b/pkg/backend/ghstack/tracker.go
index 72e5c5a..ae2256d 100644
--- a/pkg/backend/ghstack/tracker.go
+++ b/pkg/backend/ghstack/tracker.go
@@ -3,6 +3,7 @@ package ghstack
 import (
 	"context"
 	"errors"
+	"slices"
 	"strings"
 
 	"github.com/DomBlack/git-stack/pkg/git"
@@ -20,11 +21,16 @@ func (b *Backend) InitStack(ctx context.Context, repo git.Repo, trunk string, br
 	return b.gh(ctx, repo, args...)
 }
 
-// AddTop runs `gh stack add <name>` without committing (we commit natively).
+// AddTop runs `gh stack add <name>` without committing (we commit natively),
+// once the current branch's stack is in this worktree's file where gh stack
+// will look for it.
 func (b *Backend) AddTop(ctx context.Context, repo git.Repo, name string) error {
 	if err := b.Preflight(ctx); err != nil {
 		return err
 	}
+	if err := b.adoptCurrent(ctx, repo); err != nil {
+		return err
+	}
 	err := b.gh(ctx, repo, "add", name)
 	if err != nil {
 		if se, ok := errors.AsType[*stack.Error](err); ok && se.Kind == stack.KindInvalidArgs &&
@@ -38,3 +44,24 @@ func (b *Backend) AddTop(ctx context.Context, repo git.Repo, name string) error
 	}
 	return nil
 }
+
+// adoptCurrent adopts the stack of the branch checked out here, if any.
+// When every stack is already in this worktree's file there is nothing to
+// move, so git isn't asked which branch that is.
+func (b *Backend) adoptCurrent(ctx context.Context, repo git.Repo) error {
+	r, err := b.read(repo)
+	if err != nil {
+		return err
+	}
+	if !slices.ContainsFunc(r.where, func(w recRef) bool { return r.files[w.file].src.gitDir != repo.GitDir }) {
+		return nil
+	}
+	branch, err := b.git.CurrentBranch(ctx, repo)
+	if errors.Is(err, git.ErrDetached) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	return b.adopt(ctx, repo, branch)
+}
diff --git a/pkg/backend/ghstack/update_test.go b/pkg/backend/ghstack/update_test.go
index fa47703..3fb13fb 100644
--- a/pkg/backend/ghstack/update_test.go
+++ b/pkg/backend/ghstack/update_test.go
@@ -472,3 +472,63 @@ func TestUpdateMoveAcrossFilesKeepsBranchRecords(t *testing.T) {
 		t.Errorf("worktree file should only hold w2 now:\n%s", wtData)
 	}
 }
+
+func TestAdoptMovesStackRecordToCurrentWorktree(t *testing.T) {
+	b, repo, mainPath, _ := updateFixture(t)
+	ctx := context.Background()
+	gittest.Run(t, repo.TopLevel, "branch", "b")
+	dir := filepath.Join(t.TempDir(), "fresh")
+	gittest.Run(t, repo.TopLevel, "worktree", "add", "-q", dir, "b")
+	wtRepo, err := b.git.Discover(ctx, dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// b's stack lives in the main checkout's file; from the worktree where b
+	// is checked out it moves over whole.
+	if err := b.adoptCurrent(ctx, wtRepo); err != nil {
+		t.Fatal(err)
+	}
+	data, err := os.ReadFile(filepath.Join(wtRepo.GitDir, FileName))
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{`"id": "S1"`, `"number": 7`, `"extra": "yes"`, `"branch": "b"`} {
+		if !strings.Contains(string(data), want) {
+			t.Errorf("worktree file lacks %s:\n%s", want, data)
+		}
+	}
+	main, _ := os.ReadFile(mainPath)
+	if strings.Contains(string(main), `"S1"`) || !strings.Contains(string(main), `"branch": "done"`) || !strings.Contains(string(main), `"future"`) {
+		t.Errorf("main file should keep everything but S1:\n%s", main)
+	}
+	g, err := b.Load(ctx, wtRepo)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s, _, ok := g.StackOf("b"); !ok || s.ID != "S1" || s.Bottom() != "a" || s.Worktree != wtRepo.TopLevel {
+		t.Errorf("stack of b = %+v", s)
+	}
+
+	// Already here: nothing is rewritten.
+	before, _ := os.ReadFile(filepath.Join(wtRepo.GitDir, FileName))
+	if err := b.adoptCurrent(ctx, wtRepo); err != nil {
+		t.Fatal(err)
+	}
+	if after, _ := os.ReadFile(filepath.Join(wtRepo.GitDir, FileName)); string(after) != string(before) {
+		t.Errorf("a second adopt changed the file:\n%s", after)
+	}
+
+	// And back to the main checkout once b is checked out there.
+	gittest.Run(t, dir, "switch", "-q", "--detach")
+	gittest.Run(t, repo.TopLevel, "switch", "-q", "b")
+	if err := b.adoptCurrent(ctx, repo); err != nil {
+		t.Fatal(err)
+	}
+	if main, _ := os.ReadFile(mainPath); !strings.Contains(string(main), `"S1"`) {
+		t.Errorf("S1 should be back in the main file:\n%s", main)
+	}
+	if wt, _ := os.ReadFile(filepath.Join(wtRepo.GitDir, FileName)); strings.Contains(string(wt), `"S1"`) {
+		t.Errorf("S1 should have left the worktree file:\n%s", wt)
+	}
+}