fix(store): expand a leading ~ in EMCLI_DB

A literal "~/..." in EMCLI_DB has no shell to expand it, so SQLite opened
it relative to the cwd and silently created a stray "~" directory tree.
Expand a leading "~" or "~/" to the user's home dir; "~user", mid-path
tildes, and absolute/relative paths are left untouched.

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

internal/store/store.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strconv"
+	"strings"
 
 	_ "modernc.org/sqlite"
 )
@@ -77,10 +78,24 @@ func (s *Store) migrate() error {
 
 func (s *Store) Close() error { return s.db.Close() }
 
+// expandUserHome replaces a leading "~" or "~/" in p with the user's home
+// directory. Only a leading tilde is expanded (the usual shell convention) —
+// "~user" and a tilde elsewhere in the path are left untouched. This guards
+// against an EMCLI_DB set to a literal "~/..." (no shell to expand it), which
+// would otherwise be opened relative to the cwd and create a stray "~" dir.
+func expandUserHome(p string) string {
+	if p == "~" || strings.HasPrefix(p, "~/") {
+		if home, err := os.UserHomeDir(); err == nil {
+			return filepath.Join(home, strings.TrimPrefix(p[1:], "/"))
+		}
+	}
+	return p
+}
+
 // DefaultDBPath resolves EMCLI_DB or the per-OS default location.
 func DefaultDBPath() (string, error) {
 	if p := os.Getenv("EMCLI_DB"); p != "" {
-		return p, nil
+		return expandUserHome(p), nil
 	}
 	if runtime.GOOS == "windows" {
 		if dir := os.Getenv("AppData"); dir != "" {

internal/store/store_test.go

@@ -2,10 +2,53 @@ package store
 
 import (
 	"database/sql"
+	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 )
 
+// A leading "~" in EMCLI_DB must be expanded to the home dir, so a literal
+// tilde (no shell to expand it) can't be opened relative to the cwd and
+// silently create a stray "~" directory.
+func TestDefaultDBPathExpandsLeadingTilde(t *testing.T) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		t.Skipf("no home dir: %v", err)
+	}
+	cases := map[string]string{
+		"~/.config/emcli/emcli.db": filepath.Join(home, ".config", "emcli", "emcli.db"),
+		"~":                        home,
+	}
+	for in, want := range cases {
+		t.Setenv("EMCLI_DB", in)
+		got, err := DefaultDBPath()
+		if err != nil {
+			t.Fatalf("DefaultDBPath(%q): %v", in, err)
+		}
+		if got != want {
+			t.Fatalf("EMCLI_DB=%q -> %q, want %q", in, got, want)
+		}
+		if strings.Contains(got, "~") {
+			t.Fatalf("EMCLI_DB=%q left a literal tilde: %q", in, got)
+		}
+	}
+}
+
+// A non-leading tilde or "~user" is NOT a path we should rewrite — leave it be.
+func TestDefaultDBPathLeavesOtherPathsUntouched(t *testing.T) {
+	for _, p := range []string{"/var/lib/emcli.db", "./rel/emcli.db", "~user/db"} {
+		t.Setenv("EMCLI_DB", p)
+		got, err := DefaultDBPath()
+		if err != nil {
+			t.Fatalf("DefaultDBPath(%q): %v", p, err)
+		}
+		if got != p {
+			t.Fatalf("EMCLI_DB=%q was rewritten to %q", p, got)
+		}
+	}
+}
+
 // openTemp opens a fresh store in a temp dir and initialises keys so that
 // account tests (which do crypto) work without needing their own setup.
 func openTemp(t *testing.T) *Store {