diff --git a/docs/reference.md b/docs/reference.md
index 4f5c137b..0905bd27 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -1674,7 +1674,9 @@ MAGPIE_GITHUB_MIRROR=https://gh.example magpie serve
 - `~/.config/magpie/stash.json` — values magpie replaced, restored on switch-back
 - `~/.config/magpie/plugins.json`, `plugins/` — the plugins added, and their packages
 - `~/.config/magpie/plugin-auth.json` — the plugins' sign-ins (0600)
-- `~/.cache/magpie/bun/` — the Bun plugins run on
+- `~/.cache/magpie/bun/<version>/magpie-bun` — the Bun plugins run on, named
+  so that a proxy app's PROCESS-NAME rule can match it (`magpie-bun.exe` on
+  Windows)
 - `~/.cache/magpie/models.json` — models.dev catalog (OpenCode's cache at
   `~/.cache/opencode/models.json` is used when present)
 - `~/.cache/magpie/models/<provider>.json` — model lists fetched from vendors
diff --git a/internal/plugin/bun.go b/internal/plugin/bun.go
index ca13eddc..77830269 100644
--- a/internal/plugin/bun.go
+++ b/internal/plugin/bun.go
@@ -100,7 +100,7 @@ func Bun(ctx context.Context) (string, error) {
 	defer bunMu.Unlock()
 	v := inUseLocked()
 	exe := bunExeOf(v)
-	if _, err := os.Stat(exe); err == nil {
+	if haveBun(v) {
 		return exe, nil
 	}
 	if err := downloadBun(ctx, v, exe); err != nil {
diff --git a/internal/plugin/bunname_test.go b/internal/plugin/bunname_test.go
new file mode 100644
index 00000000..b522931f
--- /dev/null
+++ b/internal/plugin/bunname_test.go
@@ -0,0 +1,123 @@
+package plugin
+
+import (
+	"context"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+// The Bun magpie downloads is kept as magpie-bun, the name a proxy app's
+// PROCESS-NAME rule sees (#1048).
+func TestBunDownloadedAsMagpieBun(t *testing.T) {
+	bunHome(t, BunVersion, time.Now())
+	asked := bunReleases(t, []byte("bun"))
+	exe, err := Bun(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if filepath.Base(exe) != magpieBun() || asked.Load() != 1 {
+		t.Fatalf("Bun = %s after %d downloads, want one named %s", exe, asked.Load(), magpieBun())
+	}
+	if _, err := os.Stat(filepath.Join(filepath.Dir(exe), bunExe())); !os.IsNotExist(err) {
+		t.Fatalf("a bun beside magpie-bun: %v", err)
+	}
+}
+
+// A Bun downloaded before is renamed magpie-bun, not downloaded again.
+func TestBunDownloadedBeforeTakesTheName(t *testing.T) {
+	bunHome(t, BunVersion, time.Now())
+	asked := bunReleases(t, []byte("new download"))
+	old := filepath.Join(bunDirOf(BunVersion), bunExe())
+	if err := os.MkdirAll(filepath.Dir(old), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(old, []byte("downloaded before"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if !HasBun() {
+		t.Fatal("HasBun is false with a bun downloaded before")
+	}
+	exe, err := Bun(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if b, _ := os.ReadFile(exe); filepath.Base(exe) != magpieBun() || string(b) != "downloaded before" || asked.Load() != 0 {
+		t.Fatalf("Bun = %s holding %q after %d downloads", exe, b, asked.Load())
+	}
+	if _, err := os.Stat(old); !os.IsNotExist(err) {
+		t.Fatalf("the old bun is still there: %v", err)
+	}
+}
+
+// The plugin host runs as magpie-bun: the process name the system reports
+// for it is magpie-bun, not bun.
+func TestHostRunsAsMagpieBun(t *testing.T) {
+	real, err := exec.LookPath("bun")
+	if err != nil {
+		t.Skip("no bun on PATH")
+	}
+	bunHome(t, BunVersion, time.Now())
+	t.Cleanup(Settle)
+	// a real Bun as magpie downloaded it before: a copy (not a link, whose
+	// process would take the target's name) at the old name
+	old := filepath.Join(bunDirOf(BunVersion), bunExe())
+	if err := os.MkdirAll(filepath.Dir(old), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	copyExe(t, real, old)
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+	abs, _ := filepath.Abs("testdata/fake/index.js")
+	if _, err := Add(ctx, abs); err != nil {
+		t.Fatal(err)
+	}
+	if ps, err := Providers(ctx); err != nil || len(ps) != 1 {
+		t.Fatalf("Providers = %+v, %v", ps, err)
+	}
+	hostMu.Lock()
+	h := current
+	hostMu.Unlock()
+	if h == nil || h.cmd.Process == nil {
+		t.Fatal("no host running")
+	}
+	if got := filepath.Base(h.cmd.Path); got != magpieBun() {
+		t.Fatalf("the host runs %s", h.cmd.Path)
+	}
+	if runtime.GOOS == "windows" {
+		return
+	}
+	out, err := exec.Command("ps", "-o", "comm=", "-p", strconv.Itoa(h.cmd.Process.Pid)).Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := filepath.Base(strings.TrimSpace(string(out))); got != "magpie-bun" {
+		t.Fatalf("ps says the host is %q", got)
+	}
+}
+
+func copyExe(t *testing.T, from, to string) {
+	t.Helper()
+	in, err := os.Open(from)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer in.Close()
+	out, err := os.OpenFile(to, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o755)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := io.Copy(out, in); err != nil {
+		t.Fatal(err)
+	}
+	if err := out.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/internal/plugin/bunupdate.go b/internal/plugin/bunupdate.go
index e97e6230..62190b77 100644
--- a/internal/plugin/bunupdate.go
+++ b/internal/plugin/bunupdate.go
@@ -46,7 +46,12 @@ func bunRoot() string { return filepath.Join(filepath.Dir(catalog.CachePath()),
 
 func bunDirOf(v string) string { return filepath.Join(bunRoot(), v) }
 
-func bunExeOf(v string) string { return filepath.Join(bunDirOf(v), bunExe()) }
+// bunExeOf is where magpie keeps Bun v: named magpie-bun, so a proxy app's
+// PROCESS-NAME rule can tell the requests plugins make (and their installs)
+// from any other Bun's (#1048).
+func bunExeOf(v string) string { return filepath.Join(bunDirOf(v), magpieBun()) }
+
+func magpieBun() string { return "magpie-" + bunExe() }
 
 func bunStatePath() string { return filepath.Join(bunRoot(), "state.json") }
 
@@ -70,7 +75,13 @@ func writeBunState(s bunState) error {
 }
 
 func haveBun(v string) bool {
-	_, err := os.Stat(bunExeOf(v))
+	exe := bunExeOf(v)
+	if _, err := os.Stat(exe); err == nil {
+		return true
+	}
+	// a Bun downloaded before it was named magpie-bun takes the name
+	_ = os.Rename(filepath.Join(bunDirOf(v), bunExe()), exe)
+	_, err := os.Stat(exe)
 	return err == nil
 }