cmd: route root command server start through checkServerHeartbeat (#17245)

The bare `ollama` command (and `ollama launch` with no integration) used a
bespoke `ensureServerRunning` that forked `ollama serve` directly and polled
its heartbeat forever (no timeout, no platform-aware launch). Every other
subcommand (`ollama run`, `ollama pull`, `ollama launch <integration>`, ...)
goes through `checkServerHeartbeat` -> `startApp`, so the root command behaved
differently and could hang indefinitely.

Route `runInteractiveTUI` through `checkServerHeartbeat(cmd, nil)` — the same
path `ollama launch <thing>` uses — so the root command is consistent and no
longer runs an unbounded server-spawn loop. `ensureServerRunning` and its
`backgroundServerSysProcAttr` helpers (only it referenced them) are removed,
along with the now-unused `os/exec` import.

The platform `startApp`/`waitForServer` paths are unchanged, so behavior on
macOS/Windows is identical to the other subcommands, and on Linux the root
command now errors the same way the subcommands already do when no server is
running.

cmd/background_unix.go

@@ -1,13 +0,0 @@
-//go:build !windows
-
-package cmd
-
-import "syscall"
-
-// backgroundServerSysProcAttr returns SysProcAttr for running the server in the background on Unix.
-// Setpgid prevents the server from being killed when the parent process exits.
-func backgroundServerSysProcAttr() *syscall.SysProcAttr {
-	return &syscall.SysProcAttr{
-		Setpgid: true,
-	}
-}

cmd/background_windows.go

@@ -1,12 +0,0 @@
-package cmd
-
-import "syscall"
-
-// backgroundServerSysProcAttr returns SysProcAttr for running the server in the background on Windows.
-// CREATE_NO_WINDOW (0x08000000) prevents a console window from appearing.
-func backgroundServerSysProcAttr() *syscall.SysProcAttr {
-	return &syscall.SysProcAttr{
-		CreationFlags: 0x08000000,
-		HideWindow:    true,
-	}
-}

cmd/cmd.go

@@ -16,7 +16,6 @@ import (
 	"net"
 	"net/http"
 	"os"
-	"os/exec"
 	"os/signal"
 	"path"
 	"path/filepath"
@@ -2099,40 +2098,6 @@ Environment Variables:
 	cmd.SetUsageTemplate(cmd.UsageTemplate() + envUsage)
 }
 
-// ensureServerRunning checks if the ollama server is running and starts it in the background if not.
-func ensureServerRunning(ctx context.Context) error {
-	client, err := api.ClientFromEnvironment()
-	if err != nil {
-		return err
-	}
-
-	// Check if server is already running
-	if err := client.Heartbeat(ctx); err == nil {
-		return nil // server is already running
-	}
-
-	// Server not running, start it in the background
-	exe, err := os.Executable()
-	if err != nil {
-		return fmt.Errorf("could not find executable: %w", err)
-	}
-
-	serverCmd := exec.CommandContext(ctx, exe, "serve")
-	serverCmd.Env = os.Environ()
-	serverCmd.SysProcAttr = backgroundServerSysProcAttr()
-	if err := serverCmd.Start(); err != nil {
-		return fmt.Errorf("failed to start server: %w", err)
-	}
-
-	// Wait for the server to be ready
-	for {
-		time.Sleep(500 * time.Millisecond)
-		if err := client.Heartbeat(ctx); err == nil {
-			return nil // server has started
-		}
-	}
-}
-
 func launchInteractiveModel(cmd *cobra.Command, modelName string) error {
 	client, err := api.ClientFromEnvironment()
 	if err != nil {
@@ -2166,9 +2131,9 @@ func launchInteractiveModel(cmd *cobra.Command, modelName string) error {
 
 // runInteractiveTUI runs the main interactive TUI menu.
 func runInteractiveTUI(cmd *cobra.Command) {
-	// Ensure the server is running before showing the TUI
-	if err := ensureServerRunning(cmd.Context()); err != nil {
-		fmt.Fprintf(os.Stderr, "Error starting server: %v\n", err)
+	// Ensure the server is running via the shared checkServerHeartbeat path.
+	if err := checkServerHeartbeat(cmd, nil); err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
 		return
 	}