Move signal handling from internal/tui to pkg/core

WatchSignals and CtrlCExitWindow are generic — any frontend can use them.
Removing them from the TUI package keeps tui focused on terminal I/O only.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/tui/signals.go

@@ -1,40 +0,0 @@
-package tui
-
-import (
-	"context"
-	"fmt"
-	"io"
-	"os"
-	"os/signal"
-	"time"
-
-	"ollie/pkg/core"
-)
-
-const ctrlCExitWindow = 750 * time.Millisecond
-
-func startSignalWatcher(appCancel context.CancelCauseFunc, c core.Core, errStream io.Writer) {
-	ch := make(chan os.Signal, 16)
-	signals := []os.Signal{os.Interrupt}
-	if haveSIGTERM {
-		signals = append(signals, SIGTERM)
-	}
-	signal.Notify(ch, signals...)
-
-	go func() {
-		for sig := range ch {
-			switch sig {
-			case SIGTERM:
-				signal.Stop(ch)
-				close(ch)
-				fmt.Fprint(errStream, "\n(terminated)\n")
-				appCancel(context.Canceled)
-				continue
-			case os.Interrupt:
-				if c.Interrupt(core.ErrInterrupted) {
-					fmt.Fprint(errStream, "\n^C\n")
-				}
-			}
-		}
-	}()
-}

internal/tui/tui.go

@@ -80,7 +80,7 @@ func (t *TUI) Run(ctx context.Context) {
 	t.split = newSplitInput(tt, tt.Output(), t.core.Prompt(), nil)
 
 	appCtx, appCancel := context.WithCancelCause(ctx)
-	startSignalWatcher(appCancel, t.core, os.Stderr)
+	core.WatchSignals(appCancel, t.core, os.Stderr)
 
 	var lastCtrlC time.Time
 	firstRead := true
@@ -101,7 +101,7 @@ func (t *TUI) Run(ctx context.Context) {
 			errs := err.Error()
 			if errs == "interrupted" || errs == "^C" {
 				now := time.Now()
-				if !lastCtrlC.IsZero() && now.Sub(lastCtrlC) <= ctrlCExitWindow {
+				if !lastCtrlC.IsZero() && now.Sub(lastCtrlC) <= core.CtrlCExitWindow {
 					break
 				}
 				lastCtrlC = now

pkg/core/signals.go

@@ -0,0 +1,41 @@
+package core
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"os/signal"
+	"time"
+)
+
+const CtrlCExitWindow = 750 * time.Millisecond
+
+// WatchSignals installs OS signal handlers for the lifetime of the program.
+// SIGTERM cancels the app context; SIGINT interrupts the current agent turn.
+// It is safe to call from any frontend (TUI, HTTP, CLI one-shot, etc.).
+func WatchSignals(appCancel context.CancelCauseFunc, c Core, errStream io.Writer) {
+	ch := make(chan os.Signal, 16)
+	signals := []os.Signal{os.Interrupt}
+	if haveSIGTERM {
+		signals = append(signals, sigTERM)
+	}
+	signal.Notify(ch, signals...)
+
+	go func() {
+		for sig := range ch {
+			switch sig {
+			case sigTERM:
+				signal.Stop(ch)
+				close(ch)
+				fmt.Fprint(errStream, "\n(terminated)\n")
+				appCancel(context.Canceled)
+				continue
+			case os.Interrupt:
+				if c.Interrupt(ErrInterrupted) {
+					fmt.Fprint(errStream, "\n^C\n")
+				}
+			}
+		}
+	}()
+}

pkg/core/signals_unix.go

@@ -1,10 +1,10 @@
 //go:build !windows
 
-package tui
+package core
 
 import "syscall"
 
 const (
 	haveSIGTERM = true
-	SIGTERM     = syscall.SIGTERM
+	sigTERM     = syscall.SIGTERM
 )

pkg/core/signals_windows.go

@@ -1,9 +1,9 @@
 //go:build windows
 
-package tui
+package core
 
 import "os"
 
 const haveSIGTERM = false
 
-var SIGTERM = os.Signal(nil)
+var sigTERM = os.Signal(nil)