fix: write display cache in run.go so show-cache UserPromptSubmit hook works

cmd/displaycache.go

@@ -0,0 +1,43 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"os/user"
+	"path/filepath"
+)
+
+// displayCachePath returns the UID-based path for the display cache temp file.
+// On Windows, os.Getuid() returns -1, so we fall back to the username.
+func displayCachePath() string {
+	uid := os.Getuid()
+	var id string
+	if uid == -1 {
+		// Windows: fall back to username.
+		if u, err := user.Current(); err == nil {
+			id = u.Username
+		} else {
+			id = "windows"
+		}
+	} else {
+		id = fmt.Sprintf("%d", uid)
+	}
+	return filepath.Join(os.TempDir(), fmt.Sprintf("uncompact-display-%s.txt", id))
+}
+
+// writeDisplayCache atomically writes content to the display cache file so that
+// the UserPromptSubmit hook (show-cache) can read and display it on the next prompt.
+func writeDisplayCache(content string) error {
+	cachePath := displayCachePath()
+	tmp, err := os.CreateTemp(filepath.Dir(cachePath), "uncompact-display-*.tmp")
+	if err != nil {
+		return err
+	}
+	if _, err := tmp.WriteString(content); err != nil {
+		tmp.Close()
+		os.Remove(tmp.Name())
+		return err
+	}
+	tmp.Close()
+	return os.Rename(tmp.Name(), cachePath)
+}

cmd/run.go

@@ -180,6 +180,11 @@ func runHandler(cmd *cobra.Command, args []string) error {
 	// Emit context bomb to stdout
 	fmt.Print(output)
 
+	// Write to display cache so the UserPromptSubmit hook (show-cache) can display it.
+	if err := writeDisplayCache(output); err != nil {
+		logFn("[warn] display cache write error: %v", err)
+	}
+
 	// Log the injection
 	var staleLogTime *time.Time
 	if stale {
@@ -229,6 +234,10 @@ func runWithoutCache(cfg *config.Config, proj *project.Info, wm *project.Working
 	}
 
 	fmt.Print(output)
+
+	// Write to display cache so the UserPromptSubmit hook (show-cache) can display it.
+	_ = writeDisplayCache(output)
+
 	return nil
 }
 

cmd/showcache.go

@@ -3,8 +3,6 @@ package cmd
 import (
 	"fmt"
 	"os"
-	"os/user"
-	"path/filepath"
 
 	"github.com/spf13/cobra"
 )
@@ -22,19 +20,7 @@ func init() {
 }
 
 func showCacheHandler(cmd *cobra.Command, args []string) error {
-	uid := os.Getuid()
-	var cacheID string
-	if uid == -1 {
-		// Windows: os.Getuid() always returns -1; fall back to username.
-		if u, err := user.Current(); err == nil {
-			cacheID = u.Username
-		} else {
-			cacheID = "windows"
-		}
-	} else {
-		cacheID = fmt.Sprintf("%d", uid)
-	}
-	cachePath := filepath.Join(os.TempDir(), fmt.Sprintf("uncompact-display-%s.txt", cacheID))
+	cachePath := displayCachePath()
 
 	data, err := os.ReadFile(cachePath)
 	if os.IsNotExist(err) {