fix: critical issues in wisp hook system

Code review fixes:

1. CRITICAL: Move polecat check to start of runSling
   - Previously wrote wisp THEN failed, leaving orphan
   - Now fails fast before any file operations

2. CRITICAL: Sanitize slashes in agent IDs for filenames
   - Agent IDs like 'gastown/crew/joe' were creating subdirs
   - Now converts '/' to '--' for safe filenames
   - Added sanitizeAgentID/unsanitizeAgentID helpers

3. MODERATE: Use git root instead of WorkDir in prime.go
   - Hooks are written to clone root, not cwd
   - Added getGitRoot() helper for consistency

4. MODERATE: Fix silent error swallowing
   - Now logs non-ErrNoHook errors when reading hooks
   - Warns if bead doesn't exist before burning hook
   - Preserves hook if bead is missing for debugging

internal/cmd/prime.go

@@ -1169,15 +1169,21 @@ func checkSlungWork(ctx RoleContext) {
 		return
 	}
 
-	// Check for hook file in the clone root
-	cloneRoot := ctx.WorkDir
+	// Get the git clone root (hooks are stored at clone root, not cwd)
+	cloneRoot, err := getGitRoot()
+	if err != nil {
+		// Not in a git repo - can't have hooks
+		return
+	}
+
 	sw, err := wisp.ReadHook(cloneRoot, agentID)
 	if err != nil {
 		if errors.Is(err, wisp.ErrNoHook) {
 			// No hook - normal case, nothing to do
 			return
 		}
-		// Other error - log but continue
+		// Log other errors (permission, corruption) but continue
+		fmt.Printf("%s Warning: error reading hook: %v\n", style.Dim.Render("⚠"), err)
 		return
 	}
 
@@ -1196,14 +1202,15 @@ func checkSlungWork(ctx RoleContext) {
 	fmt.Printf("  Slung at: %s\n", sw.CreatedAt.Format("2006-01-02 15:04:05"))
 	fmt.Println()
 
-	// Show the bead details
+	// Show the bead details - verify it exists
 	fmt.Println("**Bead details:**")
 	cmd := exec.Command("bd", "show", sw.BeadID)
 	cmd.Dir = cloneRoot
 	var stdout bytes.Buffer
 	cmd.Stdout = &stdout
 	cmd.Stderr = nil
-	if cmd.Run() == nil {
+	beadExists := cmd.Run() == nil
+	if beadExists {
 		// Show first 20 lines of bead details
 		lines := strings.Split(stdout.String(), "\n")
 		maxLines := 20
@@ -1214,6 +1221,13 @@ func checkSlungWork(ctx RoleContext) {
 		for _, line := range lines {
 			fmt.Printf("  %s\n", line)
 		}
+	} else {
+		fmt.Printf("  %s Bead %s not found! It may have been deleted.\n",
+			style.Bold.Render("⚠ WARNING:"), sw.BeadID)
+		fmt.Println("  The hook will NOT be burned. Investigate this issue.")
+		fmt.Println()
+		// Don't burn - leave hook for debugging
+		return
 	}
 	fmt.Println()
 
@@ -1222,12 +1236,22 @@ func checkSlungWork(ctx RoleContext) {
 	fmt.Println("  Begin working on this bead immediately. No human input needed.")
 	fmt.Println()
 
-	// Burn the hook now that it's been read
+	// Burn the hook now that it's been read and verified
 	if err := wisp.BurnHook(cloneRoot, agentID); err != nil {
 		fmt.Printf("%s Warning: could not burn hook: %v\n", style.Dim.Render("⚠"), err)
 	}
 }
 
+// getGitRoot returns the root of the current git repository.
+func getGitRoot() (string, error) {
+	cmd := exec.Command("git", "rev-parse", "--show-toplevel")
+	out, err := cmd.Output()
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(string(out)), nil
+}
+
 // getAgentIdentity returns the agent identity string for hook lookup.
 func getAgentIdentity(ctx RoleContext) string {
 	switch ctx.Role {

internal/cmd/sling.go

@@ -50,6 +50,11 @@ func init() {
 func runSling(cmd *cobra.Command, args []string) error {
 	beadID := args[0]
 
+	// Polecats cannot sling - check early before writing anything
+	if polecatName := os.Getenv("GT_POLECAT"); polecatName != "" {
+		return fmt.Errorf("polecats cannot sling (use gt done for handoff)")
+	}
+
 	// Verify the bead exists
 	if err := verifyBeadExists(beadID); err != nil {
 		return err
@@ -166,13 +171,6 @@ func detectCloneRoot() (string, error) {
 
 // triggerHandoff restarts the agent session.
 func triggerHandoff(agentID, beadID string) error {
-	// Check if we're a polecat
-	if polecatName := os.Getenv("GT_POLECAT"); polecatName != "" {
-		fmt.Printf("%s Polecat detected - cannot sling (use gt done instead)\n",
-			style.Bold.Render("⚠"))
-		return fmt.Errorf("polecats cannot sling - use gt done for handoff")
-	}
-
 	// Must be in tmux
 	if !tmux.IsInsideTmux() {
 		return fmt.Errorf("not running in tmux - cannot restart")