feat: add destroy command and session_id validation

- Add destroy subcommand for deleting sessions
- Add destroy --all for fresh start with confirmation
- Add -y flag to skip confirmation prompts
- Add validate_session_id() to reject empty session_ids
- Remove misleading force resume error message
- Update SKILL.md to v1.1 with destroy documentation

skills/kugetsu/SKILL.md

@@ -5,7 +5,7 @@ license: MIT
 compatibility: Requires opencode CLI, bash, and filesystem access for session state.
 metadata:
   author: shoko
-  version: "1.0"
+  version: "1.1"
 ---
 
 # kugetsu - OpenCode Session Manager
@@ -85,6 +85,23 @@ kugetsu stop mytask
 - Sends SIGTERM to process
 - Sets state to `idle`
 
+### kugetsu destroy `<session_id>` [-y]
+Delete a session:
+```bash
+kugetsu destroy mytask          # Prompts for confirmation (default: N)
+kugetsu destroy mytask -y        # Skips confirmation
+```
+- Errors if session is `used` (use `stop` first)
+- Errors if session not found
+
+### kugetsu destroy --all [-y]
+Delete all sessions:
+```bash
+kugetsu destroy --all            # Prompts for confirmation (default: N)
+kugetsu destroy --all -y         # Skips confirmation
+```
+- Useful for fresh start
+
 ### kugetsu help
 Show usage help.
 
@@ -94,6 +111,9 @@ Show usage help.
 start ──────────────► used ──────► idle (stop/SIGTERM)
                          │
                          └──────► left (kill/SIGINT/crash)
+                                        │
+                                        ▼
+                                    destroy (delete)
 ```
 
 ## Example Workflow
@@ -112,6 +132,9 @@ kugetsu resume issue42
 
 # Later, when done
 kugetsu stop issue42
+
+# When you want a fresh start
+kugetsu destroy --all
 ```
 
 ## Without kugetsu

skills/kugetsu/scripts/kugetsu

@@ -14,6 +14,8 @@ Usage:
     kugetsu list [--all]                     List sessions (default: left only)
     kugetsu resume <session_id> [message]   Resume a session
     kugetsu stop <session_id>               Stop a session gracefully
+    kugetsu destroy <session_id> [-y]        Delete a session (prompts confirmation)
+    kugetsu destroy --all [-y]               Delete all sessions (prompts confirmation)
     kugetsu help                             Show this help
 
 States:
@@ -29,6 +31,10 @@ Examples:
     kugetsu resume mytask
     kugetsu resume mytask "continue working"
     kugetsu stop mytask
+    kugetsu destroy mytask
+    kugetsu destroy mytask -y
+    kugetsu destroy --all
+    kugetsu destroy --all -y
 EOF
 }
 
@@ -36,6 +42,14 @@ ensure_dirs() {
     mkdir -p "$SESSIONS_DIR" "$BIN_DIR"
 }
 
+validate_session_id() {
+    local session_id="$1"
+    if [ -z "$session_id" ]; then
+        echo "Error: session_id cannot be empty" >&2
+        exit 1
+    fi
+}
+
 get_session_dir() {
     local session_id="$1"
     echo "$SESSIONS_DIR/$session_id"
@@ -93,6 +107,7 @@ cmd_start() {
     
     local session_id="$1"
     local message="$2"
+    validate_session_id "$session_id"
     local session_dir=$(get_session_dir "$session_id")
     
     ensure_dirs
@@ -176,6 +191,7 @@ cmd_resume() {
     
     local session_id="$1"
     local message=""
+    validate_session_id "$session_id"
     
     if [ $# -ge 2 ]; then
         message="$2"
@@ -199,7 +215,6 @@ cmd_resume() {
         fi
         if [ -n "$pid" ] && is_process_running "$pid"; then
             echo "Error: process $pid is still running for this session" >&2
-            echo "Use 'kugetsu stop $session_id' first, or 'kugetsu resume $session_id' to force resume anyway" >&2
             exit 1
         else
             set_state "$session_dir" "left"
@@ -255,6 +270,7 @@ cmd_stop() {
     fi
     
     local session_id="$1"
+    validate_session_id "$session_id"
     local session_dir=$(get_session_dir "$session_id")
     
     if [ ! -d "$session_dir" ]; then
@@ -296,6 +312,95 @@ cmd_stop() {
     echo "Session '$session_id' stopped"
 }
 
+cmd_destroy() {
+    local session_id=""
+    local destroy_all=false
+    local force=false
+    
+    while [ $# -gt 0 ]; do
+        case "$1" in
+            --all)
+                destroy_all=true
+                ;;
+            -y|--yes)
+                force=true
+                ;;
+            -*)
+                echo "Error: unknown option '$1'" >&2
+                exit 1
+                ;;
+            *)
+                if [ -n "$session_id" ]; then
+                    echo "Error: too many arguments" >&2
+                    exit 1
+                fi
+                session_id="$1"
+                ;;
+        esac
+        shift
+    done
+    
+    if [ "$destroy_all" = true ]; then
+        if [ -n "$session_id" ]; then
+            echo "Error: cannot specify session_id with --all" >&2
+            exit 1
+        fi
+        
+        if [ "$force" = true ]; then
+            rm -rf "$SESSIONS_DIR"/*
+            echo "All sessions deleted"
+            return
+        fi
+        
+        echo "Delete ALL sessions? [y/N] "
+        local reply
+        read reply
+        if [ "$reply" = "y" ] || [ "$reply" = "Y" ]; then
+            rm -rf "$SESSIONS_DIR"/*
+            echo "All sessions deleted"
+        else
+            echo "Aborted"
+        fi
+        return
+    fi
+    
+    if [ -z "$session_id" ]; then
+        echo "Error: destroy requires <session_id> or --all" >&2
+        exit 1
+    fi
+    
+    validate_session_id "$session_id"
+    local session_dir=$(get_session_dir "$session_id")
+    
+    if [ ! -d "$session_dir" ]; then
+        echo "Error: session '$session_id' not found" >&2
+        exit 1
+    fi
+    
+    local state=$(get_state "$session_dir")
+    if [ "$state" = "used" ]; then
+        echo "Error: session '$session_id' is in use (state=used)" >&2
+        echo "Use 'kugetsu stop $session_id' first" >&2
+        exit 1
+    fi
+    
+    if [ "$force" = true ]; then
+        rm -rf "$session_dir"
+        echo "Session '$session_id' deleted"
+        return
+    fi
+    
+    echo "Delete session '$session_id'? [y/N] "
+    local reply
+    read reply
+    if [ "$reply" = "y" ] || [ "$reply" = "Y" ]; then
+        rm -rf "$session_dir"
+        echo "Session '$session_id' deleted"
+    else
+        echo "Aborted"
+    fi
+}
+
 main() {
     if [ $# -eq 0 ]; then
         usage
@@ -321,6 +426,9 @@ main() {
         stop)
             cmd_stop "$@"
             ;;
+        destroy)
+            cmd_destroy "$@"
+            ;;
         *)
             echo "Error: unknown command '$command'" >&2
             usage