feat: allow read-only exec commands during interview phase

LLMs need to run commands like find/ls/grep to explore project structure
during the plan interview. Add isReadOnlyCommand to whitelist safe
commands while blocking writes, path traversal, and absolute paths.

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

pkg/agent/loop.go

@@ -10,6 +10,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"
@@ -2576,6 +2577,61 @@ func isToolAllowedDuringInterview(toolName string, args map[string]interface{})
 		return strings.HasSuffix(path, "MEMORY.md")
 	}
 
+	// exec: allow read-only commands
+	switch norm {
+	case "exec":
+		cmd, _ := args["command"].(string)
+		return isReadOnlyCommand(cmd)
+	}
+
+	return false
+}
+
+// isReadOnlyCommand returns true when cmd is a safe, read-only shell command
+// that an LLM may run during the interview phase.
+func isReadOnlyCommand(cmd string) bool {
+	cmd = strings.TrimSpace(cmd)
+	if cmd == "" {
+		return false
+	}
+
+	// Reject write operators anywhere in the command
+	for _, op := range []string{">", ">>", "| tee "} {
+		if strings.Contains(cmd, op) {
+			return false
+		}
+	}
+
+	// Reject path traversal (defense in depth; ExecTool.guardCommand also enforces workspace restriction)
+	if strings.Contains(cmd, "..") {
+		return false
+	}
+	// Block absolute paths in arguments (allow "cd /path && cmd" which is stripped later)
+	for _, field := range strings.Fields(cmd) {
+		if strings.HasPrefix(field, "/") && !strings.HasPrefix(cmd, "cd ") {
+			return false
+		}
+	}
+
+	// Strip "cd /path &&" prefix (LLM habit)
+	if strings.HasPrefix(cmd, "cd ") {
+		if idx := strings.Index(cmd, "&&"); idx >= 0 {
+			cmd = strings.TrimSpace(cmd[idx+2:])
+		}
+	}
+
+	fields := strings.Fields(cmd)
+	if len(fields) == 0 {
+		return false
+	}
+	first := filepath.Base(fields[0])
+	switch first {
+	case "find", "ls", "cat", "head", "tail", "grep", "rg",
+		"tree", "wc", "file", "which", "pwd",
+		"uname", "df", "du", "stat", "realpath", "dirname",
+		"basename", "date":
+		return true
+	}
 	return false
 }
 

pkg/agent/loop_test.go

@@ -1401,8 +1401,32 @@ func TestIsToolAllowedDuringInterview_FuzzyNames(t *testing.T) {
 		// Write to non-MEMORY.md — blocked
 		{"edit_file", map[string]interface{}{"path": "/ws/main.go"}, false},
 		{"editfile", map[string]interface{}{"path": "/ws/main.go"}, false},
-		// exec — always blocked
+		// exec — read-only commands allowed
+		{"exec", map[string]interface{}{"command": "find . -name '*.py'"}, true},
+		{"exec", map[string]interface{}{"command": "ls -la"}, true},
+		{"exec", map[string]interface{}{"command": "grep -r TODO ."}, true},
+		{"exec", map[string]interface{}{"command": "cat README.md"}, true},
+		// exec — cd prefix stripped
+		{"exec", map[string]interface{}{"command": "cd /home/user/project && find . -type f"}, true},
+		{"exec", map[string]interface{}{"command": "cd /tmp && rm -rf *"}, false},
+		// exec — write operators blocked
+		{"exec", map[string]interface{}{"command": "find . > output.txt"}, false},
+		{"exec", map[string]interface{}{"command": "ls -la >> log.txt"}, false},
+		{"exec", map[string]interface{}{"command": "cat foo | tee bar.txt"}, false},
+		// exec — path traversal blocked
+		{"exec", map[string]interface{}{"command": "cat ../../etc/passwd"}, false},
+		{"exec", map[string]interface{}{"command": "find ../../"}, false},
+		{"exec", map[string]interface{}{"command": "ls ../secret"}, false},
+		// exec — absolute paths blocked
+		{"exec", map[string]interface{}{"command": "cat /etc/passwd"}, false},
+		{"exec", map[string]interface{}{"command": "find /etc -name '*.conf'"}, false},
+		{"exec", map[string]interface{}{"command": "ls /root"}, false},
+		// exec — write commands blocked
+		{"exec", map[string]interface{}{"command": "rm -rf /"}, false},
+		{"exec", map[string]interface{}{"command": "mv a b"}, false},
+		// exec — no args / empty command blocked
 		{"exec", nil, false},
+		{"exec", map[string]interface{}{"command": ""}, false},
 		{"Exec", nil, false},
 	}
 	for _, tt := range tests {