feat: integrate hardcoded path guard into tool dispatch

- Detects /Users/, /home/, ~/ in tool arguments
- Source code scanner for CI/pre-commit
- Runtime guard for tool dispatch
- noqa: hardcoded-path-ok escape hatch

Closes #921

.githooks/pre-commit-hardcoded-path.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+"""
+Pre-commit hook: Reject hardcoded home-directory paths.
+
+Install:
+    cp pre-commit-hardcoded-path.py .git/hooks/pre-commit-hardcoded-path
+    chmod +x .git/hooks/pre-commit-hardcoded-path
+    
+    Or add to .pre-commit-config.yaml
+"""
+
+import sys
+import subprocess
+import re
+
+PATTERNS = [
+    (r"/Users/[\w.\-]+/", "macOS home directory"),
+    (r"/home/[\w.\-]+/", "Linux home directory"),
+    (r"(?<![\w/])~/", "unexpanded tilde"),
+]
+
+NOQA = re.compile(r"#\s*noqa:?\s*hardcoded-path-ok")
+
+def get_staged_files():
+    result = subprocess.run(
+        ["git", "diff", "--cached", "--name-only", "--diff-filter=ACM"],
+        capture_output=True, text=True
+    )
+    return [f for f in result.stdout.strip().split("\n") if f.endswith(".py")]
+
+def check_file(filepath):
+    try:
+        result = subprocess.run(
+            ["git", "show", f":{filepath}"],
+            capture_output=True, text=True
+        )
+        content = result.stdout
+    except Exception:
+        return []
+    
+    violations = []
+    for i, line in enumerate(content.split("\n"), 1):
+        if line.strip().startswith("#"):
+            continue
+        if line.strip().startswith(("import ", "from ")):
+            continue
+        if NOQA.search(line):
+            continue
+        for pattern, desc in PATTERNS:
+            if re.search(pattern, line):
+                violations.append((filepath, i, line.strip(), desc))
+                break
+    return violations
+
+def main():
+    files = get_staged_files()
+    if not files:
+        sys.exit(0)
+    
+    all_violations = []
+    for f in files:
+        all_violations.extend(check_file(f))
+    
+    if all_violations:
+        print("ERROR: Hardcoded home directory paths detected:")
+        print()
+        for filepath, line_no, line, desc in all_violations:
+            print(f"  {filepath}:{line_no}: {desc}")
+            print(f"    {line[:100]}")
+            print()
+        print("Fix: Use $HOME, relative paths, or get_hermes_home().")
+        print("Override: Add '# noqa: hardcoded-path-ok' to the line.")
+        sys.exit(1)
+    
+    sys.exit(0)
+
+if __name__ == "__main__":
+    main()

model_tools.py

@@ -28,6 +28,7 @@ from typing import Dict, Any, List, Optional, Tuple
 
 from tools.registry import discover_builtin_tools, registry
 from tools.tool_pokayoke import validate_tool_call, reset_circuit_breaker, get_hallucination_stats
+from tools.hardcoded_path_guard import guard_tool_dispatch as _guard_hardcoded_paths
 from toolsets import resolve_toolset, validate_toolset
 from agent.tool_orchestrator import orchestrator
 
@@ -501,6 +502,12 @@ def handle_function_call(
             # Prefer the caller-provided list so subagents can't overwrite
             # the parent's tool set via the process-global.
             sandbox_enabled = enabled_tools if enabled_tools is not None else _last_resolved_tool_names
+            # Poka-yoke #921: guard against hardcoded home-directory paths
+            _hardcoded_err = _guard_hardcoded_paths(function_name, function_args)
+            if _hardcoded_err:
+                logger.warning(f"Hardcoded path blocked: {function_name}")
+                return _hardcoded_err
+
             # Poka-yoke: validate tool call before dispatch
             is_valid, corrected_name, corrected_params, pokayoke_messages = validate_tool_call(function_name, function_args)
             if not is_valid:

tools/hardcoded_path_guard.py

@@ -0,0 +1,113 @@
+#!/usr/bin/env python3
+"""
+Hardcoded Path Guard — Poka-Yoke #921
+
+Detects and blocks hardcoded home-directory paths in tool arguments.
+These paths work on one machine but break on others, VPS deployments,
+or when HOME changes.
+
+Usage:
+    from tools.hardcoded_path_guard import check_path, validate_tool_args
+    
+    # Check a single path
+    err = check_path("/Users/apayne/.hermes/config.yaml")
+    
+    # Validate all path-like args in a tool call
+    clean_args, warnings = validate_tool_args("read_file", {"path": "/home/user/file.txt"})
+"""
+
+import os
+import re
+import json as _json
+from typing import Dict, List, Optional, Tuple, Any
+
+# Patterns that indicate hardcoded home directories
+HARDCODED_PATTERNS = [
+    (r"/Users/[\w.\-]+/", "macOS home directory (/Users/...)"),
+    (r"/home/[\w.\-]+/", "Linux home directory (/home/...)"),
+    (r"(?<![\w/])~/", "unexpanded tilde (~/)"),
+    (r"/root/", "root home directory (/root/)"),
+]
+
+_COMPILED_PATTERNS = [(re.compile(p), desc) for p, desc in HARDCODED_PATTERNS]
+_NOQA_PATTERN = re.compile(r"#\s*noqa:?\s*hardcoded-path-ok")
+
+_PATH_ARG_NAMES = frozenset({
+    "path", "file_path", "filepath", "dir", "directory", "dest", "source",
+    "input", "output", "src", "dst", "target", "location", "file",
+    "image_path", "script", "config", "log_file",
+})
+
+
+def has_hardcoded_path(text: str) -> Optional[str]:
+    if _NOQA_PATTERN.search(text):
+        return None
+    for pattern, desc in _COMPILED_PATTERNS:
+        if pattern.search(text):
+            return desc
+    return None
+
+
+def check_path(path_value: str) -> Optional[str]:
+    if not isinstance(path_value, str):
+        return None
+    match_desc = has_hardcoded_path(path_value)
+    if match_desc:
+        return (
+            f"Path contains hardcoded home directory ({match_desc}): '{path_value}'. "
+            f"Use $HOME, relative paths, or get_hermes_home(). "
+            f"Add '# noqa: hardcoded-path-ok' if intentional."
+        )
+    return None
+
+
+def validate_tool_args(tool_name: str, args: Dict[str, Any]) -> Tuple[Dict[str, Any], List[str]]:
+    warnings = []
+    for key, value in args.items():
+        if key.lower() not in _PATH_ARG_NAMES:
+            continue
+        if isinstance(value, str):
+            err = check_path(value)
+            if err:
+                warnings.append(err)
+        elif isinstance(value, list):
+            for item in value:
+                if isinstance(item, str):
+                    err = check_path(item)
+                    if err:
+                        warnings.append(err)
+    return args, warnings
+
+
+def scan_source_for_violations(source_code: str, filename: str = "") -> List[Tuple[int, str, str]]:
+    violations = []
+    lines = source_code.split("\n")
+    for i, line in enumerate(lines, 1):
+        stripped = line.strip()
+        if stripped.startswith("#"):
+            if _NOQA_PATTERN.search(line):
+                continue
+            continue
+        if stripped.startswith("import ") or stripped.startswith("from "):
+            continue
+        for pattern, desc in _COMPILED_PATTERNS:
+            match = pattern.search(line)
+            if match:
+                if _NOQA_PATTERN.search(line):
+                    continue
+                violations.append((i, line.strip(), desc))
+                break
+    return violations
+
+
+def guard_tool_dispatch(tool_name: str, args: Dict[str, Any]) -> Optional[str]:
+    _, warnings = validate_tool_args(tool_name, args)
+    if warnings:
+        return _json.dumps({
+            "error": "Hardcoded home directory path detected",
+            "details": warnings,
+            "suggestion": "Use $HOME, relative paths, or get_hermes_home() instead of hardcoded paths.",
+            "pokayoke": True,
+            "rule": "hardcoded-path-guard"
+        })
+    return None

tools/skill_manager_tool.py

@@ -44,6 +44,34 @@ from typing import Dict, Any, Optional, Tuple
 
 logger = logging.getLogger(__name__)
 
+
+def _format_error(
+    message: str,
+    skill_name: str = None,
+    file_path: str = None,
+    suggestion: str = None,
+    context: dict = None,
+) -> Dict[str, Any]:
+    """Format an error with rich context for better debugging."""
+    parts = [message]
+    if skill_name:
+        parts.append(f"Skill: {skill_name}")
+    if file_path:
+        parts.append(f"File: {file_path}")
+    if suggestion:
+        parts.append(f"Suggestion: {suggestion}")
+    if context:
+        for key, value in context.items():
+            parts.append(f"{key}: {value}")
+    return {
+        "success": False,
+        "error": " | ".join(parts),
+        "skill_name": skill_name,
+        "file_path": file_path,
+        "suggestion": suggestion,
+    }
+
+
 # Import security scanner — agent-created skills get the same scrutiny as
 # community hub installs.
 try: