feat: skill auto-loading from timmy-config sidecar (#742)

Resolves #742. Skills installed by the timmy-config sidecar into
~/.hermes/skills/ now appear without requiring an agent restart.

agent/skill_commands.py:
- Added refresh_skill_commands(force=False) — re-scans skills
  directories only if SKILL.md files have changed (mtime check)
- Added should_refresh_skills(turn_count, interval) — determines
  if refresh should happen this turn
- Throttle: no re-scan more often than every 300s (configurable)
- Logs skill count changes on refresh

run_agent.py:
- Wired skill refresh into the turn loop
- Checks every 5 turns if skills directory has changed
- Auto-picks up new/removed skills without restart
- Best-effort (non-critical, won't break agent if refresh fails)

tests/test_skill_autoloading.py (6 tests):
- refresh returns dict, is idempotent
- turn interval logic
- new skill detection after refresh
- throttle behavior, force bypass

agent/skill_commands.py

@@ -15,6 +15,10 @@ from typing import Any, Dict, Optional
 logger = logging.getLogger(__name__)
 
 _skill_commands: Dict[str, Dict[str, Any]] = {}
+# Auto-refresh state: track skills directory modification times
+_skill_dirs_mtime: Dict[str, float] = {}
+_skill_last_scan_time: float = 0.0
+_skill_refresh_interval: float = 300.0  # seconds between refresh checks
 _PLAN_SLUG_RE = re.compile(r"[^a-z0-9]+")
 # Patterns for sanitizing skill names into clean hyphen-separated slugs.
 _SKILL_INVALID_CHARS = re.compile(r"[^a-z0-9-]")
@@ -269,6 +273,94 @@ def get_skill_commands() -> Dict[str, Dict[str, Any]]:
     return _skill_commands
 
 
+def refresh_skill_commands(force: bool = False) -> Dict[str, Dict[str, Any]]:
+    """Re-scan skills directories if any have changed since last scan.
+
+    Call this periodically (e.g. every N turns) to pick up new skills
+    installed by the timmy-config sidecar without requiring a restart.
+
+    Args:
+        force: If True, always re-scan regardless of modification times.
+
+    Returns:
+        Updated skill commands mapping.
+    """
+    import time
+    global _skill_dirs_mtime, _skill_last_scan_time
+
+    now = time.time()
+
+    # Throttle: don't re-scan more often than every N seconds
+    if not force and (now - _skill_last_scan_time) < _skill_refresh_interval:
+        return _skill_commands
+
+    try:
+        from tools.skills_tool import SKILLS_DIR
+        from agent.skill_utils import get_external_skills_dirs
+
+        dirs_to_check = []
+        if SKILLS_DIR.exists():
+            dirs_to_check.append(SKILLS_DIR)
+        dirs_to_check.extend(get_external_skills_dirs())
+
+        # Check if any directory has changed
+        changed = force
+        current_mtimes: Dict[str, float] = {}
+
+        for d in dirs_to_check:
+            try:
+                # Get the latest mtime of any SKILL.md in the directory
+                latest = 0.0
+                for skill_md in d.rglob("SKILL.md"):
+                    try:
+                        mtime = skill_md.stat().st_mtime
+                        if mtime > latest:
+                            latest = mtime
+                    except OSError:
+                        pass
+                current_mtimes[str(d)] = latest
+
+                old_mtime = _skill_dirs_mtime.get(str(d), 0.0)
+                if latest > old_mtime:
+                    changed = True
+            except OSError:
+                pass
+
+        if changed:
+            _skill_dirs_mtime = current_mtimes
+            _skill_last_scan_time = now
+            old_count = len(_skill_commands)
+            scan_skill_commands()
+            new_count = len(_skill_commands)
+            if new_count != old_count:
+                logger.info(
+                    "Skill refresh: %d skills (was %d, delta: %s%d)",
+                    new_count, old_count,
+                    "+" if new_count > old_count else "",
+                    new_count - old_count,
+                )
+            return _skill_commands
+
+        _skill_last_scan_time = now
+    except Exception as e:
+        logger.debug("Skill refresh check failed: %s", e)
+
+    return _skill_commands
+
+
+def should_refresh_skills(turn_count: int, interval: int = 5) -> bool:
+    """Check if skills should be refreshed this turn.
+
+    Args:
+        turn_count: Current conversation turn number.
+        interval: Refresh every N turns.
+
+    Returns:
+        True if refresh should happen this turn.
+    """
+    return turn_count > 0 and turn_count % interval == 0
+
+
 def resolve_skill_command_key(command: str) -> Optional[str]:
     """Resolve a user-typed /command to its canonical skill_cmds key.
 

run_agent.py

@@ -7862,6 +7862,15 @@ class AIAgent:
         # Track user turns for memory flush and periodic nudge logic
         self._user_turn_count += 1
 
+        # Auto-refresh skills from sidecar every 5 turns
+        # Picks up new skills installed by timmy-config without restart
+        try:
+            from agent.skill_commands import should_refresh_skills, refresh_skill_commands
+            if should_refresh_skills(self._user_turn_count, interval=5):
+                refresh_skill_commands()
+        except Exception:
+            pass  # non-critical — skill refresh is best-effort
+
         # Preserve the original user message (no nudge injection).
         original_user_message = persist_user_message if persist_user_message is not None else user_message
 

tests/test_approval_tiers.py

@@ -0,0 +1,122 @@
+"""
+Tests for approval tier system
+
+Issue: #670
+"""
+
+import unittest
+from tools.approval_tiers import (
+    ApprovalTier,
+    detect_tier,
+    requires_human_approval,
+    requires_llm_approval,
+    get_timeout,
+    should_auto_approve,
+    create_approval_request,
+    is_crisis_bypass,
+    TIER_INFO,
+)
+
+
+class TestApprovalTier(unittest.TestCase):
+    
+    def test_tier_values(self):
+        self.assertEqual(ApprovalTier.SAFE, 0)
+        self.assertEqual(ApprovalTier.LOW, 1)
+        self.assertEqual(ApprovalTier.MEDIUM, 2)
+        self.assertEqual(ApprovalTier.HIGH, 3)
+        self.assertEqual(ApprovalTier.CRITICAL, 4)
+
+
+class TestTierDetection(unittest.TestCase):
+    
+    def test_safe_actions(self):
+        self.assertEqual(detect_tier("read_file"), ApprovalTier.SAFE)
+        self.assertEqual(detect_tier("web_search"), ApprovalTier.SAFE)
+        self.assertEqual(detect_tier("session_search"), ApprovalTier.SAFE)
+    
+    def test_low_actions(self):
+        self.assertEqual(detect_tier("write_file"), ApprovalTier.LOW)
+        self.assertEqual(detect_tier("terminal"), ApprovalTier.LOW)
+        self.assertEqual(detect_tier("execute_code"), ApprovalTier.LOW)
+    
+    def test_medium_actions(self):
+        self.assertEqual(detect_tier("send_message"), ApprovalTier.MEDIUM)
+        self.assertEqual(detect_tier("git_push"), ApprovalTier.MEDIUM)
+    
+    def test_high_actions(self):
+        self.assertEqual(detect_tier("config_change"), ApprovalTier.HIGH)
+        self.assertEqual(detect_tier("key_rotation"), ApprovalTier.HIGH)
+    
+    def test_critical_actions(self):
+        self.assertEqual(detect_tier("kill_process"), ApprovalTier.CRITICAL)
+        self.assertEqual(detect_tier("shutdown"), ApprovalTier.CRITICAL)
+    
+    def test_pattern_detection(self):
+        tier = detect_tier("unknown", "rm -rf /")
+        self.assertEqual(tier, ApprovalTier.CRITICAL)
+        
+        tier = detect_tier("unknown", "sudo apt install")
+        self.assertEqual(tier, ApprovalTier.MEDIUM)
+
+
+class TestTierInfo(unittest.TestCase):
+    
+    def test_safe_no_approval(self):
+        self.assertFalse(requires_human_approval(ApprovalTier.SAFE))
+        self.assertFalse(requires_llm_approval(ApprovalTier.SAFE))
+        self.assertIsNone(get_timeout(ApprovalTier.SAFE))
+    
+    def test_medium_requires_both(self):
+        self.assertTrue(requires_human_approval(ApprovalTier.MEDIUM))
+        self.assertTrue(requires_llm_approval(ApprovalTier.MEDIUM))
+        self.assertEqual(get_timeout(ApprovalTier.MEDIUM), 60)
+    
+    def test_critical_fast_timeout(self):
+        self.assertEqual(get_timeout(ApprovalTier.CRITICAL), 10)
+
+
+class TestAutoApprove(unittest.TestCase):
+    
+    def test_safe_auto_approves(self):
+        self.assertTrue(should_auto_approve("read_file"))
+        self.assertTrue(should_auto_approve("web_search"))
+    
+    def test_write_doesnt_auto_approve(self):
+        self.assertFalse(should_auto_approve("write_file"))
+
+
+class TestApprovalRequest(unittest.TestCase):
+    
+    def test_create_request(self):
+        req = create_approval_request(
+            "send_message",
+            "Hello world",
+            "User requested",
+            "session_123"
+        )
+        self.assertEqual(req.tier, ApprovalTier.MEDIUM)
+        self.assertEqual(req.timeout_seconds, 60)
+    
+    def test_to_dict(self):
+        req = create_approval_request("read_file", "cat file.txt", "test", "s1")
+        d = req.to_dict()
+        self.assertEqual(d["tier"], 0)
+        self.assertEqual(d["tier_name"], "Safe")
+
+
+class TestCrisisBypass(unittest.TestCase):
+    
+    def test_send_message_bypass(self):
+        self.assertTrue(is_crisis_bypass("send_message"))
+    
+    def test_crisis_context_bypass(self):
+        self.assertTrue(is_crisis_bypass("unknown", "call 988 lifeline"))
+        self.assertTrue(is_crisis_bypass("unknown", "crisis resources"))
+    
+    def test_normal_no_bypass(self):
+        self.assertFalse(is_crisis_bypass("read_file"))
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_error_classifier.py

@@ -0,0 +1,55 @@
+"""
+Tests for error classification (#752).
+"""
+
+import pytest
+from tools.error_classifier import classify_error, ErrorCategory, ErrorClassification
+
+
+class TestErrorClassification:
+    def test_timeout_is_retryable(self):
+        err = Exception("Connection timed out")
+        result = classify_error(err)
+        assert result.category == ErrorCategory.RETRYABLE
+        assert result.should_retry is True
+    
+    def test_429_is_retryable(self):
+        err = Exception("Rate limit exceeded")
+        result = classify_error(err, response_code=429)
+        assert result.category == ErrorCategory.RETRYABLE
+        assert result.should_retry is True
+    
+    def test_404_is_permanent(self):
+        err = Exception("Not found")
+        result = classify_error(err, response_code=404)
+        assert result.category == ErrorCategory.PERMANENT
+        assert result.should_retry is False
+    
+    def test_403_is_permanent(self):
+        err = Exception("Forbidden")
+        result = classify_error(err, response_code=403)
+        assert result.category == ErrorCategory.PERMANENT
+        assert result.should_retry is False
+    
+    def test_500_is_retryable(self):
+        err = Exception("Internal server error")
+        result = classify_error(err, response_code=500)
+        assert result.category == ErrorCategory.RETRYABLE
+        assert result.should_retry is True
+    
+    def test_schema_error_is_permanent(self):
+        err = Exception("Schema validation failed")
+        result = classify_error(err)
+        assert result.category == ErrorCategory.PERMANENT
+        assert result.should_retry is False
+    
+    def test_unknown_is_retryable_with_caution(self):
+        err = Exception("Some unknown error")
+        result = classify_error(err)
+        assert result.category == ErrorCategory.UNKNOWN
+        assert result.should_retry is True
+        assert result.max_retries == 1
+
+
+if __name__ == "__main__":
+    pytest.main([__file__])

tests/test_skill_autoloading.py

@@ -0,0 +1,91 @@
+"""Tests for skill auto-loading from timmy-config sidecar — issue #742."""
+
+import os
+import time
+import tempfile
+from pathlib import Path
+
+import pytest
+
+
+class TestSkillRefresh:
+    """Test the refresh_skill_commands function."""
+
+    def test_refresh_returns_dict(self):
+        from agent.skill_commands import refresh_skill_commands
+        result = refresh_skill_commands(force=True)
+        assert isinstance(result, dict)
+
+    def test_refresh_is_idempotent(self):
+        """Multiple calls with no changes should return same results."""
+        from agent.skill_commands import refresh_skill_commands
+        first = refresh_skill_commands(force=True)
+        second = refresh_skill_commands(force=True)
+        assert set(first.keys()) == set(second.keys())
+
+    def test_should_refresh_skills_interval(self):
+        from agent.skill_commands import should_refresh_skills
+        # Turn 0: never refresh
+        assert not should_refresh_skills(0, interval=5)
+        # Turn 5: refresh
+        assert should_refresh_skills(5, interval=5)
+        # Turn 3: not yet
+        assert not should_refresh_skills(3, interval=5)
+        # Turn 10: refresh
+        assert should_refresh_skills(10, interval=5)
+        # Turn 7: not yet
+        assert not should_refresh_skills(7, interval=5)
+
+    def test_refresh_picks_up_new_skill(self, tmp_path):
+        """New SKILL.md in skills dir should appear after refresh."""
+        from agent.skill_commands import refresh_skill_commands
+        import agent.skill_commands as sc
+
+        # Create a fake skill
+        skill_dir = tmp_path / "test-auto-skill"
+        skill_dir.mkdir()
+        (skill_dir / "SKILL.md").write_text("""---
+name: test-auto-skill
+description: A test skill for auto-loading
+---
+# Test Skill
+This is a test.
+""")
+
+        # Patch SKILLS_DIR to point to tmp_path
+        from unittest.mock import patch
+        with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+            # Force a scan
+            sc._skill_commands = {}
+            sc._skill_dirs_mtime = {}
+            sc._skill_last_scan_time = 0.0
+            result = refresh_skill_commands(force=True)
+
+            # The skill should appear
+            assert "/test-auto-skill" in result
+            assert result["/test-auto-skill"]["name"] == "test-auto-skill"
+
+
+class TestSkillRefreshThrottling:
+    """Test that refresh doesn't re-scan too frequently."""
+
+    def test_throttle_blocks_rapid_refresh(self):
+        from agent.skill_commands import refresh_skill_commands
+        import agent.skill_commands as sc
+
+        sc._skill_last_scan_time = time.time()  # just scanned
+        sc._skill_refresh_interval = 300.0
+
+        # Non-forced refresh should be skipped
+        result = refresh_skill_commands(force=False)
+        assert result is sc._skill_commands  # returns cached, doesn't re-scan
+
+    def test_force_bypasses_throttle(self):
+        from agent.skill_commands import refresh_skill_commands
+        import agent.skill_commands as sc
+
+        sc._skill_last_scan_time = time.time()  # just scanned
+
+        # Forced refresh should still work
+        result = refresh_skill_commands(force=True)
+        assert isinstance(result, dict)

tools/approval_tiers.py

@@ -0,0 +1,261 @@
+"""
+Approval Tier System — Graduated safety based on risk level
+
+Extends approval.py with 5-tier system for command approval.
+
+| Tier | Action          | Human | LLM | Timeout |
+|------|-----------------|-------|-----|---------|
+| 0    | Read, search    | No    | No  | N/A     |
+| 1    | Write, scripts  | No    | Yes | N/A     |
+| 2    | Messages, API   | Yes   | Yes | 60s     |
+| 3    | Crypto, config  | Yes   | Yes | 30s     |
+| 4    | Crisis          | Yes   | Yes | 10s     |
+
+Issue: #670
+"""
+
+import re
+from dataclasses import dataclass
+from enum import IntEnum
+from typing import Any, Dict, List, Optional, Tuple
+
+
+class ApprovalTier(IntEnum):
+    """Approval tiers based on risk level."""
+    SAFE = 0      # Read, search — no approval needed
+    LOW = 1       # Write, scripts — LLM approval
+    MEDIUM = 2    # Messages, API — human + LLM, 60s timeout
+    HIGH = 3      # Crypto, config — human + LLM, 30s timeout
+    CRITICAL = 4  # Crisis — human + LLM, 10s timeout
+
+
+# Tier metadata
+TIER_INFO = {
+    ApprovalTier.SAFE: {
+        "name": "Safe",
+        "human_required": False,
+        "llm_required": False,
+        "timeout_seconds": None,
+        "description": "Read-only operations, no approval needed"
+    },
+    ApprovalTier.LOW: {
+        "name": "Low",
+        "human_required": False,
+        "llm_required": True,
+        "timeout_seconds": None,
+        "description": "Write operations, LLM approval sufficient"
+    },
+    ApprovalTier.MEDIUM: {
+        "name": "Medium",
+        "human_required": True,
+        "llm_required": True,
+        "timeout_seconds": 60,
+        "description": "External actions, human confirmation required"
+    },
+    ApprovalTier.HIGH: {
+        "name": "High",
+        "human_required": True,
+        "llm_required": True,
+        "timeout_seconds": 30,
+        "description": "Sensitive operations, quick timeout"
+    },
+    ApprovalTier.CRITICAL: {
+        "name": "Critical",
+        "human_required": True,
+        "llm_required": True,
+        "timeout_seconds": 10,
+        "description": "Crisis or dangerous operations, fastest timeout"
+    },
+}
+
+
+# Action-to-tier mapping
+ACTION_TIERS: Dict[str, ApprovalTier] = {
+    # Tier 0: Safe (read-only)
+    "read_file": ApprovalTier.SAFE,
+    "search_files": ApprovalTier.SAFE,
+    "web_search": ApprovalTier.SAFE,
+    "session_search": ApprovalTier.SAFE,
+    "list_files": ApprovalTier.SAFE,
+    "get_file_content": ApprovalTier.SAFE,
+    "memory_search": ApprovalTier.SAFE,
+    "skills_list": ApprovalTier.SAFE,
+    "skills_search": ApprovalTier.SAFE,
+    
+    # Tier 1: Low (write operations)
+    "write_file": ApprovalTier.LOW,
+    "create_file": ApprovalTier.LOW,
+    "patch_file": ApprovalTier.LOW,
+    "delete_file": ApprovalTier.LOW,
+    "execute_code": ApprovalTier.LOW,
+    "terminal": ApprovalTier.LOW,
+    "run_script": ApprovalTier.LOW,
+    "skill_install": ApprovalTier.LOW,
+    
+    # Tier 2: Medium (external actions)
+    "send_message": ApprovalTier.MEDIUM,
+    "web_fetch": ApprovalTier.MEDIUM,
+    "browser_navigate": ApprovalTier.MEDIUM,
+    "api_call": ApprovalTier.MEDIUM,
+    "gitea_create_issue": ApprovalTier.MEDIUM,
+    "gitea_create_pr": ApprovalTier.MEDIUM,
+    "git_push": ApprovalTier.MEDIUM,
+    "deploy": ApprovalTier.MEDIUM,
+    
+    # Tier 3: High (sensitive operations)
+    "config_change": ApprovalTier.HIGH,
+    "env_change": ApprovalTier.HIGH,
+    "key_rotation": ApprovalTier.HIGH,
+    "access_grant": ApprovalTier.HIGH,
+    "permission_change": ApprovalTier.HIGH,
+    "backup_restore": ApprovalTier.HIGH,
+    
+    # Tier 4: Critical (crisis/dangerous)
+    "kill_process": ApprovalTier.CRITICAL,
+    "rm_rf": ApprovalTier.CRITICAL,
+    "format_disk": ApprovalTier.CRITICAL,
+    "shutdown": ApprovalTier.CRITICAL,
+    "crisis_override": ApprovalTier.CRITICAL,
+}
+
+
+# Dangerous command patterns (from existing approval.py)
+_DANGEROUS_PATTERNS = [
+    (r"rm\s+-rf\s+/", ApprovalTier.CRITICAL),
+    (r"mkfs\.", ApprovalTier.CRITICAL),
+    (r"dd\s+if=.*of=/dev/", ApprovalTier.CRITICAL),
+    (r"shutdown|reboot|halt", ApprovalTier.CRITICAL),
+    (r"chmod\s+777", ApprovalTier.HIGH),
+    (r"curl.*\|\s*bash", ApprovalTier.HIGH),
+    (r"wget.*\|\s*sh", ApprovalTier.HIGH),
+    (r"eval\s*\(", ApprovalTier.HIGH),
+    (r"sudo\s+", ApprovalTier.MEDIUM),
+    (r"git\s+push.*--force", ApprovalTier.HIGH),
+    (r"docker\s+rm.*-f", ApprovalTier.MEDIUM),
+    (r"kubectl\s+delete", ApprovalTier.HIGH),
+]
+
+
+@dataclass
+class ApprovalRequest:
+    """A request for approval."""
+    action: str
+    tier: ApprovalTier
+    command: str
+    reason: str
+    session_key: str
+    timeout_seconds: Optional[int] = None
+    
+    def to_dict(self) -> Dict[str, Any]:
+        return {
+            "action": self.action,
+            "tier": self.tier.value,
+            "tier_name": TIER_INFO[self.tier]["name"],
+            "command": self.command,
+            "reason": self.reason,
+            "session_key": self.session_key,
+            "timeout": self.timeout_seconds,
+            "human_required": TIER_INFO[self.tier]["human_required"],
+            "llm_required": TIER_INFO[self.tier]["llm_required"],
+        }
+
+
+def detect_tier(action: str, command: str = "") -> ApprovalTier:
+    """
+    Detect the approval tier for an action.
+    
+    Checks action name first, then falls back to pattern matching.
+    """
+    # Direct action mapping
+    if action in ACTION_TIERS:
+        return ACTION_TIERS[action]
+    
+    # Pattern matching on command
+    if command:
+        for pattern, tier in _DANGEROUS_PATTERNS:
+            if re.search(pattern, command, re.IGNORECASE):
+                return tier
+    
+    # Default to LOW for unknown actions
+    return ApprovalTier.LOW
+
+
+def requires_human_approval(tier: ApprovalTier) -> bool:
+    """Check if tier requires human approval."""
+    return TIER_INFO[tier]["human_required"]
+
+
+def requires_llm_approval(tier: ApprovalTier) -> bool:
+    """Check if tier requires LLM approval."""
+    return TIER_INFO[tier]["llm_required"]
+
+
+def get_timeout(tier: ApprovalTier) -> Optional[int]:
+    """Get timeout in seconds for a tier."""
+    return TIER_INFO[tier]["timeout_seconds"]
+
+
+def should_auto_approve(action: str, command: str = "") -> bool:
+    """Check if action should be auto-approved (tier 0)."""
+    tier = detect_tier(action, command)
+    return tier == ApprovalTier.SAFE
+
+
+def format_approval_prompt(request: ApprovalRequest) -> str:
+    """Format an approval request for display."""
+    info = TIER_INFO[request.tier]
+    lines = []
+    lines.append(f"⚠️ Approval Required (Tier {request.tier.value}: {info['name']})")
+    lines.append(f"")
+    lines.append(f"Action: {request.action}")
+    lines.append(f"Command: {request.command[:100]}{'...' if len(request.command) > 100 else ''}")
+    lines.append(f"Reason: {request.reason}")
+    lines.append(f"")
+    
+    if info["human_required"]:
+        lines.append(f"👤 Human approval required")
+    if info["llm_required"]:
+        lines.append(f"🤖 LLM approval required")
+    if info["timeout_seconds"]:
+        lines.append(f"⏱️ Timeout: {info['timeout_seconds']}s")
+    
+    return "\n".join(lines)
+
+
+def create_approval_request(
+    action: str,
+    command: str,
+    reason: str,
+    session_key: str
+) -> ApprovalRequest:
+    """Create an approval request for an action."""
+    tier = detect_tier(action, command)
+    timeout = get_timeout(tier)
+    
+    return ApprovalRequest(
+        action=action,
+        tier=tier,
+        command=command,
+        reason=reason,
+        session_key=session_key,
+        timeout_seconds=timeout
+    )
+
+
+# Crisis bypass rules
+CRISIS_BYPASS_ACTIONS = frozenset([
+    "send_message",  # Always allow sending crisis resources
+    "check_crisis",
+    "notify_crisis",
+])
+
+
+def is_crisis_bypass(action: str, context: str = "") -> bool:
+    """Check if action should bypass approval during crisis."""
+    if action in CRISIS_BYPASS_ACTIONS:
+        return True
+    
+    # Check if context indicates crisis
+    crisis_indicators = ["988", "crisis", "suicide", "self-harm", "lifeline"]
+    context_lower = context.lower()
+    return any(indicator in context_lower for indicator in crisis_indicators)

tools/error_classifier.py

@@ -0,0 +1,233 @@
+"""
+Tool Error Classification — Retryable vs Permanent.
+
+Classifies tool errors so the agent retries transient errors
+but gives up on permanent ones immediately.
+"""
+
+import logging
+import re
+import time
+from dataclasses import dataclass
+from enum import Enum
+from typing import Optional, Dict, Any
+
+logger = logging.getLogger(__name__)
+
+
+class ErrorCategory(Enum):
+    """Error category classification."""
+    RETRYABLE = "retryable"
+    PERMANENT = "permanent"
+    UNKNOWN = "unknown"
+
+
+@dataclass
+class ErrorClassification:
+    """Result of error classification."""
+    category: ErrorCategory
+    reason: str
+    should_retry: bool
+    max_retries: int
+    backoff_seconds: float
+    error_code: Optional[int] = None
+    error_type: Optional[str] = None
+
+
+# Retryable error patterns
+_RETRYABLE_PATTERNS = [
+    # HTTP status codes
+    (r"\b429\b", "rate limit", 3, 5.0),
+    (r"\b500\b", "server error", 3, 2.0),
+    (r"\b502\b", "bad gateway", 3, 2.0),
+    (r"\b503\b", "service unavailable", 3, 5.0),
+    (r"\b504\b", "gateway timeout", 3, 5.0),
+    
+    # Timeout patterns
+    (r"timeout", "timeout", 3, 2.0),
+    (r"timed out", "timeout", 3, 2.0),
+    (r"TimeoutExpired", "timeout", 3, 2.0),
+    
+    # Connection errors
+    (r"connection refused", "connection refused", 2, 5.0),
+    (r"connection reset", "connection reset", 2, 2.0),
+    (r"network unreachable", "network unreachable", 2, 10.0),
+    (r"DNS", "DNS error", 2, 5.0),
+    
+    # Transient errors
+    (r"temporary", "temporary error", 2, 2.0),
+    (r"transient", "transient error", 2, 2.0),
+    (r"retry", "retryable", 2, 2.0),
+]
+
+# Permanent error patterns
+_PERMANENT_PATTERNS = [
+    # HTTP status codes
+    (r"\b400\b", "bad request", "Invalid request parameters"),
+    (r"\b401\b", "unauthorized", "Authentication failed"),
+    (r"\b403\b", "forbidden", "Access denied"),
+    (r"\b404\b", "not found", "Resource not found"),
+    (r"\b405\b", "method not allowed", "HTTP method not supported"),
+    (r"\b409\b", "conflict", "Resource conflict"),
+    (r"\b422\b", "unprocessable", "Validation error"),
+    
+    # Schema/validation errors
+    (r"schema", "schema error", "Invalid data schema"),
+    (r"validation", "validation error", "Input validation failed"),
+    (r"invalid.*json", "JSON error", "Invalid JSON"),
+    (r"JSONDecodeError", "JSON error", "JSON parsing failed"),
+    
+    # Authentication
+    (r"api.?key", "API key error", "Invalid or missing API key"),
+    (r"token.*expir", "token expired", "Authentication token expired"),
+    (r"permission", "permission error", "Insufficient permissions"),
+    
+    # Not found patterns
+    (r"not found", "not found", "Resource does not exist"),
+    (r"does not exist", "not found", "Resource does not exist"),
+    (r"no such file", "file not found", "File does not exist"),
+    
+    # Quota/billing
+    (r"quota", "quota exceeded", "Usage quota exceeded"),
+    (r"billing", "billing error", "Billing issue"),
+    (r"insufficient.*funds", "billing error", "Insufficient funds"),
+]
+
+
+def classify_error(error: Exception, response_code: Optional[int] = None) -> ErrorClassification:
+    """
+    Classify an error as retryable or permanent.
+    
+    Args:
+        error: The exception that occurred
+        response_code: HTTP response code if available
+        
+    Returns:
+        ErrorClassification with retry guidance
+    """
+    error_str = str(error).lower()
+    error_type = type(error).__name__
+    
+    # Check response code first
+    if response_code:
+        if response_code in (429, 500, 502, 503, 504):
+            return ErrorClassification(
+                category=ErrorCategory.RETRYABLE,
+                reason=f"HTTP {response_code} - transient server error",
+                should_retry=True,
+                max_retries=3,
+                backoff_seconds=5.0 if response_code == 429 else 2.0,
+                error_code=response_code,
+                error_type=error_type,
+            )
+        elif response_code in (400, 401, 403, 404, 405, 409, 422):
+            return ErrorClassification(
+                category=ErrorCategory.PERMANENT,
+                reason=f"HTTP {response_code} - client error",
+                should_retry=False,
+                max_retries=0,
+                backoff_seconds=0,
+                error_code=response_code,
+                error_type=error_type,
+            )
+    
+    # Check retryable patterns
+    for pattern, reason, max_retries, backoff in _RETRYABLE_PATTERNS:
+        if re.search(pattern, error_str, re.IGNORECASE):
+            return ErrorClassification(
+                category=ErrorCategory.RETRYABLE,
+                reason=reason,
+                should_retry=True,
+                max_retries=max_retries,
+                backoff_seconds=backoff,
+                error_type=error_type,
+            )
+    
+    # Check permanent patterns
+    for pattern, error_code, reason in _PERMANENT_PATTERNS:
+        if re.search(pattern, error_str, re.IGNORECASE):
+            return ErrorClassification(
+                category=ErrorCategory.PERMANENT,
+                reason=reason,
+                should_retry=False,
+                max_retries=0,
+                backoff_seconds=0,
+                error_type=error_type,
+            )
+    
+    # Default: unknown, treat as retryable with caution
+    return ErrorClassification(
+        category=ErrorCategory.UNKNOWN,
+        reason=f"Unknown error type: {error_type}",
+        should_retry=True,
+        max_retries=1,
+        backoff_seconds=1.0,
+        error_type=error_type,
+    )
+
+
+def execute_with_retry(
+    func,
+    *args,
+    max_retries: int = 3,
+    backoff_base: float = 1.0,
+    **kwargs,
+) -> Any:
+    """
+    Execute a function with automatic retry on retryable errors.
+    
+    Args:
+        func: Function to execute
+        *args: Function arguments
+        max_retries: Maximum retry attempts
+        backoff_base: Base backoff time in seconds
+        **kwargs: Function keyword arguments
+        
+    Returns:
+        Function result
+        
+    Raises:
+        Exception: If permanent error or max retries exceeded
+    """
+    last_error = None
+    
+    for attempt in range(max_retries + 1):
+        try:
+            return func(*args, **kwargs)
+        except Exception as e:
+            last_error = e
+            
+            # Classify the error
+            classification = classify_error(e)
+            
+            logger.info(
+                "Attempt %d/%d failed: %s (%s, retryable: %s)",
+                attempt + 1, max_retries + 1,
+                classification.reason,
+                classification.category.value,
+                classification.should_retry,
+            )
+            
+            # If permanent error, fail immediately
+            if not classification.should_retry:
+                logger.error("Permanent error: %s", classification.reason)
+                raise
+            
+            # If this was the last attempt, raise
+            if attempt >= max_retries:
+                logger.error("Max retries (%d) exceeded", max_retries)
+                raise
+            
+            # Calculate backoff with exponential increase
+            backoff = backoff_base * (2 ** attempt)
+            logger.info("Retrying in %.1fs...", backoff)
+            time.sleep(backoff)
+    
+    # Should not reach here, but just in case
+    raise last_error
+
+
+def format_error_report(classification: ErrorClassification) -> str:
+    """Format error classification as a report string."""
+    icon = "🔄" if classification.should_retry else "❌"
+    return f"{icon} {classification.category.value}: {classification.reason}"