Pattern-043: Defense-in-Depth Prevention

class DefenseInDepthPrevention:
    """
    Implements multi-layer prevention against discovered vulnerabilities.
    """

    def __init__(self, vulnerability: Vulnerability):
        self.vulnerability = vulnerability
        self.layers = []

    def add_layer_1_canonical_source(
        self,
        location: Path,
        content: str,
        authority_level: str = "highest"
    ):
        """Layer 1: Establish canonical source of truth."""
        layer = Layer(
            name="Canonical Source",
            location=location,
            content=content,
            authority_level=authority_level,
            order=1
        )
        self.layers.append(layer)
        return layer

    def add_layer_2_agent_briefing(
        self,
        briefing_file: Path,
        briefing_section: str,
        agents: List[str]
    ):
        """Layer 2: Educate agents in their briefings."""
        layer = Layer(
            name="Agent Education",
            location=briefing_file,
            section=briefing_section,
            agents=agents,
            order=2
        )
        self.layers.append(layer)
        return layer

    def add_layer_3_enforcement(
        self,
        enforcement_type: str,  # "pre-commit", "ci-cd", "type-check"
        script_path: Path,
        trigger_point: str
    ):
        """Layer 3: Implement technical enforcement."""
        layer = Layer(
            name="Technical Enforcement",
            location=script_path,
            enforcement_type=enforcement_type,
            trigger_point=trigger_point,
            order=3
        )
        self.layers.append(layer)
        return layer

    def add_layer_4_audit_trail(
        self,
        documentation_location: Path,
        incident_report: str,
        learning_points: List[str]
    ):
        """Layer 4: Preserve audit trail and learnings."""
        layer = Layer(
            name="Audit Trail & Learning",
            location=documentation_location,
            incident_report=incident_report,
            learning_points=learning_points,
            order=4
        )
        self.layers.append(layer)
        return layer

    def verify_all_layers(self) -> VerificationReport:
        """Verify all layers properly implemented."""
        report = VerificationReport()
        for layer in self.layers:
            verification = self._verify_layer(layer)
            report.add_layer_result(layer.name, verification)
        return report

    def test_breach_scenarios(self) -> TestReport:
        """Test that vulnerability cannot occur despite layer failures."""
        test_report = TestReport()

        # Test 1: Layer 1 fails - agents should catch from Layer 2
        test1 = self._test_without_layer(1)
        test_report.add_test("Layer 1 bypass", test1)

        # Test 2: Layer 2 fails - enforcement should catch from Layer 3
        test2 = self._test_without_layer(2)
        test_report.add_test("Layer 2 bypass", test2)

        # Test 3: Layer 3 fails - audit trail documents what happened
        test3 = self._test_without_layer(3)
        test_report.add_test("Layer 3 bypass", test3)

        # Test 4: All layers working together
        test4 = self._test_all_layers()
        test_report.add_test("All layers active", test4)

        return test_report

# GitHub URL Hallucination Prevention - Implemented Nov 18, 2025

hallucination = Vulnerability(
    name="GitHub URL Hallucination",
    pattern="incorrect-repository-name",  # Wrong URL
    correct_value="https://github.com/mediajunkie/piper-morgan-product",
    root_cause="LLM hallucination in Weekly Ship #002",
    spread_mechanism="Agent copying from Ship #002"
)

prevention = DefenseInDepthPrevention(hallucination)

# ============================================
# LAYER 1: Canonical Source of Truth
# ============================================

layer1 = prevention.add_layer_1_canonical_source(
    location=Path("docs/briefing/PROJECT.md"),
    content="""
# 🚨 CRITICAL: Repository Information

**ALWAYS use the correct GitHub repository URL:**

- **GitHub Repository**: `https://github.com/mediajunkie/piper-morgan-product`
- **Local Directory**: `piper-morgan` (legacy naming, but repo is `-product`)
- **NEVER use**: `Codewarrior1988/piper-morgan` (hallucinated URL - pre-commit hook will block it)
    """,
    authority_level="highest"
)

# Result: Commit bc110566 - Fix 8 critical files + add PROJECT.md guidance

# ============================================
# LAYER 2: Agent Education (Briefing)
# ============================================

layer2a = prevention.add_layer_2_agent_briefing(
    briefing_file=Path("CLAUDE.md"),
    briefing_section="CRITICAL: Repository Information",
    agents=["claude-code", "sonnet"]
)

layer2b = prevention.add_layer_2_agent_briefing(
    briefing_file=Path(".cursor/rules/programmer-briefing.mdc"),
    briefing_section="CRITICAL: Repository Information",
    agents=["cursor"]
)

# Result: Commit 5d52fe3a - Add repository URL guidance to both briefings
# Agent sees correct URL FIRST before other instructions
# Primes model to use correct URL in reasoning

# ============================================
# LAYER 3: Technical Enforcement
# ============================================

layer3 = prevention.add_layer_3_enforcement(
    enforcement_type="pre-commit",
    script_path=Path(".pre-commit-hooks/check-hallucinated-urls.py"),
    trigger_point="before_commit"
)

# Implementation of enforcement hook:
hook_code = '''
def check_hallucinated_urls(staged_files):
    """Prevent commits with hallucinated GitHub URL."""
    hallucinated_patterns = [
        "incorrect-repository-name",
        "another-incorrect-name"
    ]

    for file_path in staged_files:
        content = read_file(file_path)

        for pattern in hallucinated_patterns:
            if pattern in content:
                # Check if it's a [CORRECTED] note (allowed for documentation)
                if "[CORRECTED" not in content:
                    raise PreCommitError(
                        f"Hallucinated URL detected in {file_path}"
                    )

    return True  # OK to commit
'''

# Result: Commit 7d0b1237 - Create pre-commit hook blocking hallucinated URL
# Cannot commit hallucinated URL even if agent wanted to

# ============================================
# LAYER 4: Audit Trail & Learning
# ============================================

layer4 = prevention.add_layer_4_audit_trail(
    documentation_location=Path("dev/2025/11/18/"),
    incident_report="""
## GitHub URL Hallucination Incident

**Discovered**: Nov 18, 2025
**Pattern**: Incorrect repository name (wrong username)
**Correct**: `mediajunkie/piper-morgan-product`
**Spread**: 18 files (8 critical + 7 historical + 3 templates)

**Root Cause**: LLM hallucination in Weekly Ship #002
**Propagation**: Agent copying from Ship #002 via codebase search

**Learning**: LLMs can generate plausible-but-wrong URLs
""",
    learning_points=[
        "Plausible hallucinations are harder to detect than obvious errors",
        "Source documents (Weekly Ships) can spread hallucinations",
        "Multiple layers needed because single check insufficient",
        "Defense-in-depth prevents recurrence despite individual layer failures"
    ]
)

# Result: [CORRECTED 2025-11-18] notes added to files showing the incident
# Preserves evidence for learning, doesn't erase history

# ============================================
# VERIFICATION
# ============================================

verification = prevention.verify_all_layers()
# Layer 1: ✅ PROJECT.md has canonical URL at top
# Layer 2: ✅ CLAUDE.md + Cursor briefing both have guidance
# Layer 3: ✅ Pre-commit hook blocks pattern
# Layer 4: ✅ Incident documented with [CORRECTED] notes

# ============================================
# TEST: Can hallucination recur?
# ============================================

test_report = prevention.test_breach_scenarios()

# Scenario 1: Forget Layer 1 (canonical source)
# Result: Layer 2 (briefing) reminds agent
# Test: ✅ PASS - Agent educated by briefing

# Scenario 2: Ignore Layer 2 (briefing)
# Result: Layer 3 (pre-commit hook) blocks commit
# Test: ✅ PASS - Hook prevents recurrence

# Scenario 3: Bypass Layer 3 (use --no-verify)
# Result: Layer 4 (audit trail) documents what happened
# Test: ✅ PASS - Incident logged for learning

# Scenario 4: All layers active (normal case)
# Result: Hallucinated URL prevented at every step
# Test: ✅ PASS - Multiple defenses stop vulnerability