# Security Audit Report

**Branch**: fix/tech-debt-v0.3.2
**Base**: main
**Date**: 2025-12-08 20:47
**Files Analyzed**: 7
**Lines Changed**: ~350 (additions + deletions)

---

## Executive Summary

This branch contains **technical debt cleanup and performance improvements** with minimal security impact. The changes primarily involve:

1. Adding explicit type definitions for database rows (type safety improvement)
2. Adding a CHECK constraint on the `resolution` column (defense-in-depth)
3. Making `MAX_DEPENDENCY_CHAIN_DEPTH` configurable
4. Replacing `getQueueStats()` with `getQueueSize()` (performance)
5. Documentation updates (line number references)

**Overall Security Assessment: LOW RISK**

No new security vulnerabilities were introduced. The changes actually improve security posture through better type safety and database constraints.

---

## Category 1: Issues in Your Changes (BLOCKING)

### CRITICAL

*None identified*

### HIGH

*None identified*

### MEDIUM

*None identified*

### LOW

*None identified*

**Analysis of Changed Lines:**

1. **Type Safety Improvements** (`src/implementations/dependency-repository.ts`, `src/implementations/task-repository.ts`)
   - Changed `Record<string, any>` to explicit `DependencyRow` and `TaskRow` interfaces
   - **Security Impact**: POSITIVE - Prevents type confusion attacks, eliminates `any` types
   - **No vulnerability introduced**

2. **CHECK Constraint Migration** (`src/implementations/database.ts:274-314`)
   - Added `CHECK (resolution IN ('pending', 'completed', 'failed', 'cancelled'))`
   - **Security Impact**: POSITIVE - Defense-in-depth preventing invalid resolution values
   - **Migration Pattern**: Safe table recreation with data preservation
   - **No vulnerability introduced**

3. **Configurable Chain Depth** (`src/services/handlers/dependency-handler.ts`)
   - `MAX_DEPENDENCY_CHAIN_DEPTH` moved from constant to configurable option
   - Default remains 100 (safe limit)
   - **Security Impact**: NEUTRAL - Still enforced, just configurable
   - **Potential Concern**: If caller passes extremely high value, DoS risk increases
   - **Mitigation**: Factory pattern requires explicit opt-in; default is safe

4. **getQueueStats() -> getQueueSize()** (`src/services/handlers/queue-handler.ts`)
   - Removed method that returned full task list
   - **Security Impact**: POSITIVE - Reduces information exposure surface

---

## Category 2: Issues in Code You Touched (Should Fix)

### HIGH

*None identified*

### MEDIUM

**[Type Assertion Safety]** - Multiple files

The new type interfaces (`DependencyRow`, `TaskRow`) use `as` type assertions when casting database results:

```typescript
const row = this.findByIdStmt.get(taskId) as TaskRow | undefined;
const rows = this.getDependenciesStmt.all(taskId) as DependencyRow[];
```

- **Risk**: If database schema drifts from type definition, runtime errors may occur
- **Current Mitigation**: Schema is managed by migrations, reducing drift risk
- **Recommendation**: Consider runtime validation at database boundary (e.g., Zod schema)
- **Priority**: Low - This is defensive improvement, not a vulnerability
- **Location**: 
  - `/workspace/delegate/src/implementations/task-repository.ts:162,177,187`
  - `/workspace/delegate/src/implementations/dependency-repository.ts:202,242,297,324,431,489`

**[Resolution Type Assertion]** - `dependency-repository.ts:537`

```typescript
resolution: row.resolution as 'pending' | 'completed' | 'failed' | 'cancelled'
```

- **Current Mitigation**: New CHECK constraint enforces valid values at database level
- **Recommendation**: The CHECK constraint added in this branch mitigates this issue
- **Status**: RESOLVED by this branch's changes

---

## Category 3: Pre-existing Issues Found (Not Blocking)

### MEDIUM

**[Unconstrained Status Column]** - `src/implementations/database.ts`

The `tasks.status` column lacks a CHECK constraint (unlike the new `resolution` constraint):

```sql
status TEXT NOT NULL,  -- No CHECK constraint
```

- **Risk**: Invalid status values could be persisted
- **Current Mitigation**: Domain types enforce valid values at application layer
- **Location**: `/workspace/delegate/src/implementations/database.ts:203`
- **Recommendation**: Add CHECK constraint in future migration

**[Priority Column Unconstrained]** - `src/implementations/database.ts`

```sql
priority TEXT NOT NULL,  -- No CHECK constraint
```

- **Same concern as status column**
- **Location**: `/workspace/delegate/src/implementations/database.ts:205`

### LOW

**[Error Message Information Disclosure]** - Multiple locations

Error messages include internal details that could aid attackers:

```typescript
`Cannot add ${dependsOn.length} dependencies: task would exceed maximum of ${SQLiteDependencyRepository.MAX_DEPENDENCIES_PER_TASK} dependencies (currently has ${existingDepsCount})`
```

- **Risk**: Information disclosure about system limits
- **Location**: `/workspace/delegate/src/implementations/dependency-repository.ts:205`
- **Recommendation**: Consider generic error messages for external consumers
- **Priority**: LOW - This is an MCP server, not public-facing API

**[Console.log in Production Code]** - `database.ts`

```typescript
console.log(`Applying migration v${migration.version}: ${migration.description}`);
console.error('WAL mode failed, falling back to DELETE mode:', error);
```

- **Risk**: Information leakage in logs
- **Location**: `/workspace/delegate/src/implementations/database.ts:40,162,177`
- **Recommendation**: Use structured logger instead of console

---

## Summary

**Your Changes:**
- CRITICAL: 0
- HIGH: 0
- MEDIUM: 0
- LOW: 0

**Code You Touched:**
- HIGH: 0
- MEDIUM: 2 (type assertion patterns - mitigated by design)

**Pre-existing:**
- MEDIUM: 2 (unconstrained database columns)
- LOW: 2 (error message disclosure, console.log)

**Security Score**: 9/10

**Merge Recommendation**: APPROVED

---

## Detailed Analysis of Security-Relevant Changes

### 1. Database Migration Pattern (APPROVED)

The table recreation migration at `database.ts:277-312` follows safe patterns:

```sql
-- Create new table with CHECK constraint
CREATE TABLE task_dependencies_new (...);

-- Copy existing data (all existing values should be valid)
INSERT INTO task_dependencies_new SELECT * FROM task_dependencies;

-- Drop old table
DROP TABLE task_dependencies;

-- Rename new table
ALTER TABLE task_dependencies_new RENAME TO task_dependencies;

-- Recreate indexes
CREATE INDEX IF NOT EXISTS ...;
```

**Verified Safe:**
- Data is copied before dropping original table
- Transaction wraps entire migration
- Indexes are recreated after rename
- No data loss possible

### 2. Type Safety Improvements (APPROVED)

The explicit row types replace dangerous `any` patterns:

**Before:**
```typescript
private rowToDependency(row: any): TaskDependency {
```

**After:**
```typescript
private rowToDependency(row: DependencyRow): TaskDependency {
```

**Security Benefit**: Prevents accidental access to non-existent properties that could leak undefined behavior.

### 3. Configurable DoS Protection (APPROVED WITH NOTE)

```typescript
export const DEFAULT_MAX_DEPENDENCY_CHAIN_DEPTH = 100;

static async create(
  ...
  options?: DependencyHandlerOptions
): Promise<Result<DependencyHandler>> {
  const maxChainDepth = options?.maxChainDepth ?? DEFAULT_MAX_DEPENDENCY_CHAIN_DEPTH;
```

**Security Assessment:**
- Default remains safe (100)
- Requires explicit opt-in to change
- Factory pattern prevents accidental misconfiguration
- No upper bound enforcement (caller could pass `Infinity`)

**Minor Recommendation**: Consider adding an upper bound check:
```typescript
const maxChainDepth = Math.min(
  options?.maxChainDepth ?? DEFAULT_MAX_DEPENDENCY_CHAIN_DEPTH,
  1000  // Absolute maximum
);
```

This is a defense-in-depth suggestion, not a blocking issue.

---

## SQL Injection Analysis

All database queries in changed files use **prepared statements** with parameterized queries:

```typescript
this.addDependencyStmt = this.db.prepare(`
  INSERT INTO task_dependencies (
    task_id, depends_on_task_id, created_at, resolution
  ) VALUES (?, ?, ?, 'pending')
`);
```

**No SQL injection vulnerabilities** were found in changed or touched code.

---

## Remediation Priority

**Fix before merge:**
*Nothing required*

**Fix while you're here:**
*Optional - consider adding runtime validation for DB row types*

**Future work:**
1. Add CHECK constraints to `tasks.status` and `tasks.priority` columns
2. Replace `console.log/error` with structured logger in database.ts
3. Consider adding absolute upper bound for `maxChainDepth` option

---

## Conclusion

This branch represents **security-positive technical debt cleanup**. The changes:

1. Improve type safety by eliminating `any` types
2. Add defense-in-depth database constraints
3. Reduce information exposure by removing `getQueueStats()`
4. Maintain existing DoS protections while making them configurable

**No blocking security issues identified. Approved for merge.**
