# Blocker Unblock Implementation Plan

> **Created:** 2025-12-04
> **Purpose:** Step-by-step implementation plan to unblock remaining ~14 tasks
> **Estimated Effort:** 16-22 developer-days

## Executive Summary

After creating 11 specification contracts that unblocked ~61 tasks, we have **14 remaining blocked tasks** that require actual implementation work (not just specs). This plan outlines the implementation roadmap.

---

## Remaining Blockers Analysis

| Blocker | Tasks Blocked | Type | Complexity |
|---------|--------------|------|------------|
| WEB-POLICY-20-004 (Rate Limiting) | 6 | Code Implementation | SIMPLE |
| Shared Signals Library | 5+ | New Library | MODERATE |
| Postgres Repositories | 5 | Code Implementation | MODERATE |
| Test Infrastructure | N/A | Infrastructure | MODERATE |
| PGMI0101 Staffing | 3 | Human Decision | N/A |

---

## Implementation Phases

### Phase 1: Policy Engine Rate Limiting (WEB-POLICY-20-004)

**Duration:** 1-2 days
**Unblocks:** 6 tasks (WEB-POLICY-20-004 chain)
**Dependencies:** None

#### 1.1 Create Rate Limit Options

**File:** `src/Policy/StellaOps.Policy.Engine/Options/PolicyEngineRateLimitOptions.cs`

```csharp
namespace StellaOps.Policy.Engine.Options;

public sealed class PolicyEngineRateLimitOptions
{
    public const string SectionName = "RateLimiting";

    /// <summary>Default permits per window for simulation endpoints</summary>
    public int SimulationPermitLimit { get; set; } = 100;

    /// <summary>Window duration in seconds</summary>
    public int WindowSeconds { get; set; } = 60;

    /// <summary>Queue limit for pending requests</summary>
    public int QueueLimit { get; set; } = 10;

    /// <summary>Enable tenant-aware partitioning</summary>
    public bool TenantPartitioning { get; set; } = true;
}
```

#### 1.2 Register Rate Limiter in Program.cs

Add to `src/Policy/StellaOps.Policy.Engine/Program.cs`:

```csharp
// Rate limiting configuration
var rateLimitOptions = builder.Configuration
    .GetSection(PolicyEngineRateLimitOptions.SectionName)
    .Get<PolicyEngineRateLimitOptions>() ?? new();

builder.Services.AddRateLimiter(options =>
{
    options.RejectionStatusCode = StatusCodes.Status429TooManyRequests;

    options.AddTokenBucketLimiter("policy-simulation", limiterOptions =>
    {
        limiterOptions.TokenLimit = rateLimitOptions.SimulationPermitLimit;
        limiterOptions.ReplenishmentPeriod = TimeSpan.FromSeconds(rateLimitOptions.WindowSeconds);
        limiterOptions.TokensPerPeriod = rateLimitOptions.SimulationPermitLimit;
        limiterOptions.QueueLimit = rateLimitOptions.QueueLimit;
        limiterOptions.QueueProcessingOrder = QueueProcessingOrder.OldestFirst;
    });

    options.OnRejected = async (context, cancellationToken) =>
    {
        PolicyEngineTelemetry.RateLimitExceededCounter.Add(1);
        context.HttpContext.Response.StatusCode = StatusCodes.Status429TooManyRequests;
        await context.HttpContext.Response.WriteAsJsonAsync(new
        {
            error = "ERR_POL_007",
            message = "Rate limit exceeded. Please retry after the reset window.",
            retryAfterSeconds = rateLimitOptions.WindowSeconds
        }, cancellationToken);
    };
});
```

#### 1.3 Apply to Simulation Endpoints

Modify `src/Policy/StellaOps.Policy.Engine/Endpoints/RiskSimulationEndpoints.cs`:

```csharp
group.MapPost("/simulate", SimulateRisk)
    .RequireRateLimiting("policy-simulation")  // ADD THIS
    .WithName("SimulateRisk");
```

#### 1.4 Add Telemetry Counter

Add to `src/Policy/StellaOps.Policy.Engine/Telemetry/PolicyEngineTelemetry.cs`:

```csharp
public static readonly Counter<long> RateLimitExceededCounter =
    Meter.CreateCounter<long>(
        "policy_rate_limit_exceeded_total",
        unit: "requests",
        description: "Total requests rejected due to rate limiting");
```

#### 1.5 Configuration Sample

Add to `etc/policy-engine.yaml.sample`:

```yaml
RateLimiting:
  SimulationPermitLimit: 100
  WindowSeconds: 60
  QueueLimit: 10
  TenantPartitioning: true
```

---

### Phase 2: Shared Signals Contracts Library

**Duration:** 3-4 days
**Unblocks:** 5+ modules (Concelier, Scanner, Policy, Signals, Authority)
**Dependencies:** None

#### 2.1 Create Project Structure

```
src/__Libraries/StellaOps.Signals.Contracts/
├── StellaOps.Signals.Contracts.csproj
├── AGENTS.md
├── Models/
│   ├── SignalEnvelope.cs
│   ├── SignalType.cs
│   ├── ReachabilitySignal.cs
│   ├── EntropySignal.cs
│   ├── ExploitabilitySignal.cs
│   ├── TrustSignal.cs
│   └── UnknownSymbolSignal.cs
├── Abstractions/
│   ├── ISignalEmitter.cs
│   ├── ISignalConsumer.cs
│   └── ISignalContext.cs
└── Extensions/
    └── ServiceCollectionExtensions.cs
```

#### 2.2 Core Models

**SignalEnvelope.cs:**
```csharp
namespace StellaOps.Signals.Contracts;

public sealed record SignalEnvelope(
    string SignalKey,
    SignalType SignalType,
    object Value,
    DateTimeOffset ComputedAt,
    string SourceService,
    string? TenantId = null,
    string? CorrelationId = null,
    string? ProvenanceDigest = null);
```

**SignalType.cs:**
```csharp
namespace StellaOps.Signals.Contracts;

public enum SignalType
{
    Reachability,
    Entropy,
    Exploitability,
    Trust,
    UnknownSymbol,
    Custom
}
```

#### 2.3 Signal Models

Each signal type gets a dedicated record:

- `ReachabilitySignal` - package reachability from callgraph
- `EntropySignal` - code complexity/risk metrics
- `ExploitabilitySignal` - KEV status, exploit availability
- `TrustSignal` - reputation, chain of custody scores
- `UnknownSymbolSignal` - unresolved dependencies

#### 2.4 Abstractions

```csharp
public interface ISignalEmitter
{
    ValueTask EmitAsync(SignalEnvelope signal, CancellationToken ct = default);
    ValueTask EmitBatchAsync(IEnumerable<SignalEnvelope> signals, CancellationToken ct = default);
}

public interface ISignalConsumer
{
    IAsyncEnumerable<SignalEnvelope> ConsumeAsync(
        SignalType? filterType = null,
        CancellationToken ct = default);
}
```

---

### Phase 3: Postgres Repositories

**Duration:** 4-5 days
**Unblocks:** Persistence for new features
**Dependencies:** SQL migrations

#### 3.1 Repository Interfaces

Create in `src/Policy/__Libraries/StellaOps.Policy.Storage.Postgres/Repositories/`:

| Interface | Methods |
|-----------|---------|
| `ISnapshotRepository` | Create, GetById, List, Delete |
| `IViolationEventRepository` | Append, GetById, List (immutable) |
| `IWorkerResultRepository` | Create, GetById, List, Update |
| `IConflictRepository` | Create, GetById, List, Resolve |
| `ILedgerExportRepository` | Create, GetById, List, GetByDigest |

#### 3.2 SQL Migrations

Create migrations for tables:

```sql
-- policy.snapshots
CREATE TABLE policy.snapshots (
    id UUID PRIMARY KEY,
    tenant_id TEXT NOT NULL,
    policy_id UUID NOT NULL,
    version INTEGER NOT NULL,
    content_digest TEXT NOT NULL,
    metadata JSONB,
    created_by TEXT NOT NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

-- policy.violation_events (append-only)
CREATE TABLE policy.violation_events (
    id UUID PRIMARY KEY,
    tenant_id TEXT NOT NULL,
    policy_id UUID NOT NULL,
    rule_id TEXT NOT NULL,
    severity TEXT NOT NULL,
    subject_purl TEXT,
    details JSONB,
    occurred_at TIMESTAMPTZ NOT NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

-- Similar for conflicts, worker_results, ledger_exports
```

#### 3.3 Implementation Pattern

Follow `RiskProfileRepository.cs` pattern:

```csharp
public sealed class SnapshotRepository : RepositoryBase<PolicyDataSource>, ISnapshotRepository
{
    public SnapshotRepository(PolicyDataSource dataSource, ILogger<SnapshotRepository> logger)
        : base(dataSource, logger) { }

    public async Task<SnapshotEntity> CreateAsync(SnapshotEntity entity, CancellationToken ct)
    {
        const string sql = """
            INSERT INTO policy.snapshots
            (id, tenant_id, policy_id, version, content_digest, metadata, created_by)
            VALUES (@Id, @TenantId, @PolicyId, @Version, @ContentDigest, @Metadata::jsonb, @CreatedBy)
            RETURNING *
            """;

        return await ExecuteScalarAsync<SnapshotEntity>(sql, entity, ct);
    }

    // ... other CRUD methods
}
```

---

### Phase 4: Test Infrastructure

**Duration:** 2-3 days
**Unblocks:** Validation before merge
**Dependencies:** Phase 3

#### 4.1 Postgres Test Fixture

```csharp
public sealed class PostgresFixture : IAsyncLifetime
{
    private TestcontainersContainer? _container;
    public string ConnectionString { get; private set; } = string.Empty;

    public async Task InitializeAsync()
    {
        _container = new TestcontainersBuilder<TestcontainersContainer>()
            .WithImage("postgres:16-alpine")
            .WithEnvironment("POSTGRES_PASSWORD", "test")
            .WithPortBinding(5432, true)
            .Build();

        await _container.StartAsync();
        ConnectionString = $"Host=localhost;Port={_container.GetMappedPublicPort(5432)};...";

        // Run migrations
        await MigrationRunner.RunAsync(ConnectionString);
    }

    public async Task DisposeAsync() => await _container?.DisposeAsync();
}
```

#### 4.2 Test Classes

- `RateLimitingTests.cs` - quota exhaustion, recovery, tenant partitioning
- `SnapshotRepositoryTests.cs` - CRUD operations
- `ViolationEventRepositoryTests.cs` - append-only semantics
- `ConflictRepositoryTests.cs` - resolution workflow
- `SignalEnvelopeTests.cs` - serialization, validation

---

### Phase 5: New Endpoints

**Duration:** 2-3 days
**Unblocks:** API surface completion
**Dependencies:** Phase 3

#### 5.1 Endpoint Groups

| Path | Operations | Auth |
|------|------------|------|
| `/api/policy/snapshots` | GET, POST, DELETE | `policy:read`, `policy:author` |
| `/api/policy/violations` | GET | `policy:read` |
| `/api/policy/conflicts` | GET, POST (resolve) | `policy:read`, `policy:review` |
| `/api/policy/exports` | GET, POST | `policy:read`, `policy:archive` |

---

## Execution Order

```
Day 1-2: Phase 1 (Rate Limiting)
         └── WEB-POLICY-20-004 ✓ UNBLOCKED

Day 3-5: Phase 2 (Signals Library)
         └── Concelier, Scanner, Policy, Signals, Authority ✓ ENABLED

Day 6-9: Phase 3 (Repositories)
         └── Persistence layer ✓ COMPLETE

Day 10-12: Phase 4 (Tests)
           └── Validation ✓ READY

Day 13-15: Phase 5 (Endpoints)
           └── API surface ✓ COMPLETE
```

---

## Files to Create/Modify Summary

### New Files (22 files)

```
src/Policy/StellaOps.Policy.Engine/Options/
└── PolicyEngineRateLimitOptions.cs

src/__Libraries/StellaOps.Signals.Contracts/
├── StellaOps.Signals.Contracts.csproj
├── AGENTS.md
├── Models/SignalEnvelope.cs
├── Models/SignalType.cs
├── Models/ReachabilitySignal.cs
├── Models/EntropySignal.cs
├── Models/ExploitabilitySignal.cs
├── Models/TrustSignal.cs
├── Models/UnknownSymbolSignal.cs
├── Abstractions/ISignalEmitter.cs
├── Abstractions/ISignalConsumer.cs
└── Extensions/ServiceCollectionExtensions.cs

src/Policy/__Libraries/StellaOps.Policy.Storage.Postgres/Repositories/
├── ISnapshotRepository.cs
├── SnapshotRepository.cs
├── IViolationEventRepository.cs
├── ViolationEventRepository.cs
├── IConflictRepository.cs
├── ConflictRepository.cs
├── ILedgerExportRepository.cs
└── LedgerExportRepository.cs
```

### Files to Modify (5 files)

```
src/Policy/StellaOps.Policy.Engine/Program.cs
src/Policy/StellaOps.Policy.Engine/Telemetry/PolicyEngineTelemetry.cs
src/Policy/StellaOps.Policy.Engine/Endpoints/RiskSimulationEndpoints.cs
src/Policy/StellaOps.Policy.Engine/Endpoints/PathScopeSimulationEndpoint.cs
etc/policy-engine.yaml.sample
```

---

## Success Criteria

- [ ] Rate limiting returns 429 when quota exceeded
- [ ] Signals library compiles and referenced by 5+ modules
- [ ] All 5 repositories pass CRUD tests
- [ ] Endpoints return proper responses with auth
- [ ] Telemetry metrics visible in dashboards
- [ ] No regression in existing tests

---

## Risk Mitigation

| Risk | Mitigation |
|------|------------|
| Breaking existing endpoints | Feature flag rate limiting |
| Signal library circular deps | Careful namespace isolation |
| Migration failures | Test migrations in isolated DB first |
| Test flakiness | Use deterministic test data |

---

## Next Steps

1. **Start Phase 1** - Implement rate limiting (simplest, immediate impact)
2. **Parallel Phase 2** - Create Signals.Contracts scaffolding
3. **Review** - Get feedback before Phase 3