# Gitea Architecture Review & Suggestions

**Reviewer:** Senior Architect
**Date:** January 2026
**Scope:** Full codebase review with focus on API, services, and recent chunked upload implementation

---

## Executive Summary

Gitea demonstrates a **well-designed, pragmatic architecture** suitable for a mature self-hosted Git platform. The codebase follows clean layered patterns (routers → services → models) with good separation of concerns. However, there are opportunities to improve **operational observability**, **reliability**, **developer experience**, and **AI/automation friendliness**.

This document presents findings organized by priority and effort level.

---

## Table of Contents

1. [Chunked Upload Implementation Review](#1-chunked-upload-implementation-review)
2. [API Design Improvements](#2-api-design-improvements)
3. [Error Handling & Observability](#3-error-handling--observability)
4. [Reliability & Resilience](#4-reliability--resilience)
5. [Developer Experience](#5-developer-experience)
6. [AI & Automation Friendliness](#6-ai--automation-friendliness)
7. [Security Considerations](#7-security-considerations)
8. [Performance Optimizations](#8-performance-optimizations)
9. [Implementation Roadmap](#9-implementation-roadmap)

---

## 1. Chunked Upload Implementation Review

### What Was Done Well

- Clean separation: model (`upload_session.go`), service (`chunked.go`), handler (`upload.go`)
- Resumable uploads with session status tracking
- Automatic cleanup via cron job
- Follows existing Gitea patterns for API handlers and models

### Issues to Address

#### 1.1 Missing Chunk Verification (HIGH)

**Problem:** No checksum verification for uploaded chunks. Corrupted chunks will produce corrupted files.

**Suggestion:**
```go
// Add to UploadSession model
type UploadSession struct {
    // ... existing fields
    ChecksumAlgorithm string `xorm:"DEFAULT 'sha256'"` // sha256, md5, none
    ExpectedChecksum  string `xorm:""`                  // Full file checksum
}

// Add to chunk upload
type ChunkMetadata struct {
    ChunkNumber int64  `json:"chunk_number"`
    Checksum    string `json:"checksum"` // Chunk checksum
    Size        int64  `json:"size"`
}
```

#### 1.2 No Concurrent Upload Protection (MEDIUM)

**Problem:** Same chunk can be uploaded multiple times concurrently, causing race conditions.

**Suggestion:**
```go
// Add file locking or atomic operations
func SaveChunk(ctx context.Context, session *UploadSession, chunkNum int64, ...) error {
    lockPath := session.GetChunkPath(chunkNum) + ".lock"
    lock, err := acquireFileLock(lockPath)
    if err != nil {
        return fmt.Errorf("chunk %d is being uploaded by another request", chunkNum)
    }
    defer lock.Release()
    // ... save chunk
}
```

#### 1.3 Missing Progress Webhook (MEDIUM)

**Problem:** No way to notify external systems of upload progress.

**Suggestion:**
```go
// Emit webhook on upload milestones
if session.ChunksReceived % 10 == 0 || session.IsComplete() {
    notify_service.UploadProgress(ctx, session)
}
```

#### 1.4 No Rate Limiting (MEDIUM)

**Problem:** Unlimited chunk uploads could exhaust server resources.

**Suggestion:**
```go
// Add rate limiting middleware for upload endpoints
m.Group("/uploads", func() {
    // ... routes
}, rateLimit(100, time.Minute)) // 100 chunks per minute per user
```

#### 1.5 Temp File Cleanup on Failure (LOW)

**Problem:** If `AssembleChunks` fails partway through, temp files may not be cleaned up.

**Suggestion:**
```go
func AssembleChunks(...) (*Attachment, error) {
    defer func() {
        if r := recover(); r != nil {
            cleanupTempFiles(session)
            panic(r)
        }
    }()
    // ... existing logic
}
```

---

## 2. API Design Improvements

### 2.1 Standardized Error Response Format (HIGH)

**Current State:** Error responses vary in format across endpoints.

**Suggestion:** Adopt RFC 7807 Problem Details format:

```go
// modules/structs/error.go
type APIError struct {
    Type     string            `json:"type"`               // URI reference
    Title    string            `json:"title"`              // Short summary
    Status   int               `json:"status"`             // HTTP status code
    Detail   string            `json:"detail"`             // Explanation
    Instance string            `json:"instance,omitempty"` // Request URI
    Code     string            `json:"code"`               // Machine-readable code
    Errors   []ValidationError `json:"errors,omitempty"`   // Field-level errors
}

// Example response:
{
    "type": "https://gitea.io/errors/validation",
    "title": "Validation Failed",
    "status": 422,
    "detail": "The provided repository name is invalid",
    "code": "ERR_VALIDATION_FAILED",
    "errors": [
        {"field": "name", "message": "must be alphanumeric", "code": "ERR_INVALID_CHARS"}
    ]
}
```

### 2.2 Batch Operations API (HIGH)

**Current State:** No batch endpoints for bulk operations.

**Suggestion:** Add batch endpoints for common operations:

```
POST /api/v1/repos/{owner}/{repo}/issues/batch
POST /api/v1/repos/{owner}/{repo}/labels/batch
POST /api/v1/admin/users/batch
```

```go
// Example batch request
{
    "operations": [
        {"action": "close", "issue_ids": [1, 2, 3]},
        {"action": "add_label", "issue_ids": [1, 2], "label_id": 5}
    ]
}

// Example batch response
{
    "results": [
        {"index": 0, "success": true, "affected": 3},
        {"index": 1, "success": false, "error": {"code": "ERR_NOT_FOUND", "detail": "Label 5 not found"}}
    ],
    "summary": {"total": 2, "succeeded": 1, "failed": 1}
}
```

### 2.3 Cursor-Based Pagination (MEDIUM)

**Current State:** Offset-based pagination can be slow for large datasets.

**Suggestion:** Add cursor-based pagination option:

```
GET /api/v1/repos/{owner}/{repo}/issues?cursor=eyJpZCI6MTAwfQ&limit=50
```

```go
type PaginatedResponse struct {
    Data       []any  `json:"data"`
    NextCursor string `json:"next_cursor,omitempty"`
    PrevCursor string `json:"prev_cursor,omitempty"`
    HasMore    bool   `json:"has_more"`
    Total      int64  `json:"total,omitempty"` // Optional, expensive to compute
}
```

### 2.4 Field Selection (GraphQL-lite) (MEDIUM)

**Current State:** All fields returned on every request.

**Suggestion:** Add field selection parameter:

```
GET /api/v1/repos/{owner}/{repo}?fields=id,name,description,stars_count
```

```go
// Reduces payload and database load
func filterFields(obj any, fields []string) map[string]any {
    // Return only requested fields
}
```

### 2.5 API Versioning Header (LOW)

**Current State:** No API version negotiation.

**Suggestion:** Add version header support:

```
Accept: application/vnd.gitea.v2+json
X-Gitea-API-Version: 2
```

---

## 3. Error Handling & Observability

### 3.1 Centralized Error Catalog (HIGH)

**Current State:** 100+ custom error types scattered across packages.

**Suggestion:** Create centralized error registry:

```go
// modules/errors/catalog.go
package errors

type ErrorCode string

const (
    // Authentication errors (1xxx)
    ErrAuthRequired       ErrorCode = "ERR_1001"
    ErrInvalidToken       ErrorCode = "ERR_1002"
    ErrTokenExpired       ErrorCode = "ERR_1003"

    // Authorization errors (2xxx)
    ErrForbidden          ErrorCode = "ERR_2001"
    ErrNotRepoMember      ErrorCode = "ERR_2002"

    // Resource errors (3xxx)
    ErrUserNotFound       ErrorCode = "ERR_3001"
    ErrRepoNotFound       ErrorCode = "ERR_3002"
    ErrIssueNotFound      ErrorCode = "ERR_3003"

    // Validation errors (4xxx)
    ErrInvalidInput       ErrorCode = "ERR_4001"
    ErrNameTooLong        ErrorCode = "ERR_4002"

    // Upload errors (5xxx)
    ErrUploadSessionExpired ErrorCode = "ERR_5001"
    ErrChunkMissing         ErrorCode = "ERR_5002"
    ErrFileTooLarge         ErrorCode = "ERR_5003"
)

var errorMessages = map[ErrorCode]string{
    ErrAuthRequired: "Authentication required",
    ErrInvalidToken: "Invalid or malformed token",
    // ...
}

func (e ErrorCode) Error() string { return errorMessages[e] }
func (e ErrorCode) HTTPStatus() int { /* return appropriate status */ }
```

### 3.2 Request Tracing (HIGH)

**Current State:** No correlation IDs for request tracing.

**Suggestion:** Add OpenTelemetry integration:

```go
// modules/web/middleware/tracing.go
func TracingMiddleware() func(http.Handler) http.Handler {
    return func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            traceID := r.Header.Get("X-Request-ID")
            if traceID == "" {
                traceID = uuid.New().String()
            }

            ctx := context.WithValue(r.Context(), TraceIDKey, traceID)
            w.Header().Set("X-Request-ID", traceID)

            // Add to structured logging
            log := log.WithField("trace_id", traceID)
            ctx = context.WithValue(ctx, LoggerKey, log)

            next.ServeHTTP(w, r.WithContext(ctx))
        })
    }
}
```

### 3.3 Structured Logging (MEDIUM)

**Current State:** Mix of structured and unstructured logging.

**Suggestion:** Standardize on JSON structured logs:

```go
// All log entries should include:
{
    "timestamp": "2024-01-08T12:00:00Z",
    "level": "info",
    "trace_id": "abc-123",
    "user_id": 42,
    "repo_id": 100,
    "action": "create_issue",
    "duration_ms": 45,
    "message": "Issue created successfully"
}
```

### 3.4 Metrics Endpoint Enhancement (MEDIUM)

**Current State:** Basic Prometheus metrics.

**Suggestion:** Add business metrics:

```go
// Metrics to add:
gitea_api_requests_total{method, endpoint, status}
gitea_api_request_duration_seconds{method, endpoint}
gitea_upload_sessions_active
gitea_upload_bytes_total
gitea_webhook_deliveries_total{status, hook_type}
gitea_webhook_delivery_duration_seconds
gitea_repository_operations_total{operation}
```

---

## 4. Reliability & Resilience

### 4.1 Webhook Retry with Exponential Backoff (HIGH)

**Current State:** Limited retry logic visible.

**Suggestion:**

```go
// services/webhook/deliver.go
type RetryConfig struct {
    MaxRetries     int           // Default: 5
    InitialBackoff time.Duration // Default: 1s
    MaxBackoff     time.Duration // Default: 5m
    BackoffFactor  float64       // Default: 2.0
}

func DeliverWithRetry(ctx context.Context, task *HookTask, cfg RetryConfig) error {
    var lastErr error
    backoff := cfg.InitialBackoff

    for attempt := 0; attempt <= cfg.MaxRetries; attempt++ {
        err := Deliver(ctx, task)
        if err == nil {
            return nil
        }
        lastErr = err

        // Log retry
        log.Warn("Webhook delivery failed, retrying",
            "task_id", task.ID,
            "attempt", attempt+1,
            "next_backoff", backoff)

        select {
        case <-ctx.Done():
            return ctx.Err()
        case <-time.After(backoff):
        }

        backoff = time.Duration(float64(backoff) * cfg.BackoffFactor)
        if backoff > cfg.MaxBackoff {
            backoff = cfg.MaxBackoff
        }
    }

    // Move to dead letter queue
    if err := moveToDeadLetterQueue(ctx, task, lastErr); err != nil {
        log.Error("Failed to move to DLQ", "task_id", task.ID, "error", err)
    }

    return fmt.Errorf("webhook delivery failed after %d attempts: %w", cfg.MaxRetries, lastErr)
}
```

### 4.2 Circuit Breaker for External Services (MEDIUM)

**Current State:** No circuit breaker pattern.

**Suggestion:**

```go
// modules/circuitbreaker/breaker.go
type CircuitBreaker struct {
    name          string
    maxFailures   int
    resetTimeout  time.Duration
    state         State // Closed, Open, HalfOpen
    failures      int
    lastFailure   time.Time
}

func (cb *CircuitBreaker) Execute(fn func() error) error {
    if cb.state == Open {
        if time.Since(cb.lastFailure) > cb.resetTimeout {
            cb.state = HalfOpen
        } else {
            return ErrCircuitOpen
        }
    }

    err := fn()
    if err != nil {
        cb.recordFailure()
        return err
    }

    cb.recordSuccess()
    return nil
}

// Usage for webhook delivery, OAuth providers, etc.
var webhookBreaker = NewCircuitBreaker("webhook", 5, time.Minute)
```

### 4.3 Graceful Degradation (MEDIUM)

**Current State:** Services fail hard on dependency failures.

**Suggestion:** Add fallback behaviors:

```go
// Example: Search indexer fallback
func SearchIssues(ctx context.Context, query string) ([]Issue, error) {
    if indexer.IsHealthy() {
        return indexer.Search(ctx, query)
    }

    // Fallback to database search (slower but works)
    log.Warn("Search indexer unavailable, falling back to DB search")
    return db.SearchIssuesByTitle(ctx, query)
}
```

### 4.4 Health Check Endpoints (LOW)

**Current State:** Basic health check.

**Suggestion:** Add detailed health checks:

```
GET /api/v1/health
GET /api/v1/health/live    # Kubernetes liveness
GET /api/v1/health/ready   # Kubernetes readiness
```

```json
{
    "status": "healthy",
    "version": "1.24.0",
    "checks": {
        "database": {"status": "up", "latency_ms": 2},
        "redis": {"status": "up", "latency_ms": 1},
        "search_indexer": {"status": "degraded", "message": "High latency"},
        "storage": {"status": "up", "free_space_gb": 450}
    }
}
```

---

## 5. Developer Experience

### 5.1 OpenAPI Spec Improvements (HIGH)

**Current State:** Swagger docs generated from code comments.

**Suggestion:** Enhance with examples and better descriptions:

```go
// swagger:operation POST /repos/{owner}/{repo}/issues repository createIssue
// ---
// summary: Create an issue
// description: |
//   Creates a new issue in the repository. The authenticated user must have
//   write access to the repository.
//
//   ## Example
//   ```json
//   {"title": "Bug report", "body": "Description here", "labels": [1, 2]}
//   ```
// consumes:
// - application/json
// produces:
// - application/json
// parameters:
// - name: body
//   in: body
//   schema:
//     "$ref": "#/definitions/CreateIssueOption"
//   example:
//     title: "Bug: Login fails"
//     body: "When I try to login..."
//     labels: [1, 2]
// responses:
//   "201":
//     description: Issue created
//     schema:
//       "$ref": "#/definitions/Issue"
//     examples:
//       application/json:
//         id: 1
//         title: "Bug: Login fails"
//         state: "open"
```

### 5.2 SDK Generation (MEDIUM)

**Current State:** No official SDK libraries.

**Suggestion:** Generate SDKs from OpenAPI spec:

```bash
# Generate SDKs
openapi-generator generate -i api/v1/swagger.json -g python -o sdk/python
openapi-generator generate -i api/v1/swagger.json -g typescript-axios -o sdk/typescript
openapi-generator generate -i api/v1/swagger.json -g go -o sdk/go
```

### 5.3 CLI Tool Enhancement (MEDIUM)

**Current State:** Basic CLI for Git operations.

**Suggestion:** Add API CLI tool:

```bash
# Proposed gitea-cli commands
gitea-cli auth login --server https://gitea.example.com
gitea-cli repo list
gitea-cli repo create myrepo --private
gitea-cli issue create --title "Bug" --body "Description"
gitea-cli release create v1.0.0 --attach ./binary.zip
gitea-cli upload --chunked ./large-file.zip  # Uses chunked upload
```

### 5.4 Webhook Debugging Tools (LOW)

**Current State:** Limited visibility into webhook delivery.

**Suggestion:** Add webhook inspection endpoints:

```
GET /api/v1/repos/{owner}/{repo}/hooks/{id}/deliveries
GET /api/v1/repos/{owner}/{repo}/hooks/{id}/deliveries/{delivery_id}
POST /api/v1/repos/{owner}/{repo}/hooks/{id}/deliveries/{delivery_id}/redeliver
```

---

## 6. AI & Automation Friendliness

### 6.1 Machine-Readable Error Codes (HIGH)

**Current State:** Error messages are human-readable strings.

**Suggestion:** Always include machine-readable codes:

```json
{
    "code": "ERR_REPO_ARCHIVED",
    "message": "Repository is archived and cannot be modified",
    "documentation_url": "https://docs.gitea.io/errors/ERR_REPO_ARCHIVED"
}
```

### 6.2 Idempotency Keys (HIGH)

**Current State:** No idempotency support for POST requests.

**Suggestion:** Add idempotency key header:

```go
// Header: Idempotency-Key: <client-generated-uuid>

func IdempotencyMiddleware() func(http.Handler) http.Handler {
    return func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            if r.Method != "POST" && r.Method != "PUT" {
                next.ServeHTTP(w, r)
                return
            }

            key := r.Header.Get("Idempotency-Key")
            if key == "" {
                next.ServeHTTP(w, r)
                return
            }

            // Check cache
            if cached, found := idempotencyCache.Get(key); found {
                w.Header().Set("X-Idempotency-Replayed", "true")
                writeResponse(w, cached)
                return
            }

            // Capture response
            rec := httptest.NewRecorder()
            next.ServeHTTP(rec, r)

            // Cache successful responses
            if rec.Code >= 200 && rec.Code < 300 {
                idempotencyCache.Set(key, rec, 24*time.Hour)
            }

            copyResponse(w, rec)
        })
    }
}
```

### 6.3 Webhook Event Catalog (MEDIUM)

**Current State:** Events documented but not discoverable via API.

**Suggestion:** Add event discovery endpoint:

```
GET /api/v1/events
```

```json
{
    "events": [
        {
            "name": "push",
            "description": "Triggered when commits are pushed",
            "payload_schema": {"$ref": "#/definitions/PushPayload"},
            "example": {...}
        },
        {
            "name": "issues",
            "description": "Triggered for issue events",
            "actions": ["opened", "closed", "edited", "labeled"],
            "payload_schema": {"$ref": "#/definitions/IssuePayload"}
        }
    ]
}
```

### 6.4 Async Operation Pattern (MEDIUM)

**Current State:** Long operations block HTTP requests.

**Suggestion:** Add async operation pattern for long-running tasks:

```
POST /api/v1/repos/{owner}/{repo}/mirror-sync
Response: 202 Accepted
{
    "operation_id": "op_abc123",
    "status": "pending",
    "status_url": "/api/v1/operations/op_abc123",
    "estimated_completion": "2024-01-08T12:05:00Z"
}

GET /api/v1/operations/op_abc123
{
    "operation_id": "op_abc123",
    "status": "running",
    "progress": 45,
    "started_at": "2024-01-08T12:00:00Z"
}
```

### 6.5 Rate Limit Headers (MEDIUM)

**Current State:** Limited rate limit visibility.

**Suggestion:** Add standard rate limit headers:

```
X-RateLimit-Limit: 5000
X-RateLimit-Remaining: 4990
X-RateLimit-Reset: 1704720000
X-RateLimit-Resource: api
```

### 6.6 Conditional Requests (LOW)

**Current State:** Limited ETag/If-Match support.

**Suggestion:** Add conditional request support:

```
GET /api/v1/repos/owner/repo
Response Headers:
  ETag: "abc123"
  Last-Modified: Wed, 08 Jan 2024 12:00:00 GMT

GET /api/v1/repos/owner/repo
Request Headers:
  If-None-Match: "abc123"
Response: 304 Not Modified

PUT /api/v1/repos/owner/repo
Request Headers:
  If-Match: "abc123"  # Prevents lost updates
```

---

## 7. Security Considerations

### 7.1 Audit Logging (HIGH)

**Current State:** Limited audit trail.

**Suggestion:** Add comprehensive audit logging:

```go
type AuditEvent struct {
    ID          int64     `json:"id"`
    Timestamp   time.Time `json:"timestamp"`
    ActorID     int64     `json:"actor_id"`
    ActorIP     string    `json:"actor_ip"`
    Action      string    `json:"action"`      // "repo.create", "user.delete"
    Resource    string    `json:"resource"`    // "repository", "user"
    ResourceID  int64     `json:"resource_id"`
    OldValue    string    `json:"old_value,omitempty"`  // JSON
    NewValue    string    `json:"new_value,omitempty"`  // JSON
    UserAgent   string    `json:"user_agent"`
    TraceID     string    `json:"trace_id"`
}

// Store in separate audit_log table
// Expose via admin API: GET /api/v1/admin/audit-log
```

### 7.2 Token Scopes Enhancement (MEDIUM)

**Current State:** Basic token scopes.

**Suggestion:** Add granular scopes:

```
repo:read           # Read repository data
repo:write          # Push to repository
repo:delete         # Delete repository
issues:read         # Read issues
issues:write        # Create/edit issues
releases:read       # Read releases
releases:write      # Create releases
releases:upload     # Upload release assets (for CI)
admin:users         # Manage users
admin:repos         # Manage all repos
webhook:manage      # Manage webhooks
```

### 7.3 Request Signing (LOW)

**Current State:** Token-based auth only.

**Suggestion:** Add HMAC request signing for webhooks:

```go
// For high-security integrations
signature := hmac.New(sha256.New, []byte(secret))
signature.Write([]byte(timestamp + "." + requestBody))
expectedSig := hex.EncodeToString(signature.Sum(nil))

// Header: X-Gitea-Signature: sha256=<signature>
// Header: X-Gitea-Timestamp: <unix-timestamp>
```

---

## 8. Performance Optimizations

### 8.1 Response Compression (HIGH)

**Current State:** Gzip available but not always used.

**Suggestion:** Ensure compression for all JSON responses:

```go
// Middleware to compress responses > 1KB
func CompressionMiddleware(next http.Handler) http.Handler {
    return gziphandler.GzipHandler(next)
}
```

### 8.2 Database Query Optimization (MEDIUM)

**Current State:** Some N+1 query patterns.

**Suggestion:** Add eager loading for common associations:

```go
// Instead of loading issues then loading users one by one
issues, _ := GetIssues(ctx, opts)
for _, issue := range issues {
    issue.Poster, _ = GetUser(issue.PosterID)  // N+1!
}

// Use eager loading
issues, _ := GetIssuesWithUsers(ctx, opts)  // Single JOIN query
```

### 8.3 Caching Layer (MEDIUM)

**Current State:** Limited caching.

**Suggestion:** Add Redis/memory caching for hot paths:

```go
// Cache frequently accessed data
func GetRepository(ctx context.Context, id int64) (*Repository, error) {
    cacheKey := fmt.Sprintf("repo:%d", id)

    if cached, found := cache.Get(cacheKey); found {
        return cached.(*Repository), nil
    }

    repo, err := db.GetRepository(ctx, id)
    if err != nil {
        return nil, err
    }

    cache.Set(cacheKey, repo, 5*time.Minute)
    return repo, nil
}
```

### 8.4 Connection Pooling Tuning (LOW)

**Current State:** Default connection pool settings.

**Suggestion:** Add configurable pool settings:

```ini
[database]
MAX_OPEN_CONNS = 100
MAX_IDLE_CONNS = 10
CONN_MAX_LIFETIME = 1h
CONN_MAX_IDLE_TIME = 10m
```

---

## 9. Implementation Roadmap

### Phase 1: Quick Wins (1-2 weeks)

| Item | Priority | Effort | Impact |
|------|----------|--------|--------|
| Add request tracing (X-Request-ID) | HIGH | Low | High |
| Add rate limit headers | MEDIUM | Low | Medium |
| Add chunk checksum verification | HIGH | Low | High |
| Standardize error response format | HIGH | Medium | High |

### Phase 2: Foundation (2-4 weeks)

| Item | Priority | Effort | Impact |
|------|----------|--------|--------|
| Centralized error catalog | HIGH | Medium | High |
| Webhook retry with backoff | HIGH | Medium | High |
| Idempotency key support | HIGH | Medium | High |
| Audit logging | HIGH | Medium | High |
| Health check endpoints | LOW | Low | Medium |

### Phase 3: Enhancement (4-8 weeks)

| Item | Priority | Effort | Impact |
|------|----------|--------|--------|
| Batch operations API | HIGH | High | High |
| Cursor-based pagination | MEDIUM | Medium | Medium |
| SDK generation pipeline | MEDIUM | Medium | Medium |
| Circuit breaker pattern | MEDIUM | Medium | Medium |
| Event discovery endpoint | MEDIUM | Low | Medium |

### Phase 4: Advanced (8+ weeks)

| Item | Priority | Effort | Impact |
|------|----------|--------|--------|
| Async operation pattern | MEDIUM | High | Medium |
| Field selection (GraphQL-lite) | MEDIUM | High | Medium |
| API versioning | LOW | High | Low |
| Full OpenTelemetry integration | MEDIUM | High | High |

---

## Appendix A: Chunked Upload Quick Fixes

```go
// 1. Add checksum to chunk upload (upload.go)
func UploadChunk(ctx *context.APIContext) {
    // Get expected checksum from header
    expectedChecksum := ctx.Req.Header.Get("X-Chunk-Checksum")

    // ... save chunk ...

    // Verify checksum if provided
    if expectedChecksum != "" {
        actualChecksum := sha256sum(chunkData)
        if actualChecksum != expectedChecksum {
            ctx.APIError(http.StatusBadRequest, api.APIError{
                Code:   "ERR_CHECKSUM_MISMATCH",
                Detail: "Chunk checksum verification failed",
            })
            return
        }
    }
}

// 2. Add final file checksum verification (chunked.go)
func AssembleChunks(...) (*Attachment, error) {
    // ... assemble chunks ...

    // Verify final checksum if expected
    if session.ExpectedChecksum != "" {
        actualChecksum := computeFileChecksum(finalPath)
        if actualChecksum != session.ExpectedChecksum {
            return nil, fmt.Errorf("file checksum mismatch: expected %s, got %s",
                session.ExpectedChecksum, actualChecksum)
        }
    }

    // ... create attachment ...
}
```

---

## Appendix B: Sample Error Catalog

```go
// modules/errors/codes.go

package errors

// Error codes organized by category
const (
    // 1xxx - Authentication
    ErrCodeAuthRequired     = "ERR_1001"
    ErrCodeInvalidToken     = "ERR_1002"
    ErrCodeTokenExpired     = "ERR_1003"
    ErrCodeInvalidPassword  = "ERR_1004"
    ErrCode2FARequired      = "ERR_1005"

    // 2xxx - Authorization
    ErrCodeForbidden        = "ERR_2001"
    ErrCodeNotRepoMember    = "ERR_2002"
    ErrCodeNotOrgMember     = "ERR_2003"
    ErrCodeInsufficientPerm = "ERR_2004"

    // 3xxx - Resource Not Found
    ErrCodeUserNotFound     = "ERR_3001"
    ErrCodeRepoNotFound     = "ERR_3002"
    ErrCodeIssueNotFound    = "ERR_3003"
    ErrCodeReleaseNotFound  = "ERR_3004"
    ErrCodeBranchNotFound   = "ERR_3005"

    // 4xxx - Validation
    ErrCodeInvalidInput     = "ERR_4001"
    ErrCodeNameTooLong      = "ERR_4002"
    ErrCodeInvalidEmail     = "ERR_4003"
    ErrCodeDuplicateName    = "ERR_4004"

    // 5xxx - Upload
    ErrCodeSessionExpired   = "ERR_5001"
    ErrCodeChunkMissing     = "ERR_5002"
    ErrCodeFileTooLarge     = "ERR_5003"
    ErrCodeChecksumMismatch = "ERR_5004"
    ErrCodeInvalidFileType  = "ERR_5005"

    // 6xxx - Rate Limiting
    ErrCodeRateLimited      = "ERR_6001"
    ErrCodeTooManyRequests  = "ERR_6002"

    // 7xxx - Server
    ErrCodeInternal         = "ERR_7001"
    ErrCodeServiceDown      = "ERR_7002"
    ErrCodeTimeout          = "ERR_7003"
)
```

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*Document prepared for discussion. All suggestions should be evaluated against project priorities and resource constraints.*