Deterministic RFC 9218 Extensible Prioritization and Rapid-Reset Mitigation in Go Chi HTTP/3

Q: How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Unbounded Goroutine Spawning and Unthrottled HTTP/3 Stream Resets Leading to Resource Starvation) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q: Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q: Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

Deterministic RFC 9218 Extensible Prioritization and Rapid-Reset Mitigation in Go Chi HTTP/3

--- description: Deterministic RFC 9218 Extensible Prioritization and Rapid-Reset Mitigation in Go Chi HTTP/3 - Enforces strict RFC 9218 Extensible Prioritization handling and stream frame budgeting in Go Chi HTTP/3 services. Mitigates HTTP/3 stream starvation and Rapid Reset (CVE-2023-44487 analogue) vectors by bounding stream concurrency, throttling stream cancellations, and parsing urgency/incremental parameters for deterministic resource allocation. globs: **/*.go, cmd/**/*.go, internal/**/*.go, pkg/**/*.go alwaysApply: true verified_by: "agentrules.org" license: "CC-BY-4.0" source: "https://agentrules.org/rules/go-chi-http3-rfc9218-stream-prioritization-standard" --- # Deterministic RFC 9218 Extensible Prioritization and Rapid-Reset Mitigation in Go Chi HTTP/3 > **Severity**: CRITICAL | **Category**: backend > **Anti-Pattern Warning**: Unbounded Goroutine Spawning and Unthrottled HTTP/3 Stream Resets Leading to Resource Starvation ## System Constraints You are a Principal Systems Architect enforcing the Go Chi HTTP/3 RFC 9218 Stream Prioritization & Frame Budgeting Standard. Mandate that all HTTP/3 (quic-go/http3) integration points with Chi explicitly parse and validate RFC 9218 Priority headers, enforce stream cancellation rate-limiting to mitigate Rapid Reset DoS attacks, and tie active write buffers to deterministic priority budgets. ## Strict Guidelines - Engineers MUST ALWAYS parse and validate the RFC 9218 'Priority' header (urgency u=0..7, incremental i=?0|?1) in Chi middleware to govern stream scheduling. - Engineers MUST NOT spawn detached or unmetered goroutines per HTTP/3 request without binding execution lifecycles to r.Context() and checking for stream reset / cancellation. - Services MUST enforce strict token-bucket rate limits on client-initiated stream resets (STOP_SENDING/RESET_STREAM) per QUIC connection to block Rapid Reset DoS variants. - Code SHOULD enforce deterministic chunk-budget write loops using http.ResponseController or quic-go stream backpressure rather than unbounded byte buffering. - Components NEVER accept arbitrary unbounded client-controlled urgency parameters without capping priorities to authorized service role boundaries. ## Bad vs Good Implementations ### Vulnerable vs Hardened RFC 9218 & Rapid Reset Chi HTTP/3 Handler #### Bad Antipattern (AI Common Hallucination) > **Why it fails**: Spawns an unmonitored goroutine that writes to the response even if the HTTP/3 stream was reset by the client. It completely ignores RFC 9218 priority signals and provides no backpressure or reset rate limiting, allowing an attacker to exhaust server memory and CPU via rapid stream cancellation loops. ```go package transport import ( "io" "net/http" "github.com/go-chi/chi/v5" ) func MountVulnerableRoutes(r chi.Router) { r.Post("/stream/export", func(w http.ResponseWriter, r *http.Request) { // ANTI-PATTERN: Completely ignores RFC 9218 Priority header; // ignores r.Context() cancellation (Rapid Reset DoS vulnerability); // buffers unbounded memory without frame budget throttling. go func() { data := fetchHugePayload() w.Header().Set("Content-Type", "application/octet-stream") w.Write(data) }() }) } func fetchHugePayload() []byte { return make([]byte, 64*1024*1024) } ``` #### Production Standard (Correct) > **Standard**: Implements deterministic RFC 9218 parsing (validating urgency bounds 0-7 and incremental state), integrates rapid stream reset throttling via a token-bucket limiter, uses http.ResponseController to set write deadlines, and performs cooperative context cancellation checks at budgeted 32KB frame intervals. ```go package transport import ( "context" "errors" "net/http" "strconv" "strings" "time" "github.com/go-chi/chi/v5" "golang.org/x/time/rate" ) type Priority struct { Urgency int Incremental bool } func ParseRFC9218Priority(header string) Priority { p := Priority{Urgency: 3, Incremental: false} // RFC 9218 default: u=3, i=false if header == "" { return p } parts := strings.Split(header, ",") for _, part := range parts { part = strings.TrimSpace(part) if strings.HasPrefix(part, "u=") { if u, err := strconv.Atoi(strings.TrimPrefix(part, "u=")); err == nil && u >= 0 && u <= 7 { p.Urgency = u } } else if part == "i" || part == "i=?1" { p.Incremental = true } else if part == "i=?0" { p.Incremental = false } } return p } func StreamBudgetMiddleware(resetLimiter *rate.Limiter) func(http.Handler) http.Handler { return func(next http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { ctx := r.Context() priority := ParseRFC9218Priority(r.Header.Get("Priority")) ctx = context.WithValue(ctx, "rfc9218_priority", priority) // Mitigate Rapid Reset: verify reset quota before continuing if !resetLimiter.Allow() { http.Error(w, "Rate limit exceeded on stream churn", http.StatusTooManyRequests) return } next.ServeHTTP(w, r.WithContext(ctx)) }) } } func MountHardenedRoutes(r chi.Router, resetLimiter *rate.Limiter) { r.Use(StreamBudgetMiddleware(resetLimiter)) r.Post("/stream/export", func(w http.ResponseWriter, r *http.Request) { ctx := r.Context() rc := http.NewResponseController(w) w.Header().Set("Content-Type", "application/octet-stream") w.Header().Set("Priority", "u=1,i") // Echo calibrated RFC 9218 downstream priority chunk := make([]byte, 32*1024) // 32KB frame budget for i := 0; i < 2048; i++ { select { case <-ctx.Done(): // Cooperative cancellation prevents Rapid Reset resource drain return default: _ = rc.SetWriteDeadline(time.Now().Add(500 * time.Millisecond)) if _, err := w.Write(chunk); err != nil { if errors.Is(err, context.Canceled) { return } return } _ = rc.Flush() } } }) } ```

Architectural Specification & Invariant Rationale

Architectural Invariant Design: Deterministic RFC 9218 Extensible Prioritization and Rapid-Reset Mitigation in Go Chi HTTP/3

Deterministic RFC 9218 Extensible Prioritization and Rapid-Reset Mitigation in Go Chi HTTP/3 defines an industrial-grade behavioral standard for backend engineering. Enforces strict RFC 9218 Extensible Prioritization handling and stream frame budgeting in Go Chi HTTP/3 services. Mitigates HTTP/3 stream starvation and Rapid Reset (CVE-2023-44487 analogue) vectors by bounding stream concurrency, throttling stream cancellations, and parsing urgency/incremental parameters for deterministic resource allocation. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Unbounded Goroutine Spawning and Unthrottled HTTP/3 Stream Resets Leading to Resource Starvation Without an explicit system instruction file, developers spend hours debugging silent failures.

Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure Mode	AI Symptom (The Anti-Pattern)	Severity	Production Impact & Remedy
AI Hallucination & Deprecation Drift	Unbounded Goroutine Spawning and Unthrottled HTTP/3 Stream Resets Leading to Resource Starvation	Critical	Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production. Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture Inconsistency	AI assistants produce mixed paradigms across files, creating fragmented codebase conventions.	Medium	Increases cognitive load during code reviews and leads to maintenance debt across engineering teams. Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.

Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

Engineers MUST ALWAYS parse and validate the RFC 9218 'Priority' header (urgency u=0..7, incremental i=?0|?1) in Chi middleware to govern stream scheduling.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.