Go Chi Context-Bounded Goroutine Tree Termination Invariant

Q: How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Spawning Uncoordinated Goroutines Consuming Chi r.Context() with Unbuffered Channel Writes and Dangling Leaks) 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.

Go Chi Context-Bounded Goroutine Tree Termination Invariant

--- description: Go Chi Context-Bounded Goroutine Tree Termination Invariant - Enforces strict cancellation propagation and deterministic drain guarantees for all worker goroutine trees spawned within Go Chi HTTP handlers. Ensures goroutine hierarchies honor r.Context().Done(), decouple unbuffered channels to eliminate deadlocks, and use sync.WaitGroup or errgroup.Group to guarantee complete sub-task draining prior to handler return when clients abruptly disconnect. globs: **/*.go alwaysApply: true verified_by: "agentrules.org" license: "CC-BY-4.0" source: "https://agentrules.org/rules/go-chi-context-bounded-goroutine-tree-termination" --- # Go Chi Context-Bounded Goroutine Tree Termination Invariant > **Severity**: CRITICAL | **Category**: backend > **Anti-Pattern Warning**: Spawning Uncoordinated Goroutines Consuming Chi r.Context() with Unbuffered Channel Writes and Dangling Leaks ## System Constraints You are a Principal Go Systems Architect enforcing strict concurrency invariants in Go Chi HTTP services. You mandate that any goroutine spawned directly or transitively from an HTTP handler must be bound to r.Context(), propagate cancellation deterministically, guarantee drain completeness via errgroup or sync.WaitGroup, and prevent goroutine deadlocks caused by unbuffered channel writes during client disconnections. ## Strict Guidelines - Engineers MUST ALWAYS bind child goroutine lifecycles to r.Context() using x/sync/errgroup.WithContext or explicit sync.WaitGroup drain barriers. - Engineers MUST NEVER write to unbuffered channels from worker goroutines without a select branch monitoring ctx.Done() or providing an adequate channel buffer capacity matching worker concurrency. - Code MUST ensure that the HTTP handler does NOT return before all spawned worker goroutines have completely terminated or transitioned to a detached, independently managed background context. - Services MUST implement explicit timeouts via context.WithTimeout derived from r.Context() to prevent slow-loris or hanging upstream dependencies from pinning goroutine trees. - Components NEVER pass r.Context() directly to asynchronous detached tasks (e.g., background fire-and-forget logging or asynchronous DB flushes); such operations MUST explicitly derive from context.WithoutCancel(r.Context()) or context.Background() with an isolated, bounded timeout. ## Bad vs Good Implementations ### Preventing Goroutine Leaks on Client Disconnection in Chi Handlers #### Bad Antipattern (AI Common Hallucination) > **Why it fails**: When a client disconnects, r.Context() is cancelled, causing the handler select block to return immediately. The worker goroutine, however, blocks indefinitely on the unbuffered channel write `resultChan <- res` because there is no remaining receiver, leaking memory and goroutine stack frames permanently. ```go package main import ( "encoding/json" "net/http" "github.com/go-chi/chi/v5" ) func HandleSearch(w http.ResponseWriter, r *http.Request) { // ANTI-PATTERN: Unbuffered channel and uncoordinated goroutine. // If client closes connection prematurely, the handler returns or aborts, // but worker goroutines block forever writing to resultChan. resultChan := make(chan string) go func() { res := performExpensiveIO(r.Context()) resultChan <- res // Deadlocks if reader departs on client disconnect }() select { case <-r.Context().Done(): http.Error(w, r.Context().Err().Error(), http.StatusGatewayTimeout) return case res := <-resultChan: json.NewEncoder(w).Encode(map[string]string{"result": res}) } } func performExpensiveIO(ctx interface{}) string { return "ok" } ``` #### Production Standard (Correct) > **Standard**: Uses x/sync/errgroup bound to a derived context with a timeout. The deterministic barrier `g.Wait()` ensures all worker goroutines are drained prior to handler exit. If the client disconnects, `gctx.Done()` cancels downstream work, preventing blocked channel writes and memory leaks. ```go package main import ( "context" "encoding/json" "net/http" "time" "golang.org/x/sync/errgroup" ) func HandleSearch(w http.ResponseWriter, r *http.Request) { // CORRECT: Deriving bounded context and tracking lifecycle with errgroup. ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second) defer cancel() g, gctx := errgroup.WithContext(ctx) var res string g.Go(func() error { var err error res, err = performExpensiveSafeIO(gctx) return err }) // Deterministic drain barrier: handler cannot return until goroutines terminate if err := g.Wait(); err != nil { if ctx.Err() == context.Canceled { // Client disconnected; avoid writing to closed socket return } http.Error(w, err.Error(), http.StatusInternalServerError) return } w.Header().Set("Content-Type", "application/json") _ = json.NewEncoder(w).Encode(map[string]string{"result": res}) } func performExpensiveSafeIO(ctx context.Context) (string, error) { select { case <-ctx.Done(): return "", ctx.Err() case <-time.After(100 * time.Millisecond): return "ok", nil } } ```

Architectural Specification & Invariant Rationale

Architectural Invariant Design: Go Chi Context-Bounded Goroutine Tree Termination Invariant

Go Chi Context-Bounded Goroutine Tree Termination Invariant defines an industrial-grade behavioral standard for backend engineering. Enforces strict cancellation propagation and deterministic drain guarantees for all worker goroutine trees spawned within Go Chi HTTP handlers. Ensures goroutine hierarchies honor r.Context().Done(), decouple unbuffered channels to eliminate deadlocks, and use sync.WaitGroup or errgroup.Group to guarantee complete sub-task draining prior to handler return when clients abruptly disconnect. 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: Spawning Uncoordinated Goroutines Consuming Chi r.Context() with Unbuffered Channel Writes and Dangling Leaks 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	Spawning Uncoordinated Goroutines Consuming Chi r.Context() with Unbuffered Channel Writes and Dangling Leaks	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 bind child goroutine lifecycles to r.Context() using x/sync/errgroup.WithContext or explicit sync.WaitGroup drain barriers.

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.