{ "policy": { "version": 5, "patterns": { "version": 1, "method": "CURATED_PRACTICE_TOPIC", "notice": "Pattern topics identify design choices to practice. Read the ticket's acceptance criteria and justify the simplest suitable approach. Tags are not capability or ownership evidence; an untagged ticket has no curated pattern topic assigned." }, "fieldMix": { "version": 1, "method": "CURATED_ESTIMATE", "notice": "Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence." }, "contentStatus": "PRACTICE_BRIEF", "assessmentStatus": "NOT_QUALIFIED", "evidenceUse": "NONE", "aiPolicy": "AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior.", "notice": "Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included.", "outcomeEvidence": "Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.", "ownershipEvidence": "Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence." }, "patternTopics": [ { "id": "factory-method", "label": "Factory Method", "group": "Creational" }, { "id": "abstract-factory", "label": "Abstract Factory", "group": "Creational" }, { "id": "builder", "label": "Builder", "group": "Creational" }, { "id": "prototype", "label": "Prototype", "group": "Creational" }, { "id": "singleton", "label": "Singleton", "group": "Creational" }, { "id": "adapter", "label": "Adapter", "group": "Structural" }, { "id": "bridge", "label": "Bridge", "group": "Structural" }, { "id": "composite", "label": "Composite", "group": "Structural" }, { "id": "decorator", "label": "Decorator", "group": "Structural" }, { "id": "facade", "label": "Facade", "group": "Structural" }, { "id": "flyweight", "label": "Flyweight", "group": "Structural" }, { "id": "proxy", "label": "Proxy", "group": "Structural" }, { "id": "chain-of-responsibility", "label": "Chain of Responsibility", "group": "Behavioral" }, { "id": "command", "label": "Command", "group": "Behavioral" }, { "id": "interpreter", "label": "Interpreter", "group": "Behavioral" }, { "id": "iterator", "label": "Iterator", "group": "Behavioral" }, { "id": "mediator", "label": "Mediator", "group": "Behavioral" }, { "id": "memento", "label": "Memento", "group": "Behavioral" }, { "id": "observer", "label": "Observer", "group": "Behavioral" }, { "id": "state", "label": "State", "group": "Behavioral" }, { "id": "strategy", "label": "Strategy", "group": "Behavioral" }, { "id": "template-method", "label": "Template Method", "group": "Behavioral" }, { "id": "visitor", "label": "Visitor", "group": "Behavioral" }, { "id": "ports-and-adapters", "label": "Ports and Adapters", "group": "Architectural" }, { "id": "cqrs", "label": "CQRS", "group": "Architectural" }, { "id": "strangler-fig", "label": "Strangler Fig", "group": "Architectural" }, { "id": "saga", "label": "Saga", "group": "Distributed and reliability" }, { "id": "transactional-outbox", "label": "Transactional Outbox", "group": "Distributed and reliability" }, { "id": "circuit-breaker", "label": "Circuit Breaker", "group": "Distributed and reliability" }, { "id": "bulkhead", "label": "Bulkhead", "group": "Distributed and reliability" } ], "projects": [ { "id": "4eedb0cf-a8b2-46b9-ba4d-b3b11d9c61f1", "key": "BLOADSHED", "title": "Overload admission and graceful degradation", "field": "Site reliability", "summary": "Protect essential reads when optional workloads saturate a service.", "context": "A fictional ticketing service becomes unresponsive during event releases because optional recommendation calls consume the same resources as reservation checks.", "stack": [ "TypeScript", "HTTP", "Redis" ], "prerequisites": [ "Build a bounded local service and synthetic open-loop workload generator with controllable dependency delays." ], "developerValue": "Practice overload behavior, admission control, and fair performance experiments.", "companyValue": "Create predictable failure and degradation behavior under declared capacity constraints.", "delivery": "Deliver local controls and measurements; no live load generation.", "phases": [ { "id": "baseline", "title": "Characterize overload", "goal": "Define essential outcomes and bounded workload assumptions." }, { "id": "protect", "title": "Protect service capacity", "goal": "Limit queues and isolate optional work." }, { "id": "validate", "title": "Validate recovery", "goal": "Compare policies and verify return to normal operation." } ], "tickets": [ { "id": "700db22b-abb4-48dc-872e-e99f913bdcaa", "key": "BLOADSHED-101", "title": "Classify essential and optional ticketing requests", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 60, "phaseId": "baseline", "dependsOn": [], "scenario": "Recommendation requests compete with reservation checks without any priority policy.", "acceptanceCriteria": [ "List request classes and user impact.", "Define allowed degradation per class.", "Keep reservation correctness invariant." ], "implementationNotes": [ "Do not prioritize users by inferred personal traits." ], "verification": [ "Classify a reservation and recommendation request.", "Identify a request that must fail explicitly rather than degrade silently." ], "deliverables": [ "Request-class policy." ], "rollout": "Review classification before applying limits.", "skills": [ "Reliability design" ], "fieldMix": [ { "field": "Site reliability", "percentage": 60 }, { "field": "System design", "percentage": 40 } ], "patterns": [] }, { "id": "096593a7-fc9b-4341-8216-f31544e26f7e", "key": "BLOADSHED-102", "title": "Build a workload that preserves offered arrival rate", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "baseline", "dependsOn": [ "BLOADSHED-101" ], "scenario": "A closed-loop load script hides overload by sending fewer requests as responses slow.", "acceptanceCriteria": [ "Record offered, admitted, completed, and rejected rates.", "Use bounded open-loop scheduling.", "Report dropped generator work and resource limits." ], "implementationNotes": [ "Run only against the local fixture." ], "verification": [ "Generate the declared steady arrival rate.", "Overload the generator and report its invalid measurement window." ], "deliverables": [ "Load harness." ], "rollout": "Cap duration and concurrency; discard runs with unreported generator saturation.", "skills": [ "Load testing" ], "fieldMix": [ { "field": "Performance engineering", "percentage": 70 }, { "field": "Quality engineering", "percentage": 30 } ], "patterns": [] }, { "id": "e6ccbf58-4c81-4766-8c2d-1e9ecb5403b4", "key": "BLOADSHED-103", "title": "Bound the waiting queue before worker slots are exhausted", "type": "TASK", "priority": "HIGH", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "protect", "dependsOn": [ "BLOADSHED-102" ], "scenario": "Requests accumulate indefinitely while waiting for a shared dependency.", "acceptanceCriteria": [ "Enforce a finite waiting capacity.", "Return a documented overload response when full.", "Remove cancelled requests from the queue." ], "implementationNotes": [ "Never report rejected requests as successful degradation." ], "verification": [ "Admit work below the limit.", "Overflow and cancel queued requests without leaked slots." ], "deliverables": [ "Bounded admission queue." ], "rollout": "Start with conservative limits; restore the previous policy if essential outcomes regress.", "skills": [ "Backpressure" ], "fieldMix": [ { "field": "Site reliability", "percentage": 40 }, { "field": "Platform engineering", "percentage": 40 }, { "field": "Performance engineering", "percentage": 20 } ], "patterns": [] }, { "id": "47461420-3a09-4f0a-9499-677fe40ba9f8", "key": "BLOADSHED-104", "title": "Isolate optional recommendation concurrency", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "protect", "dependsOn": [ "BLOADSHED-101", "BLOADSHED-103" ], "scenario": "Slow recommendations consume every outbound connection.", "acceptanceCriteria": [ "Use a separate optional-work concurrency budget.", "Reserve declared capacity for essential requests.", "Skip optional work when its budget is unavailable." ], "implementationNotes": [ "Use a real bounded pool, not an unbounded background task list." ], "verification": [ "Serve reservations while recommendations stall.", "Exhaust optional slots and verify graceful omission." ], "deliverables": [ "Optional-work bulkhead." ], "rollout": "Enable the bulkhead before increasing overall concurrency.", "skills": [ "Bulkheads", "Concurrency" ], "fieldMix": [ { "field": "Site reliability", "percentage": 40 }, { "field": "Performance engineering", "percentage": 30 }, { "field": "Networking", "percentage": 30 } ], "patterns": [ { "pattern": "bulkhead", "activity": "APPLY", "focus": "Bound optional recommendation concurrency separately from essential requests and show that exhausted optional capacity cannot consume the essential reserve." } ] }, { "id": "eb421617-924e-4f34-9ef4-43ab5abd9b87", "key": "BLOADSHED-105", "title": "Propagate request deadlines to downstream work", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "protect", "dependsOn": [ "BLOADSHED-103", "BLOADSHED-104" ], "scenario": "The client has timed out while its dependency request continues holding a slot.", "acceptanceCriteria": [ "Derive child deadlines from remaining request time.", "Abort owned work on cancellation.", "Release capacity even when a double ignores cancellation." ], "implementationNotes": [ "Bound cleanup time and track late completions safely." ], "verification": [ "Complete within a shared deadline.", "Timeout an uncooperative dependency and reclaim the slot." ], "deliverables": [ "Deadline propagation." ], "rollout": "Default to shorter optional deadlines; retain explicit timeout responses.", "skills": [ "Cancellation", "Resource lifecycle" ], "fieldMix": [ { "field": "Backend", "percentage": 40 }, { "field": "Site reliability", "percentage": 30 }, { "field": "Networking", "percentage": 30 } ], "patterns": [] }, { "id": "852edd48-4bd6-45b1-b9da-9b979bcdf246", "key": "BLOADSHED-106", "title": "Provide retry guidance that does not synchronize every client", "type": "TASK", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "protect", "dependsOn": [ "BLOADSHED-103" ], "scenario": "All rejected clients retry exactly one second later and recreate the spike.", "acceptanceCriteria": [ "Return bounded retry guidance.", "Document jitter and attempt ceilings for clients.", "Avoid automatic retry of unsafe writes." ], "implementationNotes": [ "Use deterministic random input in tests." ], "verification": [ "Spread synthetic client retries across the window.", "Verify non-idempotent requests are not blindly retried." ], "deliverables": [ "Overload response contract." ], "rollout": "Publish guidance with admission changes; monitor repeated rejection bursts.", "skills": [ "Retry design" ], "fieldMix": [ { "field": "API design", "percentage": 50 }, { "field": "Site reliability", "percentage": 50 } ], "patterns": [] }, { "id": "be97e858-aed6-4d05-b610-799daaa0cdeb", "key": "BLOADSHED-107", "title": "Preserve fair access across tenant request queues", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 210, "phaseId": "protect", "dependsOn": [ "BLOADSHED-103", "BLOADSHED-104" ], "scenario": "One large tenant fills every waiting slot and blocks smaller tenants.", "acceptanceCriteria": [ "Bound per-tenant queued work.", "Define a transparent scheduling policy.", "Prevent idle tenant allocation from wasting all spare capacity." ], "implementationNotes": [ "Use synthetic tenant classes and document fairness assumptions." ], "verification": [ "Serve concurrent tenants under sustained load.", "Flood one tenant and verify others retain declared progress." ], "deliverables": [ "Tenant scheduling policy." ], "rollout": "Trial with fixed limits; disable new policy if starvation appears.", "skills": [ "Fair scheduling" ], "fieldMix": [ { "field": "Performance engineering", "percentage": 40 }, { "field": "Platform engineering", "percentage": 40 }, { "field": "Site reliability", "percentage": 20 } ], "patterns": [] }, { "id": "76ed83f9-7374-42b7-a7af-3a20f2d974af", "key": "BLOADSHED-108", "title": "Compare rejection policies under the same offered workload", "type": "TASK", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 300, "phaseId": "validate", "dependsOn": [ "BLOADSHED-102", "BLOADSHED-105", "BLOADSHED-106", "BLOADSHED-107" ], "scenario": "The team must choose between a larger queue and earlier rejection.", "acceptanceCriteria": [ "Compare identical arrival traces and resource budgets.", "Measure essential latency, rejection, completion, and recovery separately.", "Explain tradeoffs and remaining uncertainty." ], "implementationNotes": [ "Do not compare only successful-response latency or hide rejected work." ], "verification": [ "Run both policies on the same synthetic burst.", "Expose a policy that improves accepted latency by rejecting more work." ], "deliverables": [ "Admission policy assessment." ], "rollout": "Choose a bounded default and retain a tested configuration rollback.", "skills": [ "Performance analysis", "Reliability tradeoffs" ], "fieldMix": [ { "field": "Performance engineering", "percentage": 60 }, { "field": "Site reliability", "percentage": 40 } ], "patterns": [] }, { "id": "c4a36bc6-fc26-422a-9956-d47831944dd9", "key": "BLOADSHED-109", "title": "Prevent capacity oscillation when the burst ends", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "validate", "dependsOn": [ "BLOADSHED-108" ], "scenario": "Degradation switches on and off rapidly near the threshold.", "acceptanceCriteria": [ "Add declared hysteresis or cooldown semantics.", "Return to normal after sustained recovery.", "Keep manual emergency controls auditable." ], "implementationNotes": [ "Avoid permanent degradation after transient overload." ], "verification": [ "Recover after a controlled burst.", "Oscillate near thresholds and verify bounded mode changes." ], "deliverables": [ "Recovery controller tests." ], "rollout": "Run in observation mode first; allow a safe fixed-policy fallback.", "skills": [ "Control systems" ], "fieldMix": [ { "field": "Site reliability", "percentage": 60 }, { "field": "Platform engineering", "percentage": 40 } ], "patterns": [] }, { "id": "1000c007-b937-4b0b-8386-552d023d17d5", "key": "BLOADSHED-110", "title": "Document the customer-visible degraded service contract", "type": "CHORE", "priority": "LOW", "difficulty": "FOUNDATIONAL", "estimateMinutes": 60, "phaseId": "validate", "dependsOn": [ "BLOADSHED-109" ], "scenario": "Product support cannot explain which features disappear during overload.", "acceptanceCriteria": [ "List omitted features and explicit failures.", "Describe recovery indicators without promising exact times.", "Include support diagnosis from safe metrics." ], "implementationNotes": [ "No false success when essential work was rejected." ], "verification": [ "Review a degraded response against the guide.", "Verify a failed reservation is never described as completed." ], "deliverables": [ "Degradation guide." ], "rollout": "Ship alongside controls and update it when request classes change.", "skills": [ "Technical writing" ], "fieldMix": [ { "field": "Site reliability", "percentage": 70 }, { "field": "API design", "percentage": 30 } ], "patterns": [] } ] } ] }