{ "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": "a5cfc10b-ed66-44e0-8a0d-923bc81a4353", "key": "CTIMER", "title": "A deterministic edge-job scheduler emulator", "field": "Embedded and edge", "summary": "Schedule noncritical local maintenance jobs across clock changes, cancellation and restart.", "context": "Fictional kiosk software schedules cache refresh and display housekeeping. Build a software clock and job adapter; do not control real machinery or purchase hardware.", "stack": [ "TypeScript", "Fake clock", "Vitest" ], "prerequisites": [ "Implement injected wall and monotonic clocks.", "Create synthetic jobs with controllable completion and failure." ], "developerValue": "Practice timer semantics, cancellation and bounded scheduling.", "companyValue": "Inspect predictable edge resource use and honest execution status.", "delivery": "Use deterministic clock advancement; emulator timing does not qualify physical realtime behavior.", "phases": [ { "id": "clock", "title": "Define time semantics", "goal": "Separate elapsed deadlines from calendar schedules." }, { "id": "jobs", "title": "Control job execution", "goal": "Prevent overlap and stale callbacks." }, { "id": "restart", "title": "Recover scheduler state", "goal": "Handle restart and overload deliberately." } ], "tickets": [ { "id": "90c9ed8c-7b45-4801-a2c6-3fcbd6795296", "key": "CTIMER-101", "title": "Use monotonic time for edge-job timeout deadlines", "type": "BUG", "priority": "HIGH", "difficulty": "FOUNDATIONAL", "estimateMinutes": 75, "phaseId": "clock", "dependsOn": [], "scenario": "Moving the emulator wall clock backward extends a running job forever. Measure elapsed timeout against monotonic time.", "acceptanceCriteria": [ "Wall-clock changes do not extend timeout", "Deadline fires once", "Elapsed duration cannot become negative" ], "implementationNotes": [ "Expose both clocks through interfaces." ], "verification": [ "Move wall clock during job", "Advance monotonic clock past deadline" ], "deliverables": [ "Deadline helper and clock cases" ], "rollout": "Disable timed jobs if monotonic source is unavailable.", "skills": [ "Time", "Abstraction" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 100 } ], "patterns": [] }, { "id": "47aaebf0-d1c9-4342-9010-2e2db756e741", "key": "CTIMER-102", "title": "Validate emulated edge-job intervals before scheduling", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 60, "phaseId": "clock", "dependsOn": [ "CTIMER-101" ], "scenario": "A zero interval creates an immediate callback loop. Enforce a documented supported interval range.", "acceptanceCriteria": [ "Valid intervals register", "Zero negative and oversized values fail", "Rejected jobs allocate no timer" ], "implementationNotes": [ "Do not silently clamp invalid configuration." ], "verification": [ "Register valid interval", "Reject zero and negative interval" ], "deliverables": [ "Interval validator and cases" ], "rollout": "Reject new registrations if limits cannot be enforced.", "skills": [ "Validation", "Scheduling" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 100 } ], "patterns": [] }, { "id": "f83fcb4b-c3b0-463f-a9c1-6d1c61dc039d", "key": "CTIMER-103", "title": "Specify fixed-delay behavior for periodic kiosk maintenance", "type": "TASK", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "clock", "dependsOn": [ "CTIMER-101", "CTIMER-102" ], "scenario": "Long cache refreshes cause catch-up bursts because scheduling alternates between fixed-rate and fixed-delay behavior. Choose fixed-delay for this job class.", "acceptanceCriteria": [ "Next run starts after completion plus delay", "Slow runs do not overlap", "Failure still follows documented next-run policy" ], "implementationNotes": [ "Limit the change to the declared maintenance class." ], "verification": [ "Complete short job", "Complete job longer than interval" ], "deliverables": [ "Periodic policy and fake-clock cases" ], "rollout": "Pause periodic jobs while schedule semantics are repaired.", "skills": [ "Scheduling", "Time" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 100 } ], "patterns": [] }, { "id": "8975de5b-931f-48ea-bccc-b0ea6458669d", "key": "CTIMER-104", "title": "Cancel emulated edge jobs without accepting late callbacks", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 165, "phaseId": "jobs", "dependsOn": [ "CTIMER-103" ], "scenario": "A cancelled timer callback runs after a replacement job is registered. Bind callbacks to registration generation.", "acceptanceCriteria": [ "Cancel invalidates current generation", "Late callback performs no work", "Replacement generation can run" ], "implementationNotes": [ "Clearing the runtime timer alone is insufficient." ], "verification": [ "Cancel before deadline", "Deliver old callback after replacement" ], "deliverables": [ "Generation guard and race cases" ], "rollout": "Recreate scheduler instance if generations become inconsistent.", "skills": [ "Cancellation", "Concurrency" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 100 } ], "patterns": [] }, { "id": "ff3bb741-8c0a-4f55-8b39-9f9c1094f134", "key": "CTIMER-105", "title": "Prevent overlapping edge jobs that share one local resource", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "jobs", "dependsOn": [ "CTIMER-103", "CTIMER-104" ], "scenario": "Cache refresh and cleanup run simultaneously and contend for the same fixture directory. Add scoped single-flight admission.", "acceptanceCriteria": [ "Same resource runs one job", "Different resources remain independent", "Failure releases admission" ], "implementationNotes": [ "Do not introduce an unbounded global waiting queue." ], "verification": [ "Run separate resources", "Fail holder while another waits" ], "deliverables": [ "Resource admission and cases" ], "rollout": "Serialize all fixture maintenance temporarily if scoped locking fails.", "skills": [ "Concurrency", "Resource management" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 70 }, { "field": "Performance engineering", "percentage": 30 } ], "patterns": [] }, { "id": "a5511f30-190c-4cc2-807a-5916d2d30109", "key": "CTIMER-106", "title": "Bound emulated edge-job execution attempts after failure", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "jobs", "dependsOn": [ "CTIMER-104", "CTIMER-105" ], "scenario": "A failed maintenance job retries forever and hides the original error. Add attempt limits and a terminal visible outcome.", "acceptanceCriteria": [ "Attempts have an explicit cap", "Success clears pending retry", "Exhaustion preserves failure category" ], "implementationNotes": [ "Retrying must reuse the same logical operation identity." ], "verification": [ "Recover before cap", "Fail through exhaustion" ], "deliverables": [ "Retry policy and deterministic cases" ], "rollout": "Disable automatic retry while retaining manual restart.", "skills": [ "Backoff", "Failure handling" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 70 }, { "field": "Site reliability", "percentage": 30 } ], "patterns": [] }, { "id": "8783003f-8413-4206-bf74-90424b3d5560", "key": "CTIMER-107", "title": "Recover due edge jobs after restart without a catch-up storm", "type": "BUG", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 240, "phaseId": "jobs", "dependsOn": [ "CTIMER-103", "CTIMER-106" ], "scenario": "Restarting after a long pause runs every missed interval at once. Persist minimal schedule state and coalesce missed runs.", "acceptanceCriteria": [ "At most declared catch-up work runs", "Future schedule resumes predictably", "Unknown persisted version fails safely" ], "implementationNotes": [ "Define which jobs may be skipped because they are housekeeping." ], "verification": [ "Restart after one missed run", "Restart after many missed intervals" ], "deliverables": [ "Recovery policy and restart fixtures" ], "rollout": "Start housekeeping from a fresh delayed schedule if state is unreadable.", "skills": [ "Persistence", "Scheduling" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 70 }, { "field": "Storage systems", "percentage": 30 } ], "patterns": [] }, { "id": "37ec8df2-0b3b-4e5c-8a53-fd01e0d32637", "key": "CTIMER-108", "title": "Keep edge-job priority from starving lower-priority maintenance", "type": "TASK", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "restart", "dependsOn": [ "CTIMER-105", "CTIMER-107" ], "scenario": "Frequent urgent cache checks prevent cleanup from ever running. Add bounded fairness to the ready queue.", "acceptanceCriteria": [ "High priority gets documented preference", "Low priority eventually runs under bounded arrivals", "Queue size remains capped" ], "implementationNotes": [ "State workload assumptions used for fairness checks." ], "verification": [ "Run mixed-priority fixture", "Continuously enqueue within supported arrival bound" ], "deliverables": [ "Fair queue and execution trace" ], "rollout": "Use simple round-robin while priority fairness is uncertain.", "skills": [ "Scheduling", "Fairness" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 60 }, { "field": "Performance engineering", "percentage": 40 } ], "patterns": [] }, { "id": "b8e604e0-6103-46d8-87dc-a08391b6f7a1", "key": "CTIMER-109", "title": "Report emulated edge-job lateness separately from duration", "type": "CHORE", "priority": "LOW", "difficulty": "INTERMEDIATE", "estimateMinutes": 105, "phaseId": "restart", "dependsOn": [ "CTIMER-101", "CTIMER-108" ], "scenario": "A slow-started job is blamed on execution time because metrics combine queue delay and work duration. Separate them.", "acceptanceCriteria": [ "Lateness measures due-to-start", "Duration measures start-to-finish", "Clock corrections do not corrupt elapsed metrics" ], "implementationNotes": [ "Report synthetic local observations, not hardware deadlines." ], "verification": [ "Queue then execute job", "Change wall clock during execution" ], "deliverables": [ "Scheduler metric schema and cases" ], "rollout": "Hide derived latency fields if clock provenance is missing.", "skills": [ "Observability", "Measurement" ], "fieldMix": [ { "field": "Embedded and edge", "percentage": 50 }, { "field": "Performance engineering", "percentage": 30 }, { "field": "Site reliability", "percentage": 20 } ], "patterns": [] }, { "id": "10c7a112-109b-4699-8525-01b7d10c7593", "key": "CTIMER-110", "title": "Provide a read-only edge scheduler timeline for recovery diagnosis", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "restart", "dependsOn": [ "CTIMER-107", "CTIMER-109" ], "scenario": "Engineers cannot explain why a job was skipped after restart. Export bounded state transitions without running jobs.", "acceptanceCriteria": [ "Timeline identifies schedule and attempt IDs", "Skipped reasons are explicit", "Inspection causes no callbacks or writes" ], "implementationNotes": [ "Omit payloads and fixture file contents." ], "verification": [ "Inspect completed sequence", "Inspect exhausted and skipped job" ], "deliverables": [ "Timeline inspector and side-effect checks" ], "rollout": "Disable inspection fields that expose task payloads.", "skills": [ "Diagnostics", "State machines" ], "fieldMix": [ { "field": "Developer tooling", "percentage": 50 }, { "field": "Embedded and edge", "percentage": 50 } ], "patterns": [] } ] } ] }