{ "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": "dedbc308-dfea-443f-bdbd-4490bed97c3f", "key": "ASAGA", "title": "Coordinate equipment returns with explicit compensations", "field": "Distributed systems", "summary": "Recover a multi-step return workflow across inspection, shipping and refund providers.", "context": "A fictional equipment-rental service approves returns through several provider calls. Partial failures leave labels issued without inspections or refunds reported before provider confirmation.", "stack": [ "TypeScript", "PostgreSQL", "Provider interfaces" ], "prerequisites": [ "Create synthetic return records and fake inspection, shipping and refund adapters.", "Use integer money values and no real payments or messages." ], "developerValue": "Practice durable workflow state, compensation and uncertain outcomes.", "companyValue": "Review recoverable business operations without assuming distributed transactions.", "delivery": "Ten scoped tickets across three phases. Build a synthetic local service or select a ticket after recreating its prerequisites; estimates exclude setup.", "phases": [ { "id": "steps", "title": "Define workflow facts", "goal": "Separate requested actions from observed outcomes." }, { "id": "orchestrate", "title": "Persist multi-step progress", "goal": "Make effects idempotent and compensation explicit." }, { "id": "recover", "title": "Reconcile uncertain work", "goal": "Exercise crashes and publish accurate operational status." } ], "tickets": [ { "id": "64eaa48b-00e3-4ffd-9ed5-c9d991c7563a", "key": "ASAGA-101", "title": "Model return workflow steps as durable facts with explicit pending states", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "steps", "dependsOn": [], "scenario": "The return row has one status called processing, hiding whether inspection, label issuance or refund is outstanding.", "acceptanceCriteria": [ "Represent each step's request and observed outcome separately.", "Define legal workflow transitions and terminal conditions.", "Keep unknown provider outcomes distinct from failure." ], "implementationNotes": [ "Use synthetic provider receipts only." ], "verification": [ "Trace a successful return through all declared facts.", "Timeout shipping after acceptance and retain an unknown label outcome." ], "deliverables": [ "Return state model" ], "rollout": "Review the state table before adding adapters; preserve ambiguous existing cases as unresolved.", "skills": [ "Workflow modeling", "Uncertainty" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 60 }, { "field": "Backend", "percentage": 40 } ], "patterns": [] }, { "id": "ca4c504a-2d42-4679-b1db-ebfb315a05be", "key": "ASAGA-102", "title": "Define stable provider command keys for each return step", "type": "TASK", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "steps", "dependsOn": [ "ASAGA-101" ], "scenario": "A retry after a lost response creates a second shipping label because each request receives a new key.", "acceptanceCriteria": [ "Bind keys to return identity, step and generation.", "Reuse keys for equivalent retries.", "Reject changed canonical input under an existing key." ], "implementationNotes": [ "Do not reuse one key across unrelated provider actions." ], "verification": [ "Repeat a label request and resolve one fake provider result.", "Change shipping destination under the same key and return conflict." ], "deliverables": [ "Step identity contract and provider-key tests" ], "rollout": "Use stable keys before enabling retries; reconcile legacy ambiguous effects separately.", "skills": [ "Idempotency", "Provider contracts" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 60 }, { "field": "Integrations", "percentage": 40 } ], "patterns": [] }, { "id": "a4ec0118-e6d8-4ce5-b111-ae349ac45068", "key": "ASAGA-103", "title": "Write the compensation table for return side effects", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 120, "phaseId": "steps", "dependsOn": [ "ASAGA-101", "ASAGA-102" ], "scenario": "The team calls every reverse action rollback, although an issued label can be voided and a completed inspection cannot be undone.", "acceptanceCriteria": [ "Classify compensatable, irreversible and unresolved effects.", "State preconditions and outcomes for each compensation.", "Separate corrective actions from deletion of historical facts." ], "implementationNotes": [ "Use fake providers and document their exact capabilities." ], "verification": [ "Map a voidable unused label to its compensation.", "Map completed inspection to retained history rather than pretending it can be erased." ], "deliverables": [ "Compensation decision table" ], "rollout": "Review provider capabilities before orchestrator work; block unsupported automatic reversals.", "skills": [ "Compensation design", "Tradeoff analysis" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 60 }, { "field": "System design", "percentage": 40 } ], "patterns": [] }, { "id": "0dbad981-19df-4620-b9d4-a67ede59b486", "key": "ASAGA-104", "title": "Persist return progress and next-step dispatch atomically", "type": "STORY", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "orchestrate", "dependsOn": [ "ASAGA-101", "ASAGA-102", "ASAGA-103" ], "scenario": "Inspection completion commits but the shipping step is never scheduled after a process crash.", "acceptanceCriteria": [ "Commit the observed step fact and outbox dispatch together.", "Derive next-step identity from the durable workflow generation.", "Make repeated step completion a no-op or explicit conflict." ], "implementationNotes": [ "Keep remote provider calls outside database transactions." ], "verification": [ "Crash after inspection fact commit and recover label dispatch.", "Repeat the same completion and create no duplicate next step." ], "deliverables": [ "Workflow/outbox transaction and crash probe" ], "rollout": "Canary synthetic returns; pause advancement if durable dispatch cannot be recorded.", "skills": [ "Transactional outbox", "Workflow durability" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 50 }, { "field": "Database engineering", "percentage": 30 }, { "field": "Backend", "percentage": 20 } ], "patterns": [] }, { "id": "8350b00a-257c-4d14-afea-bdcd318c916e", "key": "ASAGA-105", "title": "Reconcile shipping acceptance before issuing a replacement label", "type": "TASK", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 300, "phaseId": "orchestrate", "dependsOn": [ "ASAGA-102", "ASAGA-104" ], "scenario": "The shipping adapter loses its response after accepting a label, and the workflow currently creates a replacement immediately.", "acceptanceCriteria": [ "Query the original provider command identity before replacement.", "Record accepted, rejected and unresolved outcomes explicitly.", "Create a new generation only under a declared replacement rule." ], "implementationNotes": [ "The fake adapter must model accepted-but-unacknowledged requests." ], "verification": [ "Recover the original accepted label after a response loss.", "Make status unavailable and retain unresolved shipping without a second label." ], "deliverables": [ "Shipping reconciliation and uncertainty probe" ], "rollout": "Enable reconciled retries first; stop automatic replacement when provider identity lookup is unavailable.", "skills": [ "Distributed failure", "Reconciliation" ], "fieldMix": [ { "field": "Integrations", "percentage": 50 }, { "field": "Distributed systems", "percentage": 50 } ], "patterns": [] }, { "id": "c238aa03-6598-46a7-b5fb-371056db39b5", "key": "ASAGA-106", "title": "Run label compensation only when its original effect is confirmed", "type": "TASK", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 210, "phaseId": "orchestrate", "dependsOn": [ "ASAGA-103", "ASAGA-104", "ASAGA-105" ], "scenario": "A cancellation request races label issuance and attempts to void a label that may not exist yet.", "acceptanceCriteria": [ "Persist cancellation intent independently of provider completion.", "Compensate only the confirmed current label generation.", "Keep failed or unknown compensation visible for retry." ], "implementationNotes": [ "Never mark a return fully cancelled solely because a compensation request was sent." ], "verification": [ "Cancel after confirmed issuance and record confirmed voiding.", "Cancel during unknown issuance and wait for reconciliation before compensation." ], "deliverables": [ "Cancellation/compensation state transitions" ], "rollout": "Canary cancellation on fake providers; retain unresolved operations for bounded reconciliation.", "skills": [ "Compensation", "Concurrency" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 60 }, { "field": "Integrations", "percentage": 40 } ], "patterns": [ { "pattern": "saga", "activity": "APPLY", "focus": "Compensate only the confirmed label generation when cancellation races issuance; preserve uncertainty instead of treating a lost response as a failed effect." } ] }, { "id": "edf84f78-38ee-4418-b96c-25efa79fc8e6", "key": "ASAGA-107", "title": "Authorize refund progression from verified return facts", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "orchestrate", "dependsOn": [ "ASAGA-101", "ASAGA-104", "ASAGA-106" ], "scenario": "An administrator can set the aggregate status to inspected and trigger a refund without an actual inspection result.", "acceptanceCriteria": [ "Require a verified inspection fact and matching return generation.", "Guard refund requests at the service boundary.", "Reject direct status edits that bypass prerequisites." ], "implementationNotes": [ "This exercise uses synthetic money and a fake refund provider." ], "verification": [ "Advance a return with a valid inspection receipt.", "Attempt refund with a forged status change and verify no provider call." ], "deliverables": [ "Refund precondition guard and bypass regression" ], "rollout": "Deploy guarded transitions before exposing administrative actions; stop refund dispatch on missing provenance.", "skills": [ "State authority", "Authorization" ], "fieldMix": [ { "field": "Security", "percentage": 50 }, { "field": "Distributed systems", "percentage": 30 }, { "field": "Backend", "percentage": 20 } ], "patterns": [] }, { "id": "4f50c7d6-085e-4ac6-b217-59d0aa1853f5", "key": "ASAGA-108", "title": "Show return workflow progress without hiding unresolved compensation", "type": "STORY", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "recover", "dependsOn": [ "ASAGA-105", "ASAGA-106", "ASAGA-107" ], "scenario": "The support console shows cancelled even when the label-void request timed out and the customer might still use it.", "acceptanceCriteria": [ "Display business intent separately from confirmed provider outcomes.", "Highlight pending reconciliation and compensation states.", "Exclude provider credentials and raw customer payloads." ], "implementationNotes": [ "Use a dedicated support projection with tenant authorization." ], "verification": [ "Display a fully compensated synthetic return.", "Display unknown voiding as unresolved and deny another tenant's workflow." ], "deliverables": [ "Scoped support workflow projection" ], "rollout": "Enable read-only status first; keep uncertainty visible when adapters are unavailable.", "skills": [ "Operational UX", "Privacy" ], "fieldMix": [ { "field": "Frontend", "percentage": 40 }, { "field": "Distributed systems", "percentage": 30 }, { "field": "Privacy engineering", "percentage": 30 } ], "patterns": [] }, { "id": "7bf43cb5-51c1-4558-8d47-25f535b13fde", "key": "ASAGA-109", "title": "Replay a return workflow from its durable history after an orchestrator crash", "type": "TASK", "priority": "MEDIUM", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "recover", "dependsOn": [ "ASAGA-104", "ASAGA-105", "ASAGA-106", "ASAGA-107" ], "scenario": "A worker restarts halfway through a return and must decide which steps can resume without repeating side effects.", "acceptanceCriteria": [ "Reconstruct the current state from durable facts and generations.", "Reconcile outstanding provider commands before redispatch.", "Preserve completed facts and compensation history." ], "implementationNotes": [ "Inject crashes between every modeled commit and provider response boundary." ], "verification": [ "Replay a completed and a partially compensated synthetic return.", "Crash after refund acceptance and verify recovery does not issue a second refund." ], "deliverables": [ "Workflow recovery harness and interruption matrix" ], "rollout": "Run before enabling automatic recovery; pause ambiguous workflows while continuing unaffected ones.", "skills": [ "Recovery", "Fault injection" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 70 }, { "field": "Site reliability", "percentage": 30 } ], "patterns": [] }, { "id": "c89403c7-8a29-4458-9503-cbb8dce01170", "key": "ASAGA-110", "title": "Write the operator handoff for a return that cannot be fully compensated", "type": "CHORE", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "recover", "dependsOn": [ "ASAGA-103", "ASAGA-108", "ASAGA-109" ], "scenario": "A provider confirms an effect that cannot be reversed, and support needs to close the technical incident without fabricating a clean rollback.", "acceptanceCriteria": [ "List confirmed effects, attempted corrections and unresolved consequences.", "Define authorized manual decisions separately from automated transitions.", "Preserve original receipts and incident provenance." ], "implementationNotes": [ "Use a fabricated return and no actual financial advice or transfer." ], "verification": [ "Document a successful full compensation case.", "Document an irreversible fake-provider outcome without marking it rolled back." ], "deliverables": [ "Return exception runbook and worked incident" ], "rollout": "Review exceptions before manual action; append resolutions instead of rewriting workflow history.", "skills": [ "Operational recovery", "Auditability" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 60 }, { "field": "Site reliability", "percentage": 40 } ], "patterns": [] } ] } ] }