{ "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": "91f3550e-2cb8-44ae-ba8c-3f540083146b", "key": "ADRIFT", "title": "Make subscription entitlements survive plan changes", "field": "Backend", "summary": "Resolve effective entitlements across scheduled and immediate plan changes.", "context": "A fictional document service grants storage and collaboration rights from subscriptions. Support cannot explain why delayed events restore old limits.", "stack": [ "TypeScript", "NestJS", "PostgreSQL" ], "prerequisites": [ "Create a local subscription API with synthetic accounts.", "Understand transactions and UTC intervals." ], "developerValue": "Practice temporal rules, concurrency and explainable API decisions.", "companyValue": "Review whether entitlement changes preserve customer access and produce supportable decisions.", "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": "contract", "title": "Define effective rights", "goal": "Specify entitlement periods and failure responses." }, { "id": "change", "title": "Apply changes safely", "goal": "Preserve ordering and concurrent update invariants." }, { "id": "support", "title": "Explain and recover", "goal": "Expose effective decisions and recover delayed changes." } ], "tickets": [ { "id": "df462ec4-a772-482b-a7bc-d6532cbfdb87", "key": "ADRIFT-101", "title": "Specify the entitlement response at an exact effective instant", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "contract", "dependsOn": [], "scenario": "Support compares screenshots from two time zones and cannot tell which storage limit applied when an upload failed.", "acceptanceCriteria": [ "Return limit, effective UTC instant and plan revision.", "Document inclusive start and exclusive end boundaries.", "Reject an invalid timestamp without resolving rights." ], "implementationNotes": [ "Use synthetic plan names and integer byte limits." ], "verification": [ "Resolve immediately before and at a plan boundary.", "Reject a timestamp without an offset and verify no write." ], "deliverables": [ "Versioned response contract and boundary fixtures" ], "rollout": "Introduce the versioned read route; remove routing if consumers reject it.", "skills": [ "API contracts", "Temporal modeling" ], "fieldMix": [ { "field": "API design", "percentage": 60 }, { "field": "Backend", "percentage": 40 } ], "patterns": [] }, { "id": "53584c31-a0d8-4bcd-86a6-94f46d8c6089", "key": "ADRIFT-102", "title": "Keep manual account restrictions separate from plan allowances", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "contract", "dependsOn": [ "ADRIFT-101" ], "scenario": "A support restriction disappears when an account upgrades because both settings currently share one mutable limit.", "acceptanceCriteria": [ "Store restriction and plan allowance with separate provenance.", "Return the effective minimum with both reasons.", "Removing a restriction restores the current plan allowance." ], "implementationNotes": [ "Restrict mutation to an authorized support role." ], "verification": [ "Upgrade a restricted account and retain its lower limit.", "Attempt a restriction change as a normal member and deny it." ], "deliverables": [ "Restriction command and permission tests" ], "rollout": "Enable for synthetic accounts; disable mutation while retaining restriction history.", "skills": [ "Domain modeling", "Authorization" ], "fieldMix": [ { "field": "Backend", "percentage": 70 }, { "field": "Security", "percentage": 30 } ], "patterns": [] }, { "id": "189ad5cd-e676-4300-b9f1-dcf946e0da64", "key": "ADRIFT-103", "title": "Reject negative and fractional seat allowances consistently", "type": "BUG", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 60, "phaseId": "contract", "dependsOn": [ "ADRIFT-101" ], "scenario": "An administrative import accepts 2.5 seats, while the runtime truncates the value differently from the billing preview.", "acceptanceCriteria": [ "Accept only nonnegative safe integers for seat limits.", "Use one validation rule for import and API commands.", "Return the offending field without echoing the entire import." ], "implementationNotes": [ "Represent unlimited explicitly rather than with negative sentinels." ], "verification": [ "Create zero-seat and unlimited synthetic plans.", "Reject fractional, negative and unsafe integer limits." ], "deliverables": [ "Shared seat schema and import regression" ], "rollout": "Deploy validation before new imports; quarantine rejected rows for correction.", "skills": [ "Validation", "TypeScript" ], "fieldMix": [ { "field": "Backend", "percentage": 80 }, { "field": "API design", "percentage": 20 } ], "patterns": [] }, { "id": "8c452e1a-d494-44fe-8c0d-9db19ffb8daa", "key": "ADRIFT-104", "title": "Apply a scheduled downgrade only after its stored effective time", "type": "STORY", "priority": "HIGH", "difficulty": "INTERMEDIATE", "estimateMinutes": 180, "phaseId": "change", "dependsOn": [ "ADRIFT-101", "ADRIFT-103" ], "scenario": "A worker runs the next day's downgrade early when a retry executes against the server's local calendar date.", "acceptanceCriteria": [ "Compare a persisted UTC instant with an injected clock.", "Early delivery leaves the schedule pending.", "Repeated eligible delivery creates one entitlement revision." ], "implementationNotes": [ "Persist the revision and dispatch record in one transaction." ], "verification": [ "Advance a fake clock through the exact effective instant.", "Deliver early and twice after the boundary; count one revision." ], "deliverables": [ "Scheduled transition and deterministic-clock tests" ], "rollout": "Canary scheduled changes; pause the consumer and retain pending schedules on failure.", "skills": [ "State transitions", "Idempotency" ], "fieldMix": [ { "field": "Backend", "percentage": 80 }, { "field": "Distributed systems", "percentage": 20 } ], "patterns": [] }, { "id": "f961e265-1e5a-4d00-a9ef-257b52638c9c", "key": "ADRIFT-105", "title": "Prevent a late upgrade event from undoing a newer cancellation", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "change", "dependsOn": [ "ADRIFT-104" ], "scenario": "Provider events arrive out of order and an old upgrade reopens collaboration after cancellation became effective.", "acceptanceCriteria": [ "Compare provider sequence within each subscription.", "Older events remain recorded without changing effective rights.", "Equal sequence with different payload is surfaced as conflict." ], "implementationNotes": [ "Do not order provider events by receipt timestamp." ], "verification": [ "Replay cancellation followed by an older upgrade.", "Submit contradictory equal-sequence events and preserve current rights." ], "deliverables": [ "Ordering guard and conflicting-event report" ], "rollout": "Run the guard in audit mode first; quarantine conflicts without deleting events.", "skills": [ "Event ordering", "Conflict handling" ], "fieldMix": [ { "field": "Backend", "percentage": 60 }, { "field": "Distributed systems", "percentage": 40 } ], "patterns": [] }, { "id": "65e1fe79-ac52-4674-b60f-676c59c6fb32", "key": "ADRIFT-106", "title": "Make plan switching and seat allocation share one consistency boundary", "type": "TASK", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "change", "dependsOn": [ "ADRIFT-102", "ADRIFT-104" ], "scenario": "A downgrade races a seat invitation; both requests pass their reads and leave more active seats than permitted.", "acceptanceCriteria": [ "Serialize competing allowance and allocation changes per account.", "One conflicting request returns a retryable conflict.", "A failed transaction leaves both seat count and rights unchanged." ], "implementationNotes": [ "Document the invariant and chosen locking order." ], "verification": [ "Run a two-client barrier test for downgrade versus invitation.", "Force transaction rollback and check both tables retain prior values." ], "deliverables": [ "Transactional guard and concurrency reproduction" ], "rollout": "Introduce with lock-wait monitoring; revert command routing if contention exceeds the documented local budget.", "skills": [ "Transactions", "Concurrency" ], "fieldMix": [ { "field": "Database engineering", "percentage": 60 }, { "field": "Backend", "percentage": 40 } ], "patterns": [] }, { "id": "3a9a138e-0fbb-48d5-b55a-b283418c58cb", "key": "ADRIFT-107", "title": "Preview entitlement changes without creating pending work", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "change", "dependsOn": [ "ADRIFT-104", "ADRIFT-105" ], "scenario": "Sales wants to preview next month's downgrade, but the current preview endpoint creates a schedule visible to the worker.", "acceptanceCriteria": [ "Preview uses the same pure decision function as execution.", "Return affected features and effective-time assumptions.", "No schedule, outbox or audit mutation occurs on preview." ], "implementationNotes": [ "Authorize account reads before computing the preview." ], "verification": [ "Compare preview with a later applied synthetic change.", "Repeat preview and assert unchanged row counts; deny another account." ], "deliverables": [ "Pure preview operation and nonmutation checks" ], "rollout": "Expose preview behind a route flag; remove the route without touching schedules.", "skills": [ "Pure functions", "API design" ], "fieldMix": [ { "field": "Backend", "percentage": 70 }, { "field": "API design", "percentage": 30 } ], "patterns": [] }, { "id": "d1fcae8c-52cc-4e8d-bbd2-d8d789d846f5", "key": "ADRIFT-108", "title": "Explain a denied upload using the exact entitlement revision", "type": "STORY", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "support", "dependsOn": [ "ADRIFT-105", "ADRIFT-106" ], "scenario": "An upload rejection says only limit exceeded, so support cannot connect it to the plan and restriction that were evaluated.", "acceptanceCriteria": [ "Return a stable denial code and evaluated revision ID.", "Include byte limit and current usage without other accounts' data.", "Keep historical revisions immutable for later explanation." ], "implementationNotes": [ "Avoid storing document contents in decision logs." ], "verification": [ "Reproduce a denial and resolve the same historical decision after upgrade.", "Request another account's decision ID and return a nondisclosing denial." ], "deliverables": [ "Decision projection and scoped history route" ], "rollout": "Enable explanation reads first; disable projection if privacy checks fail.", "skills": [ "Provenance", "Tenant isolation" ], "fieldMix": [ { "field": "Backend", "percentage": 70 }, { "field": "API design", "percentage": 30 } ], "patterns": [] }, { "id": "a888e995-caa9-4c71-90fb-baf195e41534", "key": "ADRIFT-109", "title": "Rebuild an account entitlement projection from its ordered history", "type": "CHORE", "priority": "MEDIUM", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "support", "dependsOn": [ "ADRIFT-105", "ADRIFT-108" ], "scenario": "A projection bug affected a synthetic account; operators need to repair derived rights without rewriting the source change history.", "acceptanceCriteria": [ "Rebuild into a separate generation using deterministic ordering.", "Compare differences before atomically selecting the generation.", "Interrupted rebuild leaves the active projection usable." ], "implementationNotes": [ "Require an account scope and dry-run mode." ], "verification": [ "Compare a rebuilt generation with a clean reference history.", "Interrupt before activation and prove the old generation still resolves." ], "deliverables": [ "Scoped rebuild command and difference report" ], "rollout": "Dry-run one synthetic account; restore the previous generation pointer on mismatch.", "skills": [ "Recovery", "Projection design" ], "fieldMix": [ { "field": "Data engineering", "percentage": 50 }, { "field": "Backend", "percentage": 30 }, { "field": "Database engineering", "percentage": 20 } ], "patterns": [] }, { "id": "5cd2d519-47fa-42c3-80c5-d377c3c2fa82", "key": "ADRIFT-110", "title": "Document the handoff for disputed effective entitlements", "type": "TASK", "priority": "LOW", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "support", "dependsOn": [ "ADRIFT-108", "ADRIFT-109" ], "scenario": "Support needs a repeatable path to investigate a rights dispute without editing rows directly or promising the wrong allowance.", "acceptanceCriteria": [ "Runbook starts from account, decision and revision identifiers.", "Separate delayed-provider, restriction and usage causes.", "Include escalation and projection rollback steps." ], "implementationNotes": [ "Use fabricated examples and avoid raw customer identifiers." ], "verification": [ "Follow the runbook for a scheduled downgrade dispute.", "Follow the missing-history branch and confirm it stops before mutation." ], "deliverables": [ "Support runbook and two worked synthetic incidents" ], "rollout": "Review the runbook with a fresh local reproduction; version corrections alongside the projection.", "skills": [ "Runbooks", "Incident analysis" ], "fieldMix": [ { "field": "Backend", "percentage": 60 }, { "field": "Site reliability", "percentage": 40 } ], "patterns": [] } ] } ] }