{ "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": "95589e41-9d4d-454a-be77-5bb342933b1a", "key": "ADBT", "title": "Make a subscription analytics mart reproducible", "field": "Data engineering", "summary": "Model subscription movement with explicit grains, revisions and data contracts.", "context": "A fictional SaaS analyst reports expansion revenue differently from finance because snapshots, refunds and contract changes are joined at incompatible grains.", "stack": [ "SQL", "PostgreSQL", "dbt" ], "prerequisites": [ "Create a synthetic source schema and local transformation project.", "Use integer minor units and distinct reporting currencies." ], "developerValue": "Practice analytical modeling and explainable transformation contracts.", "companyValue": "Review trustworthy reporting definitions and the cost of correcting historical reports.", "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": "grain", "title": "Define reporting grain", "goal": "Specify source and metric contracts." }, { "id": "model", "title": "Transform consistently", "goal": "Handle temporal joins and incremental updates." }, { "id": "publish", "title": "Publish reliable outputs", "goal": "Validate releases and retain reproducible reports." } ], "tickets": [ { "id": "013961bd-b99a-4f3d-bfa2-33a6e7cdf4a7", "key": "ADBT-101", "title": "Declare the subscription-movement grain before joining invoice lines", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "grain", "dependsOn": [], "scenario": "A report doubles subscription movement when a contract has two invoice lines in the same month.", "acceptanceCriteria": [ "Document one row per subscription, period and currency.", "Identify source keys and permitted multiplicity.", "Reject duplicate grain keys in a contract check." ], "implementationNotes": [ "Create a small synthetic multi-line invoice example." ], "verification": [ "Reconcile a two-line invoice to one movement row.", "Insert duplicate source identity and fail the grain check." ], "deliverables": [ "Grain specification and executable uniqueness check" ], "rollout": "Review the grain contract before enabling downstream joins.", "skills": [ "Dimensional modeling", "SQL" ], "fieldMix": [ { "field": "Data engineering", "percentage": 70 }, { "field": "Database engineering", "percentage": 30 } ], "patterns": [] }, { "id": "2865613f-3f76-4cf8-8d87-0f39a76e326b", "key": "ADBT-102", "title": "Separate recurring contract value from collected cash", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "grain", "dependsOn": [ "ADBT-101" ], "scenario": "A late payment makes the recurring-revenue chart dip even though no subscription changed.", "acceptanceCriteria": [ "Define contract value and cash collection as separate measures.", "Document refund and unpaid-invoice treatment.", "Keep currency amounts separate without implicit conversion." ], "implementationNotes": [ "Use named business definitions in model metadata." ], "verification": [ "Delay a payment and keep contracted recurring value unchanged.", "Mix currencies and reject an unsupported combined total." ], "deliverables": [ "Metric definitions and contrasting examples" ], "rollout": "Publish separate metric names; retire ambiguous aliases after consumer review.", "skills": [ "Metric design", "Data semantics" ], "fieldMix": [ { "field": "Data engineering", "percentage": 100 } ], "patterns": [] }, { "id": "eba6f358-5964-4f77-aa0b-1cd401b174bf", "key": "ADBT-103", "title": "Reject source schema drift before materializing the mart", "type": "CHORE", "priority": "HIGH", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "grain", "dependsOn": [ "ADBT-101" ], "scenario": "A partner renamed subscription_id and the daily transformation published an empty table successfully.", "acceptanceCriteria": [ "Validate required columns and accepted types.", "Fail before replacing the active reporting relation.", "Report the missing contract field and source version." ], "implementationNotes": [ "Avoid relying on a row-count check alone." ], "verification": [ "Transform a valid empty source under its declared contract.", "Rename a required column and retain the previous active mart." ], "deliverables": [ "Source contract gate" ], "rollout": "Run the contract gate before scheduled builds; keep prior output on failure.", "skills": [ "Data contracts", "Schema evolution" ], "fieldMix": [ { "field": "Data engineering", "percentage": 70 }, { "field": "Quality engineering", "percentage": 30 } ], "patterns": [] }, { "id": "bdbaa9d0-ed51-494f-aca8-95b33de1a1e9", "key": "ADBT-104", "title": "Join customer segments as of the revenue event date", "type": "BUG", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 210, "phaseId": "model", "dependsOn": [ "ADBT-101", "ADBT-102" ], "scenario": "Historical enterprise revenue changes whenever sales updates a customer's current segment.", "acceptanceCriteria": [ "Use valid-time segment intervals for the event date.", "Detect overlapping or missing segment intervals explicitly.", "Preserve the event's original reporting currency." ], "implementationNotes": [ "Do not fill missing historical segments with the current value." ], "verification": [ "Change today's segment and keep prior periods unchanged.", "Create overlapping segment periods and fail the temporal join check." ], "deliverables": [ "As-of join model and interval assertions" ], "rollout": "Build a comparison table; switch readers after historical differences are reviewed.", "skills": [ "Temporal joins", "Slowly changing dimensions" ], "fieldMix": [ { "field": "Data engineering", "percentage": 70 }, { "field": "Database engineering", "percentage": 30 } ], "patterns": [] }, { "id": "bea3352f-a9dc-4d3e-b915-e1620ea4ae57", "key": "ADBT-105", "title": "Make incremental movement loads include revised source rows", "type": "STORY", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "model", "dependsOn": [ "ADBT-103", "ADBT-104" ], "scenario": "The incremental model filters only creation time, so a corrected subscription end date never reaches the mart.", "acceptanceCriteria": [ "Track source revision or updated watermark with tie breaking.", "Recompute affected grain keys deterministically.", "Commit the output and checkpoint consistently." ], "implementationNotes": [ "Document how deletions and corrections identify affected periods." ], "verification": [ "Correct a prior end date and update the affected month.", "Retry after an interrupted run and avoid duplicate movement rows." ], "deliverables": [ "Revision-aware incremental model" ], "rollout": "Shadow full and incremental builds on a synthetic corpus; fall back to full rebuild if they diverge.", "skills": [ "Incremental processing", "Idempotency" ], "fieldMix": [ { "field": "Data engineering", "percentage": 70 }, { "field": "Database engineering", "percentage": 30 } ], "patterns": [] }, { "id": "eeacfd9e-d873-4af7-a9d6-cb76876f64d6", "key": "ADBT-106", "title": "Represent cancelled subscriptions as movements instead of deleting them", "type": "TASK", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "model", "dependsOn": [ "ADBT-102", "ADBT-105" ], "scenario": "Deleting a cancelled subscription from the source erases the churn event from the report.", "acceptanceCriteria": [ "Retain cancellation effective date and source tombstone lineage.", "Emit one cancellation movement per effective revision.", "Expose unavailable source history as incomplete reporting." ], "implementationNotes": [ "Use synthetic deletion events rather than recovering private backups." ], "verification": [ "Apply a cancellation tombstone and retain its churn movement.", "Replay the tombstone and verify no double cancellation." ], "deliverables": [ "Tombstone handling and movement fixtures" ], "rollout": "Enable tombstone capture before source deletion; halt destructive cleanup if lineage is missing.", "skills": [ "Change data", "Lineage" ], "fieldMix": [ { "field": "Data engineering", "percentage": 100 } ], "patterns": [] }, { "id": "422184d7-8cc3-4b69-84d7-5654c9ef073a", "key": "ADBT-107", "title": "Detect fan-out before publishing account-level revenue totals", "type": "BUG", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 300, "phaseId": "model", "dependsOn": [ "ADBT-104", "ADBT-105", "ADBT-106" ], "scenario": "A new feature joins account tags to movement rows and inflates revenue for accounts with multiple tags.", "acceptanceCriteria": [ "Assert row and amount conservation across the join.", "Define tag allocation or a nonduplicating existence filter.", "Fail publication when conservation fails." ], "implementationNotes": [ "Keep tag-level attribution distinct from account-level totals." ], "verification": [ "Add two tags to an account and preserve its revenue total.", "Use the naive many-to-many join in a regression and detect inflation." ], "deliverables": [ "Fan-out guard and corrected account model" ], "rollout": "Canary the model in a separate schema; restore prior view selection on failed conservation.", "skills": [ "Join cardinality", "Data invariants" ], "fieldMix": [ { "field": "Data engineering", "percentage": 70 }, { "field": "Quality engineering", "percentage": 30 } ], "patterns": [] }, { "id": "87aed20b-94d9-4594-af20-14c3712a55d9", "key": "ADBT-108", "title": "Generate a report manifest with exact model and source revisions", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "publish", "dependsOn": [ "ADBT-105", "ADBT-107" ], "scenario": "An analyst sends a CSV to finance and later cannot identify which transformation commit or source cutoff produced it.", "acceptanceCriteria": [ "Include model commit, source checkpoints and generated UTC time.", "Hash exported bytes and preserve a report identity.", "Exclude credentials and raw customer fields from the manifest." ], "implementationNotes": [ "Keep the manifest next to synthetic exports." ], "verification": [ "Regenerate the same named inputs and compare content hashes.", "Change a source revision and receive a distinct manifest." ], "deliverables": [ "Report manifest and reproducibility command" ], "rollout": "Attach manifests to new reports; label earlier exports as lacking lineage.", "skills": [ "Provenance", "Reproducibility" ], "fieldMix": [ { "field": "Data engineering", "percentage": 80 }, { "field": "Storage systems", "percentage": 20 } ], "patterns": [] }, { "id": "89ae0367-f0d8-4ff7-b2bb-ec4d82f4c7f6", "key": "ADBT-109", "title": "Prove an incremental mart matches a full refresh after corrections", "type": "TASK", "priority": "MEDIUM", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "publish", "dependsOn": [ "ADBT-106", "ADBT-107", "ADBT-108" ], "scenario": "The team wants to reduce daily build cost but needs confidence that incremental state does not drift after late corrections.", "acceptanceCriteria": [ "Author a sequence of inserts, revisions and tombstones.", "Compare every grain key and measure to a full refresh.", "Report extra, missing and changed rows separately." ], "implementationNotes": [ "Run both paths against the same immutable synthetic inputs." ], "verification": [ "Replay the complete change sequence with equal final outputs.", "Skip one revision intentionally and verify a precise discrepancy report." ], "deliverables": [ "Differential transformation harness" ], "rollout": "Require a clean differential run before changing schedule; revert to full refresh on mismatch.", "skills": [ "Differential testing", "Data reliability" ], "fieldMix": [ { "field": "Quality engineering", "percentage": 50 }, { "field": "Data engineering", "percentage": 50 } ], "patterns": [] }, { "id": "8e810bb2-2ec7-46cb-994c-69592059ac28", "key": "ADBT-110", "title": "Write the analytics incident handoff for an unexplained revenue shift", "type": "CHORE", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "publish", "dependsOn": [ "ADBT-108", "ADBT-109" ], "scenario": "A report moves after a release and on-call staff cannot tell a genuine source correction from a transformation regression.", "acceptanceCriteria": [ "Start investigation from report manifests and affected grain keys.", "Separate source, definition and implementation changes.", "Include restore-view and corrected-export procedures." ], "implementationNotes": [ "Use a fabricated incident with no real financial assertions." ], "verification": [ "Trace one legitimate correction through source lineage.", "Trace a fan-out regression and restore the prior reporting view." ], "deliverables": [ "Analytics incident runbook" ], "rollout": "Validate the runbook with local reports; version it with model publication.", "skills": [ "Incident response", "Data lineage" ], "fieldMix": [ { "field": "Data engineering", "percentage": 60 }, { "field": "Site reliability", "percentage": 40 } ], "patterns": [] } ] } ] }