{ "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": "9fa17936-5981-4507-8ee8-cf91ce14aaca", "key": "CBLOB", "title": "Reference-aware blob retention and deletion", "field": "Storage systems", "summary": "Manage shared synthetic attachments through references, tombstones and recoverable cleanup.", "context": "Fictional archive Moss deduplicates generated attachments across documents within each organization. Use local files and transactional metadata stubs.", "stack": [ "TypeScript", "SQLite", "Filesystem adapter", "Vitest" ], "prerequisites": [ "Generate duplicate and unique local byte fixtures.", "Create synthetic document references across two organizations." ], "developerValue": "Practice reclamation races and explicit data-lifecycle guarantees.", "companyValue": "Inspect whether storage cleanup avoids broken references and hidden retention.", "delivery": "Operate only on a dedicated local fixture directory; no user folders are targeted.", "phases": [ { "id": "references", "title": "Model blob references", "goal": "Separate logical use from physical bytes." }, { "id": "deletion", "title": "Guard reclamation", "goal": "Handle races and failures safely." }, { "id": "maintenance", "title": "Operate retention", "goal": "Bound scanning and verify recovery." } ], "tickets": [ { "id": "35a5e942-c9bf-407a-a42c-175159d478e2", "key": "CBLOB-101", "title": "Separate attachment display names from blob identities", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 60, "phaseId": "references", "dependsOn": [], "scenario": "Renaming an attachment currently moves its physical file and breaks another reference. Store display names on references.", "acceptanceCriteria": [ "Rename changes only reference metadata", "Blob identity stays stable", "Other references keep their names" ], "implementationNotes": [ "Content identity cannot depend on a user-facing filename." ], "verification": [ "Rename shared attachment", "Fail metadata write and inspect file identity" ], "deliverables": [ "Reference schema and rename cases" ], "rollout": "Disable rename if it touches physical blobs.", "skills": [ "Data modeling", "Storage" ], "fieldMix": [ { "field": "Storage systems", "percentage": 60 }, { "field": "Database engineering", "percentage": 40 } ], "patterns": [] }, { "id": "5ff3d4ae-b730-4efa-834c-cd257258ef2d", "key": "CBLOB-102", "title": "Scope blob deduplication to the owning organization", "type": "BUG", "priority": "HIGH", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "references", "dependsOn": [ "CBLOB-101" ], "scenario": "Equal bytes across organizations share observable lookup results. Restrict deduplication to the tenant boundary.", "acceptanceCriteria": [ "Same-tenant duplicates reuse safely", "Foreign existence is not disclosed", "All reference reads include tenant scope" ], "implementationNotes": [ "Digest equality is not authorization." ], "verification": [ "Deduplicate own fixtures", "Probe matching foreign digest" ], "deliverables": [ "Scoped blob lookup and denial cases" ], "rollout": "Disable deduplication if scope isolation fails.", "skills": [ "Tenancy", "Privacy" ], "fieldMix": [ { "field": "Privacy engineering", "percentage": 40 }, { "field": "Security", "percentage": 40 }, { "field": "Storage systems", "percentage": 20 } ], "patterns": [] }, { "id": "6358a006-70f6-488a-b719-e25a6b1d6683", "key": "CBLOB-103", "title": "Reject references to incomplete synthetic blobs", "type": "TASK", "priority": "HIGH", "difficulty": "FOUNDATIONAL", "estimateMinutes": 75, "phaseId": "references", "dependsOn": [ "CBLOB-101", "CBLOB-102" ], "scenario": "Documents can attach blobs before upload verification ends. Require available status before creating a reference.", "acceptanceCriteria": [ "Available blob can attach", "Incomplete blob cannot attach", "Denied attachment creates no reference" ], "implementationNotes": [ "Status check and reference insertion share a transaction boundary." ], "verification": [ "Attach verified fixture", "Race verification failure with attach" ], "deliverables": [ "Attachment admission and cases" ], "rollout": "Pause attachments when availability cannot be established.", "skills": [ "State transitions", "Transactions" ], "fieldMix": [ { "field": "Storage systems", "percentage": 50 }, { "field": "Database engineering", "percentage": 50 } ], "patterns": [] }, { "id": "9c919f54-dbc4-484f-b5c9-b8ff89d0ae0a", "key": "CBLOB-104", "title": "Tombstone unreferenced blobs before physical deletion", "type": "STORY", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "deletion", "dependsOn": [ "CBLOB-103" ], "scenario": "Cleanup deletes bytes immediately when count reaches zero, leaving no recoverable decision record. Add a pending-deletion state.", "acceptanceCriteria": [ "Zero references create tombstone", "Referenced blobs remain available", "Tombstone records eligibility time" ], "implementationNotes": [ "Tombstones describe metadata, not proof of physical erasure." ], "verification": [ "Remove final reference", "Remove one of two references" ], "deliverables": [ "Tombstone transition and cases" ], "rollout": "Pause physical deletion while retaining tombstones.", "skills": [ "Lifecycle", "Data integrity" ], "fieldMix": [ { "field": "Storage systems", "percentage": 60 }, { "field": "Database engineering", "percentage": 40 } ], "patterns": [] }, { "id": "c008546d-a70a-46cd-80d8-347c79ca4060", "key": "CBLOB-105", "title": "Prevent a new blob reference racing with reclamation", "type": "BUG", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 240, "phaseId": "deletion", "dependsOn": [ "CBLOB-104" ], "scenario": "A document attaches a blob while cleanup deletes its file. Coordinate reference admission and deletion eligibility.", "acceptanceCriteria": [ "New reference either cancels eligibility or fails explicitly", "Deletion cannot remove newly referenced bytes", "Retried admission is safe" ], "implementationNotes": [ "Choose and document one atomic state protocol." ], "verification": [ "Attach before claim", "Race attachment against deletion claim" ], "deliverables": [ "Reclamation protocol and interleaving tests" ], "rollout": "Disable reclamation if the mutual-exclusion invariant fails.", "skills": [ "Concurrency", "Transactions" ], "fieldMix": [ { "field": "Database engineering", "percentage": 60 }, { "field": "Storage systems", "percentage": 40 } ], "patterns": [] }, { "id": "f5bb3d7e-28d8-4601-94b4-5fd443b6cddf", "key": "CBLOB-106", "title": "Record physical blob deletion failures without claiming completion", "type": "TASK", "priority": "HIGH", "difficulty": "INTERMEDIATE", "estimateMinutes": 135, "phaseId": "deletion", "dependsOn": [ "CBLOB-104", "CBLOB-105" ], "scenario": "Permission errors are swallowed and metadata says Deleted while bytes remain. Persist retryable failure state.", "acceptanceCriteria": [ "Successful deletion records acknowledgement", "Failure remains pending", "Already absent file is idempotent success" ], "implementationNotes": [ "Do not log attachment contents or paths outside fixture scope." ], "verification": [ "Delete fixture", "Inject permission failure" ], "deliverables": [ "Deletion result handling and cases" ], "rollout": "Pause retries on repeated provider faults.", "skills": [ "Error handling", "Recovery" ], "fieldMix": [ { "field": "Storage systems", "percentage": 70 }, { "field": "Site reliability", "percentage": 30 } ], "patterns": [] }, { "id": "290b4e6e-c948-4fcc-8e78-a9f576ef4d24", "key": "CBLOB-107", "title": "Reconcile blob metadata after a crash during deletion", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "deletion", "dependsOn": [ "CBLOB-106" ], "scenario": "A process dies after file removal but before metadata commit. Recovery must distinguish absent bytes from an untouched blob.", "acceptanceCriteria": [ "Missing claimed blob completes metadata", "Existing claimed blob retries safely", "Unclaimed blob is never deleted" ], "implementationNotes": [ "Recovery requires durable deletion claim identity." ], "verification": [ "Crash after file removal", "Restart with stale unrelated claim" ], "deliverables": [ "Deletion reconciliation and restart cases" ], "rollout": "Stop automatic recovery if claims cannot be verified.", "skills": [ "Crash consistency", "Reconciliation" ], "fieldMix": [ { "field": "Storage systems", "percentage": 60 }, { "field": "Database engineering", "percentage": 40 } ], "patterns": [] }, { "id": "ae654a4f-4354-495d-b44a-0103923a22d6", "key": "CBLOB-108", "title": "Bound blob reclamation scans by eligibility cursor", "type": "CHORE", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "maintenance", "dependsOn": [ "CBLOB-107" ], "scenario": "The sweeper repeatedly scans the full blob table. Add indexed bounded batches without skipping concurrent tombstones.", "acceptanceCriteria": [ "Batch size is capped", "Cursor order is stable", "New eligible rows appear on a subsequent pass" ], "implementationNotes": [ "Document cursor reset at end of pass." ], "verification": [ "Sweep multiple pages", "Insert eligible row during scan" ], "deliverables": [ "Sweep pagination and concurrency cases" ], "rollout": "Reduce to explicit small batches while cursor logic is repaired.", "skills": [ "Pagination", "Resource limits" ], "fieldMix": [ { "field": "Database engineering", "percentage": 50 }, { "field": "Performance engineering", "percentage": 30 }, { "field": "Storage systems", "percentage": 20 } ], "patterns": [] }, { "id": "b1d2e445-0bc4-44a7-9f1c-b686ca1b81ab", "key": "CBLOB-109", "title": "Protect retained document versions from blob cleanup", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "maintenance", "dependsOn": [ "CBLOB-105", "CBLOB-108" ], "scenario": "Cleanup counts only current document references and breaks retained versions. Include every retained reference authority.", "acceptanceCriteria": [ "Retained versions preserve blobs", "Expired versions release references", "Cross-tenant records cannot affect counts" ], "implementationNotes": [ "Retention policy is a fixture contract, not a legal claim." ], "verification": [ "Retain old version", "Expire it and inspect eligibility" ], "deliverables": [ "Version-aware reference accounting" ], "rollout": "Pause cleanup until all reference sources reconcile.", "skills": [ "Retention", "Data modeling" ], "fieldMix": [ { "field": "Storage systems", "percentage": 60 }, { "field": "Database engineering", "percentage": 40 } ], "patterns": [] }, { "id": "b299c6a9-7dbd-4de1-b8e5-336cdc50f6f0", "key": "CBLOB-110", "title": "Produce a blob-reclamation report that distinguishes planned and removed bytes", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 105, "phaseId": "maintenance", "dependsOn": [ "CBLOB-106", "CBLOB-109" ], "scenario": "Operators report savings from tombstoned bytes that still exist. Separate eligible, attempted and acknowledged removal totals.", "acceptanceCriteria": [ "Planned bytes are labeled", "Failures remain outstanding", "Only acknowledged removals count as reclaimed" ], "implementationNotes": [ "State measurements are local fixture observations." ], "verification": [ "Sweep successful fixture batch", "Fail half the deletions" ], "deliverables": [ "Reclamation report projection" ], "rollout": "Hide savings totals if acknowledgements cannot be reconciled.", "skills": [ "Observability", "Reporting" ], "fieldMix": [ { "field": "Storage systems", "percentage": 60 }, { "field": "Site reliability", "percentage": 40 } ], "patterns": [] } ] } ] }