{ "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": "fb8c96f4-a9ca-40d7-889b-29060ac89f1e", "key": "CTIER", "title": "A local archive cache with explicit integrity and capacity", "field": "Storage systems", "summary": "Coordinate immutable blob caching, eviction and repair across local storage tiers.", "context": "Fictional media archive Ash serves generated byte fixtures through a fast local cache and slower provider stub. Both tiers run locally.", "stack": [ "TypeScript", "Filesystem adapter", "Vitest" ], "prerequisites": [ "Create immutable generated blobs with known digests.", "Implement controllable cache and origin adapters with read failures." ], "developerValue": "Practice cache correctness, request coalescing and capacity control.", "companyValue": "Inspect whether faster delivery preserves bytes and operating limits.", "delivery": "Use dedicated fixture directories and publish measured local observations only.", "phases": [ { "id": "reads", "title": "Define cache reads", "goal": "Keep source authority explicit." }, { "id": "capacity", "title": "Control cache mutation", "goal": "Handle contention and eviction." }, { "id": "repair", "title": "Repair and observe", "goal": "Recover damage without hiding uncertainty." } ], "tickets": [ { "id": "484f9fd8-c8ce-4862-a4f6-654065584e87", "key": "CTIER-101", "title": "Keep archive cache misses distinct from provider failures", "type": "BUG", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 60, "phaseId": "reads", "dependsOn": [], "scenario": "Any cache read error is treated as a miss and hides damaged storage. Define typed outcomes.", "acceptanceCriteria": [ "Missing key is a miss", "Permission failure is operational error", "Origin reads follow documented fallback policy" ], "implementationNotes": [ "Do not swallow arbitrary filesystem exceptions." ], "verification": [ "Read absent fixture", "Inject permission failure" ], "deliverables": [ "Cache result contract" ], "rollout": "Bypass cache on operational failure while reporting it.", "skills": [ "Error modeling", "Storage" ], "fieldMix": [ { "field": "Storage systems", "percentage": 70 }, { "field": "Site reliability", "percentage": 30 } ], "patterns": [] }, { "id": "822b4021-ffc3-4c28-90db-4ad05d21248b", "key": "CTIER-102", "title": "Key archive cache entries by immutable blob identity", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 75, "phaseId": "reads", "dependsOn": [ "CTIER-101" ], "scenario": "A mutable filename reuses stale cached bytes after replacement. Bind entries to immutable version or digest.", "acceptanceCriteria": [ "Same identity reuses entry", "New version uses new key", "User labels do not affect identity" ], "implementationNotes": [ "Tenant scope remains part of lookup authority." ], "verification": [ "Read repeated identity", "Replace logical filename with new version" ], "deliverables": [ "Cache-key contract and cases" ], "rollout": "Disable cache reuse if identity is uncertain.", "skills": [ "Caching", "Identity" ], "fieldMix": [ { "field": "Storage systems", "percentage": 70 }, { "field": "Performance engineering", "percentage": 30 } ], "patterns": [] }, { "id": "6a40ef22-f586-4bb4-a1e0-160fd48e1ae1", "key": "CTIER-103", "title": "Verify archive cache fills before promoting temporary bytes", "type": "TASK", "priority": "HIGH", "difficulty": "INTERMEDIATE", "estimateMinutes": 135, "phaseId": "reads", "dependsOn": [ "CTIER-102" ], "scenario": "Interrupted origin reads leave files that future requests treat as complete. Stage and verify each fill.", "acceptanceCriteria": [ "Fill checks declared digest", "Unverified files stay invisible", "Failed fill removes or quarantines its temporary file" ], "implementationNotes": [ "Promotion must not expose partial bytes." ], "verification": [ "Fill valid fixture", "Truncate origin stream" ], "deliverables": [ "Verified fill and failure cases" ], "rollout": "Disable cache writes while serving origin directly.", "skills": [ "Integrity", "Atomic publication" ], "fieldMix": [ { "field": "Storage systems", "percentage": 100 } ], "patterns": [] }, { "id": "acc82c94-ef80-4d65-882d-39cb3e4ed5c2", "key": "CTIER-104", "title": "Coalesce concurrent archive cache fills for one blob", "type": "BUG", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 165, "phaseId": "capacity", "dependsOn": [ "CTIER-103" ], "scenario": "Ten simultaneous misses download the same object ten times. Share one fill without joining unrelated keys.", "acceptanceCriteria": [ "Same identity shares fill", "Different identities remain independent", "Failure releases waiters consistently" ], "implementationNotes": [ "Bound the in-flight map and clear settled entries." ], "verification": [ "Issue concurrent same-key reads", "Fail shared fill then retry" ], "deliverables": [ "Fill coordinator and concurrency cases" ], "rollout": "Disable coalescing if waiters cannot be released.", "skills": [ "Concurrency", "Resource management" ], "fieldMix": [ { "field": "Performance engineering", "percentage": 50 }, { "field": "Storage systems", "percentage": 50 } ], "patterns": [] }, { "id": "25f7a74e-d927-467f-8730-c280a02c2d5e", "key": "CTIER-105", "title": "Enforce archive cache capacity before admitting a fill", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "capacity", "dependsOn": [ "CTIER-103", "CTIER-104" ], "scenario": "Parallel fills exceed the configured cache budget because each sees free space. Reserve capacity atomically.", "acceptanceCriteria": [ "Active reservations count toward limit", "Failed fills release reservation", "Oversized objects bypass with explanation" ], "implementationNotes": [ "Include temporary bytes in capacity accounting." ], "verification": [ "Admit fitting concurrent fills", "Attempt object larger than budget" ], "deliverables": [ "Admission reservations and cases" ], "rollout": "Stop cache admission until accounting reconciles.", "skills": [ "Capacity planning", "Concurrency" ], "fieldMix": [ { "field": "Storage systems", "percentage": 50 }, { "field": "Performance engineering", "percentage": 50 } ], "patterns": [] }, { "id": "080a4a24-fbf9-4d93-99fc-92f0f01dd73b", "key": "CTIER-106", "title": "Avoid evicting archive blobs while active readers hold them", "type": "BUG", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 240, "phaseId": "capacity", "dependsOn": [ "CTIER-105" ], "scenario": "Eviction deletes a file while a streaming reader still needs it. Define reader leases and reclamation behavior.", "acceptanceCriteria": [ "Active readers finish or fail explicitly by contract", "New reads cannot acquire deleting entry", "Released leases permit eviction" ], "implementationNotes": [ "Specify platform filesystem assumptions." ], "verification": [ "Evict idle fixture", "Race eviction with active reader" ], "deliverables": [ "Reader-lease protocol and race tests" ], "rollout": "Pause eviction if active-reader safety is uncertain.", "skills": [ "Concurrency", "Filesystem" ], "fieldMix": [ { "field": "Storage systems", "percentage": 80 }, { "field": "Backend", "percentage": 20 } ], "patterns": [] }, { "id": "6b4973e2-fca0-4e37-99b0-9ed0855cd8cd", "key": "CTIER-107", "title": "Record archive cache recency without writing on every byte read", "type": "CHORE", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "capacity", "dependsOn": [ "CTIER-104", "CTIER-106" ], "scenario": "Streaming a large blob rewrites recency metadata for every chunk. Update recency at a bounded operation boundary.", "acceptanceCriteria": [ "One read causes bounded metadata writes", "Eviction order remains documented", "Failed read policy is explicit" ], "implementationNotes": [ "Use injected clocks for recency tests." ], "verification": [ "Stream many chunks", "Fail midway and inspect recency" ], "deliverables": [ "Recency policy and write-count checks" ], "rollout": "Use insertion order temporarily if recency updates regress.", "skills": [ "Performance", "Metadata" ], "fieldMix": [ { "field": "Performance engineering", "percentage": 60 }, { "field": "Storage systems", "percentage": 40 } ], "patterns": [] }, { "id": "cfce3723-5de7-4def-837a-a6301c3e591c", "key": "CTIER-108", "title": "Detect corrupted archive cache entries before serving them again", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "repair", "dependsOn": [ "CTIER-103", "CTIER-106" ], "scenario": "A local byte flip persists across reads. Add a bounded verification policy and quarantine path.", "acceptanceCriteria": [ "Verification detects mismatch", "Corrupt entry is not reused", "Origin repair creates a new verified entry" ], "implementationNotes": [ "State whether verification occurs per read or scheduled scan." ], "verification": [ "Corrupt fixture then read", "Fail origin repair" ], "deliverables": [ "Integrity policy and repair cases" ], "rollout": "Bypass cache for quarantined identities.", "skills": [ "Hashing", "Recovery" ], "fieldMix": [ { "field": "Storage systems", "percentage": 80 }, { "field": "Site reliability", "percentage": 20 } ], "patterns": [] }, { "id": "4c67aabb-c755-4c7e-a7d3-77163b88d9b2", "key": "CTIER-109", "title": "Reconcile archive cache metadata after process restart", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "repair", "dependsOn": [ "CTIER-105", "CTIER-108" ], "scenario": "A restart leaves reservations and temporary files consuming phantom capacity. Rebuild accounting from valid state.", "acceptanceCriteria": [ "Abandoned reservations release", "Verified entries remain counted", "Unknown files are quarantined rather than silently trusted" ], "implementationNotes": [ "Cleanup only within the configured fixture root." ], "verification": [ "Restart after successful fill", "Crash with partial temporary file" ], "deliverables": [ "Startup reconciliation and cases" ], "rollout": "Start cache read-only until reconciliation completes.", "skills": [ "Crash recovery", "Accounting" ], "fieldMix": [ { "field": "Storage systems", "percentage": 80 }, { "field": "Site reliability", "percentage": 20 } ], "patterns": [] }, { "id": "bbaa1295-64fb-4db8-b442-ab9ee9a47c57", "key": "CTIER-110", "title": "Report archive cache hit rates with a defined denominator", "type": "CHORE", "priority": "LOW", "difficulty": "INTERMEDIATE", "estimateMinutes": 105, "phaseId": "repair", "dependsOn": [ "CTIER-107", "CTIER-109" ], "scenario": "Dashboard hit rate counts every chunk and exaggerates cache usefulness. Count logical read outcomes explicitly.", "acceptanceCriteria": [ "Denominator is logical read attempts", "Bypass and errors are separate", "No blob content enters events" ], "implementationNotes": [ "Report local measurements without generalized performance claims." ], "verification": [ "Read hit miss and bypass fixtures", "Retry failed read and inspect counts" ], "deliverables": [ "Metrics contract and captured examples" ], "rollout": "Hide hit-rate panel if event accounting changes.", "skills": [ "Observability", "Measurement" ], "fieldMix": [ { "field": "Site reliability", "percentage": 50 }, { "field": "Performance engineering", "percentage": 30 }, { "field": "Storage systems", "percentage": 20 } ], "patterns": [] } ] } ] }