{ "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": "c3d7d229-4f2e-4563-8d9c-867a2ec3412a", "key": "CPRES", "title": "Presence that remains honest during disconnection", "field": "Real-time systems", "summary": "Model ephemeral team presence with expiry, reconnects and scoped fan-out.", "context": "Fictional document team Pine shows collaboration presence for synthetic accounts. Build a loopback WebSocket server and injected clocks; no message content or activity surveillance is required.", "stack": [ "TypeScript", "WebSocket", "Redis adapter", "Vitest" ], "prerequisites": [ "Create synthetic memberships and session identifiers.", "Implement controllable sockets and an in-memory TTL adapter." ], "developerValue": "Practice ephemeral state, ordering and reconnect semantics.", "companyValue": "Inspect whether online indicators avoid stale or unauthorized claims.", "delivery": "Presence means an active connection lease only; it does not infer attention or productivity.", "phases": [ { "id": "leases", "title": "Define presence meaning", "goal": "Specify scopes and expiry." }, { "id": "fanout", "title": "Distribute state safely", "goal": "Handle identity and reconnect races." }, { "id": "operations", "title": "Bound operating behavior", "goal": "Limit work and diagnose stale indicators." } ], "tickets": [ { "id": "0e5e9b70-dd06-4b27-ac48-b35f427c20eb", "key": "CPRES-101", "title": "Define online presence as an unexpired connection lease", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 75, "phaseId": "leases", "dependsOn": [], "scenario": "A green dot remains after the browser closes. Replace the permanent flag with explicitly expiring presence.", "acceptanceCriteria": [ "Active lease shows connected", "Expiry removes connected state", "UI explains connection meaning" ], "implementationNotes": [ "Do not infer human attention from a socket." ], "verification": [ "Advance clock before expiry", "Advance beyond expiry without disconnect" ], "deliverables": [ "Lease contract and clock cases" ], "rollout": "Hide presence if lease freshness cannot be established.", "skills": [ "TTL", "State modeling" ], "fieldMix": [ { "field": "Real-time systems", "percentage": 60 }, { "field": "Distributed systems", "percentage": 40 } ], "patterns": [] }, { "id": "c61f0c42-ba2a-4cb8-bc3d-e40757c6bac8", "key": "CPRES-102", "title": "Validate presence room identifiers before subscribing", "type": "BUG", "priority": "HIGH", "difficulty": "FOUNDATIONAL", "estimateMinutes": 75, "phaseId": "leases", "dependsOn": [], "scenario": "Malformed room names reach the broker and create unbounded keys. Parse a bounded typed room identifier.", "acceptanceCriteria": [ "Valid room IDs subscribe", "Malformed IDs fail before broker access", "Error omits raw oversized input" ], "implementationNotes": [ "Room parsing does not replace membership checks." ], "verification": [ "Subscribe valid fixture room", "Send oversized room identifier" ], "deliverables": [ "Room parser and rejection tests" ], "rollout": "Reject new subscriptions if parsing fails.", "skills": [ "Input validation", "Pub-sub" ], "fieldMix": [ { "field": "Security", "percentage": 50 }, { "field": "Real-time systems", "percentage": 50 } ], "patterns": [] }, { "id": "3615cb97-e65d-49b0-8f84-a63f91672070", "key": "CPRES-103", "title": "Scope presence membership checks to each room subscription", "type": "TASK", "priority": "HIGH", "difficulty": "INTERMEDIATE", "estimateMinutes": 135, "phaseId": "leases", "dependsOn": [ "CPRES-101", "CPRES-102" ], "scenario": "Authentication alone currently permits joining any document room. Require current membership in the room boundary.", "acceptanceCriteria": [ "Member can join", "Foreign member is denied", "Revoked membership cannot renew lease" ], "implementationNotes": [ "Recheck authority at renewal using local stub." ], "verification": [ "Join authorized room", "Revoke membership before renewal" ], "deliverables": [ "Subscription authorization and denial cases" ], "rollout": "Stop renewals while membership adapter is unavailable.", "skills": [ "Authorization", "Tenancy" ], "fieldMix": [ { "field": "Security", "percentage": 70 }, { "field": "Real-time systems", "percentage": 30 } ], "patterns": [] }, { "id": "aae20ce3-3f0b-475f-aff3-bf73ab346b38", "key": "CPRES-104", "title": "Count multiple presence connections without duplicating people", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 120, "phaseId": "fanout", "dependsOn": [ "CPRES-103" ], "scenario": "Two tabs display the same teammate twice. Aggregate active connection leases under a scoped synthetic account.", "acceptanceCriteria": [ "One person entry per room", "Closing one tab preserves other lease", "Last expiry removes person" ], "implementationNotes": [ "Do not merge identities across organizations." ], "verification": [ "Open two tabs", "Expire last connection" ], "deliverables": [ "Presence aggregation and cases" ], "rollout": "Display connection counts only if person aggregation is incorrect.", "skills": [ "Aggregation", "Identity" ], "fieldMix": [ { "field": "Real-time systems", "percentage": 70 }, { "field": "Data engineering", "percentage": 30 } ], "patterns": [] }, { "id": "12b600c2-1d58-4ba9-a9bb-ce9a97266c1e", "key": "CPRES-105", "title": "Reject stale presence heartbeats after reconnect", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "fanout", "dependsOn": [ "CPRES-103", "CPRES-104" ], "scenario": "Delayed heartbeat from a replaced socket prolongs a dead session. Bind renewal to session generation.", "acceptanceCriteria": [ "New generation supersedes old", "Old heartbeat cannot renew", "Current heartbeat extends its own lease" ], "implementationNotes": [ "Generation changes must be atomic in the adapter." ], "verification": [ "Renew current session", "Deliver old heartbeat after reconnect" ], "deliverables": [ "Generation guard and race tests" ], "rollout": "Close superseded sessions and require fresh joins.", "skills": [ "Concurrency", "Fencing" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 60 }, { "field": "Real-time systems", "percentage": 40 } ], "patterns": [] }, { "id": "1493c756-a2ef-4649-adc5-d4a98f2700c7", "key": "CPRES-106", "title": "Send a presence snapshot before incremental updates", "type": "STORY", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "fanout", "dependsOn": [ "CPRES-104", "CPRES-105" ], "scenario": "A new client applies deltas to an empty list and misses existing teammates. Add snapshot sequencing at subscription.", "acceptanceCriteria": [ "Snapshot establishes sequence", "Later deltas follow its watermark", "Detected gaps trigger resnapshot" ], "implementationNotes": [ "Buffer during snapshot only within a documented limit." ], "verification": [ "Join populated room", "Drop one delta and detect gap" ], "deliverables": [ "Snapshot handshake and gap cases" ], "rollout": "Resend full snapshots while delta path is repaired.", "skills": [ "Ordering", "State synchronization" ], "fieldMix": [ { "field": "Real-time systems", "percentage": 50 }, { "field": "Distributed systems", "percentage": 50 } ], "patterns": [] }, { "id": "e2bf9730-d315-444e-afac-538f8929b1f1", "key": "CPRES-107", "title": "Expire presence independently of disconnect delivery", "type": "BUG", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 240, "phaseId": "fanout", "dependsOn": [ "CPRES-101", "CPRES-105", "CPRES-106" ], "scenario": "A server restart loses disconnect events and rooms retain ghosts. Make lease expiry authoritative across process recovery.", "acceptanceCriteria": [ "Restart cannot preserve expired entries", "Cleanup repeats safely", "Concurrent renewal cannot delete fresh lease" ], "implementationNotes": [ "Compare stored lease identity before removal." ], "verification": [ "Restart with expired leases", "Renew during cleanup" ], "deliverables": [ "Expiry reconciliation and interleaving cases" ], "rollout": "Disable cleanup writes if lease identity cannot be checked.", "skills": [ "Recovery", "Concurrency" ], "fieldMix": [ { "field": "Distributed systems", "percentage": 50 }, { "field": "Real-time systems", "percentage": 30 }, { "field": "Site reliability", "percentage": 20 } ], "patterns": [] }, { "id": "74712b3c-239c-4c07-a17e-fb5266b0641a", "key": "CPRES-108", "title": "Cap presence fan-out per room without silently losing state", "type": "TASK", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 180, "phaseId": "operations", "dependsOn": [ "CPRES-106" ], "scenario": "A synthetic busy room causes unbounded socket buffers. Introduce a per-client queue cap and resync fallback.", "acceptanceCriteria": [ "Buffer count is bounded", "Overflow requests resnapshot", "Healthy peers continue receiving" ], "implementationNotes": [ "Do not drop arbitrary deltas and claim synchronization." ], "verification": [ "Exercise normal fan-out", "Stall one client to capacity" ], "deliverables": [ "Bounded broadcaster and overflow cases" ], "rollout": "Disconnect slow clients with a clear resync reason.", "skills": [ "Backpressure", "Resource limits" ], "fieldMix": [ { "field": "Performance engineering", "percentage": 50 }, { "field": "Real-time systems", "percentage": 30 }, { "field": "Site reliability", "percentage": 20 } ], "patterns": [] }, { "id": "96146c8d-8185-444a-8fdf-b49e87410f84", "key": "CPRES-109", "title": "Distinguish disconnected and stale presence in the client", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 105, "phaseId": "operations", "dependsOn": [ "CPRES-107", "CPRES-108" ], "scenario": "Network loss freezes green dots and suggests teammates remain connected. Mark stale state during transport uncertainty.", "acceptanceCriteria": [ "Local disconnect marks snapshot stale", "Reconnect waits for fresh snapshot", "Stale entries are not labeled online" ], "implementationNotes": [ "Preserve names only while room access remains valid." ], "verification": [ "Disconnect then reconnect", "Lose authorization during reconnect" ], "deliverables": [ "Presence freshness UI" ], "rollout": "Hide entries during uncertainty if freshness labeling fails.", "skills": [ "UX", "State projection" ], "fieldMix": [ { "field": "Frontend", "percentage": 60 }, { "field": "Real-time systems", "percentage": 40 } ], "patterns": [] }, { "id": "e4a92b23-ca34-4c54-b330-b63cf085f028", "key": "CPRES-110", "title": "Expose presence lease diagnostics without activity histories", "type": "CHORE", "priority": "LOW", "difficulty": "INTERMEDIATE", "estimateMinutes": 90, "phaseId": "operations", "dependsOn": [ "CPRES-109" ], "scenario": "Operators need to locate ghost indicators without collecting behavioral timelines. Add current aggregate lease counters.", "acceptanceCriteria": [ "Counters include active and expired totals", "No per-person activity history is stored", "Room labels use bounded safe identifiers" ], "implementationNotes": [ "Use synthetic rooms in samples." ], "verification": [ "Inspect healthy counters", "Create expired lease and verify aggregation" ], "deliverables": [ "Diagnostic contract and samples" ], "rollout": "Disable diagnostics if person-level histories appear.", "skills": [ "Observability", "Privacy" ], "fieldMix": [ { "field": "Privacy engineering", "percentage": 50 }, { "field": "Site reliability", "percentage": 30 }, { "field": "Real-time systems", "percentage": 20 } ], "patterns": [] } ] } ] }