{ "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": "ee9b7116-54b1-444c-b503-3e7ca805c2ad", "key": "ACONFIG", "title": "Release configuration without restarting every service", "field": "Platform engineering", "summary": "Validate, version and distribute runtime configuration with bounded staleness.", "context": "A fictional internal reporting platform changes feature and timeout settings through environment edits. Partial rollouts leave API and worker processes interpreting different values.", "stack": [ "TypeScript", "PostgreSQL", "HTTP" ], "prerequisites": [ "Create local API and worker configuration consumers.", "Use fabricated settings without secrets." ], "developerValue": "Practice configuration contracts, compatibility and failure recovery.", "companyValue": "Review controlled configuration delivery with inspectable blast radius.", "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": "schema", "title": "Make settings explicit", "goal": "Define typed settings and safe defaults." }, { "id": "release", "title": "Distribute revisions", "goal": "Publish compatible snapshots and control adoption." }, { "id": "operate", "title": "Handle stale consumers", "goal": "Observe adoption and recover rejected changes." } ], "tickets": [ { "id": "b2ad83b8-66fd-41cb-b6bc-211d129915f4", "key": "ACONFIG-101", "title": "Inventory runtime settings with owners and restart requirements", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "schema", "dependsOn": [], "scenario": "Operators cannot tell whether changing a timeout requires a worker restart or takes effect on the next request.", "acceptanceCriteria": [ "List type, owner, default and adoption boundary for each setting.", "Separate secrets from nonsecret runtime configuration.", "Mark unknown behavior as unresolved before rollout." ], "implementationNotes": [ "Use a small fictional inventory of eight settings." ], "verification": [ "Trace one dynamic setting through its read boundary.", "Identify a startup-only setting and prevent a dynamic edit." ], "deliverables": [ "Configuration inventory and adoption contract" ], "rollout": "Review the inventory before exposing edits; keep unresolved settings read-only.", "skills": [ "Configuration management", "Technical documentation" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 100 } ], "patterns": [] }, { "id": "c4fd64b5-2baf-40ca-9f03-f13c8cdba256", "key": "ACONFIG-102", "title": "Reject invalid timeout combinations as one configuration unit", "type": "BUG", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "schema", "dependsOn": [ "ACONFIG-101" ], "scenario": "A retry timeout exceeds the entire request deadline, causing requests to continue working after callers have disconnected.", "acceptanceCriteria": [ "Validate relationships between attempt, retry and total deadlines.", "Reject the complete candidate snapshot on any invalid relation.", "Return field paths with safe values only." ], "implementationNotes": [ "Use explicit duration units; reject implicit unit conversion." ], "verification": [ "Accept a documented valid retry budget.", "Reject a larger attempt timeout than total deadline without changing active settings." ], "deliverables": [ "Snapshot validator and deadline fixtures" ], "rollout": "Add validation to drafts; preserve the active snapshot on any rejection.", "skills": [ "Validation", "Deadline budgets" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 80 }, { "field": "Backend", "percentage": 20 } ], "patterns": [] }, { "id": "43ea31c9-9a97-4843-b404-92d91b6e0785", "key": "ACONFIG-103", "title": "Define an immutable configuration snapshot envelope", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "schema", "dependsOn": [ "ACONFIG-101", "ACONFIG-102" ], "scenario": "A config endpoint returns a mutable object with no revision, so incident reports cannot establish which settings were read.", "acceptanceCriteria": [ "Include revision, canonical hash and schema version.", "Published snapshot content cannot be edited in place.", "Exclude secret material from serialization and logs." ], "implementationNotes": [ "Use opaque IDs and UTC publication metadata." ], "verification": [ "Read the same revision twice and compare hashes.", "Attempt an in-place edit and reject it." ], "deliverables": [ "Snapshot contract and immutability checks" ], "rollout": "Start versioned publication alongside legacy reads; retain published revisions for recovery.", "skills": [ "Versioning", "Immutability" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 100 } ], "patterns": [] }, { "id": "f89ccbe1-05bf-466a-ad17-c37957288310", "key": "ACONFIG-104", "title": "Atomically adopt a validated configuration snapshot in each process", "type": "STORY", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 210, "phaseId": "release", "dependsOn": [ "ACONFIG-103" ], "scenario": "A process updates settings one field at a time, briefly combining a new retry count with an old deadline.", "acceptanceCriteria": [ "Validate the full snapshot before replacing the active reference.", "Each request captures one revision for its lifetime.", "Failed adoption retains the complete previous snapshot." ], "implementationNotes": [ "Avoid mutating shared configuration objects after publication." ], "verification": [ "Switch snapshots during requests and observe one revision per request.", "Reject one invalid field and retain every previous value." ], "deliverables": [ "Atomic consumer adapter and concurrent-read probe" ], "rollout": "Canary a local worker consumer; pin its previous revision if adoption fails.", "skills": [ "Concurrency", "Configuration delivery" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 60 }, { "field": "Backend", "percentage": 40 } ], "patterns": [] }, { "id": "4f55c0ae-868b-4426-a23c-655dd5904323", "key": "ACONFIG-105", "title": "Publish configuration only against the revision reviewed by the operator", "type": "STORY", "priority": "MEDIUM", "difficulty": "ADVANCED", "estimateMinutes": 210, "phaseId": "release", "dependsOn": [ "ACONFIG-103", "ACONFIG-104" ], "scenario": "Two operators edit the same draft; the last publisher activates changes based on a stale review.", "acceptanceCriteria": [ "Require expected draft revision and reviewed hash.", "Commit publication and active selection together.", "Return a conflict with safe revision metadata on stale publication." ], "implementationNotes": [ "Record actor and reason in an append-only audit record." ], "verification": [ "Publish an unchanged reviewed snapshot.", "Race two publishers and assert one accepted active transition." ], "deliverables": [ "Optimistic publication command and race test" ], "rollout": "Enable publication for a synthetic operator role; disable writes if audit persistence fails.", "skills": [ "Optimistic concurrency", "Audit logs" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 60 }, { "field": "Database engineering", "percentage": 40 } ], "patterns": [] }, { "id": "17994255-b8c0-4be6-844f-b7a92cfc1ea3", "key": "ACONFIG-106", "title": "Keep incompatible consumers on their last valid configuration", "type": "TASK", "priority": "MEDIUM", "difficulty": "EXPERT", "estimateMinutes": 300, "phaseId": "release", "dependsOn": [ "ACONFIG-104", "ACONFIG-105" ], "scenario": "A new configuration schema reaches an older worker that silently ignores a field needed to preserve retry limits.", "acceptanceCriteria": [ "Consumers declare accepted schema versions.", "Incompatible snapshots are rejected with explicit adoption status.", "Critical missing configuration fails closed under the documented startup policy." ], "implementationNotes": [ "Do not coerce unknown versions into the current schema." ], "verification": [ "Adopt compatible settings in old and new local consumers.", "Send a new unsupported schema and preserve the old snapshot or fail startup as declared." ], "deliverables": [ "Compatibility handshake and failure matrix" ], "rollout": "Deploy compatible readers before publishing new schema; repoint to the older supported revision if needed.", "skills": [ "Compatibility", "Fail-closed design" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 80 }, { "field": "API design", "percentage": 20 } ], "patterns": [] }, { "id": "1706ef70-de4b-4861-a799-1671f55d4738", "key": "ACONFIG-107", "title": "Stage a timeout revision for a named consumer cohort", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 180, "phaseId": "release", "dependsOn": [ "ACONFIG-105", "ACONFIG-106" ], "scenario": "The team wants to test a timeout change on background reports before affecting interactive requests.", "acceptanceCriteria": [ "Bind cohort selection to stable nonpersonal service identity.", "Show intended and acknowledged revision per cohort.", "Unselected consumers retain their current target revision." ], "implementationNotes": [ "Use deterministic synthetic cohort membership." ], "verification": [ "Adopt a revision in the report-worker cohort only.", "Use an unknown cohort and reject publication without target changes." ], "deliverables": [ "Cohort rollout command and targeting cases" ], "rollout": "Begin with one synthetic cohort; restore its previous target revision on errors.", "skills": [ "Progressive delivery", "Targeting" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 100 } ], "patterns": [] }, { "id": "56898142-45ed-46bf-9614-6a87b75bb333", "key": "ACONFIG-108", "title": "Report configuration staleness separately from application health", "type": "STORY", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "operate", "dependsOn": [ "ACONFIG-106", "ACONFIG-107" ], "scenario": "A healthy process missed several configuration polls, but a green liveness check hides that it is running stale limits.", "acceptanceCriteria": [ "Expose active and target revision plus last successful poll time.", "Distinguish stale, incompatible and unavailable states.", "Avoid including configuration values in generic health payloads." ], "implementationNotes": [ "Use a fake clock for staleness boundaries." ], "verification": [ "Advance target while a consumer stays behind and report stale.", "Lose the configuration endpoint and keep the declared last-known-good behavior visible." ], "deliverables": [ "Adoption status projection" ], "rollout": "Add the status endpoint before alerts; disable noisy alerts without hiding adoption state.", "skills": [ "Observability", "Health semantics" ], "fieldMix": [ { "field": "Site reliability", "percentage": 60 }, { "field": "Platform engineering", "percentage": 40 } ], "patterns": [] }, { "id": "0983f778-385e-4435-a52d-d62bab50a5e7", "key": "ACONFIG-109", "title": "Rollback configuration by selecting a prior immutable snapshot", "type": "TASK", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "operate", "dependsOn": [ "ACONFIG-105", "ACONFIG-108" ], "scenario": "An operator attempts to repair a bad timeout by manually rewriting the active record, erasing the incident's configuration history.", "acceptanceCriteria": [ "Rollback appends a selection event with reason and actor.", "Validate old snapshot compatibility before selection.", "Retain the bad revision and its adoption record." ], "implementationNotes": [ "Use the same guarded publication boundary as forward changes." ], "verification": [ "Select a compatible prior revision and observe consumer adoption.", "Attempt rollback to an incompatible schema and leave the target unchanged." ], "deliverables": [ "Audited rollback command" ], "rollout": "Rehearse on synthetic consumers; pin a known compatible revision if adoption stalls.", "skills": [ "Recovery", "Auditability" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 70 }, { "field": "Site reliability", "percentage": 30 } ], "patterns": [] }, { "id": "032603c0-aea6-494f-8b6e-0cf13ccc70cb", "key": "ACONFIG-110", "title": "Exercise configuration service loss during a rolling deployment", "type": "TASK", "priority": "MEDIUM", "difficulty": "EXPERT", "estimateMinutes": 300, "phaseId": "operate", "dependsOn": [ "ACONFIG-106", "ACONFIG-109" ], "scenario": "The configuration endpoint becomes unavailable while old and new workers are starting with different cached snapshots.", "acceptanceCriteria": [ "Describe startup and running-process behavior separately.", "Prove critical settings cannot start from an unvalidated cache.", "Record revision selection and recovery for both consumer versions." ], "implementationNotes": [ "Use local fault injection; no production configuration changes." ], "verification": [ "Disconnect the endpoint after valid adoption and retain the declared bounded behavior.", "Start with a corrupt cache during outage and reject startup safely." ], "deliverables": [ "Outage drill and compatibility trace" ], "rollout": "Run before rollout; halt the deployment if a consumer cannot demonstrate its selected revision.", "skills": [ "Fault injection", "Operational readiness" ], "fieldMix": [ { "field": "Platform engineering", "percentage": 50 }, { "field": "Site reliability", "percentage": 30 }, { "field": "Quality engineering", "percentage": 20 } ], "patterns": [] } ] } ] }