{ "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": [ { "key": "SFFI", "title": "Stabilize a native compression boundary before wider adoption", "field": "Systems programming", "summary": "Design a safe FFI contract with explicit ownership, error mapping and compatibility.", "context": "A fictional desktop backup tool calls a small Rust compression library from Node.js. The binding leaks buffers on exceptions and treats ABI mismatches as corrupted input. Build against generated byte arrays and a local native library; no production archive format or user files are supplied.", "stack": [ "Rust", "C ABI", "Node-API", "Sanitizers" ], "prerequisites": [ "FFI ownership", "Binary compatibility", "Error handling" ], "developerValue": "Practice language-boundary contracts, native resource safety and version negotiation.", "companyValue": "Review a binding that fails safely and can be rolled back before native code enters additional application paths.", "delivery": "Ten linked tickets across three phases. Use synthetic inputs and a local harness; provide source, focused tests, measurements where requested, and a recovery note.", "phases": [ { "id": "model", "title": "Establish the machine contract", "goal": "Make representation, ownership and failure boundaries explicit." }, { "id": "control", "title": "Control resources and concurrency", "goal": "Implement bounded behavior under realistic interleavings." }, { "id": "operate", "title": "Prove recovery and handoff", "goal": "Measure, diagnose and safely replace the component." } ], "tickets": [ { "id": "29836321-c28f-4edc-953d-d714bfc57ed7", "key": "SFFI-101", "title": "Write the buffer ownership table before exposing the binding", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "model", "dependsOn": [], "scenario": "JavaScript and Rust both believe the other side frees an output buffer when conversion throws.", "acceptanceCriteria": [ "Document owner for every input, output, error, and callback value", "Each transfer has one release operation and allowed thread", "Borrowed memory cannot outlive its originating call" ], "implementationNotes": [ "Do not infer ownership from constness or language garbage collection." ], "verification": [ "Trace success and error paths through the ownership table.", "Inject failure after native allocation and verify exactly one release." ], "deliverables": [ "FFI ownership contract and allocation counter test" ], "rollout": "Keep the pure-language fallback until every path has an owner.", "skills": [ "FFI", "Ownership", "Resource cleanup" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Developer tooling", "percentage": 30 } ], "patterns": [] }, { "id": "3a048c85-03f3-4afc-91d9-ee3132f6b96b", "key": "SFFI-102", "title": "Validate lengths before converting JavaScript buffers", "type": "BUG", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "model", "dependsOn": [], "scenario": "A signed length crosses the C boundary and becomes a very large unsigned value.", "acceptanceCriteria": [ "Binding rejects lengths outside the actual buffer and native type range", "Zero-length input follows a documented contract", "Conversion failure calls no compression function" ], "implementationNotes": [ "Perform validation on the boundary side that has both pointer and buffer length." ], "verification": [ "Compress empty, small, and maximum-fixture buffers.", "Pass negative-equivalent, oversized, and detached buffers and verify rejection." ], "deliverables": [ "Length checks and boundary corpus" ], "rollout": "Reject unsupported buffers before enabling the native path.", "skills": [ "Integer conversion", "Input validation" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Security", "percentage": 30 } ], "patterns": [] }, { "id": "5b585a37-bb44-45bd-88a3-319c45e55124", "key": "SFFI-103", "title": "Map native errors without losing machine-readable causes", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "model", "dependsOn": [ "SFFI-101", "SFFI-102" ], "scenario": "Every nonzero native status becomes 'compression failed', hiding whether the caller supplied bad input or the allocator exhausted its cap.", "acceptanceCriteria": [ "Stable public codes distinguish input, capacity, version, cancellation, and internal faults", "Native diagnostic text is bounded and treated as untrusted", "Unknown statuses map to one safe internal category" ], "implementationNotes": [ "Do not include raw input bytes or native addresses in errors." ], "verification": [ "Trigger and map each declared native status.", "Return an unknown status with oversized text and verify bounded safe mapping." ], "deliverables": [ "Versioned error map and contract tests" ], "rollout": "Callers must stop branching on old free-form messages before migration.", "skills": [ "Error contracts", "Boundary validation" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "API design", "percentage": 30 } ], "patterns": [] }, { "id": "4b7c64ca-603f-4dcc-a608-61d08e41aac1", "key": "SFFI-104", "title": "Release native output after JavaScript cancellation", "type": "CHORE", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "control", "dependsOn": [ "SFFI-101", "SFFI-103" ], "scenario": "The caller abandons a promise while native work finishes later; its output buffer has no remaining JavaScript consumer and is leaked.", "acceptanceCriteria": [ "Operation state records whether a result still has a consumer", "Late output is released on the native allocation thread or declared safe path", "Cancellation and completion races release once" ], "implementationNotes": [ "Cancellation is cooperative; do not unload code while a native call is running." ], "verification": [ "Cancel before start and after successful delivery.", "Race cancellation with native completion across repeated deterministic schedules." ], "deliverables": [ "Cancellation cleanup protocol and race tests" ], "rollout": "Keep native concurrency at one until release counts reconcile.", "skills": [ "Cancellation", "FFI cleanup", "Concurrency" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Real-time systems", "percentage": 30 } ], "patterns": [] }, { "id": "eec7179e-19df-4467-9b41-1fad48d4e812", "key": "SFFI-105", "title": "Move blocking compression off the JavaScript event loop", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "control", "dependsOn": [ "SFFI-102", "SFFI-104" ], "scenario": "A 50 MB synthetic buffer blocks timers and health checks because the binding invokes native compression synchronously.", "acceptanceCriteria": [ "Large work runs in a bounded worker pool", "Completion returns on the expected runtime thread", "Queue saturation rejects before copying the full input" ], "implementationNotes": [ "Measure copy cost separately from compression time and cap fixture size." ], "verification": [ "Compress concurrent small and large buffers while measuring timer delay.", "Saturate the pool and confirm bounded memory with a typed overload result." ], "deliverables": [ "Asynchronous binding and event-loop latency report" ], "rollout": "Route buffers above a measured threshold first and retain synchronous fallback for small fixtures.", "skills": [ "Async runtimes", "Performance", "Backpressure" ], "fieldMix": [ { "field": "Systems programming", "percentage": 60 }, { "field": "Performance engineering", "percentage": 40 } ], "patterns": [] }, { "id": "396819f7-5b29-4ebd-a397-fb9c5528458a", "key": "SFFI-106", "title": "Negotiate ABI capability before the first compression call", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "control", "dependsOn": [ "SFFI-103" ], "scenario": "A newer binding calls an option function missing from the loaded native library and the process terminates during symbol resolution.", "acceptanceCriteria": [ "Initialization reads ABI version and explicit capability bits", "Unsupported required capabilities fail before accepting work", "Optional capabilities have documented fallback behavior" ], "implementationNotes": [ "Do not infer ABI compatibility from package version or filename alone." ], "verification": [ "Load current and compatible older fixture libraries.", "Load a library missing a required symbol and fail closed before dispatch." ], "deliverables": [ "ABI handshake and compatibility matrix" ], "rollout": "Probe in startup readiness while the pure-language provider remains selectable.", "skills": [ "ABI versioning", "Feature negotiation" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Platform engineering", "percentage": 30 } ], "patterns": [] }, { "id": "87030659-88f7-4949-b29d-d66a46121f58", "key": "SFFI-107", "title": "Contain a native panic without pretending the process is safe", "type": "STORY", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "control", "dependsOn": [ "SFFI-103", "SFFI-106" ], "scenario": "Malformed options trigger a Rust panic that crosses the C ABI and aborts the Node process.", "acceptanceCriteria": [ "FFI entry points catch supported unwind cases before the ABI boundary", "Panic maps to an internal fault with operation identity", "Abort-configured builds are identified and isolated out of process" ], "implementationNotes": [ "Do not claim catch_unwind protects memory after arbitrary native corruption." ], "verification": [ "Trigger a controlled recoverable panic and map its result.", "Select an aborting fixture provider and require process-isolation policy instead of in-process execution." ], "deliverables": [ "Panic-boundary policy and controlled failure fixtures" ], "rollout": "Keep risky codecs behind an external process provider until their failure mode is qualified.", "skills": [ "Panic safety", "Isolation boundaries", "FFI" ], "fieldMix": [ { "field": "Systems programming", "percentage": 60 }, { "field": "Security", "percentage": 40 } ], "patterns": [] }, { "id": "42d20473-5374-4d91-8310-aa483334b13f", "key": "SFFI-108", "title": "Compare native output against the compatibility oracle", "type": "CHORE", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "operate", "dependsOn": [ "SFFI-105", "SFFI-106" ], "scenario": "The native path is faster but emits archives the existing decompressor accepts differently around empty blocks.", "acceptanceCriteria": [ "Golden corpus defines byte compatibility or declared semantic compatibility", "Both providers round-trip every supported case", "Differences are classified before rollout" ], "implementationNotes": [ "Use generated non-sensitive bytes and pin provider versions in the report." ], "verification": [ "Compare providers across corpus sizes and option combinations.", "Inject a one-byte divergence and show the gate blocks promotion." ], "deliverables": [ "Differential harness and compatibility report" ], "rollout": "Canary only corpus classes with reconciled outputs.", "skills": [ "Differential testing", "Compatibility" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Quality engineering", "percentage": 30 } ], "patterns": [] }, { "id": "13e8f702-7568-48d6-a393-595f2461f97b", "key": "SFFI-109", "title": "Unload a retired native revision only after callbacks drain", "type": "TASK", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "operate", "dependsOn": [ "SFFI-104", "SFFI-106" ], "scenario": "Hot replacement unloads the old library while an asynchronous completion callback still points into its code.", "acceptanceCriteria": [ "Each operation pins one library revision through callback completion", "Retirement blocks new calls and observes active reference count", "Deadline reports unresolved references without forced unload" ], "implementationNotes": [ "Prefer process restart for platforms that cannot guarantee safe dynamic unloading." ], "verification": [ "Run old and new revisions concurrently, then retire the old after drain.", "Hold one completion callback and verify unload does not occur at the deadline." ], "deliverables": [ "Revision lifetime protocol and delayed-callback test" ], "rollout": "Use process replacement as the default until in-process retirement is proven for the target platform.", "skills": [ "Dynamic libraries", "Reference lifetimes", "Safe rollout" ], "fieldMix": [ { "field": "Systems programming", "percentage": 60 }, { "field": "Platform engineering", "percentage": 40 } ], "patterns": [] }, { "id": "4337ba99-6c9a-4940-bc4f-6ed2ea1218a4", "key": "SFFI-110", "title": "Package the native binding with a reversible compatibility gate", "type": "BUG", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "operate", "dependsOn": [ "SFFI-107", "SFFI-108", "SFFI-109" ], "scenario": "A package publish selects the native binary by platform name but ignores CPU features and libc compatibility.", "acceptanceCriteria": [ "Artifact metadata binds OS, architecture, ABI, runtime, and required CPU features", "Installer rejects an incompatible binary before load", "Pure-language fallback selection is explicit and observable" ], "implementationNotes": [ "Do not download or execute binaries outside the generated local fixture set." ], "verification": [ "Select each compatible fixture artifact and report its identity.", "Present wrong architecture, ABI, and feature metadata and verify safe fallback." ], "deliverables": [ "Artifact selector, compatibility cases, and rollback note" ], "rollout": "Publish metadata and fallback behavior before enabling native-by-default selection.", "skills": [ "Packaging", "Compatibility", "Release engineering" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "DevOps", "percentage": 30 } ], "patterns": [] } ], "id": "00ad18d5-9ac5-4716-888c-62e97c908b90" } ] }