{ "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": "SMEM", "title": "Repair a packet arena before it becomes shared infrastructure", "field": "Systems programming", "summary": "Build a bounded arena with explicit alignment, lifetime and corruption behavior.", "context": "A fictional telemetry collector copies decoded packet fields into a small native arena. The prototype misaligns wide values and reuses memory while readers still hold views. Create a local Rust crate or C library with generated byte fixtures; no device traffic or production allocator replacement is supplied.", "stack": [ "Rust or C", "Property tests", "AddressSanitizer or Miri" ], "prerequisites": [ "Pointers and slices", "Integer overflow", "Memory alignment" ], "developerValue": "Practice representation invariants, lifetimes, unsafe-boundary review and memory diagnostics.", "companyValue": "Review a component whose allocation failures and corruption cases are explicit before reuse in latency-sensitive code.", "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": "fda2eb6f-d3ed-4893-872f-42640a99f50f", "key": "SMEM-101", "title": "Specify aligned arena offsets without relying on host luck", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "model", "dependsOn": [], "scenario": "Eight-byte fields happen to work on one machine because the backing buffer begins aligned; a sliced buffer starts at an odd address.", "acceptanceCriteria": [ "Round every allocation to its declared power-of-two alignment", "Reject zero and unsupported alignments", "Report requested size and remaining capacity without exposing addresses" ], "implementationNotes": [ "Use checked integer arithmetic before changing the cursor." ], "verification": [ "Allocate mixed one-, four-, and eight-byte records and verify every offset.", "Start near the numeric limit and confirm overflow leaves the cursor unchanged." ], "deliverables": [ "Arena layout contract and boundary tests" ], "rollout": "Keep the current copy path until the layout suite passes on two target architectures.", "skills": [ "Alignment", "Checked arithmetic" ], "fieldMix": [ { "field": "Systems programming", "percentage": 80 }, { "field": "Embedded and edge", "percentage": 20 } ], "patterns": [] }, { "id": "35311dcc-1cc7-4b71-925b-589c340e88f8", "key": "SMEM-102", "title": "Return exhaustion without handing out a partial slice", "type": "BUG", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "model", "dependsOn": [], "scenario": "A capacity miss advances the arena cursor before returning an error, so the following small allocation also fails.", "acceptanceCriteria": [ "An exhausted allocation returns a typed capacity error", "Cursor and prior bytes remain unchanged after failure", "A later fitting allocation can still succeed" ], "implementationNotes": [ "Do not grow the backing region or panic on caller-controlled sizes." ], "verification": [ "Fill the arena exactly and inspect the final valid allocation.", "Request one byte too many, then allocate a smaller record and verify state." ], "deliverables": [ "Atomic allocation update and exhaustion regression" ], "rollout": "Treat exhaustion as backpressure in the local collector; never retry without changing capacity or workload.", "skills": [ "Failure atomicity", "Resource bounds" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Performance engineering", "percentage": 30 } ], "patterns": [] }, { "id": "504c08c1-bc84-404a-8ee2-80301eeddda6", "key": "SMEM-103", "title": "Invalidate borrowed packet views when the arena resets", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "model", "dependsOn": [ "SMEM-101", "SMEM-102" ], "scenario": "A decoder stores a view into the arena across reset and later reads bytes belonging to a different packet.", "acceptanceCriteria": [ "Views carry the generation in which they were created", "Reset advances generation before storage is reused", "Stale view access fails deterministically in the safe API" ], "implementationNotes": [ "Keep unsafe reads inside one reviewed boundary; do not claim runtime checks prove arbitrary raw pointers safe." ], "verification": [ "Read several current-generation views before reset.", "Reset, reuse the same offset, and reject the older view." ], "deliverables": [ "Generation-bound view API and stale-view reproduction" ], "rollout": "Migrate the decoder through the checked view API before enabling reset reuse.", "skills": [ "Lifetimes", "Memory safety", "Generations" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Security", "percentage": 30 } ], "patterns": [] }, { "id": "27b222b2-948b-4771-85aa-14fdc1ed778a", "key": "SMEM-104", "title": "Free large spill blocks without double-releasing arena pages", "type": "CHORE", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "control", "dependsOn": [ "SMEM-102" ], "scenario": "Oversized records spill to separate blocks. Error cleanup releases a spill block, then arena teardown releases the same block again.", "acceptanceCriteria": [ "Each spill block has one recorded owner", "Cleanup is safe when invoked repeatedly", "Arena teardown releases only blocks still attached" ], "implementationNotes": [ "Model ownership explicitly; a boolean freed flag cannot authorize access after release." ], "verification": [ "Allocate and release several spill blocks in different orders.", "Inject a decode error after spill allocation and run teardown twice under a memory checker." ], "deliverables": [ "Spill ownership model and double-free regression" ], "rollout": "Disable spill allocation if the checker reports any invalid release.", "skills": [ "Ownership", "Cleanup", "Memory diagnostics" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Quality engineering", "percentage": 30 } ], "patterns": [] }, { "id": "da3ab846-6a35-4a5c-bc1e-956374a3de95", "key": "SMEM-105", "title": "Coalesce adjacent free spans without corrupting the index", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "control", "dependsOn": [ "SMEM-101", "SMEM-104" ], "scenario": "The free-span list merges with the previous range but forgets the next range, leaving overlapping entries that can be allocated twice.", "acceptanceCriteria": [ "Free spans remain ordered, nonoverlapping, and maximal", "Freeing in any order yields the same canonical span set", "Double-free and out-of-range spans are rejected" ], "implementationNotes": [ "Update the span index under one mutation boundary and preserve the arena on validation failure." ], "verification": [ "Free three adjacent blocks in all six orders and compare the final index.", "Attempt an overlapping release and prove no index entry changes." ], "deliverables": [ "Canonical coalescing algorithm and permutation tests" ], "rollout": "Run shadow invariant checks in the local benchmark before using reclaimed spans.", "skills": [ "Data structures", "Invariants", "Property testing" ], "fieldMix": [ { "field": "Systems programming", "percentage": 75 }, { "field": "Quality engineering", "percentage": 25 } ], "patterns": [] }, { "id": "08274454-1425-4d2a-ad93-c6452c131f7d", "key": "SMEM-106", "title": "Bound fragmentation before adding a more complex allocator", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "control", "dependsOn": [ "SMEM-105" ], "scenario": "The team proposes size classes after one trace shows poor reuse, but the trace mixes long-lived metadata with short-lived packet records.", "acceptanceCriteria": [ "Measure internal and external fragmentation separately", "Replay at least three declared lifetime distributions", "Compare reset-only, free-list, and size-class approaches with correctness held constant" ], "implementationNotes": [ "Do not select an allocator from mean throughput alone; retain raw workload seeds and peak memory." ], "verification": [ "Reproduce each workload and its fragmentation measurements.", "Change the seed and show the report identifies noncomparable runs." ], "deliverables": [ "Allocator comparison with workload manifest" ], "rollout": "Adopt additional complexity only if the declared workload crosses an agreed bound.", "skills": [ "Benchmarking", "Allocator design", "Experimental design" ], "fieldMix": [ { "field": "Systems programming", "percentage": 60 }, { "field": "Performance engineering", "percentage": 40 } ], "patterns": [] }, { "id": "5a906b2f-9d95-48d7-8a5b-dcc610e1b236", "key": "SMEM-107", "title": "Contain unsafe decoding behind a length-checked cursor", "type": "STORY", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "control", "dependsOn": [ "SMEM-103" ], "scenario": "Several parsers perform pointer arithmetic independently; one reads a declared payload length before confirming those bytes remain.", "acceptanceCriteria": [ "One cursor owns offset advancement and remaining-length checks", "Primitive reads define endianness and alignment behavior", "A failed read returns no partially initialized value" ], "implementationNotes": [ "Fuzz only the local parser process and cap input length, nesting, and execution time." ], "verification": [ "Decode a complete packet containing every primitive type.", "Truncate at every byte boundary and run the corpus under sanitizer or Miri." ], "deliverables": [ "Checked decode cursor, fuzz corpus, and unsafe-boundary note" ], "rollout": "Route one packet family at a time through the cursor and retain the prior decoder for comparison.", "skills": [ "Unsafe code review", "Binary parsing", "Fuzzing" ], "fieldMix": [ { "field": "Systems programming", "percentage": 65 }, { "field": "Security", "percentage": 35 } ], "patterns": [] }, { "id": "808bc159-f44e-44f3-b2cb-17fd30f14616", "key": "SMEM-108", "title": "Expose arena pressure without logging packet contents", "type": "CHORE", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "operate", "dependsOn": [ "SMEM-102", "SMEM-106" ], "scenario": "Operators can see allocation failures only in verbose decoder logs that include synthetic payload bytes and unbounded record labels.", "acceptanceCriteria": [ "Publish bounded counters for allocations, spills, resets, and exhaustion", "Record capacity and high-water mark without payload content", "Reject unbounded caller-provided metric dimensions" ], "implementationNotes": [ "Metrics are diagnostic observations for this component, not proof of production capacity." ], "verification": [ "Drive allocations and reconcile counters with the deterministic workload.", "Supply a unique record label per request and confirm it cannot become a dimension." ], "deliverables": [ "Bounded arena telemetry and reconciliation test" ], "rollout": "Enable metrics before changing allocation policy; remove verbose payload logging.", "skills": [ "Observability", "Privacy", "Cardinality control" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Site reliability", "percentage": 30 } ], "patterns": [] }, { "id": "6b2eedee-57ee-4ae5-a811-778eab500fbd", "key": "SMEM-109", "title": "Recover a persisted arena snapshot only when its layout matches", "type": "TASK", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "operate", "dependsOn": [ "SMEM-105", "SMEM-107" ], "scenario": "A warm-start experiment maps a snapshot written by an older layout and interprets its free-list metadata as current records.", "acceptanceCriteria": [ "Snapshot header binds format version, byte order, size, and checksum", "Recovery validates every offset before exposing records", "Unknown versions fail closed without modifying the snapshot" ], "implementationNotes": [ "Use generated snapshots only; memory mapping does not make untrusted offsets safe." ], "verification": [ "Write and restore a current snapshot with identical logical records.", "Corrupt each header field and one nested offset, then confirm rejection." ], "deliverables": [ "Versioned snapshot reader and corruption matrix" ], "rollout": "Keep cold reconstruction as the default until compatible recovery is repeatable.", "skills": [ "Persistence formats", "Validation", "Recovery" ], "fieldMix": [ { "field": "Systems programming", "percentage": 65 }, { "field": "Storage systems", "percentage": 35 } ], "patterns": [] }, { "id": "f587f003-d80b-4966-9f94-2178df30a59d", "key": "SMEM-110", "title": "Hand off the arena with explicit reasons not to use it", "type": "BUG", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "operate", "dependsOn": [ "SMEM-106", "SMEM-108", "SMEM-109" ], "scenario": "A second team wants the arena for long-lived session objects even though reset semantics and spill behavior were designed for packet batches.", "acceptanceCriteria": [ "Document supported lifetimes, alignment, capacity, thread-safety, and reset rules", "List measured bounds and unresolved risks with reproduction commands", "Include rejection examples for workloads better served by standard allocation" ], "implementationNotes": [ "Do not present local benchmark results as universal performance claims." ], "verification": [ "Have a reviewer reproduce one supported workload from a clean checkout.", "Apply the documented long-lived workload and confirm the guide recommends against adoption." ], "deliverables": [ "Usage contract, decision record, and reproducible handoff" ], "rollout": "Require a separate review before any new workload adopts the component.", "skills": [ "Technical writing", "API contracts", "Operational handoff" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Developer tooling", "percentage": 30 } ], "patterns": [] } ], "id": "2a56d313-8b40-49e7-83a7-21d05effd695" } ] }