{ "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": "SRUNTIME", "title": "Evolve a bounded bytecode runtime without executing host code", "field": "Systems programming", "summary": "Implement decoding, stack safety, resource budgets and compatible bytecode revisions.", "context": "A fictional rules engine executes a tiny arithmetic bytecode over synthetic integers. Its interpreter trusts jump offsets and can run forever. Build a local Rust runtime; it has no filesystem, network, dynamic loading, host calls, or candidate-source execution.", "stack": [ "Rust", "Bytecode fixtures", "Property tests", "Fuzzing" ], "prerequisites": [ "Stacks", "Instruction decoding", "Control flow" ], "developerValue": "Practice runtime invariants, validation, resource accounting and compatibility.", "companyValue": "Review a constrained execution component whose malformed programs fail deterministically without gaining host capabilities.", "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": "dded49ac-11a5-4f77-980b-98a1e72fe2ca", "key": "SRUNTIME-101", "title": "Decode instructions without reading past the bytecode buffer", "type": "TASK", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "model", "dependsOn": [], "scenario": "A truncated PUSH instruction reads its operand from bytes beyond the supplied program.", "acceptanceCriteria": [ "Decoder checks opcode and operand length before advancing", "Unknown opcodes return a stable offset and code", "Failure exposes no partially decoded instruction" ], "implementationNotes": [ "Keep bytecode length bounded before parsing." ], "verification": [ "Decode a program containing every documented instruction.", "Truncate at every byte and confirm deterministic errors without panic." ], "deliverables": [ "Checked decoder and truncation matrix" ], "rollout": "Reject programs not validated by the new decoder.", "skills": [ "Binary parsing", "Bounds checking" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Compiler and language tooling", "percentage": 30 } ], "patterns": [] }, { "id": "417fa830-641c-4a0f-83e3-a022f5fda1ee", "key": "SRUNTIME-102", "title": "Validate stack depth across both sides of a branch", "type": "BUG", "priority": "MEDIUM", "difficulty": "FOUNDATIONAL", "estimateMinutes": 90, "phaseId": "model", "dependsOn": [ "SRUNTIME-101" ], "scenario": "One branch pushes a value and the other does not, so the merge point underflows only for certain inputs.", "acceptanceCriteria": [ "Validator computes required and resulting depth per instruction", "Control-flow merges require compatible stack shape", "Maximum stack depth is bounded before execution" ], "implementationNotes": [ "Validation must terminate on loops through a visited-state worklist." ], "verification": [ "Validate a diamond control flow with matching stack shapes.", "Change one branch to omit a push and reject the merge." ], "deliverables": [ "Stack-shape validator and branch fixtures" ], "rollout": "Keep runtime stack checks even after static validation.", "skills": [ "Data-flow analysis", "Stacks" ], "fieldMix": [ { "field": "Systems programming", "percentage": 60 }, { "field": "Compiler and language tooling", "percentage": 40 } ], "patterns": [] }, { "id": "5a6d05ea-d97f-4080-acf8-e772edc2d9c2", "key": "SRUNTIME-103", "title": "Reject jumps that land inside instruction operands", "type": "STORY", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "model", "dependsOn": [ "SRUNTIME-101", "SRUNTIME-102" ], "scenario": "A crafted jump targets the second byte of a literal and reinterprets it as an opcode.", "acceptanceCriteria": [ "Decoder records every legal instruction boundary", "Jump targets must reference a boundary in the same program", "Backward jumps remain permitted within the execution budget" ], "implementationNotes": [ "Do not normalize invalid offsets to the nearest instruction." ], "verification": [ "Execute forward and backward jumps to valid boundaries.", "Target each byte inside a multi-byte operand and reject validation." ], "deliverables": [ "Boundary-indexed control-flow validation" ], "rollout": "Invalidate cached programs when the instruction format version changes.", "skills": [ "Control flow", "Validation" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Security", "percentage": 30 } ], "patterns": [] }, { "id": "a1bcff17-ab03-4369-b58f-034b0f88cdd2", "key": "SRUNTIME-104", "title": "Report integer overflow instead of changing arithmetic by build mode", "type": "CHORE", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "control", "dependsOn": [ "SRUNTIME-101" ], "scenario": "Debug builds trap on addition overflow while optimized builds wrap, producing different rule outcomes.", "acceptanceCriteria": [ "Arithmetic semantics are identical across build profiles", "Overflow returns a typed runtime fault with instruction offset", "Division defines zero and minimum-value edge cases" ], "implementationNotes": [ "Use checked operations; do not expose floating-point values in this bytecode revision." ], "verification": [ "Evaluate boundary-safe addition, subtraction, multiplication, and division.", "Exercise every overflow boundary and division by zero in both profiles." ], "deliverables": [ "Arithmetic contract and profile-parity tests" ], "rollout": "Version any intentional arithmetic semantic change.", "skills": [ "Integer arithmetic", "Compatibility" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Quality engineering", "percentage": 30 } ], "patterns": [] }, { "id": "0507f331-7700-462c-a48c-7390b8ce2a95", "key": "SRUNTIME-105", "title": "Stop infinite programs with a deterministic instruction budget", "type": "TASK", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "control", "dependsOn": [ "SRUNTIME-103", "SRUNTIME-104" ], "scenario": "A backward jump with an always-true condition consumes a worker indefinitely.", "acceptanceCriteria": [ "Caller supplies a positive maximum instruction count", "Every executed instruction consumes budget", "Exhaustion returns current offset and no successful result" ], "implementationNotes": [ "Wall-clock timeout can be defense in depth but is not the deterministic oracle." ], "verification": [ "Run a terminating loop at exactly the declared budget.", "Run an infinite loop and verify failure at the same step in repeated executions." ], "deliverables": [ "Instruction metering and loop-bound tests" ], "rollout": "Begin with a conservative budget and expose exhaustion separately from invalid bytecode.", "skills": [ "Resource metering", "Determinism" ], "fieldMix": [ { "field": "Systems programming", "percentage": 60 }, { "field": "Security", "percentage": 40 } ], "patterns": [] }, { "id": "b11d5fb5-74e6-402b-96df-7ea4b373ed91", "key": "SRUNTIME-106", "title": "Bound heap-like values without adding a garbage collector", "type": "BUG", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "control", "dependsOn": [ "SRUNTIME-102", "SRUNTIME-105" ], "scenario": "A proposed LIST instruction allocates on every loop iteration and the prototype retains all intermediate values.", "acceptanceCriteria": [ "Compare arena reset, reference counting, and no-list alternatives for the bounded language", "Chosen design defines maximum live bytes and value count", "Budget failure releases all runtime-owned allocations" ], "implementationNotes": [ "Do not introduce tracing collection without a workload and cycle requirement that needs it." ], "verification": [ "Evaluate a bounded list program and reconcile peak live bytes.", "Allocate until the value budget and confirm clean failure without leaks." ], "deliverables": [ "Memory strategy decision and bounded-value prototype" ], "rollout": "Keep LIST disabled until the memory contract is accepted.", "skills": [ "Runtime memory", "Tradeoff analysis", "Leak testing" ], "fieldMix": [ { "field": "Systems programming", "percentage": 60 }, { "field": "Performance engineering", "percentage": 40 } ], "patterns": [] }, { "id": "52c9e232-7a46-4068-a102-65e8ab8ffc84", "key": "SRUNTIME-107", "title": "Cache validated programs without confusing bytecode revisions", "type": "STORY", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "control", "dependsOn": [ "SRUNTIME-103", "SRUNTIME-105" ], "scenario": "A cached validation result for version one is reused after an opcode gains a wider operand in version two.", "acceptanceCriteria": [ "Cache identity binds exact bytes, bytecode version, validator version, and limits", "Validation failure is not cached across a newer validator", "Hash collision handling cannot return another program" ], "implementationNotes": [ "Cache entries contain immutable validated metadata and bounded program bytes only." ], "verification": [ "Reuse one validated program under identical authority.", "Change each identity dimension and require a miss; inject a key collision and compare bytes." ], "deliverables": [ "Versioned validation cache and collision tests" ], "rollout": "Enable read-through caching after hit/miss telemetry reconciles with validation calls.", "skills": [ "Cache correctness", "Versioning", "Hashing" ], "fieldMix": [ { "field": "Systems programming", "percentage": 60 }, { "field": "Compiler and language tooling", "percentage": 40 } ], "patterns": [] }, { "id": "505583a3-2b61-4b78-a236-88d876b31589", "key": "SRUNTIME-108", "title": "Make runtime faults useful without leaking input values", "type": "CHORE", "priority": "HIGH", "difficulty": "ADVANCED", "estimateMinutes": 240, "phaseId": "operate", "dependsOn": [ "SRUNTIME-104", "SRUNTIME-105" ], "scenario": "Fault logs dump the full operand stack, which may later contain customer-derived values, while omitting the bytecode revision needed for diagnosis.", "acceptanceCriteria": [ "Fault records contain code, instruction offset, runtime version, and bounded trace identity", "Operand values and full program bytes are excluded", "Repeated identical faults aggregate under bounded dimensions" ], "implementationNotes": [ "Use synthetic values in the exercise and keep generic analytics content-free." ], "verification": [ "Produce each fault class and reconcile its diagnostic fields.", "Push a sentinel value and confirm it appears in no log or metric." ], "deliverables": [ "Redacted runtime fault schema and tests" ], "rollout": "Replace verbose stack dumps before adding any non-synthetic inputs.", "skills": [ "Observability", "Data minimization" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Privacy engineering", "percentage": 30 } ], "patterns": [] }, { "id": "7f50584a-5d7c-4655-8029-7d694831deee", "key": "SRUNTIME-109", "title": "Load a new runtime revision without changing in-flight programs", "type": "TASK", "priority": "HIGH", "difficulty": "EXPERT", "estimateMinutes": 360, "phaseId": "operate", "dependsOn": [ "SRUNTIME-107", "SRUNTIME-108" ], "scenario": "Reloading the opcode table mutates a global registry while workers execute programs validated under the old table.", "acceptanceCriteria": [ "Each execution binds one immutable runtime revision", "New programs select only fully initialized revisions", "Retirement waits for in-flight references without blocking unrelated execution" ], "implementationNotes": [ "Avoid a mutable Singleton registry; publish immutable snapshots through explicit ownership." ], "verification": [ "Run old and new program revisions concurrently and verify their semantics.", "Attempt a partial revision load and confirm no execution can select it." ], "deliverables": [ "Revision registry, concurrent load test, and retirement protocol" ], "rollout": "Publish one synthetic revision behind an explicit selector and retain rollback to the prior snapshot.", "skills": [ "Versioned runtime", "Concurrency", "Immutability" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Platform engineering", "percentage": 30 } ], "patterns": [ { "pattern": "singleton", "activity": "REMOVE", "focus": "Replace the mutable process-wide opcode registry with immutable runtime revision snapshots bound explicitly to each execution." } ] }, { "id": "47a65cd7-89ea-4bd4-993e-3dcbfa293738", "key": "SRUNTIME-110", "title": "Fuzz the runtime under fixed memory and step limits", "type": "BUG", "priority": "MEDIUM", "difficulty": "INTERMEDIATE", "estimateMinutes": 150, "phaseId": "operate", "dependsOn": [ "SRUNTIME-105", "SRUNTIME-106", "SRUNTIME-108" ], "scenario": "Random bytecode tests occasionally hang or consume the test host, so the suite is disabled in continuous integration.", "acceptanceCriteria": [ "Harness caps input bytes, instructions, value memory, and wall-clock defense", "Every failure records a minimized reproducible seed", "Crash, panic, timeout, and semantic disagreement are distinct outcomes" ], "implementationNotes": [ "Run only the capability-free local runtime; never execute generated host code." ], "verification": [ "Replay the checked-in seed corpus with deterministic results.", "Seed malformed loops and oversized allocations and confirm bounded termination." ], "deliverables": [ "Bounded fuzz harness and minimized regression corpus" ], "rollout": "Start with a short deterministic CI corpus and schedule longer local runs separately.", "skills": [ "Fuzzing", "Resource limits", "Reproducibility" ], "fieldMix": [ { "field": "Systems programming", "percentage": 70 }, { "field": "Quality engineering", "percentage": 30 } ], "patterns": [] } ], "id": "fcf41c09-df30-436e-b87a-6fd8bb78ab02" } ] }