# noCV engineering task library Content version 5 Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs. Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence. ## ADRIFT — Make subscription entitlements survive plan changes A fictional document service grants storage and collaboration rights from subscriptions. Support cannot explain why delayed events restore old limits. **Field:** Backend. **Suggested stack:** TypeScript, NestJS, PostgreSQL. **Engineer value:** Practice temporal rules, concurrency and explainable API decisions. **Company value:** Review whether entitlement changes preserve customer access and produce supportable decisions. **Delivery agreement:** Ten scoped tickets across three phases. Build a synthetic local service or select a ticket after recreating its prerequisites; estimates exclude setup. ### Setup prerequisites - Create a local subscription API with synthetic accounts. - Understand transactions and UTC intervals. ### Define effective rights Specify entitlement periods and failure responses. #### ADRIFT-101 — Specify the entitlement response at an exact effective instant **Task · Medium priority · Foundational** noCV practice brief v5 · ADRIFT-101 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Define effective rights. Depends on: No preceding ticket. Difficulty: Foundational. Estimated focused work: 90 minutes; setup and prerequisite tickets are additional. Estimated field mix: API design 60% · Backend 40%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. Support compares screenshots from two time zones and cannot tell which storage limit applied when an upload failed. Acceptance criteria - Return limit, effective UTC instant and plan revision. - Document inclusive start and exclusive end boundaries. - Reject an invalid timestamp without resolving rights. Implementation constraints - Use synthetic plan names and integer byte limits. Verification - Resolve immediately before and at a plan boundary. - Reject a timestamp without an offset and verify no write. Deliverables - Versioned response contract and boundary fixtures Rollout and recovery: Introduce the versioned read route; remove routing if consumers reject it. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. #### ADRIFT-102 — Keep manual account restrictions separate from plan allowances **Story · Medium priority · Intermediate** noCV practice brief v5 · ADRIFT-102 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Define effective rights. Depends on: ADRIFT-101. Difficulty: Intermediate. Estimated focused work: 150 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 70% · Security 30%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. A support restriction disappears when an account upgrades because both settings currently share one mutable limit. Acceptance criteria - Store restriction and plan allowance with separate provenance. - Return the effective minimum with both reasons. - Removing a restriction restores the current plan allowance. Implementation constraints - Restrict mutation to an authorized support role. Verification - Upgrade a restricted account and retain its lower limit. - Attempt a restriction change as a normal member and deny it. Deliverables - Restriction command and permission tests Rollout and recovery: Enable for synthetic accounts; disable mutation while retaining restriction history. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. #### ADRIFT-103 — Reject negative and fractional seat allowances consistently **Bug · Medium priority · Foundational** noCV practice brief v5 · ADRIFT-103 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Define effective rights. Depends on: ADRIFT-101. Difficulty: Foundational. Estimated focused work: 60 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 80% · API design 20%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. An administrative import accepts 2.5 seats, while the runtime truncates the value differently from the billing preview. Acceptance criteria - Accept only nonnegative safe integers for seat limits. - Use one validation rule for import and API commands. - Return the offending field without echoing the entire import. Implementation constraints - Represent unlimited explicitly rather than with negative sentinels. Verification - Create zero-seat and unlimited synthetic plans. - Reject fractional, negative and unsafe integer limits. Deliverables - Shared seat schema and import regression Rollout and recovery: Deploy validation before new imports; quarantine rejected rows for correction. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. ### Apply changes safely Preserve ordering and concurrent update invariants. #### ADRIFT-104 — Apply a scheduled downgrade only after its stored effective time **Story · High priority · Intermediate** noCV practice brief v5 · ADRIFT-104 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Apply changes safely. Depends on: ADRIFT-101, ADRIFT-103. Difficulty: Intermediate. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 80% · Distributed systems 20%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. A worker runs the next day's downgrade early when a retry executes against the server's local calendar date. Acceptance criteria - Compare a persisted UTC instant with an injected clock. - Early delivery leaves the schedule pending. - Repeated eligible delivery creates one entitlement revision. Implementation constraints - Persist the revision and dispatch record in one transaction. Verification - Advance a fake clock through the exact effective instant. - Deliver early and twice after the boundary; count one revision. Deliverables - Scheduled transition and deterministic-clock tests Rollout and recovery: Canary scheduled changes; pause the consumer and retain pending schedules on failure. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. #### ADRIFT-105 — Prevent a late upgrade event from undoing a newer cancellation **Bug · High priority · Advanced** noCV practice brief v5 · ADRIFT-105 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Apply changes safely. Depends on: ADRIFT-104. Difficulty: Advanced. Estimated focused work: 240 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 60% · Distributed systems 40%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. Provider events arrive out of order and an old upgrade reopens collaboration after cancellation became effective. Acceptance criteria - Compare provider sequence within each subscription. - Older events remain recorded without changing effective rights. - Equal sequence with different payload is surfaced as conflict. Implementation constraints - Do not order provider events by receipt timestamp. Verification - Replay cancellation followed by an older upgrade. - Submit contradictory equal-sequence events and preserve current rights. Deliverables - Ordering guard and conflicting-event report Rollout and recovery: Run the guard in audit mode first; quarantine conflicts without deleting events. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. #### ADRIFT-106 — Make plan switching and seat allocation share one consistency boundary **Task · High priority · Expert** noCV practice brief v5 · ADRIFT-106 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Apply changes safely. Depends on: ADRIFT-102, ADRIFT-104. Difficulty: Expert. Estimated focused work: 360 minutes; setup and prerequisite tickets are additional. Estimated field mix: Database engineering 60% · Backend 40%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. A downgrade races a seat invitation; both requests pass their reads and leave more active seats than permitted. Acceptance criteria - Serialize competing allowance and allocation changes per account. - One conflicting request returns a retryable conflict. - A failed transaction leaves both seat count and rights unchanged. Implementation constraints - Document the invariant and chosen locking order. Verification - Run a two-client barrier test for downgrade versus invitation. - Force transaction rollback and check both tables retain prior values. Deliverables - Transactional guard and concurrency reproduction Rollout and recovery: Introduce with lock-wait monitoring; revert command routing if contention exceeds the documented local budget. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. #### ADRIFT-107 — Preview entitlement changes without creating pending work **Story · Medium priority · Intermediate** noCV practice brief v5 · ADRIFT-107 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Apply changes safely. Depends on: ADRIFT-104, ADRIFT-105. Difficulty: Intermediate. Estimated focused work: 150 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 70% · API design 30%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. Sales wants to preview next month's downgrade, but the current preview endpoint creates a schedule visible to the worker. Acceptance criteria - Preview uses the same pure decision function as execution. - Return affected features and effective-time assumptions. - No schedule, outbox or audit mutation occurs on preview. Implementation constraints - Authorize account reads before computing the preview. Verification - Compare preview with a later applied synthetic change. - Repeat preview and assert unchanged row counts; deny another account. Deliverables - Pure preview operation and nonmutation checks Rollout and recovery: Expose preview behind a route flag; remove the route without touching schedules. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. ### Explain and recover Expose effective decisions and recover delayed changes. #### ADRIFT-108 — Explain a denied upload using the exact entitlement revision **Story · Medium priority · Advanced** noCV practice brief v5 · ADRIFT-108 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Explain and recover. Depends on: ADRIFT-105, ADRIFT-106. Difficulty: Advanced. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 70% · API design 30%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. An upload rejection says only limit exceeded, so support cannot connect it to the plan and restriction that were evaluated. Acceptance criteria - Return a stable denial code and evaluated revision ID. - Include byte limit and current usage without other accounts' data. - Keep historical revisions immutable for later explanation. Implementation constraints - Avoid storing document contents in decision logs. Verification - Reproduce a denial and resolve the same historical decision after upgrade. - Request another account's decision ID and return a nondisclosing denial. Deliverables - Decision projection and scoped history route Rollout and recovery: Enable explanation reads first; disable projection if privacy checks fail. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. #### ADRIFT-109 — Rebuild an account entitlement projection from its ordered history **Chore · Medium priority · Expert** noCV practice brief v5 · ADRIFT-109 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Explain and recover. Depends on: ADRIFT-105, ADRIFT-108. Difficulty: Expert. Estimated focused work: 360 minutes; setup and prerequisite tickets are additional. Estimated field mix: Data engineering 50% · Backend 30% · Database engineering 20%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. A projection bug affected a synthetic account; operators need to repair derived rights without rewriting the source change history. Acceptance criteria - Rebuild into a separate generation using deterministic ordering. - Compare differences before atomically selecting the generation. - Interrupted rebuild leaves the active projection usable. Implementation constraints - Require an account scope and dry-run mode. Verification - Compare a rebuilt generation with a clean reference history. - Interrupt before activation and prove the old generation still resolves. Deliverables - Scoped rebuild command and difference report Rollout and recovery: Dry-run one synthetic account; restore the previous generation pointer on mismatch. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence. #### ADRIFT-110 — Document the handoff for disputed effective entitlements **Task · Low priority · Foundational** noCV practice brief v5 · ADRIFT-110 · Make subscription entitlements survive plan changes Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Explain and recover. Depends on: ADRIFT-108, ADRIFT-109. Difficulty: Foundational. Estimated focused work: 90 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 60% · Site reliability 40%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. Support needs a repeatable path to investigate a rights dispute without editing rows directly or promising the wrong allowance. Acceptance criteria - Runbook starts from account, decision and revision identifiers. - Separate delayed-provider, restriction and usage causes. - Include escalation and projection rollback steps. Implementation constraints - Use fabricated examples and avoid raw customer identifiers. Verification - Follow the runbook for a scheduled downgrade dispute. - Follow the missing-history branch and confirm it stops before mutation. Deliverables - Support runbook and two worked synthetic incidents Rollout and recovery: Review the runbook with a fresh local reproduction; version corrections alongside the projection. Project prerequisites: Create a local subscription API with synthetic accounts. Understand transactions and UTC intervals. Engineer value: Practice temporal rules, concurrency and explainable API decisions. Company value: Review whether entitlement changes preserve customer access and produce supportable decisions. AI tools are welcome during implementation. Record assumptions, review the result, and verify its behavior. Planning status does not create Outcome Evidence or Ownership Evidence.