# 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. ## BSLO — Checkout service-level objectives A fictional checkout service reports process uptime while customers experience failed orders and slow confirmations. **Field:** Site reliability. **Suggested stack:** TypeScript, Prometheus, HTTP. **Engineer value:** Practice SLI semantics, alert evaluation, and reliability tradeoffs. **Company value:** Align reliability discussions with customer outcomes and explicit measurement limits. **Delivery agreement:** Deliver executable indicator queries, alert fixtures, and an SLO decision record. ### Setup prerequisites - Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. ### Define indicators Specify measurable user outcomes and valid denominators. #### BSLO-101 — Define eligible checkout attempts and successful completion **Task · Medium priority · Foundational** noCV practice brief v5 · BSLO-101 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Define indicators. Depends on: No preceding ticket. Difficulty: Foundational. Estimated focused work: 60 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 100%. Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence. Availability reports count health checks as customer success. Acceptance criteria - Define eligible attempts and completion deadlines. - Exclude synthetic probes from customer denominators. - Document validation failures and abandoned checkouts separately. Implementation constraints - Do not exclude service failures to improve the ratio. Verification - Classify representative success and failure traces. - Reject a denominator that includes only completed orders. Deliverables - SLI event contract. Rollout and recovery: Review event semantics before publishing an objective. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. #### BSLO-102 — Deduplicate retried checkout attempts in indicator calculations **Bug · High priority · Intermediate** noCV practice brief v5 · BSLO-102 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Define indicators. Depends on: BSLO-101. Difficulty: Intermediate. Estimated focused work: 150 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 60% · Data engineering 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. Client retries inflate both request volume and apparent success. Acceptance criteria - Count one logical attempt under the declared identity. - Preserve retry observations separately. - Flag missing identities without guessing deduplication. Implementation constraints - Avoid user-identifying metric labels. Verification - Count a retried successful attempt once. - Expose ambiguous records with missing attempt IDs. Deliverables - Deduplicated indicator query. Rollout and recovery: Compare old and new counts before switching dashboards. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. ### Compute and alert Handle missing data and evaluate budget burn. #### BSLO-103 — Compute completion latency from consistent event pairs **Task · High priority · Advanced** noCV practice brief v5 · BSLO-103 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Compute and alert. Depends on: BSLO-102. Difficulty: Advanced. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 60% · Data engineering 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. Latency is measured from different start events across client versions. Acceptance criteria - Specify start and completion event semantics. - Reject negative or unmatched durations. - Track excluded samples and instrumentation version. Implementation constraints - State clock assumptions explicitly. Verification - Compute known synthetic durations. - Detect clock skew and unmatched completion events. Deliverables - Latency indicator implementation. Rollout and recovery: Run both definitions during comparison; retain the prior dashboard for diagnosis. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. #### BSLO-104 — Keep missing telemetry distinct from successful service **Bug · High priority · Intermediate** noCV practice brief v5 · BSLO-104 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Compute and alert. Depends on: BSLO-103. Difficulty: Intermediate. Estimated focused work: 120 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 80% · Frontend 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 metrics outage produces an empty query that the dashboard renders as healthy. Acceptance criteria - Represent no data separately from zero failures. - Display data freshness and coverage. - Alert on measurement failure independently. Implementation constraints - Unknown reliability cannot consume zero budget by default. Verification - Show healthy complete telemetry. - Drop a source stream and display unknown coverage. Deliverables - Missing-data handling. Rollout and recovery: Enable measurement alerts before relying on budget policy. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. #### BSLO-105 — Implement multi-window error-budget burn calculations **Task · High priority · Advanced** noCV practice brief v5 · BSLO-105 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Compute and alert. Depends on: BSLO-102, BSLO-104. Difficulty: Advanced. Estimated focused work: 210 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 70% · Data engineering 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 brief spike pages the team while a slower sustained incident passes unnoticed. Acceptance criteria - Calculate burn against the declared objective. - Require aligned short and long windows for the chosen alert. - Handle window edges and low sample counts explicitly. Implementation constraints - Thresholds are scenario assumptions, not universal defaults. Verification - Trigger on sustained synthetic burn. - Avoid paging for an isolated low-volume failure under the documented policy. Deliverables - Burn-rate queries and fixtures. Rollout and recovery: Run alerts without notifications locally before operational adoption. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. #### BSLO-106 — Separate dependency failure from the customer-facing objective **Task · Medium priority · Advanced** noCV practice brief v5 · BSLO-106 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Compute and alert. Depends on: BSLO-105. Difficulty: Advanced. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 80% · System 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. The team wants to exclude payment-provider outages from checkout reliability. Acceptance criteria - Keep customer outcome accounting intact. - Add dependency attribution as a separate diagnostic dimension. - Expose uncertain attribution without changing the denominator. Implementation constraints - Do not transfer responsibility by redefining failed outcomes away. Verification - Count a dependency-caused customer failure. - Show attribution missing while retaining the failure. Deliverables - Attribution dashboard contract. Rollout and recovery: Add diagnostics alongside the objective; preserve historical customer outcomes. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. ### Use the objective Connect reliability policy to reviewable operational decisions. #### BSLO-107 — Define release actions for exhausted error budget **Task · High priority · Expert** noCV practice brief v5 · BSLO-107 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Use the objective. Depends on: BSLO-105, BSLO-106. Difficulty: Expert. Estimated focused work: 300 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 80% · System 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 exhausted budget triggers a blanket release freeze, including urgent reliability fixes. Acceptance criteria - Distinguish feature, risk-reduction, and emergency changes. - Define reviewed exception authority and expiry. - Compare business urgency against measured reliability risk. Implementation constraints - Policy provides decision support, not automatic business authority. Verification - Apply policy to a normal feature release. - Document an emergency exception with unresolved risks. Deliverables - Error-budget policy decision record. Rollout and recovery: Trial the policy in a tabletop; preserve human release accountability. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. #### BSLO-108 — Build an SLO dashboard with bounded diagnostic dimensions **Story · Medium priority · Intermediate** noCV practice brief v5 · BSLO-108 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Use the objective. Depends on: BSLO-106. Difficulty: Intermediate. Estimated focused work: 150 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 50% · Frontend 30% · Privacy 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. Engineers cannot relate budget burn to endpoint versions without exposing user data. Acceptance criteria - Show objective, burn, eligible volume, and coverage. - Allow only bounded endpoint/version dimensions. - Keep customer identifiers out of labels and URLs. Implementation constraints - Dashboard totals must reconcile with source fixtures. Verification - Reconcile known synthetic totals. - Reject an unbounded user-ID dimension. Deliverables - SLO dashboard definition. Rollout and recovery: Publish read-only views first; restore prior queries if totals diverge. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. #### BSLO-109 — Rehearse an objective change without rewriting historical results **Task · High priority · Advanced** noCV practice brief v5 · BSLO-109 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Use the objective. Depends on: BSLO-107, BSLO-108. Difficulty: Advanced. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 70% · Data engineering 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 new completion deadline would make last month's results look better if applied retrospectively. Acceptance criteria - Version objective and indicator definitions. - Compute new results from an explicit effective time. - Preserve historical values under their original definition. Implementation constraints - Show comparison overlap without relabeling old performance. Verification - Run old and new definitions on the same fixture. - Verify historical records remain bound to the old version. Deliverables - SLO revision rehearsal. Rollout and recovery: Run overlapping views before changing the active objective. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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. #### BSLO-110 — Write an SLO interpretation guide for low-traffic periods **Chore · Low priority · Foundational** noCV practice brief v5 · BSLO-110 · Checkout service-level objectives Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Use the objective. Depends on: BSLO-109. Difficulty: Foundational. Estimated focused work: 60 minutes; setup and prerequisite tickets are additional. Estimated field mix: Site reliability 100%. 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 single failure overnight produces a dramatic percentage without explaining the sample size. Acceptance criteria - Display eligible event count with the ratio. - Explain low-volume uncertainty. - Document when to inspect individual synthetic traces. Implementation constraints - Avoid promises of perfect reliability. Verification - Interpret one failure in a small sample. - Distinguish zero traffic from a healthy measured window. Deliverables - SLO interpretation guide. Rollout and recovery: Link guidance from dashboards and alert descriptions. Project prerequisites: Create synthetic request and order-event traces plus a local query or metrics fixture; no production telemetry required. Engineer value: Practice SLI semantics, alert evaluation, and reliability tradeoffs. Company value: Align reliability discussions with customer outcomes and explicit measurement limits. 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.