# 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. ## ARULE — Ship a reviewable pricing-rule service A fictional parts supplier combines contract prices with promotions. Sales needs repeatable quotes when rules change during checkout. **Field:** Backend. **Suggested stack:** TypeScript, PostgreSQL, JSON Schema. **Engineer value:** Practice deterministic rule evaluation, revision control and bounded execution. **Company value:** Review explainable commercial rules without trusting opaque price changes. **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 synthetic products and integer minor-unit prices. - Implement a small local quote API. ### Constrain rule input Define a safe, deterministic rule language. #### ARULE-101 — Define the supported promotion predicates without executable expressions **Task · Medium priority · Foundational** noCV practice brief v5 · ARULE-101 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Constrain rule input. Depends on: No preceding ticket. Difficulty: Foundational. Estimated focused work: 90 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 60% · API design 20% · Security 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. Sales requested a formula textbox; evaluating arbitrary expressions would make quote behavior difficult to bound and audit. Acceptance criteria - Allow explicit product, quantity and date predicates. - Reject unknown operators and excessive nesting. - Publish a schema with accepted and rejected examples. Implementation constraints - Treat rule documents as data; never evaluate source strings. Verification - Parse a quantity-band promotion. - Reject a function expression and a nesting-limit violation. Deliverables - Promotion schema and parser cases Rollout and recovery: Accept drafts only initially; disable new drafts if parser compatibility fails. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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. #### ARULE-102 — Resolve overlapping promotions with an explicit tie-break policy **Task · Medium priority · Intermediate** noCV practice brief v5 · ARULE-102 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Constrain rule input. Depends on: ARULE-101. Difficulty: Intermediate. Estimated focused work: 150 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 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. Two promotions match the same part and the chosen discount depends on database return order. Acceptance criteria - Define priority and stable-ID tie breaking. - Return the winning rule and losing-match reasons. - Evaluation is independent of input array order. Implementation constraints - Use integer arithmetic and a documented rounding boundary. Verification - Shuffle matching rules and retain the same price. - Exercise equal priorities and invalid discount bounds. Deliverables - Deterministic resolver and ordering tests Rollout and recovery: Compare decisions on synthetic quotes; retain the previous resolver version for rollback. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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. #### ARULE-103 — Validate promotion date ranges before publishing drafts **Bug · Medium priority · Foundational** noCV practice brief v5 · ARULE-103 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Constrain rule input. Depends on: ARULE-101. Difficulty: Foundational. Estimated focused work: 60 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 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 promotion with its end before its start passes draft review and can never apply. Acceptance criteria - Require offset-bearing UTC-normalizable dates. - Reject empty and reversed ranges at publication. - Display validation paths without raw rule documents in logs. Implementation constraints - Use half-open intervals consistently. Verification - Publish an adjacent pair of valid promotions. - Reject reversed, missing-offset and empty intervals. Deliverables - Publication date guard Rollout and recovery: Deploy guard for unpublished drafts; preserve existing published versions. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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 frozen rules Make quote decisions consistent and auditable. #### ARULE-104 — Freeze product and rule versions when a quote is accepted **Story · High priority · Advanced** noCV practice brief v5 · ARULE-104 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Apply frozen rules. Depends on: ARULE-102, ARULE-103. Difficulty: Advanced. Estimated focused work: 240 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 60% · Database 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. A buyer accepts a quote after a promotion edit and receives a different total from the amount previously displayed. Acceptance criteria - Accepted quotes retain product and rule version identities. - Acceptance checks expiry and expected quote revision. - Retries resolve one accepted quote with an unchanged total. Implementation constraints - Store a canonical calculation input hash with the quote. Verification - Accept a quote after changing current rules and retain its frozen total. - Attempt acceptance after expiry and create no order. Deliverables - Quote acceptance command and frozen-input checks Rollout and recovery: Enable acceptance for synthetic accounts; suspend new acceptance while preserving accepted records. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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. #### ARULE-105 — Bound pricing work for a cart with many matching rules **Task · Medium priority · Expert** noCV practice brief v5 · ARULE-105 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Apply frozen rules. Depends on: ARULE-102. Difficulty: Expert. Estimated focused work: 300 minutes; setup and prerequisite tickets are additional. Estimated field mix: Performance engineering 50% · Backend 50%. 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 unusually broad rule set makes checkout evaluate thousands of predicates per item and blocks unrelated quotes. Acceptance criteria - Set explicit cart, rule-count and predicate-work limits. - Reject over-budget requests before partial quote publication. - Return a bounded-work error distinct from invalid pricing. Implementation constraints - Choose limits from a repeatable local synthetic workload and document conditions. Verification - Measure work counters for 100 items and 200 rules. - Exceed each limit and verify no accepted quote is created. Deliverables - Evaluation budget and reproducible workload Rollout and recovery: Canary limits in observation mode; lower admitted work or restore prior limits on regressions. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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. #### ARULE-106 — Keep negotiated account prices outside shared quote caches **Bug · High priority · Advanced** noCV practice brief v5 · ARULE-106 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Apply frozen rules. Depends on: ARULE-104. Difficulty: Advanced. Estimated focused work: 210 minutes; setup and prerequisite tickets are additional. Estimated field mix: Security 50% · Backend 50%. 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 shared cache returns one customer's negotiated rate to another account requesting the same product list. Acceptance criteria - Bind cache identity to organization, account and frozen price version. - Authorize before cache lookup. - Never cache an authorization failure as a valid quote. Implementation constraints - Include all price-affecting inputs in canonical cache keys. Verification - Quote identical carts for two negotiated-price accounts. - Attempt cross-account access and inspect cache hits and response fields. Deliverables - Scoped cache key and isolation regression Rollout and recovery: Invalidate the affected namespace before enabling the new key format. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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. #### ARULE-107 — Report why a cart missed a promotion without leaking contract terms **Story · Medium priority · Intermediate** noCV practice brief v5 · ARULE-107 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Apply frozen rules. Depends on: ARULE-102, ARULE-106. Difficulty: Intermediate. Estimated focused work: 150 minutes; setup and prerequisite tickets are additional. Estimated field mix: Security 50% · Backend 30% · 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. Sales wants to explain an unmet minimum quantity, but the current debug endpoint exposes every account's price rules. Acceptance criteria - Explain only rules visible to the requesting account. - Show failed predicate names with permitted thresholds. - Omit internal contract identifiers and unrelated rule matches. Implementation constraints - Build a dedicated explanation projection. Verification - Explain a visible minimum-quantity miss. - Request explanation for an inaccessible contract and receive no rule details. Deliverables - Scoped pricing explanation endpoint Rollout and recovery: Enable the projection for one synthetic sales role; disable debug routes on disclosure failure. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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. ### Release rule versions Compare revisions and recover rejected releases. #### ARULE-108 — Compare a draft pricing revision against a named quote corpus **Chore · Medium priority · Intermediate** noCV practice brief v5 · ARULE-108 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Release rule versions. Depends on: ARULE-104, ARULE-107. Difficulty: Intermediate. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Quality engineering 50% · Backend 30% · Developer tooling 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 promotion revision fixes bulk orders but may unintentionally discount small carts. Acceptance criteria - Create and version a synthetic quote corpus. - Report old and new totals plus changed rule identities. - Flag unexplained differences before publication. Implementation constraints - The corpus is authored for this exercise; do not claim production coverage. Verification - Include bulk, small-cart and no-match examples. - Insert an invalid draft and report validation failure instead of a comparison. Deliverables - Revision comparison command and synthetic corpus Rollout and recovery: Require comparison review for draft publication; preserve earlier reports. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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. #### ARULE-109 — Publish a pricing revision with optimistic review protection **Story · High priority · Advanced** noCV practice brief v5 · ARULE-109 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Release rule versions. Depends on: ARULE-103, ARULE-108. Difficulty: Advanced. Estimated focused work: 240 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 60% · Database 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. A reviewer approves a draft while an editor changes its discount; publication currently activates content nobody reviewed. Acceptance criteria - Approval binds the exact canonical draft hash. - Publication rejects a changed draft or stale expected revision. - Published rule content cannot be updated in place. Implementation constraints - Commit active-pointer selection and audit metadata together. Verification - Publish an unchanged approved draft. - Edit between approval and publish and retain the previous active revision. Deliverables - Guarded publication command Rollout and recovery: Publish to synthetic accounts first; restore the prior active pointer without rewriting versions. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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. #### ARULE-110 — Replay a pricing dispute from immutable quote inputs **Task · Medium priority · Expert** noCV practice brief v5 · ARULE-110 · Ship a reviewable pricing-rule service Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Release rule versions. Depends on: ARULE-104, ARULE-109. Difficulty: Expert. Estimated focused work: 300 minutes; setup and prerequisite tickets are additional. Estimated field mix: Backend 70% · Developer tooling 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. Support receives a disputed total after three rule releases and cannot reproduce which calculation the buyer accepted. Acceptance criteria - Replay selects the recorded evaluator and input versions. - Report missing versions as unreproducible rather than guessing. - Compare computed total and hash with the accepted record. Implementation constraints - Keep replay read-only and use fabricated customer data. Verification - Replay an accepted synthetic quote across later releases. - Remove an available version in the test double and assert explicit failure. Deliverables - Read-only dispute replay and failure cases Rollout and recovery: Expose replay to scoped support users; revoke access if provenance cannot be resolved. Project prerequisites: Create synthetic products and integer minor-unit prices. Implement a small local quote API. Engineer value: Practice deterministic rule evaluation, revision control and bounded execution. Company value: Review explainable commercial rules without trusting opaque price changes. 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.