# 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. ## CPRES — Presence that remains honest during disconnection Fictional document team Pine shows collaboration presence for synthetic accounts. Build a loopback WebSocket server and injected clocks; no message content or activity surveillance is required. **Field:** Real-time systems. **Suggested stack:** TypeScript, WebSocket, Redis adapter, Vitest. **Engineer value:** Practice ephemeral state, ordering and reconnect semantics. **Company value:** Inspect whether online indicators avoid stale or unauthorized claims. **Delivery agreement:** Presence means an active connection lease only; it does not infer attention or productivity. ### Setup prerequisites - Create synthetic memberships and session identifiers. - Implement controllable sockets and an in-memory TTL adapter. ### Define presence meaning Specify scopes and expiry. #### CPRES-101 — Define online presence as an unexpired connection lease **Task · Medium priority · Foundational** noCV practice brief v5 · CPRES-101 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Define presence meaning. Depends on: No preceding ticket. Difficulty: Foundational. Estimated focused work: 75 minutes; setup and prerequisite tickets are additional. Estimated field mix: Real-time systems 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. A green dot remains after the browser closes. Replace the permanent flag with explicitly expiring presence. Acceptance criteria - Active lease shows connected - Expiry removes connected state - UI explains connection meaning Implementation constraints - Do not infer human attention from a socket. Verification - Advance clock before expiry - Advance beyond expiry without disconnect Deliverables - Lease contract and clock cases Rollout and recovery: Hide presence if lease freshness cannot be established. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. #### CPRES-102 — Validate presence room identifiers before subscribing **Bug · High priority · Foundational** noCV practice brief v5 · CPRES-102 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Define presence meaning. Depends on: No preceding ticket. Difficulty: Foundational. Estimated focused work: 75 minutes; setup and prerequisite tickets are additional. Estimated field mix: Security 50% · Real-time systems 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. Malformed room names reach the broker and create unbounded keys. Parse a bounded typed room identifier. Acceptance criteria - Valid room IDs subscribe - Malformed IDs fail before broker access - Error omits raw oversized input Implementation constraints - Room parsing does not replace membership checks. Verification - Subscribe valid fixture room - Send oversized room identifier Deliverables - Room parser and rejection tests Rollout and recovery: Reject new subscriptions if parsing fails. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. #### CPRES-103 — Scope presence membership checks to each room subscription **Task · High priority · Intermediate** noCV practice brief v5 · CPRES-103 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Define presence meaning. Depends on: CPRES-101, CPRES-102. Difficulty: Intermediate. Estimated focused work: 135 minutes; setup and prerequisite tickets are additional. Estimated field mix: Security 70% · Real-time systems 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. Authentication alone currently permits joining any document room. Require current membership in the room boundary. Acceptance criteria - Member can join - Foreign member is denied - Revoked membership cannot renew lease Implementation constraints - Recheck authority at renewal using local stub. Verification - Join authorized room - Revoke membership before renewal Deliverables - Subscription authorization and denial cases Rollout and recovery: Stop renewals while membership adapter is unavailable. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. ### Distribute state safely Handle identity and reconnect races. #### CPRES-104 — Count multiple presence connections without duplicating people **Story · Medium priority · Intermediate** noCV practice brief v5 · CPRES-104 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Distribute state safely. Depends on: CPRES-103. Difficulty: Intermediate. Estimated focused work: 120 minutes; setup and prerequisite tickets are additional. Estimated field mix: Real-time systems 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. Two tabs display the same teammate twice. Aggregate active connection leases under a scoped synthetic account. Acceptance criteria - One person entry per room - Closing one tab preserves other lease - Last expiry removes person Implementation constraints - Do not merge identities across organizations. Verification - Open two tabs - Expire last connection Deliverables - Presence aggregation and cases Rollout and recovery: Display connection counts only if person aggregation is incorrect. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. #### CPRES-105 — Reject stale presence heartbeats after reconnect **Bug · High priority · Advanced** noCV practice brief v5 · CPRES-105 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Distribute state safely. Depends on: CPRES-103, CPRES-104. Difficulty: Advanced. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Distributed systems 60% · Real-time 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. Delayed heartbeat from a replaced socket prolongs a dead session. Bind renewal to session generation. Acceptance criteria - New generation supersedes old - Old heartbeat cannot renew - Current heartbeat extends its own lease Implementation constraints - Generation changes must be atomic in the adapter. Verification - Renew current session - Deliver old heartbeat after reconnect Deliverables - Generation guard and race tests Rollout and recovery: Close superseded sessions and require fresh joins. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. #### CPRES-106 — Send a presence snapshot before incremental updates **Story · Medium priority · Advanced** noCV practice brief v5 · CPRES-106 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Distribute state safely. Depends on: CPRES-104, CPRES-105. Difficulty: Advanced. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Real-time systems 50% · Distributed systems 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 new client applies deltas to an empty list and misses existing teammates. Add snapshot sequencing at subscription. Acceptance criteria - Snapshot establishes sequence - Later deltas follow its watermark - Detected gaps trigger resnapshot Implementation constraints - Buffer during snapshot only within a documented limit. Verification - Join populated room - Drop one delta and detect gap Deliverables - Snapshot handshake and gap cases Rollout and recovery: Resend full snapshots while delta path is repaired. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. #### CPRES-107 — Expire presence independently of disconnect delivery **Bug · High priority · Expert** noCV practice brief v5 · CPRES-107 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Distribute state safely. Depends on: CPRES-101, CPRES-105, CPRES-106. Difficulty: Expert. Estimated focused work: 240 minutes; setup and prerequisite tickets are additional. Estimated field mix: Distributed systems 50% · Real-time systems 30% · Site reliability 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 server restart loses disconnect events and rooms retain ghosts. Make lease expiry authoritative across process recovery. Acceptance criteria - Restart cannot preserve expired entries - Cleanup repeats safely - Concurrent renewal cannot delete fresh lease Implementation constraints - Compare stored lease identity before removal. Verification - Restart with expired leases - Renew during cleanup Deliverables - Expiry reconciliation and interleaving cases Rollout and recovery: Disable cleanup writes if lease identity cannot be checked. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. ### Bound operating behavior Limit work and diagnose stale indicators. #### CPRES-108 — Cap presence fan-out per room without silently losing state **Task · Medium priority · Advanced** noCV practice brief v5 · CPRES-108 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Bound operating behavior. Depends on: CPRES-106. Difficulty: Advanced. Estimated focused work: 180 minutes; setup and prerequisite tickets are additional. Estimated field mix: Performance engineering 50% · Real-time systems 30% · Site reliability 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 synthetic busy room causes unbounded socket buffers. Introduce a per-client queue cap and resync fallback. Acceptance criteria - Buffer count is bounded - Overflow requests resnapshot - Healthy peers continue receiving Implementation constraints - Do not drop arbitrary deltas and claim synchronization. Verification - Exercise normal fan-out - Stall one client to capacity Deliverables - Bounded broadcaster and overflow cases Rollout and recovery: Disconnect slow clients with a clear resync reason. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. #### CPRES-109 — Distinguish disconnected and stale presence in the client **Story · Medium priority · Intermediate** noCV practice brief v5 · CPRES-109 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Bound operating behavior. Depends on: CPRES-107, CPRES-108. Difficulty: Intermediate. Estimated focused work: 105 minutes; setup and prerequisite tickets are additional. Estimated field mix: Frontend 60% · Real-time 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. Network loss freezes green dots and suggests teammates remain connected. Mark stale state during transport uncertainty. Acceptance criteria - Local disconnect marks snapshot stale - Reconnect waits for fresh snapshot - Stale entries are not labeled online Implementation constraints - Preserve names only while room access remains valid. Verification - Disconnect then reconnect - Lose authorization during reconnect Deliverables - Presence freshness UI Rollout and recovery: Hide entries during uncertainty if freshness labeling fails. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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. #### CPRES-110 — Expose presence lease diagnostics without activity histories **Chore · Low priority · Intermediate** noCV practice brief v5 · CPRES-110 · Presence that remains honest during disconnection Fictional engineering practice briefs. Starter repositories, fixtures, automated grading, and verified ownership are not included. Phase: Bound operating behavior. Depends on: CPRES-109. Difficulty: Intermediate. Estimated focused work: 90 minutes; setup and prerequisite tickets are additional. Estimated field mix: Privacy engineering 50% · Site reliability 30% · Real-time 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. Operators need to locate ghost indicators without collecting behavioral timelines. Add current aggregate lease counters. Acceptance criteria - Counters include active and expired totals - No per-person activity history is stored - Room labels use bounded safe identifiers Implementation constraints - Use synthetic rooms in samples. Verification - Inspect healthy counters - Create expired lease and verify aggregation Deliverables - Diagnostic contract and samples Rollout and recovery: Disable diagnostics if person-level histories appear. Project prerequisites: Create synthetic memberships and session identifiers. Implement controllable sockets and an in-memory TTL adapter. Engineer value: Practice ephemeral state, ordering and reconnect semantics. Company value: Inspect whether online indicators avoid stale or unauthorized claims. 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.