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Actions, Entities, Write Shapes, and Mechanisms by Archetype Cheat Sheet

Actions, Entities, Write Shapes, and Mechanisms by Archetype Cheat Sheet #

Use this as an internal derivation note.

Each line follows this form:

  • action -> entity touched (write shape, base mechanism)

For reads:

  • action -> entity touched (read source)
  • action -> entity touched (read projection)

This is useful because one line often gives you:

  1. the entity model
  2. the API shape
  3. the HLD owner
  4. the NFR posture
  5. the failure vocabulary

1. Current-Value Entity #

  • create X -> XState (create target, insert/create)
  • edit X -> XState (overwrite, versioned overwrite)
  • delete/archive X -> XState (state transition, guarded conditional update)
  • view X -> XState (read source)

2. Relation / Edge #

  • add relation -> XRelationState (state transition, guarded add/remove)
  • remove relation -> XRelationState (state transition, guarded add/remove)
  • view relation list -> XRelationState (read source)
  • view relation count -> XCountView (read projection)

3. Append-Only Child Object #

  • create child -> XChildState (append, append log/table)
  • edit child -> XChildState (overwrite, versioned overwrite)
  • delete/moderate child -> XChildState (state transition, guarded conditional update)
  • view thread/log -> XChildState or XThreadView (read source or read projection)

4. Workflow / Lifecycle State #

  • create request -> XWorkflowState (create target, insert/create)
  • approve/reject/cancel/start/complete -> XWorkflowState (state transition, guarded conditional update)
  • view status -> XWorkflowState (read source)

5. Derived Projection #

  • source write -> XSourceState (varies by source path)
  • update projection -> XView (overwrite, counter/projection update or materialized view update)
  • read projection -> XView (read projection)

6. Catalog + Scoped Relation #

  • create/update catalog entry -> XDefinitionState (create target/overwrite, insert/create or versioned overwrite)
  • attach X to parent -> ParentXRelationState (state transition, guarded add/remove)
  • remove X from parent -> ParentXRelationState (state transition, guarded add/remove)
  • search/top X -> XView (read projection)

7. Inventory / Constrained Resource #

  • view availability -> XInventoryState (read source)
  • reserve/allocate/release -> XInventoryState (state transition, guarded conditional update)

8. Critical Transaction Process #

  • start request -> XRequestState (create target, insert/create)
  • validate/approve/commit -> XTransactionState (state transition, guarded conditional update)
  • execute side effect -> XMovementState (state transition, outbox/worker or idempotent side-effect orchestration)
  • view status -> XTransactionState (read source)

9. Time-Bounded Exclusive Allocation #

  • create hold -> XHoldState + XInventoryState (state transition, guarded exclusive hold)
  • expire hold -> XHoldState + XInventoryState (state transition, expiry scan + guarded release)
  • confirm booking -> XBookingState + XInventoryState (state transition, guarded confirm/commit)
  • cancel booking -> XBookingState + XInventoryState (state transition, guarded release/restore)
  • view availability -> XInventoryState (read source)

10. Future Constraint + Claimable Run #

  • schedule work -> XScheduleState (create target, insert/create)
  • materialize due run -> XRunnableJobState (create target, due scan + create runnable job)
  • claim run -> XRunnableJobState (state transition, claim/lease)
  • complete/fail run -> XExecutionState or XRunnableJobState (state transition, guarded conditional update)
  • view history -> XHistoryView (read projection)

11. Frontier + Claimable Run #

  • initialize frontier -> XFrontierState (create target, insert/create)
  • materialize batch -> XBatchRunState (create target, guarded frontier advance + insert/create)
  • claim/process batch -> XBatchRunState (state transition, claim/lease)
  • advance checkpoint/frontier -> XCheckpointState / XFrontierState (state transition, guarded frontier advance)
  • view progress -> XProgressView (read projection)

12. Control Plane + Local Snapshot #

  • write config/policy -> XConfigState (overwrite, versioned overwrite)
  • publish snapshot -> XSnapshotState (create target/overwrite, snapshot publication)
  • apply snapshot locally -> XAppliedVersionState (state transition, monotonic version apply)
  • evaluate request -> XSnapshotState (read source from local snapshot)

13. Matching / Assignment #

  • create request -> XRequestState (create target, insert/create)
  • propose assignment -> XAssignmentState (state transition, guarded assignment/claim)
  • accept/reject/expire assignment -> XAssignmentState (state transition, guarded conditional update)
  • start/complete execution -> XExecutionState (state transition, guarded conditional update)
  • view current state -> XRequestState / XAssignmentState / XExecutionState (read source)

14. Ranking / Leaderboard / Current Best #

  • append submission -> XSubmissionState (append, append log/table)
  • update best/aggregate -> XBestState / XAggregateState (overwrite, counter/projection update)
  • serve leaderboard -> XLeaderboardView (read projection)

15. Realtime Fanout #

  • append message/comment -> XMessageState (append, append log/table)
  • fanout delivery -> XDeliveryState (create target/state transition, async fanout worker)
  • ack delivery -> XDeliveryState (state transition, guarded conditional update)
  • replay recent window -> XRecentWindowView (read projection)

16. Search-First Product #

  • create/update listing -> XListingState (create target/overwrite, insert/create or versioned overwrite)
  • index/update search doc -> XIndexEntryState (overwrite, materialized view/index update)
  • search -> XSearchView (read projection)
  • view detail -> XListingState (read source)

17. Auction / Competitive Window #

  • create auction -> XAuctionState (create target, insert/create)
  • place bid -> XBidState (append, append log/table)
  • update current best -> XBestBidState (overwrite, guarded best-state update)
  • close auction/commit winner -> XAuctionState + XWinnerState (state transition, guarded close/commit)
  • view current best -> XBestBidState (read source)
  • view history -> XHistoryView (read projection)

18. Shared Mutable Subject #

  • apply edit/operation -> XOperationLog + XSubjectState (append + overwrite/state transition, ordered apply/OT/CRDT/guarded version update)
  • reconcile concurrent ops -> XVersionState / XSubjectState (state transition, merge/order logic)
  • snapshot state -> XSnapshotState (create target, snapshot publication)
  • view current state -> XSubjectState (read source)

19. Versioned Namespace + Immutable Content Units #

  • upload blob -> XBlobState (create target, insert/create/content-addressed write)
  • update namespace/version -> XNamespaceState + XVersionState (state transition, CAS/versioned overwrite)
  • advance sync cursor -> XSyncCursorState (overwrite, versioned overwrite)
  • detect/store conflict -> XConflictState or XVersionState (create target/state transition, conflict materialization)
  • sync/read namespace -> XNamespaceState (read source)

How to use this note #

For any prompt:

  1. find the matching archetype
  2. map the user action to one of the canonical action lines
  3. derive the entity touched
  4. derive the API shape
  5. derive the HLD ownership and NFR posture

This is a study note, not the final spoken interview format.