错误码
框架应答请求时使用的每个代码，即 application/problem+json 正文与命令结果中的 code，由 FrameworkErrors 生成；说明取自源码，为英文。领域拒绝的代码由领域自己定义，以 422 应答，除非宿主为它配置了别的状态（wow.http.errors.[<code>].status）。请求带 If-Match 时，wow.aggregate.version-mismatch 以 412 应答。每个 problem 都以 retry 成员说明重试能做什么：none，重试同样失败；same-request，以同一个 Wow-Request-Id 再发；new-request，原样再发；只要重试可能成功，就带 Retry-After。领域自己的代码为 none。
框架错误码
| 代码 | 状态 | 重试 | 标题 | 含义 |
|---|---|---|---|---|
wow.auth.unauthenticated | 401 | none | Unauthenticated | The request carries no valid credentials. |
wow.auth.forbidden | 403 | none | Command forbidden | The caller may not send this command. |
wow.aggregate.forbidden | 403 | none | Aggregate out of scope | The aggregate is outside the caller's scope. |
wow.request.malformed | 400 | none | Malformed request | A request header or parameter does not parse, or names what Wow does not take. |
wow.command.malformed | 400 | none | Malformed command | The command body cannot be read as the command type. |
wow.command.invalid | 400 | none | Invalid command | The command failed validation; the problem lists the violations. |
wow.wait.invalid | 400 | none | Invalid wait | The wait is not a chain the runtime can follow; the command was not run. |
wow.command.unhandled | 400 | none | Command not handled | The aggregate does not handle this command. |
wow.aggregate.not-found | 404 | none | Aggregate not found | The aggregate does not exist. |
wow.aggregate.exists | 409 | none | Aggregate exists | The aggregate already exists. |
wow.aggregate.version-mismatch | 409 | none | Version mismatch | The aggregate is not at the expected version (412 when the request carried If-Match). |
wow.command.request-id-reused | 409 | none | Request id reused | The request id was used by another command. |
wow.command.contended | 409 | same-request | Command contended | Concurrent writers kept winning the version; retrying with the same request id is safe. |
wow.aggregate.deleted | 410 | none | Aggregate deleted | The aggregate is deleted; only RestoreAggregate applies. |
wow.command.busy | 429 | same-request | Command busy | The command was not taken: its aggregate has too many commands waiting, or the node too many in flight; retry later. |
wow.command.unknown | 503 | same-request | Command outcome unknown | Whether the command committed is unknown; retrying with the same request id is safe. |
wow.command.failed | 500 | none | Command failed | The command's handling failed with an unexpected error; it committed nothing, and a retry fails alike. |
wow.command.refused | 409 | none | Command refused | The aggregate's current state refuses the command (a check of its decide function); the message says why. |
wow.command.undeclared-event | 500 | none | Undeclared event | The command's handling produced an event its decide function or after hooks do not declare: a bug in the model, which the message names; it committed nothing. |
wow.node.closing | 503 | same-request | Node closing | The node is shutting down; retry on another node. |
wow.node.standby | 503 | same-request | Node on standby | The node is on standby until the cut-over: it serves reads only. |
wow.storage.unavailable | 503 | same-request | Storage unavailable | A store could not be reached or did not answer in time; retry later, a command with the same request id. |
wow.schedule.not-due | 503 | same-request | Schedule not due | A scheduled command arrived too long before its due time on this node's clock; it is sent again later. |
wow.schedule.job-invalid | 400 | none | Invalid schedule job | The job command does not fit its job or instance: an unknown job, another scope, or an instance not enabled. |
wow.ledger.stale | 409 | none | Stale ledger action | The action names a parking the entry no longer is: the aggregate was resolved and parked again since; read the entry again before acting on it. |
wow.subscription.parked | 500 | none | Subscription parked | A subscription on the wait chain parked the aggregate; the wait cannot be reached until the aggregate is retried. |
wow.wait.timeout | 504 | same-request | Wait timed out | The wait ran out of time; the command may have committed. The problem carries the last stage reached. |
wow.route.malformed | 400 | none | Malformed route request | A service route's parameter or body cannot be read as its type; the violation names the parameter. |
wow.query.malformed | 400 | none | Malformed query | The query body cannot be read as a query. |
wow.query.invalid | 400 | none | Invalid query | The query failed admission; the problem lists the violations, each with its code (UNKNOWN_FIELD, ...). |
wow.query.failed | 500 | none | Query failed | The query backend failed to run the query. |
wow.query.not-found | 404 | none | No matching record | A single query matched no record: a query result, not a statement that an aggregate does not exist. |
wow.query.dataset-not-found | 404 | none | Dataset not found | No dataset of that name is served to the caller. |
wow.query.too-many-groups | 400 | none | Too many groups | An aggregation that names no sort has more groups than its limit; add a sort for a top-N, or raise limit. |
wow.query.timeout | 504 | none | Query timed out | The query ran longer than its budget allows; narrow it rather than run it again. |
wow.query.min-version-not-reached | 409 | new-request | Version not reached | The state read asked for a version the aggregate has not reached within the wait; the problem carries its current version: retry later. |
wow.query.busy | 429 | new-request | Query busy | The query was not run: its store has as many queries running as it allows; retry later. |
wow.query.dataset-unavailable | 409 | none | Dataset unavailable | The dataset is served but cannot be queried now, for the reason the problem names (it needs revision). |
wow.call.command-forbidden | 403 | none | Call forbidden | The calling service may not call this command: its wow.callers.<service>.commands do not list it. |
wow.peer.unavailable | 503 | new-request | Peer unavailable | A client reached no node of the peer, or lost the connection before a query's answer; nothing was changed, so the request may be sent again. |
查询请求的代码
被拒绝的查询请求（wow.query.malformed 或 wow.query.invalid）会列出它拒绝的每一处，各带下列一个代码与它所指的请求部分，由 QueryErrorCodes 生成。代码只增不改，也不复用。
| 代码 | 分组 |
|---|