MSC2663: Errors for dealing with non-existent push rules

proposals/2663-errors-nonexistent-push-rules.md

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+# MSC2663: Errors for dealing with non-existent push rules
+
+This MSC proposes that homeservers respond with a HTTP 404 ('Not Found') status
+code and an `errcode` of `M_NOT_FOUND` when a client attempts to read or write
+the `enabled` status or `actions` of a non-existent push rule.
+
+## Background
+
+The current revision of the Client-Server specification does not make clear what
+a homeserver implementation is meant to do when getting or setting the `enabled`
+or `actions` properties of a supposed push rule that does not exist.
+
+## Motivation
+
+This change is considered minor and the proposed error code is deemed
+unsurprising as it matches the remainder of the specification.
+
+## Proposal
+
+The following endpoints of the Client-Server specification are affected:
+
+- `GET /_matrix/client/r0/pushrules/{scope}/{kind}/{ruleId}`
+- `DELETE /_matrix/client/r0/pushrules/{scope}/{kind}/{ruleId}`
+- `PUT /_matrix/client/r0/pushrules/{scope}/{kind}/{ruleId}`
+- `GET /_matrix/client/r0/pushrules/{scope}/{kind}/{ruleId}/enabled`
+- `PUT /_matrix/client/r0/pushrules/{scope}/{kind}/{ruleId}/enabled`
+- `GET /_matrix/client/r0/pushrules/{scope}/{kind}/{ruleId}/actions`
+- `PUT /_matrix/client/r0/pushrules/{scope}/{kind}/{ruleId}/actions`
+
+The affected endpoints will have the following response status code added:
+
+**Status code 404:**
+
+The push rule does not exist.
+
+**Example**
+```json
+{
+  "errcode": "M_NOT_FOUND"
+}
+```
+
+This error response is to be returned when the push rule represented by
+`{scope}/{kind}/{ruleId}` does not exist.