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W3.3 (format): an event may be kept in a stream of its own with an age and a cap

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The seat mesh-delivery's and mesh-delivery-checker's owed events are kept on each owner's stream owed, 7 days and at
most 64 MiB (design 47, What the gate owes the forge); the format could only keep an event last per subject.

Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ
This commit is contained in:
jschoubben
2026-11-09 20:39:43 +01:00
parent 7d04e0df29
commit eddb2d4bf6
2 changed files with 31 additions and 10 deletions
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go/seatdef/seatdef.go
+24 -9
View File
@@ -122,15 +122,26 @@ type Message struct {
// still knows the event. Empty, the subject is the name. A part `<node>` is the node that publishes it, which
// the grants part grants a node's account alone (ADR 0363 §2).
Subject string `json:"subject,omitempty"`
// Keep says how an event is kept when not as the family keeps the seat's others: KeepLastPerSubject, in a stream
// of its own named KeptStream, the last message of each subject and no age limit (design 47: the node-engine's
// running.<node>.<module>, so the last build of every module on every node stays on the bus however long ago
// it was said, and a durable consumer starting from the last message per subject holds them all).
// Keep says how an event is kept when not as the family keeps the seat's others, in a stream of its own named
// KeptStream: KeepLastPerSubject, the last message of each subject and no age limit (design 47: the node-engine's
// running.<node>.<module>, so the last build of every module on every node stays on the bus however long ago it
// was said, and a durable consumer starting from the last message per subject holds them all); or KeepStream,
// every message within MaxAgeDays and MaxMiB.
Keep string `json:"keep,omitempty"`
// MaxAgeDays and MaxMiB bound an event kept KeepStream: how long a message is kept and how much the stream holds
// (design 47 *What the gate owes the forge*: the stream `owed`, 7 days and at most 64 MiB). Given with KeepStream
// alone.
MaxAgeDays int `json:"max-age-days,omitempty"`
MaxMiB int `json:"max-mib,omitempty"`
}
// KeepLastPerSubject is an event kept last per subject with no age limit, in a stream of its own.
const KeepLastPerSubject = "last-per-subject"
// The ways an event is kept in a stream of its own, KeptStream, instead of its seat's family.
const (
// KeepLastPerSubject keeps the last message of each subject, with no age limit.
KeepLastPerSubject = "last-per-subject"
// KeepStream keeps every message for MaxAgeDays, at most MaxMiB in all.
KeepStream = "stream"
)
// KeptStream is the stream an event with Keep is kept in: `<seat>.<event>`, as a family is `<seat>.events`.
func KeptStream(seat string, m Message) string { return seat + "." + m.Name }
@@ -677,10 +688,14 @@ func checkMessages(field string, ms []Message, whole bool) Problems {
switch {
case m.Keep != "" && field != "events":
ps = append(ps, Problem{where + ".keep", "only an event is kept"})
case m.Keep != "" && m.Keep != KeepLastPerSubject:
ps = append(ps, Problem{where + ".keep", fmt.Sprintf("%q is not %s", m.Keep, KeepLastPerSubject)})
case m.Keep != "" && len(m.Parts()) == 0 && !m.ByCaller:
case m.Keep != "" && m.Keep != KeepLastPerSubject && m.Keep != KeepStream:
ps = append(ps, Problem{where + ".keep", fmt.Sprintf("%q is not %s or %s", m.Keep, KeepLastPerSubject, KeepStream)})
case m.Keep == KeepLastPerSubject && len(m.Parts()) == 0 && !m.ByCaller:
ps = append(ps, Problem{where + ".keep", "an event of one subject kept last per subject is one message: give it a subject with parts"})
case m.Keep == KeepStream && (m.MaxAgeDays <= 0 || m.MaxMiB <= 0):
ps = append(ps, Problem{where + ".keep", "an event kept in a stream of its own gives its max-age-days and max-mib"})
case m.Keep != KeepStream && (m.MaxAgeDays != 0 || m.MaxMiB != 0):
ps = append(ps, Problem{where + ".max-age-days", "only an event kept as a stream of its own gives max-age-days and max-mib"})
}
if m.Subject != "" && field != "events" {
ps = append(ps, Problem{where + ".subject", "only an event carries a subject of its own"})
go/seatdef/seatdef_test.go
+7 -1
View File
@@ -66,7 +66,13 @@ func TestADefinitionIsReadStrictlyNamingWhatIsWrong(t *testing.T) {
{"an event kept last per subject", strings.Replace(whole, `"name":"created"`,
`"name":"running","subject":"running.<node>.<module>","keep":"last-per-subject"`, 1), ""},
{"an event kept otherwise", strings.Replace(whole, `"name":"created"`,
`"name":"running","subject":"running.<node>","keep":"forever"`, 1), `events[0].keep: "forever" is not last-per-subject`},
`"name":"running","subject":"running.<node>","keep":"forever"`, 1), `events[0].keep: "forever" is not last-per-subject or stream`},
{"an event kept in a stream of its own, bounded", strings.Replace(whole, `"name":"created"`,
`"name":"owed","subject":"owed.<repository>.<number>","keep":"stream","max-age-days":7,"max-mib":64`, 1), ""},
{"an event kept in a stream of its own, unbounded", strings.Replace(whole, `"name":"created"`,
`"name":"owed","subject":"owed.<repository>.<number>","keep":"stream","max-age-days":7`, 1), "gives its max-age-days and max-mib"},
{"a bound on an event kept by its family", strings.Replace(whole, `"name":"created"`,
`"name":"owed","max-mib":64`, 1), "events[0].max-age-days: only an event kept as a stream"},
{"an event of one subject kept last per subject", strings.Replace(whole, `"name":"created"`,
`"name":"running","keep":"last-per-subject"`, 1), "give it a subject with parts"},
{"an accept with dotted words", strings.Replace(whole, `"events":`,