fix(session): log --last 0 means no backlog

debug.log handed `last` to the timeline query, where 0 means every
entry, so `log --follow --last 0` streamed the whole ring of up to 8192
entries before the new ones, where an agent reads it as tail -n 0 -f:
nothing old, only what comes next. 0 now means no backlog, followed or
not, and the guide says that --follow starts with the last 50.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Jorijn van der Graaf 2026-11-01 03:06:38 +01:00
commit b95c594be8
Signed by: jorijnvdgraaf
GPG key ID: 2937E59CDCC1BCFB
2 changed files with 7 additions and 3 deletions

View file

@ -462,11 +462,14 @@ namespace Crafter::Debug {
}
if (!known) return exchange->Reply(MakeErrorReply(Codes::invalidParams, std::format("kinds: '{}' is not one of log, warn, error, check, event, agent, pause, stdio", kind)));
}
// `last` 0 means none, as with tail -n 0: a follower that only
// wants what comes next. (A TimelineQuery's 0 means all.)
Detail::TimelineQuery backlog = query;
backlog.last = decoded->last;
const auto recent = [&] { return decoded->last == 0 ? std::vector<TimelineEntry>() : Detail::Timeline::Instance().Query(backlog); };
if (!decoded->follow) {
Value entries = Value::MakeArray();
for (const TimelineEntry& entry : Detail::Timeline::Instance().Query(backlog)) entries.Push(EntryValue(entry));
for (const TimelineEntry& entry : recent()) entries.Push(EntryValue(entry));
return exchange->Reply(MakeReply(Object({ { "entries", std::move(entries) }, { "lastSequence", Value(Detail::Timeline::Instance().LastSequence()) } })));
}
// The backlog and the registration happen under one lock, which
@ -474,7 +477,7 @@ namespace Crafter::Debug {
// every entry once and in order. Stream never blocks.
std::lock_guard lock(mutex);
const std::uint64_t upTo = Detail::Timeline::Instance().LastSequence();
for (const TimelineEntry& entry : Detail::Timeline::Instance().Query(backlog)) {
for (const TimelineEntry& entry : recent()) {
if (entry.sequence > upTo) continue;
if (!exchange->Stream(Object({ { "entry", EntryValue(entry) } }))) return;
}

View file

@ -984,7 +984,8 @@ memory are a debugger's job; `crafter-debug debugger` prints how to attach one.
trace <sample> --history a Debug::Sample's recent history
log [--last 50] [--level info|warn|error] [--cat <glob>] [--grep <text>]
[--since-frame n] [--kinds log,warn,error,check,event,agent,pause,stdio]
log --follow [--for 30m] streams new entries; run it under Monitor
log --follow [--for 30m] the last 50 (--last; 0 for none), then new
entries as they come; run it under Monitor
screenshot [-o shot.png] default ./build/crafter-debug-shots/
quit [--force] --force exits even if the loop is stuck
debugger how to attach lldb or gdb