Feed is now read-write (0666):
- Write: store data, signal via notifyChange
- Read (BlockOnce): block until content hash differs from base
Dedup lives in the read layer (same pattern as statewait). The
internal consumer goroutine and external 9P clients both call
FeedBlockingRead — same codepath, same dedup logic.
Consumer started from AddAgent (if ctx available) and session resume.
Feed is a write-only file in the agent namespace. Writes are
deduplicated against the previous value; the internal consumer
(blocking on WaitChange/WatchFeed) only wakes when genuinely new
data arrives.
Wiring is external and source-agnostic:
# human → observer (poll git):
while :; do git diff HEAD; sleep 5; done | ollie-9p write .../feed
# agent → observer (stream chat):
ollie-9p read .../coder/chat | ollie-9p write .../observer/feed
Uses the agent's existing signalCh/notifyChange plumbing — no new
channel infrastructure. Consumer goroutine spawned at agent creation
(AddAgent) and session resume, tied to session context.