Concurrency review, September 2026

The work that came out of @danshearer's concurrency review of the forge layer, at trunk 4910c69016e5: https://markdownpastebin.com/?id=ba05d64fb32940588fab39b1827db23e

Every item below is a ticket. Each ticket carries what happens, what should happen, where in the code, and the fix shape. The lists are in priority order.

Single node

1. 54dc6a4148 Chat presence: a tab opening or closing during a presence change crashes the whole server — Critical, Immediate
2. 508fd44ab0 Live-update streams leak one goroutine per closed tab — Severe, High
3. 61cd995161 No HTTP timeouts and no limit on anonymous chat streams — Severe, High
4. c21e27c2d6 Any error reading the ingest cursor triggers a full reindex that empties the index first — Severe, High
5. 7ae62edbcc SQLite pragmas and busy_timeout reach one pooled connection; concurrent writes fail busy — Important, High
6. fe5069ef76 The login rate limiter trusts X-Forwarded-For — Important, High
7. e60889c0d7 Landing accept: two accepts both proceed, and a push between check and merge lands an unchecked tip — Severe, Medium
8. 3d2980cf29 Check-then-write outside a transaction: invite redemption, last-admin/owner checks, ticket promotion — Important, Medium
9. 8e6ecbb15c Store writes that bypass the lease guard: attachments, settings, config import, CI pipeline save — Important, Medium
10. 86a22fabef A failed reindex leaves the census goroutine and its zit frames process behind — Important, Medium
11. b880cb13c8 A node that falls behind the stream's one-hour window is never detected — Important, Medium
12. 2af687e64f A CI result can be lost: run marked complete before its tag is written — Important, Medium
13. 4a9f45bab5 CI webhook events carry no hash, so their ids collide — Minor, Medium
14. 83b111e004 HandlerWith sets package-level variables that request goroutines read — Minor, Medium
15. 128ffbf478 No graceful shutdown; imgproxy lock map never pruned — Minor, Medium

Several nodes

Designed in RFC 0001; needed before a second node runs. All Low priority until then.

1. a598314e3f Node identity comes from --addr, so two nodes can share a lease owner name and a consumer
2. 935f72e648 The lease is checked once before a zit write; a long write can overlap the next holder's; the grace period depends on process history
3. 1d09827992 Background jobs run on every node: CI dispatch and polling, mirror pulls, auto-accept, the chat bridge, event publishing
4. 18ca45f20e The shared OLTP file assumes one host (design)
5. 4116d2f4a2 Write routing to the lease holder is designed but not built (design)
6. 8af7bf74ca The private-repository list is cached per process

Not ticketed

The review names about 25 lower-severity findings but lists only three, all filed above. Two fixes need zit's cooperation and say so in their tickets: an expected-tip check on merge (landing accept) and a pre-commit lease check for long writes.