agent-, project-, and company-fallback workspaces resolved to
`shared`, so four agents sharing one repo wrote concurrently and
corrupted both the working tree and git's own index state before
the per-file `index.lock` even got a chance to kick in. The
previous comment justified this as "the normal case", but pi's
`createCodingTools()` hands every agent bash/write/edit — there is
no read-only category left where shared is safe.
This promotes every resolved workspace to `exclusive`. Contention
is still handled at the one place it must be: `run-dispatch.ts`
synchronously claims the workspace lock, and `finishRun`'s
never-started branch rolls the task back to `todo` on a lost
race. The "shared mode prevents deadlocks" story was really
"shared mode prevents one specific bug in the checkout rollback
path that has since been fixed"; the right invariant is single
writer per repo, enforced by the DB lock. Concurrent heartbeats
for the same workspace now queue through the wakeup table on the
next cycle rather than racing the filesystem.
ZacharyZhang-NY
4842a9a2e2