ForgeProvider.diff now takes the head commit it must describe. The GitHub
provider reads headRefOid before and after `gh pr diff` and returns the new
ForgeFailure code `stale` when either read names another commit, so the
forge panel never caches a patch under a head it does not describe. A stale
read polls the change request at once, and the changes view waits for the
next status before reading again.
Status polling pages reviewThreads up to the new `maxReviewThreads` setting
(default 1,000) instead of counting only the first 100, and sets
ChangeRequestSnapshot.threadsTruncated when the count is a lower bound.
Add the experimental forge capability seam:
- dsh-experimental-forge: provider-neutral repository and change request
references, a provider registry, and shared status polling. Watchers of
one change request share one loop; each forge has one batched fetch in
flight, and the cadence follows check, mergeability, and lifecycle state.
- dsh-experimental-forge-github: GitHub provider that runs the GitHub CLI
on the host with a scrubbed environment and reads every due pull request
of a host in one GraphQL query.
- dsh-experimental-forge-session: a host-only projection derives Session
bindings from gh pr create and git push shell results and from
plugin:forge-session/binding records; push results trigger head-branch
discovery of open pull requests, and Session watchers poll bound change
requests through ctx.forge.