Merge a2acc7d3eb620bb52f09f7ea3b5a3a1c23353e18 after preserving the earlier
master checkpoint and its successful CI. Carry current provider input-history
handling, UI controls, agent targeting, and runner-concurrency changes into
the integration base without changing the Session migration feature layers.
Keep durable direct-child catalog semantics alongside the upstream running /
inactive vocabulary. Resolve the snapshot description conflicts by retaining
that upstream status text and the existing descendants-only diagnostic rule;
the source and all 53 JSON tool descriptions agree. Preserve parent-session
availability handling with the upstream stale-blank and batched-history fixes.
The merged application builds, all 41 documentation gates pass, and focused
provider, tool-control, and Session Controller tests pass (98, 29, and 125).
Recorded input changes come from master: one refreshed v3 list-agents sample
and three new v3 scenarios; no migration bumps an existing snapshot generation.
Tianyi Cui