Preserve sidebar section when creating a thread in an environment

[ymichael]

Human comments

What was wrong

“New thread in environment” passed the environment to the composer but omitted the source thread’s section. The composer cleared its section target, so a new thread created from a thread in section A landed in the unsectioned Threads list.

What changed

Pass the source section through the shared environment creation action from the thread view, environment details, and sidebar environment groups. Creating from section A now keeps the new thread in section A; an unsectioned source explicitly clears any previous section target.

How you verified

• pnpm exec turbo run test --filter=@bb/app -- useCreateThreadInEnvironment.test.ts RootComposeView.test.ts ProjectRow.interactions.test.tsx — 82 tests passed, including section preservation and unsectioned-source coverage.
• pnpm exec turbo run typecheck --filter=@bb/app — passed.
• In an isolated source app, opened a thread in a custom section, clicked “New thread in this environment,” and submitted. Verified both threads had the same persisted section and environment IDs, then reloaded and confirmed sidebar placement.
• Started the production build with pnpm start:worktree; server and daemon health checks passed.

AGENT GENERATED