[Improve] Preserve source context for child tasks

[roomote-roomote]

​Opened on behalf of @daniel-lxs. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

Related issue

No linked issue. This is internal Roomote work requested from the communication-context launch flow.

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

What changed

Child tasks launched from a run token now retain the parent task's provider-neutral communication coordinates (provider, channel, thread, and message identifiers). Standard agents see those coordinates in a read-only <task_source_context> block so they know where the work originated; the block carries coordinates only, with no extra behavioral rules.

The parent pointer for this inheritance travels in a dedicated transient communicationContextSourceRunId field rather than sourceRunId, so relaunch lineage, settle notifications, and the activation metric keep their existing semantics. Inheritance skips launches that already carry their own live communication context, and payloads are flagged communicationContextInherited only when coordinates were actually copied. Inherited coordinates stay informational: they do not register live reply tools, messaging instructions, or turn-satisfaction closeout hooks, while direct communication turns are unchanged.

The shared populateCommunicationMetadata helper extracted from the snapshot-resume path keeps the historical semantics where empty-string options fall back to the source payload.

How it was tested

• Worker coverage for inherited provider-neutral context, enqueue coverage for inheritance, the own-live-context guard, and unchanged sourceRunId stamping, and prompt coverage for the source-context block.
• Ran the touched Vitest suites in types, cloud-agents, api, and worker, plus pnpm lint:fast and pnpm check-types:fast.
• pnpm knip reports a pre-existing configuration hint that also reproduces on develop locally; unrelated to this change.

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

[roomote-community]

1 issue outstanding. See task

• Slack child reports cannot reach the inherited source thread because Slack reply routing ignores the copied provider-neutral coordinates.
• Inherited source coordinates are still treated as live chat reply context, so child tasks can post to or be forced to close the parent conversation.
• Inherited Teams, Telegram, and Discord coordinates still enable request_user_input callbacks, allowing a child task to post a question to the parent conversation.

_{Reviewed 9f6996c}

[roomote-roomote]

Fixed inherited source-context reply safety in f955061. Inherited provider-neutral coordinates now remain informational: the worker does not export active reply environment or register turn-satisfaction closeout hooks for them. Added focused worker coverage; targeted tests, worker static checks, and the repository pre-push suite pass.