Does collection mean I can reply?
No. Source access, account identity and the intended action each have their own boundary. A public post that can be collected is not necessarily a target your connected account can reply to.
For Threads and LinkedIn, complete the connected-identity requirements before planning the corresponding collection or reply path. Entitlement and target permissions still matter.
What are the important limits?
The current maintained collection scope includes Threads, LinkedIn, X and Reddit paths. Eligible Threads and LinkedIn targets have native reply paths. Cold replies to arbitrary X posts are unsupported.
Reddit native reply support remains partial. A public demo or an available provider endpoint does not establish that a live product reply is ready for your account. Confirm the exact operation before treating a platform as part of an automated play.
How should I test a source?
Start with one narrow question and one source. Check the returned conversation's identity, date and evidence. Inspect the saved result and draft before attempting a permitted external reply.
If the reply route is unsupported, keep the result as a reviewed signal or research input. Do not substitute another identity, destination or send mechanism without an explicit decision.