Use Gemini Deep Research to build the first source map. Work in gemini and google docs and capture the concrete operating details: campaign name, audience, channel, offer, message angle, asset URL, performance baseline, owner, and approval status. When you use the prompt template attached to this step, paste the real source material, name the expected output sections, and ask the model to flag uncertainty instead of filling gaps. Before moving on, check that the output is specific enough for the next person to use without guessing what happened; the expected handoff is A source discovery map with links, source types, themes, and decision relevance.