Creates and maintains `.claude/product-marketing-context.md`, one sourced file that records what the product is, who buys it, what they use instead, the proof behind each claim, customer wording, pricing and goals, so later marketing tasks read facts instead of asking again or guessing. Drafts it from the repository and site, interviews the user for the gaps, tags every statement with its source, and checks the file with a script. Use when someone says "set up marketing context", "product context", "positioning document", "write down our messaging", "we repositioned, update the context", or before the first copywriting, CRO, SEO or email task in a project.
