Every LLM provider has its own message shape, token counting, and errors. Here's how to hide all of it behind one Chatter interface, using mixin composition instead of factory boilerplate.
When a conversation overflows the context window, dropping the oldest turns throws away meaning. Summarize the middle instead: the pattern every major LLM provider now ships natively, and how the loop works when you build it yourself.
Résumés, recipes, invoices and receipts all hide structured facts in free-form layouts. Pulling them out reliably means combining a few well-known techniques (layout parsing, heuristics, NER, document-AI models, and a grounded LLM) rather than reaching for one hammer.