The context window crossed a real threshold this year: a mid-size repository now fits inside a single prompt. The mistake most people make is treating this as “I can paste more”. The actual unlock is different - a handful of tasks that used to need days of human grep-work are now one brief and a review.
The five tasks
1. Cross-cutting renames and API migrations. Change a function signature or an endpoint shape and let the agent walk every call site in one pass. Brief: “Rename X to Y across the repo, update all call sites and tests, run the test suite, list every file you touched.”
2. The test-gap audit. Ask for coverage in terms of behavior, not lines: “List the user-facing flows with no test coverage. For each, name the file, the risk, and the smallest test that would lock it down. Do not write code yet.” You get a prioritized backlog in minutes.
3. Dependency upgrades with call-site fixes. “Upgrade lib from v2 to v4. Read its changelog for breaking changes, fix every affected call site, run tests.” The long window means it sees your usage and the migration notes at the same time - the combination that used to be pure drudgery.
4. Onboarding docs written from the real code. “Write a new-developer guide: what this system does, how data flows, where the sharp edges are. Base every claim on actual code and cite file paths.” Review it like any doc - but the first draft now costs a brief, not a week.
5. Code archaeology before refactoring. Before touching legacy: “Explain how feature X works end to end: entry points, state, side effects, and what would break if I changed Y.” You refactor with a map instead of a hunch.
The rules that keep it honest
- Point, don’t dump. Models still reason best near what you aim them at. Name the target files or subsystem even when you load everything.
- Verify with execution, not vibes. Any artifact that claims “all call sites updated” must be backed by a green test run or a search you can re-run.
- Garbage in, confident garbage out. A big window is not a substitute for clean code - dead code and stale branches scale up just as faithfully.
- Watch the meter. Context is the new compute bill. Cache repeated prefixes and batch related questions instead of reloading the world every message.
The takeaway
Stop asking longer questions and start delegating wider tasks. The teams getting value from big context aren’t the ones with clever prompts - they’re the ones who recognized that five boring, expensive chores just became one brief each.