Professional Agentic Product Engineering

Chapter

Unlearn the old playbook — so stale advice stops sabotaging you

Before frontier models, prompting was a craft of coaxing. Most moves that worked then backfire now. Worth knowing, because half the advice still circulating is from this era.

The old move Why it worked then What to do now
Magic thinking words — "think", "think hard", "ultrathink" They mapped to literal reasoning-token budgets (ultrathink ≈ 32k) Adaptive thinking + effort settings; Opus 4.8 defaults to high. Use /effort; reserve ultrathink for one hard turn
Anti-laziness pep talks — "Don't hold back. Give it your all. Go above and beyond." Older models under-delivered without a push Newer models over-trigger and over-engineer. Push thoroughness down; scope tight
Negative constraints — "Don't use X" Models were loose enough to need fencing Literal instruction-following makes negations backfire. Say what to do
Context babysitting — cram everything under 200k, trim obsessively Context was scarce and precious 1M is the default; manage by signal, not a percentage (rot is still real)
"Be conservative" reviews Kept review noise down 4.8 obeys and suppresses real findings. Ask for everything, severity-labeled
Turn-by-turn steering Models lost the thread fast Multi-turn costs more and the model rewards autonomy. Front-load the brief
Manual subagent choreography The only way to parallelize It can self-orchestrate parallel subagents now. Give it the goal + the bar

The throughline: you used to push the model to do more. Now you constrain it to do exactly the right thing, and move your effort to the system around it.