I ran five reviewer agents over a 16K-token PR. The naive setup cost $1.32. Two architectural changes brought it to $0.49. Here's the bill, and what the experiment surprised me with along the way.
Five specialist agents reviewed the same pull request. Security, tests, perf, observability, API design. Each one re-read the full diff. Each one paid full price. The bill landed at $1.32 for a single PR pass on Claude Opus 4.6.
One PR. One review pass. Buck thirty-two.
If you're running multi-agent code review at any scale, you're bleeding money on the exact same tokens, over and over, paid in full each time.
I built a harness to measure the bleed and test the two obvious fixes. The numbers were sharper than I expected, and one of them inverted my assumptions about prompt caching.
