The Anvil produces a design. The Forge turns the design into a working cartridge. Our blacksmith is not one person; it is a coordinated team of AI models that takes the spec, drafts the code, reviews the code, files the pull request, runs the tests, and lands the cartridge on the playground.
The Forge has two parts: the AI team that does the work, and the routing layer that picks which AI does which step. Both matter. Getting either wrong makes the Forge slow or expensive (or both).
Modern AI work uses multiple specialized models, not one big one. The right tool per step. A typical Forge run on a new cartridge looks like:
The cheap scout models do the rough work; the expensive writer model does the high-stakes work. Without this split, every step pays the expensive price and the bill compounds.
Today's cheap scout model is Claude Haiku via Bedrock. Tomorrow it might be a local model running on a Mac Mini under someone's desk. Two years from now it might be an open-source model that has caught up to Claude. The Forge has to absorb each of those changes without rewriting cartridge code.
The answer is a router. Cartridges call route("scout") and route("writer"); the router decides which actual backend serves each route. Today both routes hit Bedrock. Tomorrow the scout route quietly switches to a local model and the Forge keeps working. Cartridges never know the difference.
What competitors who hard-coded vendor IDs are paying. Opus everywhere. Fast but expensive.
Scouts run free on a Mac Mini in the office. Writer is Sonnet via Bedrock. 88% cost reduction with no code change in any cartridge.
When open-source models close the gap on Sonnet, the writer route flips local too. Cost flips to electricity. Sovereignty becomes structural; competitors who hard-coded vendor IDs cannot follow.
This is why the model router doctrine (Step 6.m) is the moat doc. The Forge is not "cheap Claude calls"; it is "the right model per step, swappable as the landscape changes, structurally locked into PayCargo's substrate." That asymmetric switching cost is what we keep emphasizing in executive materials.
| Forge component | State today |
|---|---|
| Vibe coding workflow with Claude | Live. Every cartridge in the repo today was built this way. |
| Two-turn pattern (scout, then writer) | Specced in Step 6.l. Code-agents cartridge will be the first to use it end-to-end. |
| Model router substrate | Specced in Step 6.m. Ships behind code-agents Phase 1.5. |
| Mac Mini local inference | Planned. Reachable from AWS via Tailscale. Pilot once router substrate lands. |
| Human review gate | Live. Every Forge-generated change goes through a pull request with CODEOWNERS review. |
The Forge produces code fast and cheap; that does not make it correct. Every cartridge change goes through a pull request. A human reads the diff before it merges. Terraform Apply requires a literal "APPLY" confirmation typed by a human. AI scales the writing; humans gate the landing. Both halves are non-negotiable.
Forge engineering depth lives in Step 6.l (code-agents and the two-turn pattern), Step 6.m (model router substrate and the moat argument), and the executive narrative in the AI infrastructure moat memo.