How the core is built

How the subsystems are built in Rust. The what and why are in the spec’s 20-architecture; this covers implementation detail only — the decisions that are ours because they are about Rust rather than about the product.

Page	Covers
module-layout.md	Where things live, and what the architecture test enforces
dispatch.md	The one entry point every surface goes through
rehearsal.md	What --dry-run means per command, and the three things that stop a handler ignoring it
ports-and-adapters.md	The seam to the outside world, and how to fake it
engine-api.md	What the container engine is asked, and testing it without a daemon
error-model.md	Typed errors, one operator-facing value, and how the coverage gate proves it
embedded-stack.md	How the stack gets into the binary, and why a bad pairing cannot compile
form-closure.md	Forms to profiles to a Compose invocation, and the golden files
surface-parity.md	What each surface reaches, the one intrinsic exception, and the guard that reads the table
parental-controls.md	Which service carries which half of a limit, the regional rating table, the mapping that stands in for it, and what the media server then shows a restricted member

The rule of thumb

If a reader needs it to change this code, and it is not a decision about what the product does, it belongs here. If it is a decision about what the product does, it belongs in the spec and this page links to it.

Code links here. These pages cite the spec. Code never cites the spec directly — an architecture test enforces that.