2026-09-11 - A CLI verb, so a C consumer can reach the shader builder

selfish-shader (worklog 069) is a Rust crate. Its one consumer, obSCEne's dispatch probe, is freestanding C that drives the selfish binary from a shell - it cannot link a Rust crate. So the crate, as shipped, was unreachable by the project that needs it, and obSCEne could not retire its disassembled container without a build-time way to generate a clean one.

selfish shader is that way. It is a thin wrapper over Container::compute().build():

selfish shader (--code <file> | --shader-size N) [--target 0xN] [--sh-reg OFF=VAL]... -o <file>

• --code records the bytecode's size (the bytes are not embedded - a console fills the code pointer), or --shader-size gives the size directly.
• --target defaults to 0x0e, RDNA2.
• --sh-reg OFFSET=VALUE, repeatable, are the shader's SH registers - the caller's, read from its own bytecode. The verb lays them out; it does not interpret them.

It draws the same line the crate does. The container format is the tool's; the register contents are the shader's. So the verb warns - it does not refuse - when fewer than two SH registers are given: a console needs at least the program-address pair (0x20c/0x20d) it patches from the code pointer, but which registers a shader carries is the shader's business, and this crate does not own that rule (D103).

Nothing new about the format; this is only the surface that lets a non-Rust consumer reach it, so obSCEne's dedup (its inbox 9f4c) has a clean generator to move to. Compute only, because that is the stage with a consumer - the other stages stay unbuilt until something needs them.