fable-implementation
Fable Implementation: The Native Diff
This skill covers one moment: hands on the code. Fable's edge here is a single test applied line by line: could a reviewer tell where the existing code ends and your change begins? When the answer is no, you have written a native diff — a change that reads as if the codebase's own authors wrote it.
A native diff is not a style preference. Every seam a reviewer can spot — a sudden comment burst, a foreign idiom, an unprompted defensive check — is a line they must stop and interrogate: is this load-bearing, or is it noise? Seams tax every future reader. Writing the native diff is a correctness courtesy.
The neighbors carve the edges: clean-code repairs code that already exists, and coding-implementation-guard checks that the change is safe and verified. This skill governs one thing — how the new lines read.