Development record

2026-09-27 — A pipe into a group and a redirect into a shell string reach every command there, and the reading keeps two over-blocks, recorded so they are not mistaken for defects (lane fix3-drainG, autonomous run A, on iss-2609270028388291 from review-drainG2). A pipe into a `{ … }` or `( … )` group is the standard input of every command in it, so each command emitted inside the group reads it, not only those before the group's first separator; a shell in the group reads it as a stream too. A command in a group is read as handed its group's input even when a pipe inside the group hands it another, because the command before that pipe may pass the group's input on (`cat`), and which commands do is not modelled; so `pgrep make | { true; echo 4242 | { xargs kill; }; }` blocks. The runs of the open groups are held as one covering run, which keeps each command's reading constant however deep groups nest, at the cost of also counting a search that sits inside an outer piped group before an inner one opens. A shell passes its standard input to the commands of its string, and a here-string or a process substitution redirected into the shell is that input, as a pipe is; the `<` that redirects a process substitution is not kept by the tokenizer, so a process substitution handed to the shell as an operand is read as its input as well, which is what `sh -c 'xargs kill < "$1"' _ <(pgrep make)` does with it.