`cli <tool>` resolved its JSON arguments from stdin whenever stdin was not a
terminal and no --args-file, raw-JSON positional or --flag form was supplied,
and cli_slurp_stream reads to EOF. An ordinary automation caller never sends
that EOF: Node's child_process.spawn defaults to stdio ['pipe','pipe','pipe']
and the parent must call child.stdin.end() explicitly, which almost nobody does
for a command it is not writing to. fd 0 then stays open with no writer and the
read never returns. The reporter's shell script was still parked in fread(0)
fourteen minutes later.
`list_projects` advertises "properties":{} — stdin could never have carried
anything it accepts, so the read was pure deadlock with nothing to gain. Gate
the stdin path on the tool's input_schema actually declaring properties, in a
seam (cbm_cli_args_from_stdin_allowed) that main.c's resolution chain calls.
An unknown tool also stops blocking: dispatch rejects it by name and no stdin
content can change that verdict. Tools that do declare properties keep the
documented `echo '<json>' | cli <tool>` channel untouched, and interactive runs
are unchanged because isatty(0) already short-circuited them.
Measured on the pre-fix binary, stdin held open by a writer that never writes,
15-second watchdog: `cli list_projects` was killed at 15s with 0 bytes of
output, while `cli list_projects < /dev/null` returned in 3s with 90 bytes.
After the fix the same open-pipe invocation returns in 3s with 90 bytes.
Regression tests (tests/test_cli.c): the reported hang, the piped-argument
channel that must survive, the interactive path, unknown/NULL tool names, and a
sweep asserting the gate tracks the advertised schema across the whole tool
table so a future zero-argument tool cannot reintroduce this silently.
Revert-check: with the schema gate reverted to the pre-fix `return
!stdin_is_tty`, both tests fail on the list_projects assertion and the suite
reports 2 failed; with the gate applied, 272 passed / 0 failed.
Known limit, not addressed here: a tool that DOES declare properties, invoked
with its required flag omitted (`cli index_status` without --project), still
blocks on an open pipe. Distinguishing "arguments are coming" from "nobody will
ever write" needs a bounded wait, which is a public-surface decision (deadline
value, and the cross-platform pipe-readiness probe Windows would need) rather
than a mechanical fix.
Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>
Martin Vogel
9ca108fce9