Address review on the bash stdin/env seam PR: the seam spawned stdin as a
`'pipe'` for EVERY call, closing it empty when no stdin was supplied. That is
NOT observationally equivalent to the pre-seam `'ignore'` default — node's
spawn pipe is an AF_UNIX socket, so `test -c /dev/stdin` (and any fd-0 type
probe) flipped for every model-driven bash call, even though the code claimed
the no-stdin path was unchanged.
Spawn stdin as `'pipe'` only when the caller supplies bytes; otherwise
`'ignore'` (fd 0 → /dev/null), the exact prior default. A literal `stdio`
tuple per branch preserves the typed `spawn` overload's non-null stdout/stderr.
Regression test asserts fd 0 is a char device with no stdin and a socket when
supplied — proven red on the always-pipe code.
Address review: the "trusted-plugin surface" framing overstated the security
story. A model driving the `bash` tool already has equivalent power to set env
vars and feed stdin through ordinary shell syntax (`FOO=bar cmd`, heredocs), so
the `env`/`stdin` seam fields grant it no new capability — and they cannot
exfiltrate the harness's ambient credentials, because the credential SCRUB in
dsh-bash-local (which strips *KEY*/*SECRET*/*TOKEN* from process.env before the
child sees it) is the actual control, and it works regardless of these fields
(tool-call args are static JSON, never shell-evaluated).
So drop the "dangerous / trusted-plugin boundary" language across the RFC, the
three bash-package READMEs, the bash/src/types.ts JSDoc, and docs/bash.md (both
the type-equiv blocks — kept 1:1 with source — and the prose). The reality that
remains: the `bash` tool doesn't EXPOSE env/stdin as parameters because they'd
be redundant with shell syntax; the fields exist for in-process plugins (the
hooks bridges) to pass a JSON payload + CLAUDE_* vars cleanly. The guard test is
kept but reframed: it catches a future `...args` spread that would silently
forward model input into the post-scrub env merge, NOT a trust wall. No code or
behavior change.
- The implemented RFC named stack positions (PR-A…PR-F, "the hooks bridges (PR-F)")
as shipped reality, violating the rule that an implemented RFC describes current
truth and docs never name a change unit the reader cannot see. Rephrased to
describe the hooks subsystem / a hook bridge as the standing motivating consumer,
without PR/stack references. The decision and rationale are unchanged.
- childEnv's comment pointed at dsh-tool-bash's "module doc" for the trusted-plugin
boundary, but that explanation lives in the package README (§ "Trusted-plugin
boundary"), not the module JSDoc. Fixed the reference.
The hooks subsystem runs external hook commands the Claude Code / Codex way:
JSON payload on stdin, context in CLAUDE_PROJECT_DIR / CLAUDE_PLUGIN_ROOT env.
Reusing the ctx.bash seam for that needs two new inputs — but stdin and arbitrary
env are exactly what dsh-bash-local's credential scrub exists to keep away from
model-driven commands. So this adds them as a TRUSTED-PLUGIN surface:
- BashExecRequest + BashExecSpec gain optional `stdin` and `env`. They are plain
optionals on the resolved spec (not required-but-nullable like `owner`): a
missing one means "none", the safe default, not a security footgun.
- dsh-bash-local threads them through resolve/run/start. `env` merges AFTER the
credential scrub, so a trusted caller's explicit entry wins even on a
credential-shaped name — the scrub guards the harness's OWN ambient creds from
model-driven commands, not a trusted plugin. stdin is always a pipe, closed
immediately (with bytes when supplied, empty otherwise — EOF as before); an
EPIPE from a child that exits without reading is swallowed.
- The model-facing dsh-tool-bash NEVER forwards model input into stdin/env (its
request is command/workdir/timeoutMs/signal/owner only). A regression guard
drives the real tool with adversarial args and asserts the request carries
neither field — proven to go red if the consumer ever forwards them.
Configurable scrub (in an earlier sketch) is dropped as speculative: the explicit
`env` field already gives a trusted caller full control, and no caller needs to
broaden the ambient scrub. Documented in a new architecture RFC, the bash.md
type-equiv blocks, and the three bash READMEs.
Tianyi Cui