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
13c6e847a2