Inject secrets into a process

arca run is the agent path — resolved values become env vars in the child and nowhere else. arca env is the human path — export lines for eval.

Declare the surface

[secrets] in arca.toml bounds what run/env may inject:

[secrets]
STRIPE_KEY   = "arca://billing/stripe"
DATABASE_URL = "arca://prod/db/url"     # env pin: prod, always

Nothing outside this table (plus -s ad-hoc pairs) is injectable — least privilege, and arca check verifies every entry resolves.

arca run — two exec modes

# one arg → bash -c — pipes, redirects, $VAR expansion
arca run -- 'psql "$DATABASE_URL" -c "select 1" | tee out.log'

# several args → argv[0] exec'd directly, NO shell —
# the program reads its own environment
arca run -- stripe charges list --limit 3

Prefer argv mode when the command has arguments — no quoting puzzles. One caveat: with no shell in the child there is no $VAR expansion — write $STRIPE_KEY in argv and your outer shell eats it (to an empty string) before arca runs. Use bash -c mode when the command line itself needs the value.

Exit code is the child's; a child's non-zero exit is not an arca failure (no error audit event).

Ad-hoc pairs: -s VAR=arca://ref

Repeatable, merged over [secrets] (same VAR — the -s pair wins):

arca run -s TEMP_TOKEN=arca://ci/token -- ./deploy.sh

Missing secrets fail closed

If any declared or -s ref isn't stored in its env, run fails before spawning — partial injection is worse than none.

arca env — the human path

eval "$(arca env)"                              # export every declared VAR
eval "$(arca env -s EXTRA=arca://misc/extra)"   # plus ad-hoc pairs
arca env --json                                 # {"VAR": "value"} map

Output is export VAR='…' with shell-safe quoting for any value. This prints plaintext into your shell environment — that's why it's the human path: agents should run instead. A [guardrails] deny on env is the owner's hint.

The audit trail

Each resolved ref emits one materialization event on stderr — op is run or env, rref the ref path, outcome: "ok". See the audit wire.