#2924 Auth gate blocks nested swamp in workflow shell steps when the credential is in SWAMP_API_KEY

Description

With the auth gate (swamp-club#2231), a swamp command run from a workflow's command/shell step is blocked when the credential is in the environment rather than in auth.json:

"code": "auth_gate_blocked", "reason": { "kind": "no_credential" }

The outer swamp workflow run passes the gate. The shell model builds the child's environment with createSafeMethodEnv (src/domain/remote/environment_snapshot.ts), which strips every SWAMP_* variable, including SWAMP_API_KEY and SWAMP_SIGNIN_TOKEN, and keeps HOME and PATH. So the nested swamp passes the gate only if HOME has a saved login.

That breaks the setup the gate's own error message recommends for CI ("set SWAMP_API_KEY and SWAMP_SIGNIN_TOKEN"). Any workflow step that calls swamp fails in CI, while it keeps working for someone logged in with swamp auth login.

Stripping SWAMP_* from method children is right for external tools. It now also blocks swamp from calling itself, the case swamp-club#296 handled for locks by passing SWAMP_LOCK_HOLDER_PID to nested commands.

Steps to reproduce

1. Put the credential only in the environment: SWAMP_API_KEY=<key>, with HOME and XDG_CONFIG_HOME pointing at an empty directory.
2. swamp repo init --tool none
3. Add a command/shell model (shell-consumer, run: "echo default") and a workflow whose step runs that model's execute with input run: "swamp model search --json". These are swamp-uat's fixtures tests/cli/fixtures/models/shell-consumer.yaml and tests/cli/fixtures/workflows/nested-swamp-command.yaml.
4. swamp workflow run nested-swamp-command

Expected: the workflow completes, as it does on 20261001.182044.0-sha.aa8acf26 (before the gate).

Actual on 20261001.202145.0-sha.a3515474: exit 1, "Failed workflow nested-swamp-command". The nested step prints auth_gate_blocked / no_credential.

swamp-uat's tests/cli/adversarial/subprocess_lock_test.ts (adversarial tier 6) fails the same way in CI: both of its tests, with SWAMP_API_KEY and SWAMP_SIGNIN_TOKEN set on the job.

Possible fixes

• Pass the credential to nested swamp processes, as SWAMP_LOCK_HOLDER_PID is passed, or
• Allow SWAMP_API_KEY and SWAMP_SIGNIN_TOKEN through createSafeMethodEnv's allow list when the child is swamp itself.

Environment

• swamp 20261001.202145.0-sha.a3515474 (also 20261001.191636.0-sha.71c25269)
• Linux x86_64; reproduced locally and on GitHub Actions ubuntu-latest

Related

swamp-club#2916 lists the silent exit of a blocked audit record. In swamp-uat, that same behaviour makes swamp audit record --help print nothing on CI shards whose key has no matching signin token: hook mode checks locally only and gates --help too.