#21707 test(acpmux): run three test binaries hermetically before the base-red skip expires (cx-5j26a)

acpmux's every_test_binary_runs_in_the_hermetic_environment has been red on every OS since 2026-10-15 (cx-5j26a). complete_rpc, session_mcp_servers and prompt_images came in without tests/support/daemon_env.rs and its HERMETIC constant. scripts/ci/cmux-tui-base-red.tsv skips the test until 2026-10-18 UTC, and after that cmux-tui-rust-check.sh fails the step for every head.

The three binaries now include the helper and define HERMETIC = Process::stand_in(), like the other tests that run stand-in agents (fake python agents, or shell scripts for Claude Code in complete_rpc). They re-exec with the bare PATH and scratch HOME before main. This PR also removes the skip line, as the file asks.

Testing

• cargo test -p acpmux --test hermetic_daemon_guard --test complete_rpc --test session_mcp_servers --test prompt_images on macOS (arm64): all 5 tests passed. That includes both guard tests, and the three binaries' tests now run under the hermetic environment.
• Not run: the full cmux-tui-rust-check.sh test and Linux.

Changelog

none

🤖 Generated with Claude Code

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Summary by cubic

Fixes the hermetic environment guard for three acpmux test binaries so the CI step no longer fails once the base-red skip expires.

• Adds the daemon_env helper and HERMETIC = Process::stand_in() to complete_rpc, session_mcp_servers, and prompt_images, which all run stand-in agents.
• Removes the skip line for every_test_binary_runs_in_the_hermetic_environment from cmux-tui-base-red.tsv, resolving cx-5j26a.