Claude Code 2.1.x changed the flag's signature to take an *allowlist* of
tagged entries — `server:<name>` for manually-configured MCP servers,
`plugin:<name>@<marketplace>` for plugin channels. PR #25's
`{flag: None}` rendered as a bare `--<flag>` with no value, the CLI
rejected with `argument missing`, and the SDK timed out at `initialize`,
surfacing upstream as `Control request timeout: initialize` (caught
live on workspace dd40faf8 on 2026-05-01 — 100% of A2A turns wedged).
Pass `server:molecule` so the SDK forwards
`--dangerously-load-development-channels server:molecule`. Live-verified
end-to-end: A2A returns coherent replies AND the host claude session
renders inbound canvas messages as `<channel source="molecule" ...>`
tags inline (push UX without inbox poll).
Tests: replace the unconditional `None` pin with a tagged-form pin
that asserts the exact `server:molecule` value, plus a defense-in-depth
test that pins the invariants (non-None, non-empty, contains tag
colon) so any regression to the bare-switch shape fails at unit-test
time instead of surfacing as a live SDK initialize wedge. 38/38 pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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