specter-agent-protocolslisted

# SPECTER External-Agent Protocols Single source of truth for the mechanics every Codex/Antigravity station shares. A command that invokes an external agent applies these five protocols and states inline only what is specific to it (its report paths, single- vs dual-agent station, and any degrade direction that differs). ## 1. Preflight (session-level, once) Check external-agent availability **once per session** and remember the result — do not re-check on every command invocation within the same session: - **Codex**: the `codex` binary is on PATH, auth is configured, and its sandbox mode in `~/.codex/config.toml` is not read-only (e.g. `workspace-write` or `danger-full-access`). A cheap config check, not a live probe run. - **Antigravity**: the `agy` binary is on PATH, auth is configured, and its write flag is set (see `docs/ops/antigravity-write-flag.md` for the re-apply procedure — a plugin update can transiently reset it). On failure, retry once. If it still fails, apply the Degrade Rule (§2) instead of blocking the command. ## 2. Degrade Rule (one agent down) - If one agent of a dual-agent station is unavailable after retry: run the station with the remaining agent only, force the station result to at most `WARN`, and write `<Agent>: UNAVAILABLE (<reason>)` into the missing agent's report path in place of a normal report. - **Never** present a single-agent run as if both agents ran. - **Never** block a cycle on an external-agent environment issue alo