**Gate verdict (doyle, 2026-09-08 07:50Z): PASS at `bccfaee8` — landed by fast-forward, tested sha == merged sha.**

Head = F17 (`6e075f7e`, ServeFor dispatcher arm) + F19 (`bccfaee8`, rig: B seeds A as roster member + A's audience row, asserts through `node_hosting_endpoint`). Battery ran from a frozen driver in the gate worktree, pool `ws272-w2`, with every leg's exit read from its file:

- claim / treqs / prebuild / xtask check / clippy `--workspace --all-targets -D warnings` — all 0
- nextest list: 11 named W2 cells + 5 twohost_web cells present
- spt-daemon + spt-net libs: 1162 run / 1162 passed (1 skipped), incl. `a_serve_for_request_opens_the_web_family_and_a_newer_kind_drops`
- e2e witnesses: io_events_undriven_kinds 7/7, webserve_attachment 1/1, webserve_cross_node 1/1 (arm markers present)
- **One-box pair, Windows: WITNESSED** — owner `WEB_SERVE_FOR … outcome=registered audience=w2-helper-audience`, verdicts `[Merged(Inserted)]`, helper_role_a PASS 66.2 s, role_b PASS 86.7 s, 5/5 both roles, exits 0/0
- **One-box pair, Linux (kitsubito): WITNESSED** — same lines, helper_role_a PASS 65.1 s, 5/5 both roles
- Cross-box pair: A→B deny/fetch PASS; helper/range/role_b red under the ABSENT firewall rule → F18-INFRA, IR-83 rider (not a verdict)
- **Mutation D** (revert the ServeFor classify arm): libs 1162 run / 1161 passed / **1 failed = only the classify cell** (`left: Unknown, right: Web`); one-box pair then reproduces the F17 signature (owner `family=Unknown`, no `WEB_SERVE_FOR`, helper red, deny/fetch PASS); revert → dirty 0

Riders: (1) the helper round trip is a stable ~65 s on both OSes (six 10 s `A not ready` dials before the user-msg is admitted) — hertz, window-vs-cadence discriminator; (2) cross-box helper witness on the operator's `spt-twohost-rig` firewall rule — IR-83; (3) rig WAIT must stay under nextest's 240 s terminate bound (driver runs 120).

Raws: `.worktrees/gate-w2-401a19ad/.spt/gate-f17-bccfaee8/`, pairs under `.spt/twohost-web/f17-bccfaee8-*` and `.spt/gate-f17-bccfaee8/k-local-none/`. Record: `GATE-W2-272-CHECKLIST.md`.