Host Admission (N+1)

Last updated: 2026-07-09 (Phase 111.1)

This page is the checklist for adding a new agent host to Claude Code Harness. It pairs with the multi-host bar H1–H8 in docs/spec/planning-and-host-adapter.md and the machine SSOT hosts/registry.json.

Why a registry

Without a registry, each new host copies case statements in:

• scripts/build-host-plugin-dist.sh
• scripts/model-routing.sh
• scripts/release-preflight.sh
• README / matrix / onboarding tier tables

That snowflake cost does not scale. New hosts start as one registry row plus thin setup/smoke scripts.

SSOT layout

File	Role
hosts/registry.json	Machine SSOT: id, tier, setup, dist, routing, floor_member, smoke paths
hosts.toml	Hook generation descriptors for harness gen (event/deny/codec) — separate concern
scripts/lib/host-registry.sh	Bash/node helpers to read the registry
tests/test-host-registry.sh	Tier tables and script paths must match the registry

Admission checklist (12 items)

Complete before raising public tier above future/unsupported.

1. Native intercept or explicit none Can the host stop an action before it runs? If no, set safety_model: none and max public tier is packaging / candidate until a documented post-gate model exists.

2. Deny semantics Document fail-closed vs fail-open (e.g. Cursor non-exit-2 fail-open).

3. Event coverage Shell only? File write? MCP? Read? Record Bash-only gaps honestly.

4. Install unit test Isolated HOME / install root; no writes to the operator's live config in CI.

5. Static smoke in CI Package shape, no .. in dist manifests, core skills present.

6. Optional runtime flagHARNESS_<HOST>_*_SMOKE_REQUIRED=1 for hard fail when CLI is expected.

7. Bootstrap route named Entry in docs/bootstrap-routing-contract.md (not false SessionStart parity).

8. support-claim wording Block EN supported and JP 正式対応 / 対応済み for this host until H1–H8 green (tests/test-support-claim-wording.sh).

9. Evidence research notedocs/research/<host>-adapter-candidate.md with observed / missing / commands.

10. Floor join or explicit exclusionfloor_member: true only after harness hook pre-tool --host <id> live deny; otherwise false and never claim 3cli parity.

11. Public wording template Allowed vs blocked phrases in registry blocked_public_phrases + onboarding.

12. Capability matrix row Every capability cell has strength language; same name ≠ same enforcement.

How to add host example

1. Implement thin scripts/setup-example.sh (--check + isolated install).
2. Add dist profile in build-host-plugin-dist.sh or generic copy profile driven by registry fields (prefer generic).
3. Add routing catalog in model-routing.sh if the host is an execution/routing surface.
4. Append a row to hosts/registry.json.
5. Add tests/test-example-adapter-*.sh and point smoke.adapter at it.
6. Update README / matrix / onboarding tier tables (or generate from registry later).
7. Run:

bash tests/test-host-registry.sh
bash tests/test-host-plugin-dist.sh
bash tests/test-model-routing.sh
bash tests/test-support-claim-wording.sh

8. Do not set tier: supported until H1–H8 pass on one claim path (Phase 111).

Registry field contract

Field	Meaning
id	Stable slug (grok, cursor)
display_name	Public table label (Grok, Claude Code)
tier	supported | internal-compatible | candidate | future/unsupported
setup_script	Path or null
dist_host	Value for build-host-plugin-dist.sh --host
routing_host	Value for model-routing.sh --host
safety_model	Free-form enum string for docs/tests
floor_member	boolean — shared pre-tool floor
smoke.adapter / smoke.setup_check	Commands/paths for preflight
blocked_public_phrases	Patterns that must not appear as public claims

Related

• docs/bootstrap-routing-contract.md
• docs/tool-capability-matrix.md
• docs/plans/phase-111-multi-host-supported.md
• docs/spec/planning-and-host-adapter.md (H1–H8)