# G6 Host Bridge Workflow Design

> Date: 2026-04-18
> Status: Initial implementation slice

## Goal

Define `G6 宿主桥接多步查询型` as a separate scene family so boundary samples no longer fall back into `G1` or `G1-E`.

The initial implementation goal is classification and fail-closed safety, not runnable generation.

## Family Definition

`G6` covers scenes where the business workflow is primarily advanced by host-browser bridge actions instead of direct request contracts.

Minimum signals:

1. explicit host bridge action such as `BrowserAction(...)`
2. explicit browser script bridge such as `sgBrowserExcuteJsCode(...)`
3. callback-driven request progression
4. business endpoints nested behind the host callback chain
5. optional `localhost:*` dependency as host runtime evidence

## P0 Boundary Sample

`电能表现场检验完成率指标报表`

Repo-local representative:

`tests/fixtures/generated_scene/g6_host_bridge_workflow`

## Contract Policy

The first slice intentionally does not generate runnable skills for `G6`.

Instead, it must:

1. classify the scene as `host_bridge_workflow`
2. preserve host bridge actions as evidence
3. preserve `localhost:*` dependencies as host-runtime evidence
4. prevent fallback to `single_request_table`
5. prevent fallback to `single_request_enrichment`
6. fail closed with a stable blocker

## Non-Goals

1. no host transport redesign
2. no callback runtime implementation
3. no full browser bridge orchestration
4. no broad `G7/G8` expansion
5. no weakening of `G1-E` or `G3` gates

## Readiness Gates

The first slice adds these G6-specific gates:

1. `g6_host_bridge_detected`
2. `g6_fail_closed`

`g6_fail_closed` is expected to fail until a real G6 runtime contract exists.

## Acceptance Criteria

1. `G6` fixture is classified as `host_bridge_workflow`
2. generation fails closed instead of writing a pseudo-runnable skill
3. ordinary localhost export noise does not get promoted to `G6`
4. existing `G1-E`, `G3`, `G2`, and canonical tests remain green