P7 E A4 First Expansion Corridor Decision Memo

# P7-E-A4: First Expansion Corridor Decision Memo (CN->US)
 
**Status:** Approved for planning, gated for activation  
**Date:** 2026-02-22  
**Owners:** Product + Engineering  
**Plan linkage:** `P7-E` rollout gate (`G1 Corridor Decision Memo`)
 
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## Executive Decision
 
The first non-`US->CA` expansion corridor is **`CN->US`**.
 
This memo selects the corridor and regulatory scope. It is **not** an activation approval. Activation still requires `G2`-`G6` evidence in `docs/runbooks/corridor-rollout-trigger-checklist.md`.
 
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## Alternatives Considered
 
| Corridor | Pros | Cons | Decision |
| --- | --- | --- | --- |
| `CN->US` | High demand signal for tariff risk, strong overlap with existing US trade-remedy data, reuses corridor scope model already exercised in ADR examples | Higher policy complexity (Section 301 + Section 232 + AD/CVD interactions) | **Selected** |
| `US->UK` | Lower policy complexity than CN->US in near term, clean bilateral corridor framing | Data and rule coverage not yet prepared in current platform baseline | Deferred |
 
Decision basis:
 
1. Maximize near-term customer value from known risk-heavy flows.
2. Reuse already-built foundations (`scope_type` metadata, wrong-corridor isolation tests, US AD/CVD data layer).
3. Keep implementation bounded to one corridor with explicit gates.
 
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## Regulatory Set Mapping (CN->US)
 
| Regulatory set | Applicability scope | Why it is in scope for `CN->US` | Current state | Required before activation |
| --- | --- | --- | --- | --- |
| Section 301 tariff lists | `CORRIDOR` (`CN->US`) | Primary corridor-specific tariff program for China-origin imports into US | Modeled in ADR guidance; production data/rules not yet fully seeded for this corridor | Seed + validate rule data, add positive-path tests (`G4`), verify fixtures (`G5`) |
| Section 232 steel/aluminum | `DESTINATION` (`->US`) | Can apply to US imports and must be evaluated alongside corridor rules | Concept documented; no dedicated activation evidence yet | Destination-scoped rule pack + regression tests for interactions with corridor rules |
| US AD/CVD orders | Destination/origin scoped remedies in `ref.trade_remedies` | Existing US data layer is the baseline for trade-remedy risk in this corridor | Thin slice seeded as BETA in prior work | Promote required measures, verify authority-filtered runtime behavior, golden coverage (`G5`) |
| Denied party screening (OFAC SDN, BIS Entity/DPL) | `PARTY` (orthogonal) | Mandatory compliance control for US nexus transactions | Deferred gate in ADR (`before GA`) | Enable and validate before general availability for US nexus customers (`G6`) |
 
Notes:
 
- ITAR/EAR are origin-export control regimes and are tracked as separate implementation gates in ADR-004; they are not part of this `CN->US` import-corridor activation slice.
- Scope precedence remains unchanged: applicability filtering occurs before rule evaluation.
 
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## Explicit Non-Goals
 
1. No immediate activation of `CN->US` in production from this memo alone.
2. No commitment to `US->UK` rollout timeline in this cycle.
3. No full global US AD/CVD coverage target in this slice.
4. No ITAR/EAR product classification implementation in this slice.
5. No denied-party GA promise until the dedicated gate is completed.
 
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## Gate Evidence Plan
 
Use this memo as `G1` evidence, then complete remaining required gates:
 
- `G2`: Applicability metadata present and explicit on rollout rules.
- `G3`: Wrong-corridor negative tests pass in CI.
- `G4`: Positive-path tests prove in-corridor rules fire.
- `G5`: Reference data + golden fixtures pass for rollout set.
- `G6`: Rollback/on-call/observability evidence is documented.
 
Final go/no-go for activation remains a separate decision record tied to a target customer/pilot.
 
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## Completed Gate Evidence (CN→US)
 
| Gate | Status | Evidence |
| --- | --- | --- |
| G1 | Complete | This memo |
| G2 | Complete | `scope_type` metadata on `rule_definitions` (ADR-004 §Applicability Metadata) |
| G3 | Complete | 20 corridor isolation tests + 3 cross-scope loader integration tests |
| G4 | Complete | corridor-isolation.test.ts §CN→US (7 tests) + loader.integration.test.ts CN→US cross-scope + load→compile chain |
| G5 | Complete | SECT301_CHECK + US_232_CHECK seeded in both runtime and CI paths; existing US golden fixtures pass |
| G6 | Complete | Corridor activation runbook (`docs/operations/p7-e-a7-cnus-corridor-activation-runbook.md`) — rollback plan (3-tier), on-call owner, observability baseline, and rollback rehearsal evidence |