What is sdk-adapter-extension?

A pattern for adding fields from an external software library to an application’s interface, adapter, and cached data model. An adapter translates one system’s types into types used by another system.

Use it when exposing a new field from an SDK through mockable interfaces, adapter code, cache records, tests, and service logic.

It keeps these layers synchronized and helps older cached data continue to load when new fields are introduced.

How lewing/helix.mcp configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to lewing/helix.mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/lewing/helix.mcp/main/.squad/skills/sdk-adapter-extension/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/lewing/helix.mcp

Made for: Claude Code, Codex.

Wrote this? Show the measurements

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README.md

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Your own site · 80×15

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Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 581 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00000	$0.00581
Opus 5	$0.00000	$0.00291
Sonnet 5	$0.00000	$0.00116
Haiku 4.5	$0.00000	$0.00058

Measured 10d ago against content hash 37446fac89ab, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

sdk-adapter-extension scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.squad/skills/sdk-adapter-extension/SKILL.md · 45 lines

How it starts

The opening of the file, as written. The whole thing — 45 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: Extending SDK-Backed Adapter Interfaces

When to use: Adding new fields from an upstream SDK (e.g., Microsoft.DotNet.Helix.Client) through our mockable interface → adapter → cache-DTO layer.

Pattern

Our Core layer wraps SDK concrete types behind mockable interfaces (IWorkItemSummary, IJobDetails, etc.). Three classes must stay in sync when a new SDK field is surfaced:

Interface (IHelixApiClient.cs) — add nullable property
Adapter (HelixApiClient.cs inner class) — map from SDK type
Cache DTO (CachingHelixApiClient.cs record) — add to constructor + From() factory

Checklist

New property is nullable (SDK may not populate on older data)
Adapter delegates directly to SDK property (no transformation)
Cache DTO includes field in both the record positional params and From() method
Old cached data (missing new fields) deserializes to null — verify JSON round-trip
Update any mocks/fakes in test projects that implement the interface
If the field enables skipping a downstream API call, add the optimization in HelixService, not in the adapter layer

Files (always this set)

Layer	File
Interface	`src/HelixTool.Core/Helix/IHelixApiClient.cs`
SDK Adapter	`src/HelixTool.Core/Helix/HelixApiClient.cs`
Cache Adapter	`src/HelixTool.Core/Helix/CachingHelixApiClient.cs`
Service Logic	`src/HelixTool.Core/Helix/HelixService.cs`

Anti-patterns

Don't rename SDK fields at the interface boundary — keep names aligned to reduce cognitive load
Don't add transformation logic in adapters — they are pass-through only
Don't make non-nullable what the SDK provides as nullable

Testing pattern

When the adapter/cache types stay private nested classes, cover them without widening visibility:

Use reflection (GetNestedType, Activator.CreateInstance) to instantiate the private adapter against the real SDK model.
Invoke the private DTO's public static From() factory via reflection, then JsonSerializer.Serialize/Deserialize(..., dtoType) to validate the cache round-trip.
Add an explicit backward-compat test that deserializes legacy JSON missing the new fields and asserts the surfaced interface properties come back as null.
Keep behavior tests separate: assert service-layer call-count optimizations through IHelixApiClient mocks, and assert MCP JSON shape by serializing the real result type.

Read the full file on GitHub · 45 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

10d ago First seen · 45 lines · 0 tokens per session scan A 37446fac89ab

Subscribe to this mod's changes

sdk-adapter-extension is a skill published in the GitHub repository lewing/helix.mcp (4 stars, last pushed today), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 581 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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