Commit graph experimental-ext-interceptors/go/sdk/examples/validator
Author SHA1 Message Date
monikaicampbell
bd57572579
Go SDK: Align mode with SEP (#40)
<!-- Provide a brief summary of your changes -->

## Motivation and Context
The SEP-2624 spec defines interceptor modes as "active" | "audit". This
change aligns the Go SDK's interceptor `Mode` value with the SEP spec.

## How Has This Been Tested?
- go test ./... from go/sdk — all packages pass (chain, extension,
integrations/gomiddleware).
- gofmt -l . — clean.
- go vet ./... — clean.

## Breaking Changes
Yes:
- The exported constant interceptors.ModeEnforce is removed and replaced
by interceptors.ModeActive. Callers referencing ModeEnforce must rename.
- The serialized mode value changes from "enforce" to "active". Any
config expecting "enforce" must be updated.

## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [x] Breaking change (fix or feature that would cause existing
functionality to change)
- [x] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [x] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->

Signed-off-by: monikaicampbell <mcampbell350@bloomberg.net>
2026-08-21 15:56:07 +01:00
Ukjae Jeong
8704137635
Go SDK: Upgrade MCP SDK and remove vendored copy (#35)
<!-- Provide a brief summary of your changes -->
Update the Go interceptor SDK to use
`github.com/modelcontextprotocol/go-sdk` v1.7.0 custom method APIs and
remove the vendored Go SDK copy. This shouldn't update the behaviours,
but addding following functions.

Changed public/user-facing interfaces:
extension.Extension.Install now returns an error:

```
// before
ext.Install(mcpServer)

// after
if err := ext.Install(mcpServer); err != nil {
	return err
}
```

New helper added:

```
extension.RegisterSendingMethods(client *mcp.Client) error
```

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->

Pick up MCP Go SDK 1.7.0. This provides upstream custom method support,
so the local vendored SDK copy is no longer needed.

## How Has This Been Tested?
<!-- Have you tested this in a real application? Which scenarios were
tested? -->

- `go test -v ./...`

## Breaking Changes
<!-- Will users need to update their code or configurations? -->

```go
if err := ext.Install(mcpServer); err != nil {
    return err
}
```

The Go SDK module now requires Go 1.25 via
github.com/modelcontextprotocol/go-sdk v1.7.0.

## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [x] Breaking change (fix or feature that would cause existing
functionality to change)
- [x] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->
LocalChain now registers interceptor custom sending methods internally.
Manual remote chain setup should call
`extension.RegisterSendingMethods(client)` before connecting the MCP
client session used with chain.AddMCPServer.

Signed-off-by: Ukjae Jeong <jeongukjae@gmail.com>
2026-08-12 14:48:17 -07:00
Ukjae Jeong
23d889254b
Go SDK: Align hooks with SEP (#23)
The SEP spec and C# SDK use hooks (plural, JSON array) but the Go SDK
had hook (singular, single object). This meant the wire formats were
incompatible — Go would send `{"hook": {...}}` while everything else
expects `{"hooks": [...]}`.

Signed-off-by: Ukjae Jeong <jeongukjae@gmail.com>
2026-06-16 15:49:49 +01:00
Kurt Degiorgio
074dc6cdbd
Rename mcpserver package to extension, remove *mcp.Server field (#11)
## Summary

- Rename `interceptors/mcpserver/` → `interceptors/extension/`,
replacing the `Server` wrapper with a lightweight `Extension` that can
install itself on any `*mcp.Server`
- Remove the stored `*mcp.Server` field — `Extension` is now a pure
interceptor container with no server reference
- Add `Install(server)` method to register JSON-RPC methods and init
middleware on a given server
- Update `LocalChain(ctx)` → `LocalChain(ctx, server)` to accept the
server as a parameter
- Remove `MCPServer()`, `Run()`, and `NewStreamableHTTPHandler()`
wrapper methods — users interact with `mcp.Server` directly
- Update all examples, tests, and documentation to use the new API

## Why

`mcpserver.Server` pretended to *be* the server — it had `Run()`,
`NewStreamableHTTPHandler()`, etc. — but it could never cover the full
`*mcp.Server` API, so users constantly needed `MCPServer()` to unwrap
it.

`Extension` doesn't pretend to be the server. It's a pure interceptor
container that can install itself on any server (or multiple servers)
on the fly. No stored server reference, no wrapping, no delegation
surface to maintain.

### Before

```go
mcpServer := mcp.NewServer(...)
srv := mcpserver.NewServer(mcpServer)
srv.AddInterceptor(v)
chain, err := srv.LocalChain(ctx)
```

### After

```go
mcpServer := mcp.NewServer(...)
ext := extension.New()
ext.AddInterceptor(v)
ext.Install(mcpServer)
chain, err := ext.LocalChain(ctx, mcpServer)
```

Signed-off-by: Kurt Degiorgio <kdegiorgio@bloomberg.net>
2026-04-30 15:57:18 +01:00
Kurt Degiorgio
c9900f02ab
Implement Go interceptor chain (#4)
## Summary

Implements the Go SDK for MCP interceptors — validation and mutation
middleware for any MCP server.

The framework treats interceptors as first-class MCP primitives: they
are registered on an MCP server, discoverable via `interceptors/list`,
and invocable via `interceptor/invoke` — the same JSON-RPC pattern as
tools, prompts, and resources. A chain engine orchestrates execution
across one or more interceptor servers, and an optional go-sdk
middleware integration applies interceptors automatically on every
matching request/response.

## Architecture

**Three-layer design:**

1. **`interceptors`** — Protocol-agnostic core. Defines interceptor
types (validators, mutators), metadata, invocation, wire types, and
results. Zero MCP dependencies.

2. **`interceptors/mcpserver`** — MCP server integration. Wraps
`mcp.Server` to register `interceptors/list` and `interceptor/invoke` as
custom JSON-RPC methods and advertise interceptor capabilities during
`initialize`.

3. **`interceptors/chain`** — Chain engine. Orchestrates execution
across N interceptor servers with trust-boundary-aware ordering,
priority-based mutation sequencing, parallel validation, audit-mode
isolation, and fail-open/fail-closed semantics.

4. **`interceptors/integrations/gomiddleware`** — Optional go-sdk
middleware. Installs on `mcp.Server` via `AddReceivingMiddleware()` to
automatically run the interceptor chain on every matching
request/response.

**Key design decisions:**

- **Trust-boundary ordering** — request phase: validate → mutate;
response phase: mutate → validate. Validation always guards the boundary
crossing.
- **Wire-level invocation** — the chain calls `interceptor/invoke` over
the MCP transport (even in-process via `LocalChain()`), so local and
remote interceptor servers use the same interface.
- **Audit-mode isolation** — audit-mode mutators compute transformations
without applying them. Only audit mutators pay the serialization cost.
- **Concurrency** — validators run in parallel; mutators run
sequentially in priority order.

### Package Structure

| Package | File | Responsibility |
|---------|------|----------------|
| `interceptors` | `interceptor.go` | Enums, Metadata, Interceptor
interface, Validator/Mutator structs, handler types, Invocation |
| `interceptors` | `wire.go` | Wire types: ListParams/Result,
InvokeParams/Result, InterceptorInfo, event/method constants |
| `interceptors` | `priority.go` | Priority with phase-aware resolution
and JSON marshaling |
| `interceptors` | `doc.go` | Package documentation with examples |
| `interceptors/chain` | `chain.go` | Chain engine: discovery,
filtering, sorting, execution orchestration |
| `interceptors/chain` | `result.go` | ExecutionResult, AbortInfo |
| `interceptors/chain` | `doc.go` | Sub-package documentation |
| `interceptors/mcpserver` | `server.go` | MCP server wrapper,
interceptor registry, capability advertisement, `LocalChain()` |
| `interceptors/mcpserver` | `rpc.go` | `interceptors/list` and
`interceptor/invoke` JSON-RPC handlers |
| `interceptors/mcpserver` | `doc.go` | Sub-package documentation |
| `integrations/gomiddleware` | `middleware.go` | go-sdk `Middleware`
that runs the chain on every request/response |
| `integrations/gomiddleware` | `errors.go` | Abort-to-JSONRPC error
conversion |
| `integrations/gomiddleware` | `doc.go` | Sub-package documentation |

### Documentation

- `doc/DESIGN.md` — architecture, execution model, integration with
go-sdk
- `doc/CONFORMANCE.md` — SEP conformance status
- `doc/PERFORMANCE.md` — per-request cost model

### Examples

- `examples/validator` — blocks dangerous tool calls, demonstrates
`WithContextProvider`
- `examples/mutator` — tags tool responses with audit trail

## Vendor: go-sdk v1.4.0 with custom method support

Vendors `go-sdk` with minimal extensions for custom JSON-RPC methods:

- `Server.AddCustomMethod` — registers a handler that bypasses the typed
pipeline
- `ClientSession.CallCustom` — sends raw JSON-RPC calls for custom
methods

These changes are generic (not interceptor-specific) and enable any MCP
extension to define its own JSON-RPC methods.

## TODO

- More integration tests
- Unit tests
- Support wildcards for event interception (separate PR)

---------

Signed-off-by: Kurt Degiorgio <kdegiorgio@bloomberg.net>
2026-04-29 15:29:25 +01:00