dedo

README

dedo

Define once, deploy everywhere. Author one .proto, ship it everywhere. The same contract serves your API as RPC (Connect and gRPC), REST and MCP tools for AI agents, with the same auth, documentation and behaviour on every transport:

From one .proto you get	How
RPC over Connect and gRPC	connect-go
REST, with resource-style URLs	google.api.http annotations, served by Vanguard
REST reference docs (OpenAPI 3.1)	protoc-gen-rest-openapi
MCP tools for AI agents	protoc-gen-go-mcp with the mcpserver adapter
Authorization, cache and deprecation headers, flow IDs, error audit	The policy runtime, read from options in the .proto

First-class lint guidance. A Buf check plugin turns the standard into findings in your editor as you type, each linked to an explanation in HOUSE_RULES.md. The same buf lint gates CI. Handlers carry business logic only.

New here? install.md builds a new product from scratch, step by step. guideline.md explains the reasoning.

Latest release: v0.3.0. The options module is buf.build/r-a/dedo. The lint plugins come as native binaries on the GitHub release (make tools) and as Wasm plugins on the BSR. The Go modules are github.com/raveesh-me/dedo/...@v0.3.0.

Contract rules come from Google's AIPs. Operational rules (audience, ownership, scopes, caching, deprecation, error reasons) come from Zalando's guidelines. Both live in the schema.

What is in this repository

Component	Path	Job
Options module	proto/dedo/v1/options.proto	Declares audience, owner, scopes, cache policy, deprecation, error reasons, sensitive fields, message descriptions, and how each RPC appears as an MCP tool (title, description and the MCP specification's ToolAnnotations). Published as buf.build/r-a/dedo.
House lint plugin	lint/	Fourteen house rules, HOUSE_* in the HOUSE category. Released as native binaries per platform (fast in editors) and as the Wasm check plugin buf.build/r-a/dedo-lint.
Policy table	policy/	Reads the options from descriptors at startup. Fails on a missing declaration.
Flow ID	flowid/	Reads or creates X-Flow-ID and propagates it on outbound calls.
Policy interceptor	interceptor/	Checks scopes, sets Cache-Control, Deprecation and Sunset, and logs undeclared error reasons.
REST doc generator	openapi/	protoc-gen-rest-openapi: an OpenAPI 3.1 document from the google.api.http bindings, with scopes, error reasons, deprecation and the declared descriptions. Connect routes are left out.
MCP adapter and schemas	mcp/	protoc-gen-mcp-schema writes each tool's input schema at code-generation time: field descriptions from comments, OUTPUT_ONLY fields left out, partial-update and create semantics from AIP. mcpserver serves the tools protoc-gen-go-mcp generates under short snake_case names (get_todo), with those schemas, the declared title, description, ToolAnnotations and error reasons, and without deprecated RPCs. Tool calls run through the same auth and policy as REST.
Templates	templates/	buf.yaml, buf.gen.yaml, Makefile.api, VS Code settings, a Jenkins stage and a policy-table test for service repositories.
Examples	examples/	library: a contract-only module. todo and bad-todo: two runnable services with the same interface, one compliant and one breaking every rule.

The root Go module (github.com/raveesh-me/dedo) holds the runtime and the generated options code. lint/, openapi/ and mcp/ are separate modules, so services pull in only what they use.

Declaring a contract

One RPC with every declaration the standard asks for, from examples/library (which CI lints):

service LibraryService {
  option (dedo.v1.service) = {
    audience: AUDIENCE_EXTERNAL_PUBLIC
    owner_team: "library-team"
  };

  // GetBook returns one book.
  //
  // Errors: BOOK_NOT_FOUND.
  rpc GetBook(GetBookRequest) returns (GetBookResponse) {
    option idempotency_level = NO_SIDE_EFFECTS;
    option (google.api.http) = {
      get: "/v1/{name=shelves/*/books/*}"
      response_body: "book"
    };
    option (dedo.v1.method) = {
      tool: {
        title: "Get a book"
        description: "Returns one book by its resource name, such as shelves/1/books/2."
        annotations: {
          read_only_hint: true
          open_world_hint: false
        }
      }
      scopes: "library.book.read"
      cache: {
        visibility: VISIBILITY_PRIVATE
        max_age: {seconds: 30}
      }
      errors: {
        reason: "BOOK_NOT_FOUND"
        code: NOT_FOUND
      }
    };
  }
}

// GetBookRequest is the request of GetBook.
message GetBookRequest {
  option (dedo.v1.message) = {description: "Which book to get."};

  // The resource name of the book.
  string name = 1 [
    (google.api.field_behavior) = REQUIRED,
    (google.api.resource_reference) = {type: "library.raveesh.me/Book"}
  ];
}

See examples/library/proto for a complete module.

Lint rules

Rule ID	Checks
HOUSE_SERVICE_RULES_REQUIRED	Every service declares the service option with an audience and an owner team
HOUSE_METHOD_RULES_REQUIRED	Every RPC declares the method option with at least one scope and one error reason
HOUSE_SCOPE_NAME_FORMAT	Scopes match <app>.<resource>.<read|write>
HOUSE_ERROR_REASON_FORMAT	Reasons are UPPER_SNAKE_CASE. Codes are neither OK nor UNKNOWN.
HOUSE_CACHE_REQUIRES_NO_SIDE_EFFECTS	A cache policy appears only on NO_SIDE_EFFECTS methods, with a visibility and a positive max age
HOUSE_DEPRECATION_CONSISTENT	deprecated = true and a deprecation schedule appear together, sunset follows deprecation, and the successor exists
HOUSE_READ_METHOD_NO_SIDE_EFFECTS	Unary Get* and List* RPCs set idempotency_level = NO_SIDE_EFFECTS
HOUSE_HTTP_RESPONSE_BODY	HTTP rules of Get*, Create* and Update* RPCs set response_body
HOUSE_HTTP_PATH_VERSION	Every HTTP path, additional bindings included, contains the package version, such as /v1/, after a root that is the same for the whole service. The root itself, such as /commerce/pim, is the owner's choice.
HOUSE_NO_JSON_NAME	No field overrides the protojson default name
HOUSE_MONEY_FIELD_TYPE	Fields named price, amount, *_price or *_amount use google.type.Money
HOUSE_TOOL_REQUIRED	Every unary RPC declares a tool title and description for MCP and the REST docs
HOUSE_TOOL_ANNOTATIONS	Every unary RPC declares the MCP ToolAnnotations hints (spec 2026-07-28), consistent with its idempotency_level
HOUSE_MESSAGE_DESCRIPTION_REQUIRED	Every message declares a consumer-facing description

HOUSE_RULES.md explains each rule with examples. Every finding ends with a link to its section, pinned to the plugin's release tag.

Suppress one finding with // buf:lint:ignore HOUSE_MONEY_FIELD_TYPE above the element, followed by the reason.

Using it in a service repository

install.md walks through it end to end with a working example. In short:

1. Copy the files in templates/ (buf.yaml, buf.gen.yaml, Makefile.api, CODEOWNERS, VS Code settings, the Jenkins stage) and replace the YOUR_* placeholders.
2. Pin the code generators in go.mod with go get -tool, run make tools for the native lint plugins, and run buf dep update.
3. Write the contract, then make api-check (lint, format, breaking) and buf generate (Go, Connect, MCP tools, REST docs).
4. Wire the runtime: policy.Build for the policy table, interceptor.New for scopes and headers, Vanguard for REST, mcpserver.New with the generated MCPInputSchemas for MCP, and the docs handler. Start with EnforceScopes: false (audit mode), then enforce.
5. Add templates/policy_table_test.go.tmpl as a test, so a missing declaration fails before deploy.

buf.gen.yaml uses managed mode. A module-scoped go_package_prefix override points imports of the options module at this repository's Go module, so generated code links against the runtime's types.

Known gaps: error responses carry no deprecation headers, and streaming calls get the scope check only, with no error audit.

Examples: todo and bad-todo

Two Go services, each laid out like a service repository built from templates/, with its own buf.yaml, buf.gen.yaml, go.mod and proto files. Both serve the same TodoService over Connect, gRPC and REST (through Vanguard), with the same server code and the full runtime: policy table, scope interceptor, flow IDs and error audit.

• examples/todo follows the standard. buf lint is clean. Its tests check scopes, CRUD, pagination, cache and deprecation headers, REST unwrapping and the error audit end to end. It also serves the REST reference at /docs (Stoplight Elements, rendering the generated /openapi.json) and an MCP server at /mcp. Its tests check that MCP tools carry the declared text and ToolAnnotations and enforce the same scopes, and that a change made through MCP reaches an open WatchTodos stream at once.
• examples/bad-todo breaks all fourteen house rules, plus one Buf and one AIP rule. Open proto/raveesh_me/todo/v1/todo.proto in VS Code to see the findings. expected-lint.txt lists them, and app/app_test.go shows what each mistake does at runtime: a misnamed scope locks out writers, an unversioned path moves the endpoint, undeclared reasons show up in logs, and a custom json_name renames the field for every JSON client.

examples/todo also runs as a deployment, with everything built in containers (podman, kind and kubectl are the only host tools):

cd examples/todo
make up      # kind cluster "todo-example": the service and a live Vue UI at http://localhost:8090
make e2e     # Playwright: an agent adds a to-do over MCP and the open UI shows it without a reload
make down

The UI (web/) uses TanStack Query through connect-tan-vue's createClientWithQuery, and stays live through the WatchTodos server stream. examples/todo/MCP.md shows how to connect Claude Code or Claude Desktop to the service's MCP endpoint.

The examples test this repository's working tree, not a release: each vendors options.proto under third_party/ and loads the lint plugins from dist/. Run make plugins once so the editor finds them, then make examples. Rerun make plugins after changing a rule. Service repositories use the published module and plugins instead.

cd examples/todo && go run . &
curl -H 'Authorization: Bearer writer' -H 'Content-Type: application/json' -d '{"title":"try it"}' localhost:8080/commerce/todo/v1/todos
curl -i -H 'Authorization: Bearer reader' localhost:8080/commerce/todo/v1/todos/1
open http://localhost:8080/docs

Lint performance

The plugins run natively wherever they can. On examples/todo, one buf lint with both plugins takes:

Plugin form	Time
Native binaries (default)	0.34 s
WebAssembly	6.0 s

The editor reruns the lint as you type, so this is the difference between findings that keep up and findings that lag. Most of the WebAssembly time is the AIP plugin: a 45 MB module. Buf caches the compiled module, so the cost is in running it, and a smaller build does not help. buf.yaml refers to the native binaries by path, so an editor started outside a shell finds them too. The WebAssembly plugins on the BSR stay available for setups that cannot download binaries, such as Windows.

Developing

make check          # format, generate, Go tests, plugin builds, buf lint, examples
make plugins        # both lint plugins, natively for this machine, into dist/
make wasm-plugins   # both lint plugins as WebAssembly, for the BSR
make breaking       # options module against main

make check needs buf and jq. Code generators are pinned in each go.mod as Go tools and run through go tool. The root buf.yaml lints the options module (Buf rules only, since it defines the extensions) and examples/library (all rules, with the locally built plugin from dist/).

Lint rule tests live in lint/rules/testdata/<rule>/{pass,fail}. A pass fixture must produce no finding. A fail fixture marks each line that must produce one with // want.

Releasing

A pull request that breaks the options module fails CI's buf breaking check. When the break is deliberate, label the PR allow-breaking, re-run the check, and release a new minor version.

To release, tag the merge commit on main with lint/vX.Y.Z, openapi/vX.Y.Z and mcp/vX.Y.Z (so go get works for the nested modules) and push those first. Then push vX.Y.Z on its own: GitHub starts no workflow when more than three tags arrive in one push.

The v* tag runs .github/workflows/ci.yaml, which publishes one version everywhere:

• buf push of the options module with the tag and main as labels; main is the default label that unpinned dependencies resolve to
• buf plugin push of buf.build/r-a/dedo-lint and buf.build/r-a/buf-plugin-aip
• a GitHub release carrying both plugins as native binaries for macOS and Linux (arm64 and amd64), which make tools downloads, and as .wasm files

The Go module version is the same tag. The job reads a BUF_KEY repository secret: a Buf token for the r-a organization with module and plugin create and push scopes.

buf-plugin-aip is a young third-party project (hestiatechnology/buf-plugin-aip, Apache-2.0). It is pinned to commit 5158ec0f16f3 and republished from that commit.

License

Apache License 2.0.