feat(mcp): initial implementation — MCP server, framework indexer, 10 tools, 8 validation rules (v0.1.0)

Introduces code.nochebuena.dev/einherjar/mcp — the Einherjar Model Context Protocol
server. A remote, streamable-HTTP service that teaches AI assistants about every
other module of the framework: which package exposes which type, what each module
guarantees through its compliance tests, the canonical wiring shape for a service,
and whether a Go snippet follows the conventions. Indexes the framework on disk at
build time and ships a self-contained binary via go:embed; imports nothing from
other einherjar/* modules at compile time.

server (cmd/server):
- Streamable-HTTP MCP server built on github.com/modelcontextprotocol/go-sdk v1.0.0
- mcp.NewServer + mcp.NewStreamableHTTPHandler, served via net/http on EINHERJAR_MCP_ADDR
  (default :8080) and EINHERJAR_MCP_PATH (default /mcp)
- /healthz liveness endpoint; structured JSON logging via log/slog
- Loads the embedded data/index.json once at startup; in-memory for the process lifetime

indexer (cmd/indexer):
- Walks an Einherjar repository checkout (default ../), parses every sibling
  module's go.mod, README.md, CHANGELOG.md, docs/adr/ADR-*.md, doc.go package
  comments, every exported type/interface/func/method/const/var (via go/doc on
  go/parser ASTs), and compliance_test.go
- Captures module dependency edges by regex over each go.mod's require lines
  (einherjar/* paths only; self-reference filtered)
- Appends a synthetic "wire" module documenting canonical application wiring
  conventions, authored at internal/index/builtins/README.md and embedded via
  go:embed; participates in list_modules / get_module / get_example like a real module

internal/index:
- Schema einherjar.mcp/index/v1; types: Index, Module, SubPackage, Symbol, ADR,
  Example, Compliance, InterfaceAssert, ComplianceTest
- Build(repoRoot) → *Index walks the repo; BuildBuiltins() returns the synthetic
  wire module from the embedded markdown
- Load([]byte) → *Index validates the schema version on read
- FindModule, SearchSymbols helpers used by tools

internal/tools (10 tools):
- list_modules — enumerate every module with purpose + sub-packages
- get_module — package doc, dependencies, sub-packages, key symbols, ADRs,
  compliance counts; optional embedded README
- search_symbols — full-text across name, doc, sub-package, module; filterable by
  module and kind
- get_symbol — full signature, doc comment, source file:line for one symbol
- list_adrs — list ADRs across the framework or within one module
- get_adr — fetch one ADR's markdown body
- get_example — canonical usage snippets extracted from module READMEs and from
  the synthetic wire conventions
- get_compliance — interface assertions (var _ Iface = impl) and structural test
  names from a module's compliance_test.go
- get_changelog — full CHANGELOG.md markdown for one module
- validate_snippet — pattern-match a Go snippet against framework conventions

internal/rules (8 rules, registered via init() against a single registered slice):
- launcher.missing-run — launcher constructed but Run() never called
- launcher.no-components — launcher.New() called without any .Append(...)
- launcher.run-error-discarded — lc.Run() invoked as an ExprStmt (return ignored)
- logz.direct-env-read — os.Getenv("EINHERJAR_LOG_*") bypassing logz config
- web.server-not-appended — web/server constructed but not added to the launcher
- wire.hook-bad-signature — with<Feature>(...) first param is not launcher.Launcher
- wire.hook-outside-beforestart — repo/service/handler construction or route
  registration at the top level of a hook (outside lc.BeforeStart)
- wire.route-specific-after-param — /users/{id} registered before a sibling
  /users/me of the same length and method (chi would shadow the literal route)

Synthetic wire module (internal/index/builtins/README.md):
- Project layout (cmd/<app>/main.go + internal/wire/*.go + per-feature domain dirs)
- Canonical Run() shape: config → logger → infra (db, cache, pool, mc, srv) → cross-
  cutting (validator, permission provider) → launcher.New → lc.Append(infra...) →
  withMigrations / withSuperAdminSeed / withHealth / withFeature hooks → return lc.Run()
- Canonical with<Feature> hook shape: signature (launcher.Launcher first, server.Server
  second, deps last), single lc.BeforeStart closure containing all construction +
  route registration
- chi route ordering, srv.With(authz(...)) authorization, middleware helpers
  (authz / skipPublicPaths / skipMethodPath), tokenSignerAdapter pattern showing
  that the framework exposes Signer.Sign as a primitive and the application owns
  the access/refresh response shape

Packaging:
- Multi-stage Dockerfile that builds from the einherjar repository root
  (docker build -f mcp/Dockerfile .) so cmd/indexer can walk every sibling module
  at image-build time; runtime layer is gcr.io/distroless/static-debian12:nonroot
- 86-byte placeholder data/index.json committed once with `git add -f`; subsequent
  indexer runs overwrite it locally but the file is .gitignored
- .gitea/CODEOWNERS and pull_request_template.md mirror the sibling layout

Design notes:
- mcp depends on nothing in einherjar/* — it reads the framework via the filesystem
  at index time. This keeps mcp outside the framework dependency graph and lets it
  index any version of einherjar without versioning itself in lock-step.
- All structured-output tool responses initialise empty slices ([]Type{}) rather
  than relying on Go's nil-marshals-to-null default, so the SDK's JSON-schema
  output validator never rejects a tools/call result.
This commit is contained in:
2026-05-29 18:12:45 +00:00
commit cc62906c6f
33 changed files with 3560 additions and 0 deletions

415
internal/index/builder.go Normal file
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package index
import (
"bytes"
"fmt"
"go/ast"
"go/doc"
"go/parser"
"go/printer"
"go/token"
"io/fs"
"os"
"path/filepath"
"regexp"
"sort"
"strings"
"time"
)
// Build walks the Einherjar repository rooted at repoRoot, indexes every
// sibling module (any immediate subdirectory containing a go.mod), and
// returns an Index ready to be written to disk.
//
// The mcp module itself is skipped to avoid self-reference.
func Build(repoRoot string) (*Index, error) {
idx := &Index{
Schema: SchemaVersion,
Framework: "einherjar",
BuiltAt: time.Now().UTC(),
}
entries, err := os.ReadDir(repoRoot)
if err != nil {
return nil, fmt.Errorf("read repo root: %w", err)
}
for _, e := range entries {
if !e.IsDir() {
continue
}
name := e.Name()
if strings.HasPrefix(name, ".") || name == "mcp" || name == "vendor" {
continue
}
modDir := filepath.Join(repoRoot, name)
if _, err := os.Stat(filepath.Join(modDir, "go.mod")); err != nil {
continue
}
mod, err := buildModule(modDir, name)
if err != nil {
return nil, fmt.Errorf("module %s: %w", name, err)
}
idx.Modules = append(idx.Modules, *mod)
}
return idx, nil
}
func buildModule(modDir, name string) (*Module, error) {
m := &Module{
Name: name,
DependsOn: []string{},
Compliance: Compliance{
InterfaceAsserts: []InterfaceAssert{},
Tests: []ComplianceTest{},
},
}
if data, err := os.ReadFile(filepath.Join(modDir, "go.mod")); err == nil {
m.ImportPath = parseModulePath(data)
m.GoVersion = parseGoVersion(data)
m.DependsOn = parseDependsOn(data, name)
}
if data, err := os.ReadFile(filepath.Join(modDir, "README.md")); err == nil {
m.Readme = string(data)
m.Purpose = extractPurpose(string(data))
m.Examples = extractExamples(name, string(data))
}
if data, err := os.ReadFile(filepath.Join(modDir, "CHANGELOG.md")); err == nil {
m.Changelog = string(data)
}
m.Compliance = parseCompliance(name, modDir)
adrDir := filepath.Join(modDir, "docs", "adr")
if adrs, err := os.ReadDir(adrDir); err == nil {
for _, a := range adrs {
if a.IsDir() || !strings.HasPrefix(a.Name(), "ADR-") || !strings.HasSuffix(a.Name(), ".md") {
continue
}
body, err := os.ReadFile(filepath.Join(adrDir, a.Name()))
if err != nil {
continue
}
id, title := parseADRHeader(a.Name(), body)
m.ADRs = append(m.ADRs, ADR{Module: name, ID: id, Title: title, Body: string(body)})
}
}
if err := indexPackages(modDir, m); err != nil {
return nil, err
}
return m, nil
}
func indexPackages(modDir string, m *Module) error {
return filepath.WalkDir(modDir, func(path string, d fs.DirEntry, err error) error {
if err != nil {
return nil
}
if !d.IsDir() {
return nil
}
base := d.Name()
if base != filepath.Base(modDir) && (strings.HasPrefix(base, ".") || base == "vendor" || base == "testdata" || base == "docs") {
return filepath.SkipDir
}
fset := token.NewFileSet()
pkgs, err := parser.ParseDir(fset, path, func(fi os.FileInfo) bool {
return !strings.HasSuffix(fi.Name(), "_test.go")
}, parser.ParseComments)
if err != nil || len(pkgs) == 0 {
return nil
}
rel, _ := filepath.Rel(modDir, path)
if rel == "." {
rel = ""
}
for pkgName, pkg := range pkgs {
if pkgName == "main" {
continue
}
subName := pkgName
if rel == "" {
subName = ""
}
docPkg := doc.New(pkg, "./", doc.AllDecls)
if rel == "" && m.Doc == "" && docPkg.Doc != "" {
m.Doc = strings.TrimSpace(docPkg.Doc)
}
if rel != "" || docPkg.Doc != "" {
m.SubPackages = append(m.SubPackages, SubPackage{
Name: subName,
ImportPath: joinImport(m.ImportPath, rel),
Doc: strings.TrimSpace(docPkg.Doc),
})
}
collectSymbols(m, subName, modDir, fset, docPkg)
}
return nil
})
}
func collectSymbols(m *Module, sub, modDir string, fset *token.FileSet, p *doc.Package) {
for _, t := range p.Types {
kind := "type"
if isInterface(t.Decl) {
kind = "interface"
}
m.Symbols = append(m.Symbols, newSymbol(m.Name, sub, kind, t.Name, t.Doc, t.Decl, fset, modDir))
for _, f := range t.Funcs {
m.Symbols = append(m.Symbols, newSymbol(m.Name, sub, "func", f.Name, f.Doc, f.Decl, fset, modDir))
}
for _, f := range t.Methods {
m.Symbols = append(m.Symbols, newSymbol(m.Name, sub, "method", t.Name+"."+f.Name, f.Doc, f.Decl, fset, modDir))
}
}
for _, f := range p.Funcs {
m.Symbols = append(m.Symbols, newSymbol(m.Name, sub, "func", f.Name, f.Doc, f.Decl, fset, modDir))
}
for _, v := range p.Consts {
for _, name := range v.Names {
m.Symbols = append(m.Symbols, newSymbol(m.Name, sub, "const", name, v.Doc, v.Decl, fset, modDir))
}
}
for _, v := range p.Vars {
for _, name := range v.Names {
m.Symbols = append(m.Symbols, newSymbol(m.Name, sub, "var", name, v.Doc, v.Decl, fset, modDir))
}
}
}
func newSymbol(mod, sub, kind, name, docStr string, decl ast.Node, fset *token.FileSet, modDir string) Symbol {
pos := fset.Position(decl.Pos())
rel, _ := filepath.Rel(modDir, pos.Filename)
return Symbol{
Module: mod,
SubPackage: sub,
Kind: kind,
Name: name,
Signature: formatNode(fset, decl),
Doc: strings.TrimSpace(docStr),
File: rel,
Line: pos.Line,
}
}
func formatNode(fset *token.FileSet, node ast.Node) string {
var buf bytes.Buffer
cfg := printer.Config{Mode: printer.UseSpaces, Tabwidth: 4}
if err := cfg.Fprint(&buf, fset, node); err != nil {
return ""
}
s := buf.String()
if i := strings.Index(s, "{"); i > 0 && (strings.HasPrefix(s, "func") || strings.HasPrefix(s, "type")) {
return strings.TrimSpace(s[:i])
}
return strings.TrimSpace(s)
}
func isInterface(decl *ast.GenDecl) bool {
if decl == nil {
return false
}
for _, spec := range decl.Specs {
ts, ok := spec.(*ast.TypeSpec)
if !ok {
continue
}
if _, ok := ts.Type.(*ast.InterfaceType); ok {
return true
}
}
return false
}
var (
modulePathRe = regexp.MustCompile(`(?m)^module\s+(\S+)`)
goVersionRe = regexp.MustCompile(`(?m)^go\s+(\S+)`)
adrNameRe = regexp.MustCompile(`^(ADR-\d+)-(.+)\.md$`)
h1Re = regexp.MustCompile(`(?m)^#\s+(.+)$`)
fenceRe = regexp.MustCompile("(?s)```([a-zA-Z0-9_+\\-]*)\\n(.*?)```")
einherjarDepRe = regexp.MustCompile(`code\.nochebuena\.dev/einherjar/([a-zA-Z0-9_-]+)`)
)
func parseModulePath(data []byte) string {
if m := modulePathRe.FindSubmatch(data); m != nil {
return string(m[1])
}
return ""
}
func parseGoVersion(data []byte) string {
if m := goVersionRe.FindSubmatch(data); m != nil {
return string(m[1])
}
return ""
}
// parseDependsOn extracts the set of einherjar modules referenced by go.mod's
// require/replace lines. The module's own name is filtered out so a module
// never lists itself as a dependency.
func parseDependsOn(data []byte, self string) []string {
seen := map[string]bool{}
for _, m := range einherjarDepRe.FindAllSubmatch(data, -1) {
name := string(m[1])
if name == self {
continue
}
seen[name] = true
}
out := make([]string, 0, len(seen))
for k := range seen {
out = append(out, k)
}
sort.Strings(out)
return out
}
// parseCompliance parses compliance_test.go (when present) and returns its
// interface assertions and test functions. Missing or unparseable files yield
// an empty Compliance, not an error — the file is optional.
func parseCompliance(modName, modDir string) Compliance {
c := Compliance{
InterfaceAsserts: []InterfaceAssert{},
Tests: []ComplianceTest{},
}
path := filepath.Join(modDir, "compliance_test.go")
data, err := os.ReadFile(path)
if err != nil {
return c
}
fset := token.NewFileSet()
file, err := parser.ParseFile(fset, path, data, parser.ParseComments)
if err != nil {
return c
}
rel, _ := filepath.Rel(modDir, path)
for _, decl := range file.Decls {
switch d := decl.(type) {
case *ast.GenDecl:
if d.Tok != token.VAR {
continue
}
for _, spec := range d.Specs {
vs, ok := spec.(*ast.ValueSpec)
if !ok {
continue
}
if len(vs.Names) != 1 || vs.Names[0].Name != "_" {
continue
}
if vs.Type == nil || len(vs.Values) == 0 {
continue
}
c.InterfaceAsserts = append(c.InterfaceAsserts, InterfaceAssert{
Module: modName,
Interface: formatNode(fset, vs.Type),
Impl: formatNode(fset, vs.Values[0]),
File: rel,
Line: fset.Position(vs.Pos()).Line,
})
}
case *ast.FuncDecl:
if d.Recv != nil {
continue
}
if !strings.HasPrefix(d.Name.Name, "Test") {
continue
}
testDoc := ""
if d.Doc != nil {
testDoc = strings.TrimSpace(d.Doc.Text())
}
c.Tests = append(c.Tests, ComplianceTest{
Module: modName,
Name: d.Name.Name,
Doc: testDoc,
File: rel,
Line: fset.Position(d.Pos()).Line,
})
}
}
return c
}
func parseADRHeader(filename string, body []byte) (id, title string) {
if m := adrNameRe.FindStringSubmatch(filename); m != nil {
id = m[1]
title = strings.ReplaceAll(m[2], "-", " ")
}
if m := h1Re.FindSubmatch(body); m != nil {
title = strings.TrimSpace(string(m[1]))
}
return id, title
}
// extractPurpose returns the first non-empty, non-heading, non-badge paragraph
// from the README — typically the blockquote tagline or opening sentence.
func extractPurpose(readme string) string {
for _, line := range strings.Split(readme, "\n") {
t := strings.TrimSpace(line)
if t == "" || strings.HasPrefix(t, "#") || strings.HasPrefix(t, "[!") || strings.HasPrefix(t, "[![") {
continue
}
t = strings.TrimPrefix(t, "> ")
t = strings.TrimPrefix(t, ">")
if t == "" {
continue
}
return t
}
return ""
}
// extractExamples lifts fenced code blocks from a README, attaching them to
// the most recent H2/H3 heading as the example title and the best-guess
// sub-package (the heading lowercased, matched against known sub-packages
// later — or left blank).
func extractExamples(module, readme string) []Example {
var out []Example
lines := strings.Split(readme, "\n")
currentHeading := ""
for _, l := range lines {
t := strings.TrimSpace(l)
if strings.HasPrefix(t, "## ") || strings.HasPrefix(t, "### ") {
currentHeading = strings.TrimSpace(strings.TrimLeft(t, "# "))
}
}
_ = currentHeading // headings are walked again below to correlate blocks
matches := fenceRe.FindAllStringSubmatchIndex(readme, -1)
for _, m := range matches {
lang := readme[m[2]:m[3]]
code := readme[m[4]:m[5]]
title := nearestHeading(readme, m[0])
out = append(out, Example{
Module: module,
Title: title,
Code: strings.TrimSpace(code),
Language: lang,
})
}
return out
}
func nearestHeading(readme string, before int) string {
prefix := readme[:before]
lines := strings.Split(prefix, "\n")
for i := len(lines) - 1; i >= 0; i-- {
t := strings.TrimSpace(lines[i])
if strings.HasPrefix(t, "## ") || strings.HasPrefix(t, "### ") {
return strings.TrimSpace(strings.TrimLeft(t, "# "))
}
}
return ""
}
func joinImport(base, rel string) string {
if base == "" {
return ""
}
if rel == "" || rel == "." {
return base
}
return base + "/" + filepath.ToSlash(rel)
}

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package index
import (
_ "embed"
)
//go:embed builtins/README.md
var builtinsReadme string
// BuildBuiltins returns the synthetic "wire" module that documents canonical
// Einherjar application wiring conventions. The content is authored as
// markdown in builtins/README.md and embedded at compile time.
//
// The returned module participates in list_modules, get_module, and
// get_example exactly like a real Einherjar module — applications can ask
// the MCP server for "wire" knowledge the same way they ask for "core" or
// "web" knowledge.
func BuildBuiltins() Module {
m := Module{
Name: "wire",
ImportPath: "(application internal/wire)",
Purpose: extractPurpose(builtinsReadme),
Readme: builtinsReadme,
DependsOn: []string{},
SubPackages: []SubPackage{},
Symbols: []Symbol{},
ADRs: []ADR{},
Compliance: Compliance{
InterfaceAsserts: []InterfaceAssert{},
Tests: []ComplianceTest{},
},
}
m.Examples = extractExamples("wire", builtinsReadme)
return m
}

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# Wiring Conventions
> Forging a service is mostly wiring. Do it the same way every time.
This is not an Einherjar *module* — it is the canonical *application* shape
that uses Einherjar modules. Apps live in their own repository with an
`internal/wire/` package that mirrors this template. The conventions here are
distilled from a production service that has shipped on the predecessor
micro-libs (`code.nochebuena.dev/go/*`) and have been re-mapped to the
einherjar import paths.
## Project layout
```
cmd/<app>/main.go one-line entrypoint that calls wire.Run()
internal/wire/launcher.go Run() — builds infra and registers feature hooks
internal/wire/<feature>.go one file per feature, hosts a with<Feature> hook
internal/wire/middleware.go authz, skipPublicPaths, skipMethodPath helpers
internal/wire/migrations.go withMigrations hook
internal/wire/seed.go withSuperAdminSeed and other startup seeds
internal/<feature>/dto/ request/response DTOs
internal/<feature>/handler/ HTTP handlers
internal/<feature>/repository/ data access
internal/<feature>/service/ domain logic
```
`cmd/<app>/main.go` must contain nothing but the call to `wire.Run()` and an
`os.Exit(1)` on error. Everything else lives in `internal/wire/`.
## Run
The application entry point. The order below is load-bearing: configuration
first, observability second, infrastructure third, cross-cutting helpers
fourth, then the launcher with every component appended, then feature hooks,
then `lc.Run()`.
```go
package wire
import (
"strings"
"github.com/google/uuid"
authjwt "code.nochebuena.dev/einherjar/auth-jwt"
"code.nochebuena.dev/einherjar/auth/authmw"
"code.nochebuena.dev/einherjar/auth/rbac"
"code.nochebuena.dev/einherjar/cache-valkey"
"code.nochebuena.dev/einherjar/core/launcher"
"code.nochebuena.dev/einherjar/core/logz"
"code.nochebuena.dev/einherjar/core/valid"
"code.nochebuena.dev/einherjar/db-postgres"
"code.nochebuena.dev/einherjar/storage-minio"
"code.nochebuena.dev/einherjar/web/mw"
"code.nochebuena.dev/einherjar/web/server"
"code.nochebuena.dev/einherjar/worker"
"myapp/internal/config"
)
func Run() error {
cfg, err := config.Load()
if err != nil {
return err
}
logger := logz.New(logz.Config{
JSON: !strings.EqualFold(cfg.AppEnv, "local"),
StaticArgs: []any{"service", "myapp", "env", cfg.AppEnv},
})
signer := authjwt.NewHMACSigner([]byte(cfg.JWT.Secret))
publicPaths := []string{
"/health",
"/api/v1/auth/login",
"/api/v1/auth/refresh",
}
db := postgres.New(logger, cfg.PG)
cache := valkey.New(logger, cfg.VK)
pool := worker.New(logger, cfg.Worker)
mc := minio.New(logger, cfg.MinIO)
srv := server.New(logger, cfg.Server,
server.WithMiddleware(
mw.RequestID(uuid.NewString),
mw.Recover(logger),
mw.CORS(cfg.CORSOrigins),
mw.RequestLogger(logger),
authjwt.AuthMiddleware(logger, signer, publicPaths),
authmw.EnrichmentMiddleware(logger, &claimsEnricher{}),
),
)
v := valid.New(valid.WithMessageProvider(valid.SpanishMessages))
provider := rbac.NewClaimsPermissionProvider("masks", claimsFromCtx)
lc := launcher.New(logger)
lc.Append(db, cache, pool, mc, srv)
withMigrations(lc, logger, cfg)
withSuperAdminSeed(lc, db, logger, cfg)
withHealth(lc, srv, logger, db, cache, mc)
withUsers(lc, srv, db, logger, provider, v)
// … one withFeature(...) call per feature in your domain.
return lc.Run()
}
```
## Feature hook
One file per feature in `internal/wire/`. The function signature is fixed:
`launcher.Launcher` first, `server.Server` second when registering routes,
deps last. The body is *one* call to `lc.BeforeStart`. Everything else —
repository construction, service construction, handler construction, route
registration — lives inside the closure.
```go
package wire
import (
"code.nochebuena.dev/einherjar/contracts/security"
"code.nochebuena.dev/einherjar/core/launcher"
"code.nochebuena.dev/einherjar/core/logz"
"code.nochebuena.dev/einherjar/core/valid"
"code.nochebuena.dev/einherjar/db-postgres"
"code.nochebuena.dev/einherjar/web/server"
"myapp/internal/domains"
userhandler "myapp/internal/user/handler"
userrepo "myapp/internal/user/repository"
usersvc "myapp/internal/user/service"
)
func withUsers(
lc launcher.Launcher,
srv server.Server,
db postgres.Component,
logger logz.Logger,
provider security.PermissionProvider,
v valid.Validator,
) {
lc.BeforeStart(func() error {
repo := userrepo.New(db)
uow := postgres.NewUnitOfWork(logger, db)
svc := usersvc.New(repo, uow)
h := userhandler.New(svc, v)
// Literal-segment routes register BEFORE parametrised siblings.
// chi matches the first registered route that fits; if /users/{id}
// came first, "me" would bind to {id} and /users/me/password would
// never be reached.
srv.Put("/api/v1/users/me/password", h.ChangeOwnPassword)
srv.With(authz(provider, domains.ResourceUsers, domains.GrantReadUser)).
Get("/api/v1/users", h.ListUsers)
srv.With(authz(provider, domains.ResourceUsers, domains.GrantCreateUser)).
Post("/api/v1/users", h.CreateUser)
srv.With(authz(provider, domains.ResourceUsers, domains.GrantUpdateUser)).
Put("/api/v1/users/{user_id}", h.UpdateUser)
srv.With(authz(provider, domains.ResourceUsers, domains.GrantDeleteUser)).
Delete("/api/v1/users/{user_id}", h.DeleteUser)
return nil
})
}
```
## Route ordering
chi matches paths in registration order. Always register literal-segment
routes before parametrised-segment routes that share the same prefix.
✅ Correct:
```go
srv.Put("/api/v1/users/me/password", h.ChangeOwnPassword)
srv.Put("/api/v1/users/{user_id}", h.UpdateUser)
```
❌ Wrong — chi binds `me` to `{user_id}` and the literal route is unreachable:
```go
srv.Put("/api/v1/users/{user_id}", h.UpdateUser)
srv.Put("/api/v1/users/me/password", h.ChangeOwnPassword)
```
## Authorization
Every protected route registers with `.With(authz(provider, resource, grant))`:
```go
srv.With(authz(provider, domains.ResourceUsers, domains.GrantReadUser)).
Get("/api/v1/users", h.ListUsers)
```
Resource constants and grant bits live in `internal/domains/`. Routes that
the caller owns (`/me/...`) intentionally skip authz — they are reachable to
any authenticated user.
## Middleware helpers
These belong in `internal/wire/middleware.go` and are used across every
feature hook.
```go
// authz returns a per-route authorization middleware that checks one bit.
func authz(p security.PermissionProvider, resource string, bit int) func(http.Handler) http.Handler {
return authmw.AuthzMiddleware(nil, p, resource, security.Permission(bit))
}
// skipPublicPaths wraps mw so it is bypassed for any path that matches publicPaths.
// Use this for middleware that must not run on unauthenticated endpoints
// (e.g. EnrichmentMiddleware).
func skipPublicPaths(publicPaths []string, mw func(http.Handler) http.Handler) func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
inner := mw(next)
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
for _, p := range publicPaths {
if matched, _ := path.Match(p, r.URL.Path); matched {
next.ServeHTTP(w, r)
return
}
}
inner.ServeHTTP(w, r)
})
}
}
// skipMethodPath bypasses mw only when BOTH method and path match. Use this
// to expose ONE method on an otherwise-authenticated path (e.g. GET
// /api/v1/config public while PUT is not). Adding such a path to
// publicPaths would silently strip identity from context on the protected
// methods, breaking authz().
func skipMethodPath(method, pathPattern string, mw func(http.Handler) http.Handler) func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
inner := mw(next)
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method == method {
if matched, _ := path.Match(pathPattern, r.URL.Path); matched {
next.ServeHTTP(w, r)
return
}
}
inner.ServeHTTP(w, r)
})
}
}
```
## Adapters at the wire boundary
When a framework type does not match a service-layer port, write a small
typed adapter in `internal/wire/`. Always compile-time assert with
`var _ TargetIface = (*adapter)(nil)`.
The framework intentionally exposes only `Signer.Sign(claims) (string, error)`
— **the framework gives you a signing primitive; the access/refresh strategy,
claim layout, and response shape are application concerns.** A "helper" that
returned a fixed `{access, refresh, type, expiresIn}` struct would silently
decide for every app whether refresh tokens exist, what fields to expose,
and what casing to use. Those are wire-format choices the app owns.
```go
import (
"time"
"github.com/golang-jwt/jwt/v5"
"github.com/google/uuid"
authjwt "code.nochebuena.dev/einherjar/auth-jwt"
)
type tokenSignerAdapter struct {
signer authjwt.Signer
cfg authjwt.TokenConfig
}
var _ authsvc.TokenSigner = (*tokenSignerAdapter)(nil)
func (a *tokenSignerAdapter) IssueTokenPair(subject string, custom map[string]any) (authdto.TokenPairResponse, error) {
now := time.Now()
access := jwt.MapClaims{
"sub": subject,
"iss": a.cfg.Issuer,
"iat": now.Unix(),
"exp": now.Add(a.cfg.AccessTTL).Unix(),
}
for k, v := range custom {
access[k] = v
}
accessToken, err := a.signer.Sign(access)
if err != nil {
return authdto.TokenPairResponse{}, err
}
refreshToken, err := a.signer.Sign(jwt.MapClaims{
"sub": subject,
"jti": uuid.NewString(),
"iat": now.Unix(),
"exp": now.Add(a.cfg.RefreshTTL).Unix(),
})
if err != nil {
return authdto.TokenPairResponse{}, err
}
return authdto.TokenPairResponse{
AccessToken: accessToken,
RefreshToken: refreshToken,
TokenType: "Bearer",
ExpiresIn: int(a.cfg.AccessTTL.Seconds()),
}, nil
}
```
## Migrations and seeds
Migrations and seeds register as `BeforeStart` hooks too. They run after all
components have initialised but before any of them have started, so the
database is reachable and the server is not yet accepting traffic.
```go
func withMigrations(lc launcher.Launcher, logger logz.Logger, cfg config.Config) {
lc.BeforeStart(func() error {
if err := migrations.RunMigrations(context.Background(), logger, cfg); err != nil {
logger.Error("migrations: failed to apply", err)
return err
}
return nil
})
}
```
Seeds must be **idempotent**: count first, only mutate when needed, log the
skip when nothing was done.

164
internal/index/index.go Normal file
View File

@@ -0,0 +1,164 @@
// Package index defines the on-disk schema of the Einherjar framework index
// and provides a loader for the embedded JSON blob.
//
// The index is built once at deploy time by cmd/indexer and consumed by every
// MCP tool. Keeping it small, denormalised, and JSON-shaped means tools can
// be implemented as straightforward in-memory filters.
package index
import (
"encoding/json"
"fmt"
"strings"
"time"
)
// SchemaVersion identifies the on-disk index format. Bump when fields change
// in a way that breaks older consumers.
const SchemaVersion = "einherjar.mcp/index/v1"
// Index is the root of the embedded framework knowledge.
type Index struct {
Schema string `json:"schema"`
Framework string `json:"framework"`
BuiltAt time.Time `json:"builtAt"`
Modules []Module `json:"modules"`
}
// Module describes one Einherjar module (e.g. core, web, auth-jwt).
type Module struct {
Name string `json:"name"`
ImportPath string `json:"importPath"`
Purpose string `json:"purpose"`
Doc string `json:"doc,omitempty"`
GoVersion string `json:"goVersion"`
DependsOn []string `json:"dependsOn"`
SubPackages []SubPackage `json:"subPackages"`
Symbols []Symbol `json:"symbols"`
ADRs []ADR `json:"adrs"`
Examples []Example `json:"examples"`
Compliance Compliance `json:"compliance"`
Readme string `json:"readme,omitempty"`
Changelog string `json:"changelog,omitempty"`
}
// Compliance captures a module's compliance_test.go contents: compile-time
// interface assertions and the names of structural tests. It exists so an AI
// assistant can know about machine-checked conventions before it writes code
// that would violate them.
type Compliance struct {
InterfaceAsserts []InterfaceAssert `json:"interfaceAsserts"`
Tests []ComplianceTest `json:"tests"`
}
// InterfaceAssert mirrors one `var _ Iface = impl` line in compliance_test.go.
type InterfaceAssert struct {
Module string `json:"module"`
Interface string `json:"interface"`
Impl string `json:"impl"`
File string `json:"file"`
Line int `json:"line"`
}
// ComplianceTest mirrors one Test* function in compliance_test.go.
type ComplianceTest struct {
Module string `json:"module"`
Name string `json:"name"`
Doc string `json:"doc"`
File string `json:"file"`
Line int `json:"line"`
}
// SubPackage is one importable sub-package of a module.
type SubPackage struct {
Name string `json:"name"`
ImportPath string `json:"importPath"`
Doc string `json:"doc"`
}
// Symbol is one exported declaration (type, func, interface, const, var).
type Symbol struct {
Module string `json:"module"`
SubPackage string `json:"subPackage"`
Kind string `json:"kind"`
Name string `json:"name"`
Signature string `json:"signature"`
Doc string `json:"doc"`
File string `json:"file"`
Line int `json:"line"`
}
// ADR is one architectural decision record.
type ADR struct {
Module string `json:"module"`
ID string `json:"id"`
Title string `json:"title"`
Body string `json:"body"`
}
// Example is a fenced code block lifted from a module README.
type Example struct {
Module string `json:"module"`
SubPackage string `json:"subPackage"`
Title string `json:"title"`
Code string `json:"code"`
Language string `json:"language"`
}
// Load parses the embedded JSON blob into an Index. It validates the schema
// version and returns an empty (but non-nil) Index when the blob is the
// placeholder shipped before the indexer has been run.
func Load(raw []byte) (*Index, error) {
if len(raw) == 0 {
return &Index{Schema: SchemaVersion, Framework: "einherjar"}, nil
}
idx := &Index{}
if err := json.Unmarshal(raw, idx); err != nil {
return nil, fmt.Errorf("index: parse: %w", err)
}
if idx.Schema != "" && idx.Schema != SchemaVersion {
return nil, fmt.Errorf("index: schema mismatch: got %q want %q", idx.Schema, SchemaVersion)
}
return idx, nil
}
// FindModule returns the module with the given name, or nil if absent.
func (i *Index) FindModule(name string) *Module {
for k := range i.Modules {
if i.Modules[k].Name == name {
return &i.Modules[k]
}
}
return nil
}
// SearchSymbols returns up to limit symbols whose name or doc contains q
// (case-insensitive). Module name and sub-package are also searched.
func (i *Index) SearchSymbols(q string, limit int) []Symbol {
if limit <= 0 {
limit = 25
}
needle := strings.ToLower(q)
out := make([]Symbol, 0, limit)
for _, m := range i.Modules {
for _, s := range m.Symbols {
if matches(s, needle) {
out = append(out, s)
if len(out) >= limit {
return out
}
}
}
}
return out
}
func matches(s Symbol, needle string) bool {
if needle == "" {
return true
}
return strings.Contains(strings.ToLower(s.Name), needle) ||
strings.Contains(strings.ToLower(s.Doc), needle) ||
strings.Contains(strings.ToLower(s.SubPackage), needle) ||
strings.Contains(strings.ToLower(s.Module), needle)
}