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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.

2026-05-29 18:12:45 +00:00

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Changelog — einherjar/mcp

All notable changes to this module are documented here. Format follows Keep a Changelog. This module adheres to Semantic Versioning.

[0.1.0] — 2026-05-29

Initial release. The mcp module hosts the Einherjar Model Context Protocol server — a remote, streamable-HTTP service that teaches AI assistants about every other module of the framework.

Added

Server (`cmd/server`)

Streamable-HTTP MCP server built on github.com/modelcontextprotocol/go-sdk v1.0.0
Listen address and HTTP path configurable via EINHERJAR_MCP_ADDR (default :8080) and EINHERJAR_MCP_PATH (default /mcp)
/healthz liveness endpoint
Embedded framework index loaded once at startup; in-memory for the lifetime of the process

Indexer (`cmd/indexer`)

Walks an Einherjar repository checkout and produces data/index.json
For each sibling module captures: import path, Go version, README (full + extracted tagline), CHANGELOG, root doc.go package comment, sub-package doc comments, every exported symbol (type/interface/func/method/const/var) with signature + godoc, ADRs, README code-fence examples, dependency edges from go.mod, and the contents of compliance_test.go (interface assertions + structural test names)
Appends a synthetic wire module documenting canonical Einherjar application wiring conventions

Tools (10)

list_modules — enumerate every Einherjar module with purpose and sub-packages
get_module — package doc, dependencies, sub-packages, key symbols, ADRs, compliance counts; optional embedded README
search_symbols — full-text search across name, doc, sub-package, module
get_symbol — full signature, doc, and source location for one symbol
list_adrs — list architectural decision records, optionally filtered by module
get_adr — fetch one ADR's markdown body
get_example — canonical usage snippets extracted from module READMEs and the wire conventions
get_compliance — interface assertions 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; returns findings with severity, hint, and line

Validation rules (8)

launcher.missing-run, launcher.no-components, launcher.run-error-discarded
logz.direct-env-read
web.server-not-appended
wire.hook-bad-signature, wire.hook-outside-beforestart, wire.route-specific-after-param

Synthetic `wire` module

Authored in internal/index/builtins/README.md; participates in list_modules, get_module, and get_example exactly like a real module
Sections: project layout, Run() shape, feature hook shape, route ordering, authorization, middleware helpers, adapters at the wire boundary, migrations and seeds
All examples use einherjar import paths

Packaging

Multi-stage Dockerfile that builds from the einherjar repository root (docker build -f mcp/Dockerfile .) so the indexer can walk every sibling module at image-build time
Distroless runtime image; static binary; non-root user

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