feat(mcp): systemd socket activation and healthz under /mcp (v0.1.1)
Patch release. Two changes to cmd/server, both motivated by running the
service behind a unix socket on a reverse-proxied host: the binary now
inherits a systemd-passed listener when present, and the healthz handler
moves under the same path prefix as the MCP endpoint so a single proxy
location forwards both. Bundled with two repository-hygiene changes.
cmd/server:
- chooseListener (new) — picks a listener at startup. When systemd has
passed a LISTEN_FDS fd via github.com/coreos/go-systemd/v22/activation,
the binary uses the inherited listener; otherwise it binds TCP at -addr
as before. The startup log records "mode":"socket-activated" or
"mode":"tcp" so operators can confirm which path is live. Same binary
works for local dev and for systemd-managed deployment with no flags
or env vars to toggle.
- Health probe path is now derived from -path. With the default -path /mcp
the probe is served at /mcp/healthz; the legacy /healthz route is no
longer registered. A reverse proxy can now route the whole MCP service
through a single "/mcp" location prefix instead of maintaining a second
forward for /healthz. Consumers of v0.1.0 that hit /healthz directly
must switch to /mcp/healthz.
Dependencies:
- github.com/coreos/go-systemd/v22 v22.7.0 — listener inheritance via
LISTEN_FDS. Loaded only by cmd/server.
Docs:
- README.md "Deployment" section rewritten to be hosting-agnostic. The
v0.1.0 draft prescribed a specific systemd-on-HestiaCP layout; the new
text points at the Dockerfile and at systemd socket activation as a
supported binary mode without dictating one operator's setup. Adds an
explicit note that any reverse proxy must disable response buffering on
the /mcp location — streamable MCP delivers tool results via Server-Sent
Events and default proxy buffering breaks the stream.
Repository hygiene:
- /deploy/ is now .gitignored. Local deployment artefacts (systemd units,
reverse-proxy templates, per-release scripts) are operator-specific by
design and live outside the public repository. The Dockerfile at the
module root remains the only portable, public-facing build artefact.
No tool surface, no validation rules, no index schema, and no behaviour of
the indexer changed. Operators upgrading from v0.1.0 must update their
health-probe URL to /mcp/healthz (or whichever path matches their -path
flag); MCP-protocol clients (Claude, Cursor, Zed, etc.) need no changes.
2026-05-29 14:09:06 -06:00
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github.com/coreos/go-systemd/v22 v22.7.0 h1:LAEzFkke61DFROc7zNLX/WA2i5J8gYqe0rSj9KI28KA=
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github.com/coreos/go-systemd/v22 v22.7.0/go.mod h1:xNUYtjHu2EDXbsxz1i41wouACIwT7Ybq9o0BQhMwD0w=
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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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github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
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github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
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github.com/google/jsonschema-go v0.3.0 h1:6AH2TxVNtk3IlvkkhjrtbUc4S8AvO0Xii0DxIygDg+Q=
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github.com/google/jsonschema-go v0.3.0/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
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github.com/modelcontextprotocol/go-sdk v1.0.0 h1:Z4MSjLi38bTgLrd/LjSmofqRqyBiVKRyQSJgw8q8V74=
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github.com/modelcontextprotocol/go-sdk v1.0.0/go.mod h1:nYtYQroQ2KQiM0/SbyEPUWQ6xs4B95gJjEalc9AQyOs=
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github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
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github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
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golang.org/x/tools v0.34.0 h1:qIpSLOxeCYGg9TrcJokLBG4KFA6d795g0xkBkiESGlo=
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golang.org/x/tools v0.34.0/go.mod h1:pAP9OwEaY1CAW3HOmg3hLZC5Z0CCmzjAF2UQMSqNARg=
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