CHANGELOG.md

@@ -6,6 +6,56 @@ This module adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html
 
 ---
 
+## [1.1.0] — 2026-08-07
+
+Minor release. The env-var story is now **derived from the framework's real struct tags** end
+to end: a tool to read the truth, `.env.example` generated from it, and a rule that rejects
+invented names. Also folds in the scaffold-symbol fixes that were staged as v1.0.1 (never
+tagged separately). The generated scaffold compiles clean against einherjar v1.0.0.
+
+### Added
+
+- **`get_config_env` tool.** Lists the real environment variables a component config reads —
+  name, declaring module/struct/field, `required`, and default — parsed from the indexed
+  struct tags (`internal/envspec`). The single source of truth for which `EINHERJAR_*` vars
+  exist; no hand-maintained list to drift.
+- **`check_env` tool.** Checks a `.env` / `.env.example` against the framework: flags
+  `EINHERJAR_*` names that don't exist (e.g. `EINHERJAR_PG_DATABASE`), required vars missing
+  for the modules an app composes, and vars set for a module it does not compose (dead vars,
+  the way `EINHERJAR_SERVER_CORS_ORIGINS` is inert unless you compose `web.Config`).
+- **`config.unknown-env-var` rule** (now twelve). `validate_snippet` rejects any struct field
+  tagged `env:"EINHERJAR_*"` whose name the framework does not declare — the exact class of
+  drift that shipped `EINHERJAR_PG_DATABASE` / `_SERVER_ADDR`. The valid-name set is injected
+  from the index at startup, so the rule can never drift from the real tags.
+
+### Changed
+
+- **`get_scaffold` now derives `.env.example` from the index** instead of a hand-written
+  string. Required vars (no default) are emitted uncommented with a runnable dev value;
+  defaulted vars are emitted commented, documenting the framework default. Names and defaults
+  can no longer drift from the modules the scaffold composes (`core/logz` + `web/server` +
+  `db-postgres`).
+- **The scaffold composes `logz.Config`** instead of hard-coding the logger, so
+  `EINHERJAR_LOG_LEVEL` / `_JSON` are live and documented rather than silently ignored.
+  Verified end to end: `env.Parse` loads `slog.Level` from `EINHERJAR_LOG_LEVEL`. (Log format
+  is now env-driven; set `EINHERJAR_LOG_JSON=true` in production.)
+- **The `wire` builtin routes the incremental flow to the new tools.** Composing a component
+  later now points at `get_config_env("<module>")` for its exact vars and `check_env` to
+  confirm `.env.example` is complete — and spells out the split between framework `EINHERJAR_*`
+  (discoverable, name-checked) and app-owned `APP_*` (your discipline).
+
+### Fixed
+
+- **`logz.Logger` → `logging.Logger`.** The logger interface is `contracts/logging.Logger`;
+  `logz.New` returns it. The scaffold's health hook and the `wire` builtin's `withUsers`
+  example typed loggers as the non-existent `logz.Logger`.
+- **`postgres.Component` → `postgres.Provider`** in hook signatures. `postgres.New` returns a
+  `Component` (a lifecycle component that embeds `Provider`); hooks and `NewUnitOfWork` take a
+  `Provider`.
+- **The real env tags throughout:** `EINHERJAR_SERVER_ADDR` → `EINHERJAR_SERVER_HOST` +
+  `_PORT`, and `EINHERJAR_PG_DATABASE` → `EINHERJAR_PG_NAME` (plus `EINHERJAR_PG_SSL_MODE`).
+- The scaffold's minimal health hook no longer takes unused `logger`/`db` parameters.
+
 ## [1.0.0] — 2026-08-07
 
 The MCP reaches **v1.0.0**, aligned with the v1.0.0 framework. The headline is the

README.md

@@ -1,6 +1,6 @@
 # einherjar/mcp
 
-[![version](https://img.shields.io/badge/version-v1.0.0-5C4EE5?style=flat-square)](https://code.nochebuena.dev/einherjar/mcp)
+[![version](https://img.shields.io/badge/version-v1.1.0-5C4EE5?style=flat-square)](https://code.nochebuena.dev/einherjar/mcp)
 [![license](https://img.shields.io/badge/license-AGPL--3.0-22863A?style=flat-square)](LICENSE)
 [![go](https://img.shields.io/badge/Go-1.26+-00ADD8?style=flat-square&logo=go&logoColor=white)](https://go.dev)
 
@@ -38,7 +38,7 @@ under pressure.
 
 ## Tools
 
-The server exposes **eleven** tools to MCP-aware clients (Claude desktop, Claude Code,
+The server exposes **thirteen** tools to MCP-aware clients (Claude desktop, Claude Code,
 Cursor, Zed, and anything else that speaks MCP):
 
 | Tool | Purpose |
@@ -50,16 +50,19 @@ Cursor, Zed, and anything else that speaks MCP):
 | `list_adrs` | List architectural decision records, optionally restricted to one module |
 | `get_adr` | Fetch a single ADR's markdown body |
 | `get_example` | Canonical usage snippet — pulled from module READMEs and from the synthetic `wire` conventions |
-| `get_scaffold` | The canonical **minimum application scaffold** as ready-to-write files — a clean `main.go`, `internal/wire/wire.go`, a composed `internal/config`, a health hook, and `.env.example`. Use it when starting a new Einherjar service |
+| `get_scaffold` | The canonical **minimum application scaffold** as ready-to-write files — a clean `main.go`, `internal/wire/wire.go`, a composed `internal/config`, a health hook, and a **`.env.example` derived from the real component-config tags**. Use it when starting a new Einherjar service |
+| `get_config_env` | The **real** env vars a component config reads — name, declaring module/struct/field, required, and default — derived from the framework's struct tags. The source of truth for building a global config or a `.env` |
+| `check_env` | Check a `.env` / `.env.example` against the framework: flags EINHERJAR_* names that don't exist (e.g. `EINHERJAR_PG_DATABASE`), missing required vars for the modules you compose, and vars set for a module you don't compose |
 | `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 |
 
-`validate_snippet` ships **eleven** wiring-convention rules at v1.0.0:
+`validate_snippet` ships **twelve** wiring-convention rules:
 `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`,
-`main.dirty`, `main.no-godotenv-autoload`, and `config.raw-getenv`.
+`main.dirty`, `main.no-godotenv-autoload`, `config.raw-getenv`, and
+`config.unknown-env-var` (rejects an `env:"EINHERJAR_*"` tag the framework doesn't declare).
 
 ---
 

cmd/server/main.go

@@ -23,7 +23,7 @@ import (
 
 const (
 	serverName    = "einherjar-mcp"
-	serverVersion = "v1.0.0"
+	serverVersion = "v1.1.0"
 )
 
 func main() {

internal/envspec/envspec.go

@@ -0,0 +1,157 @@
+// Package envspec derives the real environment variables of Einherjar's
+// component configs from the framework index — the single source of truth for
+// which EINHERJAR_* vars exist, which are required, and what they default to.
+//
+// Every Einherjar component (db-postgres, web/server, core/logz, …) exposes a
+// Config struct whose fields carry caarlos0/env tags. The indexer already
+// captures those tags (index.Field.Tag); this package parses them so tools can
+// build a correct global config, generate an accurate .env.example, and reject
+// invented or misspelled var names — instead of anyone maintaining that list by
+// hand and drifting from the framework.
+package envspec
+
+import (
+	"reflect"
+	"sort"
+	"strings"
+
+	"code.nochebuena.dev/einherjar/mcp/internal/index"
+)
+
+// Var is one environment variable declared by a component Config field.
+type Var struct {
+	Name       string `json:"name"`                 // e.g. EINHERJAR_PG_HOST
+	Module     string `json:"module"`               // e.g. db-postgres
+	SubPackage string `json:"subPackage,omitempty"` // e.g. server (empty at module root)
+	Struct     string `json:"struct"`               // the declaring struct, e.g. Config
+	Field      string `json:"field"`                // the Go field, e.g. Host
+	Type       string `json:"type"`                 // the Go type, e.g. string
+	Required   bool   `json:"required"`             // env:"...,required"
+	Default    string `json:"default,omitempty"`    // envDefault:"..." (empty when none)
+	HasDefault bool   `json:"hasDefault"`           // distinguishes "" default from no default
+	Doc        string `json:"doc,omitempty"`        // field doc comment, if any
+}
+
+// ParseTag extracts the env var declared by a raw struct tag (backticks already
+// stripped, as stored in the index). ok is false when the tag has no env key or
+// the key is "-" (explicitly excluded, e.g. an http.RoundTripper field).
+func ParseTag(tag string) (v struct {
+	Name       string
+	Required   bool
+	Default    string
+	HasDefault bool
+}, ok bool) {
+	st := reflect.StructTag(tag)
+	raw, present := st.Lookup("env")
+	if !present {
+		return v, false
+	}
+	parts := strings.Split(raw, ",")
+	name := strings.TrimSpace(parts[0])
+	if name == "" || name == "-" {
+		return v, false
+	}
+	v.Name = name
+	for _, opt := range parts[1:] {
+		if strings.TrimSpace(opt) == "required" {
+			v.Required = true
+		}
+	}
+	if def, has := st.Lookup("envDefault"); has {
+		v.Default = def
+		v.HasDefault = true
+	}
+	ok = true
+	return v, ok
+}
+
+// varsForSymbol returns the env vars declared directly by a struct symbol's
+// fields. Nested component-config fields (a field whose type is another Config,
+// carrying no env tag of its own) are not expanded here — caller-facing helpers
+// surface them because sibling structs are indexed independently.
+func varsForSymbol(m index.Module, s index.Symbol) []Var {
+	var out []Var
+	for _, f := range s.Fields {
+		parsed, ok := ParseTag(f.Tag)
+		if !ok {
+			continue
+		}
+		out = append(out, Var{
+			Name:       parsed.Name,
+			Module:     m.Name,
+			SubPackage: s.SubPackage,
+			Struct:     s.Name,
+			Field:      f.Name,
+			Type:       f.Type,
+			Required:   parsed.Required,
+			Default:    parsed.Default,
+			HasDefault: parsed.HasDefault,
+			Doc:        strings.TrimSpace(f.Doc),
+		})
+	}
+	return out
+}
+
+// ForModule returns every env var declared by any struct in a module, across
+// all its sub-packages (e.g. web yields web/server's EINHERJAR_SERVER_* plus
+// web's EINHERJAR_SERVER_CORS_ORIGINS plus web/health's timeout). Returns nil
+// when the module is unknown. Order is deterministic: sub-package, then struct,
+// then declaration order.
+func ForModule(idx *index.Index, module string) []Var {
+	m := idx.FindModule(module)
+	if m == nil {
+		return nil
+	}
+	var out []Var
+	for _, s := range m.Symbols {
+		if s.Kind != "type" || len(s.Fields) == 0 {
+			continue
+		}
+		out = append(out, varsForSymbol(*m, s)...)
+	}
+	return out
+}
+
+// FindStruct returns the env vars of one specific struct, identified by module,
+// sub-package (empty for a module-root package), and struct name — the precise
+// selector a scaffold uses to compose named component configs. Returns nil when
+// no such struct is indexed.
+func FindStruct(idx *index.Index, module, subPackage, name string) []Var {
+	m := idx.FindModule(module)
+	if m == nil {
+		return nil
+	}
+	for _, s := range m.Symbols {
+		if s.Kind == "type" && s.Name == name && s.SubPackage == subPackage {
+			return varsForSymbol(*m, s)
+		}
+	}
+	return nil
+}
+
+// All returns every env var declared anywhere in the framework, sorted by name.
+func All(idx *index.Index) []Var {
+	var out []Var
+	for i := range idx.Modules {
+		m := idx.Modules[i]
+		for _, s := range m.Symbols {
+			if s.Kind != "type" || len(s.Fields) == 0 {
+				continue
+			}
+			out = append(out, varsForSymbol(m, s)...)
+		}
+	}
+	sort.Slice(out, func(i, j int) bool { return out[i].Name < out[j].Name })
+	return out
+}
+
+// KnownNames returns the set of every valid framework env-var name. It backs the
+// config.unknown-env-var rule, which rejects any EINHERJAR_* tag that is not in
+// this set (the exact bug class that shipped EINHERJAR_PG_DATABASE / _SERVER_ADDR).
+func KnownNames(idx *index.Index) map[string]struct{} {
+	names := map[string]struct{}{}
+	for _, v := range All(idx) {
+		names[v.Name] = struct{}{}
+	}
+	return names
+}

internal/envspec/envspec_test.go

@@ -0,0 +1,132 @@
+package envspec
+
+import (
+	"testing"
+
+	"code.nochebuena.dev/einherjar/mcp/internal/index"
+)
+
+func TestParseTag(t *testing.T) {
+	cases := []struct {
+		tag      string
+		wantOK   bool
+		wantName string
+		wantReq  bool
+		wantDef  string
+		wantHas  bool
+	}{
+		{`env:"EINHERJAR_PG_HOST,required"`, true, "EINHERJAR_PG_HOST", true, "", false},
+		{`env:"EINHERJAR_PG_PORT"                envDefault:"5432"`, true, "EINHERJAR_PG_PORT", false, "5432", true},
+		{`env:"EINHERJAR_LOG_JSON" envDefault:"false"`, true, "EINHERJAR_LOG_JSON", false, "false", true},
+		{`env:"-"`, false, "", false, "", false},
+		{`json:"x"`, false, "", false, "", false},
+		{``, false, "", false, "", false},
+	}
+	for _, c := range cases {
+		got, ok := ParseTag(c.tag)
+		if ok != c.wantOK {
+			t.Errorf("ParseTag(%q) ok=%v want %v", c.tag, ok, c.wantOK)
+			continue
+		}
+		if !ok {
+			continue
+		}
+		if got.Name != c.wantName || got.Required != c.wantReq || got.Default != c.wantDef || got.HasDefault != c.wantHas {
+			t.Errorf("ParseTag(%q) = %+v, want name=%q req=%v def=%q has=%v",
+				c.tag, got, c.wantName, c.wantReq, c.wantDef, c.wantHas)
+		}
+	}
+}
+
+// synthIndex mirrors the shape of the real index: a web module whose server
+// sub-package and root both declare env vars, plus a db-postgres module.
+func synthIndex() *index.Index {
+	return &index.Index{
+		Modules: []index.Module{
+			{
+				Name: "web",
+				Symbols: []index.Symbol{
+					{Kind: "type", Name: "Config", SubPackage: "server", Fields: []index.Field{
+						{Name: "Host", Type: "string", Tag: `env:"EINHERJAR_SERVER_HOST" envDefault:"0.0.0.0"`},
+						{Name: "Port", Type: "int", Tag: `env:"EINHERJAR_SERVER_PORT" envDefault:"8080"`},
+					}},
+					{Kind: "type", Name: "Config", SubPackage: "", Fields: []index.Field{
+						{Name: "Server", Type: "server.Config"}, // nested, no env tag
+						{Name: "AllowedOrigins", Type: "[]string", Tag: `env:"EINHERJAR_SERVER_CORS_ORIGINS" envSeparator:","`},
+					}},
+				},
+			},
+			{
+				Name: "db-postgres",
+				Symbols: []index.Symbol{
+					{Kind: "type", Name: "Config", SubPackage: "", Fields: []index.Field{
+						{Name: "Host", Type: "string", Tag: `env:"EINHERJAR_PG_HOST,required"`},
+						{Name: "Name", Type: "string", Tag: `env:"EINHERJAR_PG_NAME,required"`},
+						{Name: "Port", Type: "int", Tag: `env:"EINHERJAR_PG_PORT" envDefault:"5432"`},
+					}},
+				},
+			},
+		},
+	}
+}
+
+func TestForModule(t *testing.T) {
+	idx := synthIndex()
+	got := ForModule(idx, "web")
+	if len(got) != 3 { // 2 server + 1 CORS; the nested Server field is not a leaf
+		t.Fatalf("ForModule(web) = %d vars, want 3: %+v", len(got), got)
+	}
+	names := map[string]bool{}
+	for _, v := range got {
+		names[v.Name] = true
+	}
+	for _, want := range []string{"EINHERJAR_SERVER_HOST", "EINHERJAR_SERVER_PORT", "EINHERJAR_SERVER_CORS_ORIGINS"} {
+		if !names[want] {
+			t.Errorf("ForModule(web) missing %s", want)
+		}
+	}
+	if ForModule(idx, "nope") != nil {
+		t.Error("ForModule(unknown) should be nil")
+	}
+}
+
+func TestFindStruct(t *testing.T) {
+	idx := synthIndex()
+	server := FindStruct(idx, "web", "server", "Config")
+	if len(server) != 2 {
+		t.Fatalf("FindStruct(web/server/Config) = %d, want 2", len(server))
+	}
+	// The root web.Config must NOT be returned for the server selector.
+	for _, v := range server {
+		if v.Name == "EINHERJAR_SERVER_CORS_ORIGINS" {
+			t.Error("server selector leaked the root web.Config CORS var")
+		}
+	}
+	pg := FindStruct(idx, "db-postgres", "", "Config")
+	if len(pg) != 3 {
+		t.Fatalf("FindStruct(db-postgres//Config) = %d, want 3", len(pg))
+	}
+	var host envspecVarFound
+	for _, v := range pg {
+		if v.Name == "EINHERJAR_PG_HOST" {
+			host = envspecVarFound{found: true, required: v.Required, hasDefault: v.HasDefault}
+		}
+	}
+	if !host.found || !host.required || host.hasDefault {
+		t.Errorf("EINHERJAR_PG_HOST: %+v, want required with no default", host)
+	}
+}
+
+type envspecVarFound struct {
+	found, required, hasDefault bool
+}
+
+func TestKnownNames(t *testing.T) {
+	names := KnownNames(synthIndex())
+	if _, ok := names["EINHERJAR_PG_NAME"]; !ok {
+		t.Error("KnownNames missing EINHERJAR_PG_NAME")
+	}
+	if _, ok := names["EINHERJAR_PG_DATABASE"]; ok {
+		t.Error("KnownNames must not contain the bogus EINHERJAR_PG_DATABASE")
+	}
+}

internal/index/builtins/README.md

@@ -84,6 +84,7 @@ import (
 
 	"github.com/caarlos0/env/v11"
 
+	"code.nochebuena.dev/einherjar/core/logz"
 	"code.nochebuena.dev/einherjar/db-postgres"
 	"code.nochebuena.dev/einherjar/web/server"
 )
@@ -108,6 +109,7 @@ type Config struct {
 
 	// Framework component configs — composed verbatim. Their own EINHERJAR_* tags
 	// load through this one env.Parse call.
+	Log    logz.Config     // EINHERJAR_LOG_*
 	Server server.Config   // EINHERJAR_SERVER_*
 	PG     postgres.Config // EINHERJAR_PG_*
 }
@@ -133,6 +135,21 @@ var, the same change adds its `env:"..."` tag to `config` **and** a documented l
 `.env.example`. This is not optional bookkeeping — it is what stops a long feature from shipping
 and then failing at boot because nobody knew which variables to set.
 
+**Two kinds of var, two ways to keep them honest:**
+
+- **Framework component vars (`EINHERJAR_*`)** — when you compose a new component later (e.g.
+  `cachevalkey.Config`, `minio.Config`, `smtp.Config`), the MCP knows its real vars: call
+  `get_config_env("<module>")` for the exact set (name, required, default) and add each to
+  `.env.example`. The `config.unknown-env-var` rule rejects any `EINHERJAR_*` tag the framework
+  doesn't declare, so a typo like `EINHERJAR_PG_DATABASE` is caught at `validate_snippet` time.
+- **App-owned vars (`APP_*`)** — like `APP_JWT_SECRET` above: the framework can't know these, so
+  keeping them in `.env.example` is your discipline, not something it can name-check.
+
+After you compose a component, run **`check_env`** with the modules the app composes: it flags
+`EINHERJAR_*` names that don't exist, required vars you forgot to document, and vars set for a
+module you don't actually compose (dead vars). `get_scaffold` already emits a `.env.example`
+derived from these same tags, so the starting point is correct by construction.
+
 ```bash
 # .env.example — copy to .env for local dev. Every var the app reads lives here.
 
@@ -142,19 +159,25 @@ APP_CORS_ORIGINS=*
 APP_JWT_SECRET=change-me
 APP_JWT_ISSUER=myapp
 
+# ── Einherjar: logging (EINHERJAR_LOG_*) ──────────────────────────────────
+# EINHERJAR_LOG_LEVEL=INFO
+# EINHERJAR_LOG_JSON=false
+
 # ── Einherjar: HTTP server (EINHERJAR_SERVER_*) ───────────────────────────
-EINHERJAR_SERVER_ADDR=:8080
+EINHERJAR_SERVER_HOST=0.0.0.0
+EINHERJAR_SERVER_PORT=8080
 
 # ── Einherjar: PostgreSQL (EINHERJAR_PG_*) ────────────────────────────────
 EINHERJAR_PG_HOST=localhost
 EINHERJAR_PG_PORT=5432
 EINHERJAR_PG_USER=postgres
 EINHERJAR_PG_PASSWORD=postgres
-EINHERJAR_PG_DATABASE=myapp
+EINHERJAR_PG_NAME=myapp
 ```
 
-To discover the full set, walk every `env:"..."` tag reachable from `config.Config` (including the
+To discover the full set for any component you compose, use `get_config_env("<module>")` rather
-nested framework configs) — every one of them belongs in `.env.example`.
+than reading source by hand; every var it returns belongs in `.env.example`, and `check_env`
+confirms none are missing, misspelled, or dead.
 
 ## wire.go — Run()
 
@@ -166,8 +189,6 @@ appended, then feature hooks, then `lc.Run()`.
 package wire
 
 import (
-	"strings"
-
 	"github.com/google/uuid"
 
 	authjwt "code.nochebuena.dev/einherjar/auth-jwt"
@@ -189,10 +210,11 @@ func Run() error {
 		return err
 	}
 
-	logger := logz.New(logz.Config{
+	// logz.Config is composed in config, so EINHERJAR_LOG_LEVEL / _JSON load from
-		JSON:       !strings.EqualFold(cfg.AppEnv, "local"),
+	// the environment; StaticArgs are set here (they carry no env tag).
-		StaticArgs: []any{"service", "myapp", "env", cfg.AppEnv},
+	logCfg := cfg.Log
-	})
+	logCfg.StaticArgs = []any{"service", "myapp", "env", cfg.AppEnv}
+	logger := logz.New(logCfg)
 
 	signer := authjwt.NewHMACSigner([]byte(cfg.JWT.Secret))
 
@@ -239,9 +261,9 @@ registration — lives inside the closure.
 package wire
 
 import (
+	"code.nochebuena.dev/einherjar/contracts/logging"
 	"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"
@@ -255,8 +277,8 @@ import (
 func withUsers(
 	lc       launcher.Launcher,
 	srv      server.Server,
-	db       postgres.Component,
+	db       postgres.Provider,
-	logger   logz.Logger,
+	logger   logging.Logger,
 	provider security.PermissionProvider,
 	v        valid.Validator,
 ) {

internal/rules/env_rules.go

@@ -0,0 +1,82 @@
+package rules
+
+import (
+	"go/ast"
+	"reflect"
+	"strings"
+)
+
+// knownEnvVars is the set of every real framework env-var name, injected once at
+// server startup from the index (see rules.SetKnownEnvVars). When empty — e.g.
+// in unit tests that exercise rules without an index — config.unknown-env-var is
+// a no-op, so it never fires on incomplete knowledge.
+var knownEnvVars map[string]struct{}
+
+// SetKnownEnvVars installs the authoritative set of framework env-var names that
+// backs config.unknown-env-var. Call once before serving; the server derives the
+// set from the index so the rule can never drift from the real struct tags.
+func SetKnownEnvVars(names map[string]struct{}) {
+	knownEnvVars = names
+}
+
+func init() {
+	registered = append(registered,
+		Rule{
+			ID:       "config.unknown-env-var",
+			Severity: SeverityError,
+			Module:   "wire",
+			Check:    checkUnknownEnvVar,
+		},
+	)
+}
+
+// checkUnknownEnvVar flags any struct field tagged with an EINHERJAR_* env var
+// that the framework does not actually declare — the exact class of drift that
+// shipped EINHERJAR_PG_DATABASE (real name: _PG_NAME) and EINHERJAR_SERVER_ADDR
+// (real: _SERVER_HOST/_PORT). App-owned prefixes (APP_*) are never flagged.
+func checkUnknownEnvVar(c *Context) []Finding {
+	if len(knownEnvVars) == 0 {
+		return nil
+	}
+	var hits []Finding
+	ast.Inspect(c.File, func(n ast.Node) bool {
+		st, ok := n.(*ast.StructType)
+		if !ok || st.Fields == nil {
+			return true
+		}
+		for _, field := range st.Fields.List {
+			if field.Tag == nil {
+				continue
+			}
+			name, ok := envName(strings.Trim(field.Tag.Value, "`"))
+			if !ok || !strings.HasPrefix(name, "EINHERJAR_") {
+				continue
+			}
+			if _, real := knownEnvVars[name]; real {
+				continue
+			}
+			hits = append(hits, Finding{
+				Message: name + " is not a real Einherjar env var (invented or misspelled)",
+				Hint:    "Verify the exact tag with get_config_env. The framework never invents EINHERJAR_* names; compose the component's real Config or fix the tag.",
+				Line:    c.Fset.Position(field.Tag.Pos()).Line,
+			})
+		}
+		return true
+	})
+	return hits
+}
+
+// envName extracts the env-var name from a raw (backtick-stripped) struct tag,
+// dropping the ,required / ,unset options. ok is false when there is no env key
+// or it is "-".
+func envName(tag string) (string, bool) {
+	raw, present := reflect.StructTag(tag).Lookup("env")
+	if !present {
+		return "", false
+	}
+	name := strings.TrimSpace(strings.Split(raw, ",")[0])
+	if name == "" || name == "-" {
+		return "", false
+	}
+	return name, true
+}

internal/rules/env_rules_test.go

@@ -0,0 +1,63 @@
+package rules
+
+import "testing"
+
+const configWithBadTag = `package config
+
+type Config struct {
+	Host string ` + "`" + `env:"EINHERJAR_PG_HOST,required"` + "`" + `
+	Bad  string ` + "`" + `env:"EINHERJAR_PG_DATABASE"` + "`" + `
+	App  string ` + "`" + `env:"APP_ENV" envDefault:"local"` + "`" + `
+}
+`
+
+func findingsFor(fs []Finding, ruleID string) []Finding {
+	var out []Finding
+	for _, f := range fs {
+		if f.RuleID == ruleID {
+			out = append(out, f)
+		}
+	}
+	return out
+}
+
+func TestUnknownEnvVarFires(t *testing.T) {
+	SetKnownEnvVars(map[string]struct{}{"EINHERJAR_PG_HOST": {}})
+	defer SetKnownEnvVars(nil)
+
+	got := findingsFor(Run(configWithBadTag), "config.unknown-env-var")
+	if len(got) != 1 {
+		t.Fatalf("want 1 unknown-env-var finding, got %d: %+v", len(got), got)
+	}
+	if got[0].Severity != SeverityError {
+		t.Errorf("want error severity, got %s", got[0].Severity)
+	}
+	// EINHERJAR_PG_HOST is known and APP_ENV is app-owned — neither may be flagged.
+	for _, f := range got {
+		if f.Message == "" || f.Line == 0 {
+			t.Errorf("finding should carry a message and line: %+v", f)
+		}
+	}
+}
+
+func TestUnknownEnvVarNoopWithoutIndex(t *testing.T) {
+	SetKnownEnvVars(nil) // simulate no injected index
+	if got := findingsFor(Run(configWithBadTag), "config.unknown-env-var"); len(got) != 0 {
+		t.Errorf("rule must be a no-op without an injected var set, got %+v", got)
+	}
+}
+
+func TestUnknownEnvVarCleanConfig(t *testing.T) {
+	SetKnownEnvVars(map[string]struct{}{"EINHERJAR_PG_HOST": {}, "EINHERJAR_PG_NAME": {}})
+	defer SetKnownEnvVars(nil)
+
+	clean := `package config
+type Config struct {
+	Host string ` + "`" + `env:"EINHERJAR_PG_HOST,required"` + "`" + `
+	Name string ` + "`" + `env:"EINHERJAR_PG_NAME,required"` + "`" + `
+}
+`
+	if got := findingsFor(Run(clean), "config.unknown-env-var"); len(got) != 0 {
+		t.Errorf("clean config should not fire, got %+v", got)
+	}
+}

internal/tools/check_env.go

@@ -0,0 +1,179 @@
+package tools
+
+import (
+	"context"
+	"fmt"
+	"sort"
+	"strings"
+
+	"code.nochebuena.dev/einherjar/mcp/internal/envspec"
+	"code.nochebuena.dev/einherjar/mcp/internal/index"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+type checkEnvInput struct {
+	Env     string   `json:"env" jsonschema:"the .env or .env.example contents to check (KEY=value lines; comments and blanks ignored)."`
+	Modules []string `json:"modules,omitempty" jsonschema:"the framework modules whose component configs the app composes, e.g. [\"db-postgres\",\"web\"]. Their required vars must be present; omit to only validate that EINHERJAR_* names are real."`
+}
+
+type envFinding struct {
+	Severity string `json:"severity"` // error | warning | info
+	Kind     string `json:"kind"`     // unknown-var | missing-required | not-composed
+	Var      string `json:"var"`
+	Message  string `json:"message"`
+	Hint     string `json:"hint,omitempty"`
+}
+
+type checkEnvOutput struct {
+	Findings []envFinding `json:"findings"`
+	OK       bool         `json:"ok"`
+	Summary  string       `json:"summary"`
+}
+
+func registerCheckEnv(s *mcp.Server, idx *index.Index) {
+	mcp.AddTool(s, &mcp.Tool{
+		Name: "check_env",
+		Description: "Check a .env / .env.example against the framework's real env vars. Flags EINHERJAR_* names that don't exist (invented or misspelled, e.g. EINHERJAR_PG_DATABASE), " +
+			"and — when you pass the modules the app composes — required vars that are missing, plus framework vars set for a module you don't compose (dead vars). " +
+			"This is the enforcement half of building a correct global config: get_scaffold emits an accurate .env.example, get_config_env lists the truth, and check_env catches drift in an existing file.",
+	}, func(ctx context.Context, req *mcp.CallToolRequest, args checkEnvInput) (*mcp.CallToolResult, checkEnvOutput, error) {
+		findings, err := checkEnvVars(idx, args.Env, args.Modules)
+		if err != nil {
+			return errorResult(err.Error()), checkEnvOutput{}, nil
+		}
+		ok := true
+		for _, f := range findings {
+			if f.Severity == "error" {
+				ok = false
+			}
+		}
+		out := checkEnvOutput{Findings: findings, OK: ok, Summary: summariseEnvCheck(findings, ok)}
+		return jsonText(out), out, nil
+	})
+}
+
+// checkEnvVars is the pure core of check_env: given the framework index, an env
+// file body, and the modules the app composes, it returns the drift findings.
+func checkEnvVars(idx *index.Index, env string, modules []string) ([]envFinding, error) {
+	present := parseEnvKeys(env)
+	known := envspec.KnownNames(idx)
+
+	// Expected vars from the composed modules, and the module each real var belongs to.
+	expected := map[string]envspec.Var{}
+	composed := map[string]bool{}
+	for _, mod := range modules {
+		mod = strings.TrimSpace(mod)
+		if mod == "" {
+			continue
+		}
+		if idx.FindModule(mod) == nil {
+			return nil, fmt.Errorf("module not found: %s", mod)
+		}
+		composed[mod] = true
+		for _, v := range envspec.ForModule(idx, mod) {
+			expected[v.Name] = v
+		}
+	}
+	varModule := map[string]string{}
+	for _, v := range envspec.All(idx) {
+		varModule[v.Name] = v.Module
+	}
+
+	var findings []envFinding
+
+	// 1. EINHERJAR_* present in the file that is not a real framework var.
+	for name := range present {
+		if !strings.HasPrefix(name, "EINHERJAR_") {
+			continue
+		}
+		if _, real := known[name]; real {
+			continue
+		}
+		findings = append(findings, envFinding{
+			Severity: "error", Kind: "unknown-var", Var: name,
+			Message: name + " is not a real Einherjar env var",
+			Hint:    "Confirm the exact name with get_config_env; e.g. the db name is EINHERJAR_PG_NAME (not _DATABASE) and the server bind is EINHERJAR_SERVER_HOST/_PORT (not _ADDR).",
+		})
+	}
+
+	// 2. Required vars of a composed module that the file never sets.
+	for name, v := range expected {
+		if !v.Required {
+			continue
+		}
+		if _, ok := present[name]; !ok {
+			findings = append(findings, envFinding{
+				Severity: "error", Kind: "missing-required", Var: name,
+				Message: name + " is required by " + v.Module + "." + v.Struct + " but is absent from the file",
+				Hint:    "Add " + name + "= to the file; a required var with no default fails config.Load() at boot.",
+			})
+		}
+	}
+
+	// 3. Real framework var set for a module the app doesn't compose → dead.
+	if len(composed) > 0 {
+		for name := range present {
+			mod, real := varModule[name]
+			if !real || composed[mod] {
+				continue
+			}
+			findings = append(findings, envFinding{
+				Severity: "info", Kind: "not-composed", Var: name,
+				Message: name + " belongs to module " + mod + ", which this app does not list as composed — it will be ignored",
+				Hint:    "Either compose " + mod + "'s Config, or drop the var. (This is how EINHERJAR_SERVER_CORS_ORIGINS is dead unless you compose web.Config.)",
+			})
+		}
+	}
+
+	sort.Slice(findings, func(i, j int) bool {
+		if findings[i].Kind != findings[j].Kind {
+			return findings[i].Kind < findings[j].Kind
+		}
+		return findings[i].Var < findings[j].Var
+	})
+	if findings == nil {
+		findings = []envFinding{}
+	}
+	return findings, nil
+}
+
+// parseEnvKeys returns the set of assigned variable names in an env file body,
+// tolerating `export KEY=`, leading whitespace, comments, and blank lines.
+func parseEnvKeys(body string) map[string]bool {
+	keys := map[string]bool{}
+	for _, line := range strings.Split(body, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		line = strings.TrimPrefix(line, "export ")
+		eq := strings.IndexByte(line, '=')
+		if eq <= 0 {
+			continue
+		}
+		key := strings.TrimSpace(line[:eq])
+		if key != "" {
+			keys[key] = true
+		}
+	}
+	return keys
+}
+
+func summariseEnvCheck(fs []envFinding, ok bool) string {
+	if len(fs) == 0 {
+		return "No issues — every EINHERJAR_* name is real and all required vars are present."
+	}
+	var errs, infos int
+	for _, f := range fs {
+		if f.Severity == "error" {
+			errs++
+		} else {
+			infos++
+		}
+	}
+	status := "OK"
+	if !ok {
+		status = "FAILED"
+	}
+	return status + ": " + itoa(errs) + " error(s), " + itoa(infos) + " note(s)."
+}

internal/tools/env_tools_test.go

@@ -0,0 +1,160 @@
+package tools
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"code.nochebuena.dev/einherjar/mcp/internal/index"
+)
+
+// loadRealIndex builds the index from the sibling framework checkout at test
+// time, so the env tools are tested against the framework's actual struct tags.
+// It deliberately does NOT read data/index.json: that file is only an empty
+// placeholder in the repo (the real index is regenerated by cmd/indexer at
+// image-build time). When the sibling modules aren't present — e.g. a CI that
+// checks out only this module — the test skips rather than fails.
+func loadRealIndex(t *testing.T) *index.Index {
+	t.Helper()
+	idx, err := index.Build(filepath.Join("..", "..", ".."))
+	if err != nil || idx == nil || len(idx.Modules) == 0 {
+		t.Skip("framework checkout not available; skipping index-derived test")
+	}
+	return idx
+}
+
+func TestRenderEnvExample(t *testing.T) {
+	idx := loadRealIndex(t)
+	got := renderEnvExample(idx, "myapp")
+
+	// Required, no default → uncommented with a runnable dev value.
+	mustContain := []string{
+		"APP_ENV=local",
+		"APP_CORS_ORIGINS=*",
+		"EINHERJAR_PG_HOST=localhost",
+		"EINHERJAR_PG_USER=postgres",
+		"EINHERJAR_PG_PASSWORD=postgres",
+		"EINHERJAR_PG_NAME=myapp",
+		// logz is composed → its vars (both defaulted) are documented, commented.
+		"# EINHERJAR_LOG_LEVEL=INFO",
+		"# EINHERJAR_LOG_JSON=false",
+		// Has a framework default → commented line documenting it.
+		"# EINHERJAR_SERVER_HOST=0.0.0.0",
+		"# EINHERJAR_SERVER_PORT=8080",
+		"# EINHERJAR_PG_PORT=5432",
+		"# EINHERJAR_PG_SSL_MODE=disable",
+	}
+	for _, s := range mustContain {
+		if !strings.Contains(got, s) {
+			t.Errorf(".env.example missing line: %q\n---\n%s", s, got)
+		}
+	}
+
+	// The historical drift names must never appear.
+	mustNotContain := []string{
+		"EINHERJAR_PG_DATABASE",
+		"EINHERJAR_SERVER_ADDR",
+		// CORS lives on web.Config, which the scaffold does not compose — so it
+		// must not be emitted (it would be a dead var).
+		"EINHERJAR_SERVER_CORS_ORIGINS",
+	}
+	for _, s := range mustNotContain {
+		if strings.Contains(got, s) {
+			t.Errorf(".env.example must not contain %q\n---\n%s", s, got)
+		}
+	}
+
+	// A required var must never be silently emitted as a commented line.
+	for _, line := range strings.Split(got, "\n") {
+		if strings.HasPrefix(strings.TrimSpace(line), "# EINHERJAR_PG_NAME") {
+			t.Errorf("required EINHERJAR_PG_NAME emitted commented: %q", line)
+		}
+	}
+}
+
+func TestCheckEnvUnknownVar(t *testing.T) {
+	idx := loadRealIndex(t)
+	env := "EINHERJAR_PG_DATABASE=x\nEINHERJAR_SERVER_ADDR=:8080\nAPP_ENV=local\n"
+	findings, err := checkEnvVars(idx, env, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	unknown := map[string]bool{}
+	for _, f := range findings {
+		if f.Kind == "unknown-var" {
+			unknown[f.Var] = true
+		}
+	}
+	for _, want := range []string{"EINHERJAR_PG_DATABASE", "EINHERJAR_SERVER_ADDR"} {
+		if !unknown[want] {
+			t.Errorf("expected unknown-var finding for %s; got %+v", want, findings)
+		}
+	}
+	// APP_* must never be flagged.
+	for _, f := range findings {
+		if f.Var == "APP_ENV" {
+			t.Errorf("APP_ENV should never be flagged: %+v", f)
+		}
+	}
+}
+
+func TestCheckEnvMissingRequired(t *testing.T) {
+	idx := loadRealIndex(t)
+	// Compose db-postgres but set none of its required vars.
+	findings, err := checkEnvVars(idx, "APP_ENV=local\n", []string{"db-postgres"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	missing := map[string]bool{}
+	for _, f := range findings {
+		if f.Kind == "missing-required" {
+			missing[f.Var] = true
+		}
+	}
+	for _, want := range []string{"EINHERJAR_PG_HOST", "EINHERJAR_PG_USER", "EINHERJAR_PG_PASSWORD", "EINHERJAR_PG_NAME"} {
+		if !missing[want] {
+			t.Errorf("expected missing-required for %s; got %+v", want, findings)
+		}
+	}
+}
+
+func TestCheckEnvNotComposed(t *testing.T) {
+	idx := loadRealIndex(t)
+	// A real MinIO var while only composing db-postgres → dead (not-composed).
+	env := "EINHERJAR_MINIO_ENDPOINT=x\nEINHERJAR_PG_HOST=h\nEINHERJAR_PG_USER=u\nEINHERJAR_PG_PASSWORD=p\nEINHERJAR_PG_NAME=n\n"
+	findings, err := checkEnvVars(idx, env, []string{"db-postgres"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got bool
+	for _, f := range findings {
+		if f.Kind == "not-composed" && f.Var == "EINHERJAR_MINIO_ENDPOINT" {
+			got = true
+		}
+	}
+	if !got {
+		t.Errorf("expected not-composed for EINHERJAR_MINIO_ENDPOINT; got %+v", findings)
+	}
+}
+
+func TestCheckEnvClean(t *testing.T) {
+	idx := loadRealIndex(t)
+	// The scaffold's own output, checked against the modules it composes, is clean.
+	env := renderEnvExample(idx, "myapp")
+	findings, err := checkEnvVars(idx, env, []string{"core", "web", "db-postgres"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, f := range findings {
+		if f.Severity == "error" {
+			t.Errorf("scaffold .env.example should have no errors, got %+v", f)
+		}
+	}
+}
+
+func TestCheckEnvUnknownModule(t *testing.T) {
+	idx := loadRealIndex(t)
+	if _, err := checkEnvVars(idx, "", []string{"nope"}); err == nil {
+		t.Error("expected error for unknown module")
+	}
+}

internal/tools/get_config_env.go

@@ -0,0 +1,60 @@
+package tools
+
+import (
+	"context"
+	"strings"
+
+	"code.nochebuena.dev/einherjar/mcp/internal/envspec"
+	"code.nochebuena.dev/einherjar/mcp/internal/index"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+type getConfigEnvInput struct {
+	Module string `json:"module,omitempty" jsonschema:"restrict to one module's env vars, e.g. db-postgres or web. Omit to return every framework env var."`
+}
+
+type getConfigEnvOutput struct {
+	Vars    []envspec.Var `json:"vars"`
+	Count   int           `json:"count"`
+	Summary string        `json:"summary"`
+}
+
+func registerGetConfigEnv(s *mcp.Server, idx *index.Index) {
+	mcp.AddTool(s, &mcp.Tool{
+		Name: "get_config_env",
+		Description: "List the REAL environment variables an Einherjar component config reads, derived from the framework's struct tags (never hand-maintained). " +
+			"Each entry gives the var name, the declaring module/struct/field, whether it is required, and its default. " +
+			"Use this before composing a global Config or writing a .env — it is the source of truth for which EINHERJAR_* vars exist. " +
+			"Pass a module (e.g. db-postgres, web, core, storage-minio) to scope it; omit to get all.",
+	}, func(ctx context.Context, req *mcp.CallToolRequest, args getConfigEnvInput) (*mcp.CallToolResult, getConfigEnvOutput, error) {
+		module := strings.TrimSpace(args.Module)
+		var vars []envspec.Var
+		if module == "" {
+			vars = envspec.All(idx)
+		} else {
+			if idx.FindModule(module) == nil {
+				return errorResult("module not found: " + module), getConfigEnvOutput{}, nil
+			}
+			vars = envspec.ForModule(idx, module)
+		}
+		if vars == nil {
+			vars = []envspec.Var{}
+		}
+		out := getConfigEnvOutput{Vars: vars, Count: len(vars), Summary: summariseEnv(vars, module)}
+		return jsonText(out), out, nil
+	})
+}
+
+func summariseEnv(vars []envspec.Var, module string) string {
+	var required int
+	for _, v := range vars {
+		if v.Required {
+			required++
+		}
+	}
+	scope := "the framework"
+	if module != "" {
+		scope = module
+	}
+	return itoa(len(vars)) + " env var(s) for " + scope + ", " + itoa(required) + " required."
+}

internal/tools/scaffold.go

@@ -2,8 +2,10 @@ package tools
 
 import (
 	"context"
+	"fmt"
 	"strings"
 
+	"code.nochebuena.dev/einherjar/mcp/internal/envspec"
 	"code.nochebuena.dev/einherjar/mcp/internal/index"
 	"github.com/modelcontextprotocol/go-sdk/mcp"
 )
@@ -54,11 +56,11 @@ func registerGetScaffold(s *mcp.Server, idx *index.Index) {
 				{Path: "internal/wire/wire.go", Content: repl.Replace(tplWire)},
 				{Path: "internal/wire/health.go", Content: repl.Replace(tplHealth)},
 				{Path: "internal/config/config.go", Content: repl.Replace(tplConfig)},
-				{Path: ".env.example", Content: repl.Replace(tplEnvExample)},
+				{Path: ".env.example", Content: renderEnvExample(idx, service)},
 			},
 			Notes: []string{
 				"main.go contains ONLY the godotenv autoload blank import and wire.Run() — never construct components there.",
-				"Every env var the config reads must also appear in .env.example, kept in lock-step. When a feature adds a var, update both.",
+				".env.example is DERIVED from the framework's real component-config tags (web/server + db-postgres), so the EINHERJAR_* names and defaults are always correct. When you compose another component, add its section — get_config_env(module) lists the exact vars, and check_env catches drift.",
 				"App-owned config fields use the APP_* prefix; framework component configs load their own EINHERJAR_* tags through the same env.Parse.",
 				"Add one internal/wire/<feature>.go per feature (a with<Feature> hook) plus its internal/<feature>/{dto,handler,repository,service} layers; call validate_snippet / get_example(\"wire\") for the hook shape.",
 				"Migrations and seeding are the developer's choice — not part of this scaffold.",
@@ -98,8 +100,6 @@ func main() {
 const tplWire = `package wire
 
 import (
-	"strings"
-
 	"github.com/google/uuid"
 
 	"code.nochebuena.dev/einherjar/core/launcher"
@@ -120,10 +120,11 @@ func Run() error {
 		return err
 	}
 
-	logger := logz.New(logz.Config{
+	// logz.Config is composed in config.Config, so EINHERJAR_LOG_LEVEL / _JSON load
-		JSON:       !strings.EqualFold(cfg.AppEnv, "local"),
+	// from the environment; StaticArgs are set here in code (they carry no env tag).
-		StaticArgs: []any{"service", "%%APP%%", "env", cfg.AppEnv},
+	logCfg := cfg.Log
-	})
+	logCfg.StaticArgs = []any{"service", "%%APP%%", "env", cfg.AppEnv}
+	logger := logz.New(logCfg)
 
 	db := postgres.New(logger, cfg.PG)
 	srv := server.New(logger, cfg.Server,
@@ -138,7 +139,7 @@ func Run() error {
 	lc := launcher.New(logger)
 	lc.Append(db, srv)
 
-	withHealth(lc, srv, logger, db)
+	withHealth(lc, srv)
 	// … one withFeature(lc, srv, …) call per feature in your domain.
 
 	return lc.Run()
@@ -151,14 +152,13 @@ import (
 	"net/http"
 
 	"code.nochebuena.dev/einherjar/core/launcher"
-	"code.nochebuena.dev/einherjar/core/logz"
-	"code.nochebuena.dev/einherjar/db-postgres"
 	"code.nochebuena.dev/einherjar/web/server"
 )
 
-// withHealth registers a liveness endpoint. Grow it into a readiness check
+// withHealth registers a liveness endpoint — the simplest with<Feature> hook.
-// (ping db and other dependencies) as the service gains infrastructure.
+// A real feature hook takes its deps (logging.Logger, postgres.Provider, …) and
-func withHealth(lc launcher.Launcher, srv server.Server, logger logz.Logger, db postgres.Component) {
+// wires repo→service→handler inside the closure; see get_example("wire").
+func withHealth(lc launcher.Launcher, srv server.Server) {
 	lc.BeforeStart(func() error {
 		srv.Get("/health", func(w http.ResponseWriter, r *http.Request) {
 			w.Header().Set("Content-Type", "application/json")
@@ -181,19 +181,21 @@ package config
 import (
 	"github.com/caarlos0/env/v11"
 
+	"code.nochebuena.dev/einherjar/core/logz"
 	"code.nochebuena.dev/einherjar/db-postgres"
 	"code.nochebuena.dev/einherjar/web/server"
 )
 
 // Config is the fully-resolved startup configuration. caarlos0/env recurses into
-// the nested framework configs, populating their EINHERJAR_SERVER_* / EINHERJAR_PG_*
+// the nested framework configs, populating their EINHERJAR_LOG_* / EINHERJAR_SERVER_* /
-// tags from the environment next to the app-owned APP_* fields.
+// EINHERJAR_PG_* tags from the environment next to the app-owned APP_* fields.
 type Config struct {
 	AppEnv      string   ` + "`" + `env:"APP_ENV"          envDefault:"local"` + "`" + `
 	CORSOrigins []string ` + "`" + `env:"APP_CORS_ORIGINS" envSeparator:","` + "`" + `
 
 	// Framework component configs — composed verbatim; their EINHERJAR_* tags
 	// load through this same env.Parse call.
+	Log    logz.Config     // EINHERJAR_LOG_*
 	Server server.Config   // EINHERJAR_SERVER_*
 	PG     postgres.Config // EINHERJAR_PG_*
 }
@@ -207,20 +209,57 @@ func Load() (Config, error) {
 }
 `
 
-const tplEnvExample = `# .env.example — copy to .env for local dev (godotenv autoloads it).
+// renderEnvExample builds .env.example from the framework's real component-config
-# Every variable the config package reads lives here, documented. Keep in sync.
+// tags rather than a hand-maintained string, so the EINHERJAR_* names and defaults
+// can never drift from the modules the scaffold composes (web/server + db-postgres).
+// Required vars (no default) are emitted uncommented with a runnable dev value;
+// vars that carry a framework default are emitted commented — documented, inert
+// until overridden.
+func renderEnvExample(idx *index.Index, app string) string {
+	var b strings.Builder
+	b.WriteString("# .env.example — copy to .env for local dev (godotenv autoloads it).\n")
+	b.WriteString("# Derived from the framework's real config tags. Required vars are uncommented;\n")
+	b.WriteString("# a commented line documents that var's framework default — uncomment to override.\n\n")
 
-# ── App (APP_*) ────────────────────────────────────────────────────────────
+	b.WriteString("# ── App (APP_*) ────────────────────────────────────────────────────────────\n")
-APP_ENV=local
+	b.WriteString("APP_ENV=local\n")
-APP_CORS_ORIGINS=*
+	b.WriteString("APP_CORS_ORIGINS=*\n\n")
 
-# ── Einherjar: HTTP server (EINHERJAR_SERVER_*) ───────────────────────────
+	writeEnvSection(&b, "Einherjar: logging", envspec.FindStruct(idx, "core", "logz", "Config"), app)
-EINHERJAR_SERVER_ADDR=:8080
+	writeEnvSection(&b, "Einherjar: HTTP server", envspec.FindStruct(idx, "web", "server", "Config"), app)
+	writeEnvSection(&b, "Einherjar: PostgreSQL", envspec.FindStruct(idx, "db-postgres", "", "Config"), app)
+	return b.String()
+}
 
-# ── Einherjar: PostgreSQL (EINHERJAR_PG_*) ────────────────────────────────
+// envDevDefaults gives required vars (which carry no framework default) a value
-EINHERJAR_PG_HOST=localhost
+// that runs against the local devtools stack out of the box.
-EINHERJAR_PG_PORT=5432
+var envDevDefaults = map[string]string{
-EINHERJAR_PG_USER=postgres
+	"EINHERJAR_PG_HOST":     "localhost",
-EINHERJAR_PG_PASSWORD=postgres
+	"EINHERJAR_PG_USER":     "postgres",
-EINHERJAR_PG_DATABASE=%%APP%%
+	"EINHERJAR_PG_PASSWORD": "postgres",
-`
+}
+
+func envDevValue(v envspec.Var, app string) string {
+	if v.Name == "EINHERJAR_PG_NAME" {
+		return app
+	}
+	return envDevDefaults[v.Name]
+}
+
+func writeEnvSection(b *strings.Builder, title string, vars []envspec.Var, app string) {
+	if len(vars) == 0 {
+		return
+	}
+	fmt.Fprintf(b, "# ── %s ──────────────────────────────────────\n", title)
+	for _, v := range vars {
+		switch {
+		case v.HasDefault:
+			fmt.Fprintf(b, "# %s=%s\n", v.Name, v.Default)
+		case v.Required:
+			fmt.Fprintf(b, "%s=%s\n", v.Name, envDevValue(v, app))
+		default:
+			fmt.Fprintf(b, "# %s=%s\n", v.Name, envDevValue(v, app))
+		}
+	}
+	b.WriteString("\n")
+}

internal/tools/tools.go

@@ -20,6 +20,8 @@ func Register(s *mcp.Server, idx *index.Index) {
 	registerGetADR(s, idx)
 	registerGetExample(s, idx)
 	registerGetScaffold(s, idx)
+	registerGetConfigEnv(s, idx)
+	registerCheckEnv(s, idx)
 	registerValidateSnippet(s, idx)
 	registerGetCompliance(s, idx)
 	registerGetChangelog(s, idx)

internal/tools/validate_snippet.go

@@ -3,6 +3,7 @@ package tools
 import (
 	"context"
 
+	"code.nochebuena.dev/einherjar/mcp/internal/envspec"
 	"code.nochebuena.dev/einherjar/mcp/internal/index"
 	"code.nochebuena.dev/einherjar/mcp/internal/rules"
 	"github.com/modelcontextprotocol/go-sdk/mcp"
@@ -17,7 +18,10 @@ type validateSnippetOutput struct {
 	Summary  string          `json:"summary"`
 }
 
-func registerValidateSnippet(s *mcp.Server, _ *index.Index) {
+func registerValidateSnippet(s *mcp.Server, idx *index.Index) {
+	// Inject the real framework env-var names so config.unknown-env-var can reject
+	// invented/misspelled EINHERJAR_* tags instead of guessing.
+	rules.SetKnownEnvVars(envspec.KnownNames(idx))
 	mcp.AddTool(s, &mcp.Tool{
 		Name:        "validate_snippet",
 		Description: "Validate a Go snippet against Einherjar wiring conventions: lifecycle setup, logger configuration, env-var handling, server registration. Findings are advisory, not a substitute for go vet or the project's tests.",