feat(web): add mw.RequestIDFrom (resolver sees the request); dependency refresh; v1.4.0

CHANGELOG.md

@@ -6,6 +6,109 @@ This module adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html
 
 ---
 
+## [1.4.0] — 2026-08-09
+
+Minor — resolvable request IDs, plus a dependency refresh.
+
+### Added
+
+- **`mw.RequestIDFrom(resolve func(*http.Request) string)`** — the resolver sees the request,
+  so a service can continue a correlation ID a client already sent (a distributed trace survives
+  this boundary). The framework provides plumbing only: it does not read a header, choose a header
+  name, or validate the value — that policy is the application's, because a value the framework
+  accepts on a service's behalf may be one that service cannot store. Generation becomes the
+  fallback branch of resolution rather than a separate mode.
+
+### Changed
+
+- `mw.RequestID(generator func() string)` is unchanged in signature and behaviour (always
+  generates, ignores inbound); it is now expressed as `RequestIDFrom` with a request-ignoring resolver.
+- Refreshed dependencies (`go-chi/chi/v5` v5.3.1, `golang.org/x/time` v0.15.0).
+- Bumped `contracts`, `core` to v1.4.0.
+
+### Notes
+
+- An empty resolver result attaches no ID (header omitted, context carries none) rather than a
+  silently-empty value; a resolver that can return "" is a caller error.
+
+## [1.3.0] — 2026-08-08
+
+Minor release carrying a **breaking API change** to CORS configuration. The framework is
+private with controlled consumers, so this ships in the 1.x line with a loud compile break
+instead of a v2 module-path (`/v2`) migration.
+
+### Removed
+
+- **⚠️ BREAKING: `web.Config.AllowedOrigins` removed.** CORS origins now have a single
+  home: `server.Config.CORSOrigins` (env `EINHERJAR_SERVER_CORS_ORIGINS`). The field was
+  env-backed through v1.1.x and a code-only override in v1.2.0 — reading it after the env
+  tag moved silently served *no* CORS. Removing it turns that runtime trap into a compile
+  error.
+
+  **Migration:** replace `cfg.Web.AllowedOrigins` with `cfg.Server.CORSOrigins`, and
+  `web.Config{AllowedOrigins: o}` with `web.Config{Server: server.Config{CORSOrigins: o}}`
+  — or just let `web.New` read `EINHERJAR_SERVER_CORS_ORIGINS`. The MCP flags any leftover
+  reference (`validate_snippet` rule `web.allowedorigins-removed`).
+
+### Changed
+
+- Bumped `contracts`, `core` to v1.3.0.
+
+## [1.2.0] — 2026-08-08
+
+Minor — CORS configuration moved to its rightful struct; `web.New` made safe-by-default.
+
+### Changed
+
+- **`CORSOrigins` now lives on `server.Config`** (env var `EINHERJAR_SERVER_CORS_ORIGINS`), the
+  struct its name advertises — it previously loaded into `web.Config`. `web.Config.AllowedOrigins`
+  remains as a code-only override (no env tag). Wiring via `web.New` or the env var is unaffected.
+- Bumped `contracts`, `core` to v1.2.0.
+
+### Added
+
+- `web.New` logs a warning when no CORS origins are configured, instead of silently disabling CORS.
+- Package docs (`web`, `web/server`) document when to use `web.New` vs `server.New`, with compiling
+  examples and the env-gated allow-all CORS convention.
+
+## [1.1.3] — 2026-08-08
+
+Patch — CORS documentation discoverability.
+
+### Fixed
+
+- `mw.CORS` and `CORSAllowAll` doc comments now document the `"*"` rejection (panic) and the
+  env-gated CORS convention (`local -> CORSAllowAll`, else `mw.CORS(origins)`), so `search_symbols`
+  surfaces it — previously the convention lived only in code comments and the wire example.
+
+### Changed
+
+- Bumped `contracts`, `core` to v1.1.3.
+
+## [1.1.2] — 2026-08-08
+
+Patch — CORS wildcard hardening plus documentation fixes.
+
+### Changed
+
+- **`mw.CORS` now rejects `"*"` (panics at construction)** instead of silently no-op'ing it.
+  `"*"` matched nothing (exact-match only), so a service passing it ran with CORS effectively
+  off — a silent trap. Fail loud at boot; use `mw.CORSAllowAll()` (development) or list explicit origins.
+- Bumped `contracts`, `core` to v1.1.2.
+
+### Fixed
+
+- README Go examples now compile: `mw.Recover(logger)`, `health.NewHandler(...).ServeHTTP`, and the
+  `mw.CORS` example no longer passes `"*"`. Corrected the `CORSAllowAll` description.
+
+## [1.1.1] — 2026-08-07
+
+Patch — coordinated framework version alignment.
+
+### Changed
+
+- Bumped `contracts` and `core` to v1.1.1 (framework version alignment). No code or API changes.
+
 ## [1.1.0] — 2026-08-07
 
 Coordinated framework release. Documentation fixes plus the framework version bump
@@ -61,7 +164,7 @@ Coordinated framework release. Documentation fixes plus the framework version bu
   request logging: method, path, status, latency; uses `StatusRecorder` to capture code
 - `CORS(origins []string) func(http.Handler) http.Handler` — sets
   `Access-Control-Allow-Origin` for listed origins; supports preflight (`OPTIONS`)
-- `CORSAllowAll() func(http.Handler) http.Handler` — shorthand for `CORS([]string{"*"})`
+- `CORSAllowAll() func(http.Handler) http.Handler` — allows any origin by reflecting the request `Origin` (no `Access-Control-Allow-Credentials`); development only
 - `RateLimiterStore` interface — `Allow(ctx context.Context, key string) (bool, error)`;
   pluggable backend; `error` return allows infrastructure failures to surface; fail-open
   contract: non-nil error allows the request

README.md

@@ -1,6 +1,6 @@
 # einherjar/web
 
-[![version](https://img.shields.io/badge/version-v1.1.0-5C4EE5?style=flat-square)](https://code.nochebuena.dev/einherjar/web)
+[![version](https://img.shields.io/badge/version-v1.4.0-5C4EE5?style=flat-square)](https://code.nochebuena.dev/einherjar/web)
 [![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)
 
@@ -46,7 +46,7 @@ logger := logz.New(logz.Config{JSON: true, StaticArgs: []any{"service", "api"}})
 srv := web.New(logger)
 // Pre-wired stack: Recover → RequestID (UUID v7/v4) → RequestLogger → [CORS]
 
-srv.Get("/health", health.NewHandler(logger, db, cache))
+srv.Get("/health", health.NewHandler(logger, db, cache).ServeHTTP)
 
 lc := launcher.New(logger)
 lc.Append(srv)
@@ -57,12 +57,16 @@ lc.BeforeStart(func() error {
 lc.Run()
 ```
 
-With origins (CORS auto-applied):
+With origins set in code (CORS auto-applied). `Server.CORSOrigins` is the single
+source of truth — normally it loads from `EINHERJAR_SERVER_CORS_ORIGINS`, but you
+can set it directly to override without the env var:
 
 ```go
 srv := web.New(logger, web.Config{
-    Server:         server.Config{Port: 9090},
+    Server: server.Config{
-    AllowedOrigins: []string{"https://example.com"},
+        Port:        9090,
+        CORSOrigins: []string{"https://example.com"},
+    },
 })
 ```
 
@@ -76,7 +80,7 @@ Environment variables for `web.New`:
 | `EINHERJAR_SERVER_WRITE_TIMEOUT` | `10s` | HTTP write timeout |
 | `EINHERJAR_SERVER_IDLE_TIMEOUT` | `120s` | Keep-alive idle timeout |
 | `EINHERJAR_SERVER_SHUTDOWN_TIMEOUT` | `10s` | Graceful shutdown budget |
-| `EINHERJAR_SERVER_CORS_ORIGINS` | _(empty — CORS off)_ | Comma-separated allowed origins |
+| `EINHERJAR_SERVER_CORS_ORIGINS` | _(empty — CORS off)_ | Comma-separated allowed origins (`*` is rejected — use `mw.CORSAllowAll()` in code for allow-all) |
 
 ### Tier 2 — Full control (`server.New`)
 
@@ -90,9 +94,9 @@ import (
 
 srv := server.New(logger, server.Config{Port: 9090},
     server.WithMiddleware(
-        mw.Recover(),
+        mw.Recover(logger),
         mw.RequestID(myIDGenerator),
-        mw.CORS([]string{"*"}),
+        mw.CORS([]string{"https://example.com"}),
         mw.RequestLogger(logger),
         myOwnMiddleware,
     ),
@@ -177,7 +181,7 @@ values are mapped to their canonical HTTP status codes (full 16-code table below
 import "code.nochebuena.dev/einherjar/web/health"
 
 // db and cache implement observability.Checkable
-srv.Get("/health", health.NewHandler(logger, db, cache))
+srv.Get("/health", health.NewHandler(logger, db, cache).ServeHTTP)
 
 // Response shape:
 // {"status":"UP","components":{"db":{"status":"UP","latency":"1.2ms"}}}

doc.go

@@ -12,22 +12,46 @@
 //   - [code.nochebuena.dev/einherjar/web/httputil] — typed handler adapters and HTTP response helpers
 //   - [code.nochebuena.dev/einherjar/web/health]  — concurrent health check handler
 //
-// # Happy path
+// # Choosing web.New vs server.New
+//
+// Two tiers over the same underlying server:
+//
+//   - [New] (web.New) — batteries-included. The recommended middleware stack is wired
+//     for you; CORS uses explicit origins from EINHERJAR_SERVER_CORS_ORIGINS. Use it for
+//     most services. It does NOT support allow-all CORS.
+//   - [code.nochebuena.dev/einherjar/web/server.New] — full control. You compose the
+//     middleware list yourself. Use it when you need a custom middleware order, a custom
+//     request-ID generator, or allow-all CORS in development ([mw.CORSAllowAll], gated by
+//     environment).
+//
+// # web.New — batteries included (explicit CORS origins)
 //
 //	logger := logz.New(logz.Config{JSON: true})
 //	lc := launcher.New(logger)
 //
-//	srv := web.New(logger)
+//	// CORS from EINHERJAR_SERVER_CORS_ORIGINS (explicit origins; empty ⇒ CORS off + log).
+//	srv := web.New(logger, web.Config{Server: cfg.Server})
 //	srv.Get("/health", health.NewHandler(logger, db, cache).ServeHTTP)
 //
 //	lc.Append(srv)
-//	lc.BeforeStart(func() error {
-//	    // register routes
-//	    return nil
-//	})
-//
 //	if err := lc.Run(); err != nil {
 //	    logger.Error("launcher failed", err)
 //	    os.Exit(1)
 //	}
+//
+// # server.New — full control (allow-all CORS in dev)
+//
+// For allow-all CORS in local development, gate it by environment and compose the
+// stack yourself. mw.CORS panics on "*", so allow-all is [mw.CORSAllowAll], never a
+// "*" in the origins list:
+//
+//	var corsMW func(http.Handler) http.Handler
+//	if strings.EqualFold(cfg.AppEnv, "local") {
+//	    corsMW = mw.CORSAllowAll()               // dev: any origin
+//	} else {
+//	    corsMW = mw.CORS(cfg.Server.CORSOrigins)  // prod: explicit origins from env
+//	}
+//	srv := server.New(logger, cfg.Server, server.WithMiddleware(
+//	    mw.Recover(logger), mw.RequestID(uuid.NewString), corsMW, mw.RequestLogger(logger),
+//	))
 package web

docs/adr/index.md

@@ -19,3 +19,4 @@ Decisions worth noting (not ADR-worthy individually):
 | UUID v7 for request IDs | v7 with v4 fallback | Time-ordered IDs sort chronologically in logs; fallback ensures generation never fails |
 | `observability.Checkable` not redefined | Imported from contracts | Starters implement contracts directly; no web import needed by db/cache starters |
 | Background goroutine for in-memory eviction | `time.Ticker` goroutine | Avoids `worker` module dependency; in-memory store is self-contained |
+| `mw.RequestIDFrom` resolver sees the request (v1.4.0) | New entry point takes `func(*http.Request) string`; `RequestID` becomes a request-ignoring wrapper over it | An inbound correlation id must be able to survive this boundary, but acceptability is per-service — a typed audit column rejects what an opaque log accepts. The framework provides plumbing only (context + header, once per request); the app owns policy (which header, validation, generation fallback). An empty resolver result attaches nothing rather than a silently-empty value |

go.mod

@@ -3,20 +3,20 @@ module code.nochebuena.dev/einherjar/web
 go 1.26
 
 require (
-	code.nochebuena.dev/einherjar/contracts v1.1.0
+	code.nochebuena.dev/einherjar/contracts v1.4.0
-	code.nochebuena.dev/einherjar/core v1.1.0
+	code.nochebuena.dev/einherjar/core v1.4.0
-	github.com/go-chi/chi/v5 v5.2.1
+	github.com/go-chi/chi/v5 v5.3.1
 	github.com/google/uuid v1.6.0
-	golang.org/x/time v0.11.0
+	golang.org/x/time v0.15.0
 )
 
 require (
-	github.com/gabriel-vasile/mimetype v1.4.12 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.15 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
-	github.com/go-playground/validator/v10 v10.30.1 // indirect
+	github.com/go-playground/validator/v10 v10.30.3 // indirect
-	github.com/leodido/go-urn v1.4.0 // indirect
+	github.com/leodido/go-urn v1.5.0 // indirect
-	golang.org/x/crypto v0.46.0 // indirect
+	golang.org/x/crypto v0.55.0 // indirect
-	golang.org/x/sys v0.39.0 // indirect
+	golang.org/x/sys v0.47.0 // indirect
-	golang.org/x/text v0.32.0 // indirect
+	golang.org/x/text v0.41.0 // indirect
 )

go.sum

@@ -1,36 +1,36 @@
-code.nochebuena.dev/einherjar/contracts v1.1.0 h1:GsGr6reyrd9qCc7D8CqbT1LWPTeeK9lT4r4EdsNA5Ro=
+code.nochebuena.dev/einherjar/contracts v1.4.0 h1:rv/93dGXmXvO90G0uxCu8y3+5+EobkVvcoxh/BywIFk=
-code.nochebuena.dev/einherjar/contracts v1.1.0/go.mod h1:ccltUtrFb5+MEJdkx2VVEUL+xC5pupVlVVsMM8AlCWI=
+code.nochebuena.dev/einherjar/contracts v1.4.0/go.mod h1:ccltUtrFb5+MEJdkx2VVEUL+xC5pupVlVVsMM8AlCWI=
-code.nochebuena.dev/einherjar/core v1.1.0 h1:zxj9bFPthEEFRnvWV/vgNZqWa2y/kAo3p5pODWablyk=
+code.nochebuena.dev/einherjar/core v1.4.0 h1:YBRFzgeWNh8BCHueNYGo+V754BjzvJvq2CddJcc5ZjQ=
-code.nochebuena.dev/einherjar/core v1.1.0/go.mod h1:Ot2JbjsnZ33Ed5C9Ev1kSn2PW+F4dLz/LRwIUh+fYt0=
+code.nochebuena.dev/einherjar/core v1.4.0/go.mod h1:dILfAATF++TBeLOwUTQsYci+Ft7yK5ivt00iRYctfGk=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/gabriel-vasile/mimetype v1.4.12 h1:e9hWvmLYvtp846tLHam2o++qitpguFiYCKbn0w9jyqw=
+github.com/gabriel-vasile/mimetype v1.4.15 h1:05iP/CYtZ/w455R/KZM6rZ5ieAdh99UPtd+d3YzLmaI=
-github.com/gabriel-vasile/mimetype v1.4.12/go.mod h1:d+9Oxyo1wTzWdyVUPMmXFvp4F9tea18J8ufA774AB3s=
+github.com/gabriel-vasile/mimetype v1.4.15/go.mod h1:azpTcoLcDZRNgFou5j+APrqQx9HqVPWa6ijYQIIVswQ=
-github.com/go-chi/chi/v5 v5.2.1 h1:KOIHODQj58PmL80G2Eak4WdvUzjSJSm0vG72crDCqb8=
+github.com/go-chi/chi/v5 v5.3.1 h1:3j4HZLGZQ3JpMCrPJF/Jl3mYJfWLKBfNJ6quurUGCf8=
-github.com/go-chi/chi/v5 v5.2.1/go.mod h1:L2yAIGWB3H+phAw1NxKwWM+7eUH/lU8pOMm5hHcoops=
+github.com/go-chi/chi/v5 v5.3.1/go.mod h1:R+tYY2hNuVUUjxoPtqUdgBqevM9s9njzkTLutVsOCto=
 github.com/go-playground/assert/v2 v2.2.0 h1:JvknZsQTYeFEAhQwI4qEt9cyV5ONwRHC+lYKSsYSR8s=
 github.com/go-playground/assert/v2 v2.2.0/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
 github.com/go-playground/locales v0.14.1 h1:EWaQ/wswjilfKLTECiXz7Rh+3BjFhfDFKv/oXslEjJA=
 github.com/go-playground/locales v0.14.1/go.mod h1:hxrqLVvrK65+Rwrd5Fc6F2O76J/NuW9t0sjnWqG1slY=
 github.com/go-playground/universal-translator v0.18.1 h1:Bcnm0ZwsGyWbCzImXv+pAJnYK9S473LQFuzCbDbfSFY=
 github.com/go-playground/universal-translator v0.18.1/go.mod h1:xekY+UJKNuX9WP91TpwSH2VMlDf28Uj24BCp08ZFTUY=
-github.com/go-playground/validator/v10 v10.30.1 h1:f3zDSN/zOma+w6+1Wswgd9fLkdwy06ntQJp0BBvFG0w=
+github.com/go-playground/validator/v10 v10.30.3 h1:4MU6YkEwx7GbcPJOZxrtbu+QfF3pJLJuaYTeAH0DYy8=
-github.com/go-playground/validator/v10 v10.30.1/go.mod h1:oSuBIQzuJxL//3MelwSLD5hc2Tu889bF0Idm9Dg26cM=
+github.com/go-playground/validator/v10 v10.30.3/go.mod h1:4Axh7oCNGcoGkqLoE4YWt6n20mcEIsPRlB7vPk3lpyc=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/leodido/go-urn v1.4.0 h1:WT9HwE9SGECu3lg4d/dIA+jxlljEa1/ffXKmRjqdmIQ=
+github.com/leodido/go-urn v1.5.0 h1:pLqT2kq1zpHW/1D18QMjMpdtX7cekxqtJJjg5ANyWw0=
-github.com/leodido/go-urn v1.4.0/go.mod h1:bvxc+MVxLKB4z00jd1z+Dvzr47oO32F/QSNjSBOlFxI=
+github.com/leodido/go-urn v1.5.0/go.mod h1:9BORnCDhdPBJNDEX+w1bJisa8yOKYi116VeO96s4ifE=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
-golang.org/x/crypto v0.46.0 h1:cKRW/pmt1pKAfetfu+RCEvjvZkA9RimPbh7bhFjGVBU=
+golang.org/x/crypto v0.55.0 h1:+KWHjbgOaAQ66dh/YlkZKHlz9ZUlq61AFirAR9ntP8M=
-golang.org/x/crypto v0.46.0/go.mod h1:Evb/oLKmMraqjZ2iQTwDwvCtJkczlDuTmdJXoZVzqU0=
+golang.org/x/crypto v0.55.0/go.mod h1:uq0V9dE/fzQuJtbnL+2EhWOE63vo164FY8xqEnV9xis=
-golang.org/x/sys v0.39.0 h1:CvCKL8MeisomCi6qNZ+wbb0DN9E5AATixKsvNtMoMFk=
+golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
-golang.org/x/sys v0.39.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
-golang.org/x/text v0.32.0 h1:ZD01bjUt1FQ9WJ0ClOL5vxgxOI/sVCNgX1YtKwcY0mU=
+golang.org/x/text v0.41.0 h1:vz/seA0lnX87Othu2f/0L24RcgrXD9/YFTSuGjj3rH8=
-golang.org/x/text v0.32.0/go.mod h1:o/rUWzghvpD5TXrTIBuJU77MTaN0ljMWE47kxGJQ7jY=
+golang.org/x/text v0.41.0/go.mod h1:jvf1O8ajNzZqhSrQBPbutR/EB83Cc0CFrezNQIwbb5M=
-golang.org/x/time v0.11.0 h1:/bpjEDfN9tkoN/ryeYHnv5hcMlc8ncjMcM4XBk5NWV0=
+golang.org/x/time v0.15.0 h1:bbrp8t3bGUeFOx08pvsMYRTCVSMk89u4tKbNOZbp88U=
-golang.org/x/time v0.11.0/go.mod h1:CDIdPxbZBQxdj6cxyCIdrNogrJKMJ7pr37NYpMcMDSg=
+golang.org/x/time v0.15.0/go.mod h1:Y4YMaQmXwGQZoFaVFk4YpCt4FLQMYKZe9oeV/f4MSno=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

mw/cors.go

@@ -7,10 +7,29 @@ const (
 	allowedHeaders = "Content-Type, Authorization, X-Request-ID"
 )
 
-// CORS sets cross-origin resource sharing headers for the provided origins.
+// CORS sets cross-origin resource sharing headers for the provided origins
-// Returns 204 No Content for OPTIONS preflight requests.
+// (exact match; an empty slice is a no-op). Returns 204 No Content for OPTIONS
-// Pass the outermost origins first; an empty slice is a no-op.
+// preflight requests.
+//
+// It panics on "*": a wildcard matches no real Origin here, so passing it would
+// silently disable CORS. For allow-all use [CORSAllowAll] (development only). The
+// recommended wiring gates CORS by environment:
+//
+//	var corsMW func(http.Handler) http.Handler
+//	if strings.EqualFold(cfg.AppEnv, "local") {
+//	    corsMW = mw.CORSAllowAll()            // dev: any origin
+//	} else {
+//	    corsMW = mw.CORS(cfg.CORSOrigins)     // prod: explicit origins
+//	}
 func CORS(origins []string) func(http.Handler) http.Handler {
+	// "*" would be a silent no-op (exact-match only) — reject it loudly so a
+	// misconfigured service fails to boot instead of quietly blocking browsers.
+	for _, o := range origins {
+		if o == "*" {
+			panic(`mw.CORS: "*" is not a valid origin — list explicit origins, or use CORSAllowAll() for allow-all`)
+		}
+	}
+
 	originSet := make(map[string]struct{}, len(origins))
 	for _, o := range origins {
 		originSet[o] = struct{}{}
@@ -37,8 +56,12 @@ func CORS(origins []string) func(http.Handler) http.Handler {
 	}
 }
 
-// CORSAllowAll is a convenience wrapper that allows any origin.
+// CORSAllowAll allows any origin by reflecting the request Origin (it does not set
-// Use only in development — never in production.
+// Access-Control-Allow-Credentials). Development only — never in production.
+//
+// Use it for the local branch of the env-gated CORS convention; use [CORS] with
+// explicit origins everywhere else. Because [CORS] panics on "*", CORSAllowAll — not
+// a "*" in the origins list — is the way to allow all.
 func CORSAllowAll() func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

mw/doc.go

@@ -12,6 +12,21 @@
 //	    mw.CORS([]string{"https://example.com"}),
 //	)
 //
+// # Request IDs
+//
+// [RequestID] always generates a fresh ID. To continue a correlation ID a client
+// already sent — so a distributed trace survives this boundary — use [RequestIDFrom]
+// and read the ID off the request in your resolver. The framework does not read the
+// header or validate the value: what is acceptable is per-service (a typed audit
+// column rejects what an opaque log accepts), so that policy stays with the caller.
+//
+//	mw.RequestIDFrom(func(r *http.Request) string {
+//	    if id, err := uuid.Parse(r.Header.Get("X-Request-ID")); err == nil {
+//	        return id.String()   // continue the client's id
+//	    }
+//	    return uuid.NewString()  // otherwise mint one
+//	})
+//
 // # Rate limiting
 //
 //	// In-memory (default — no extra dependencies)

mw/requestid.go

@@ -6,17 +6,43 @@ import (
 	"code.nochebuena.dev/einherjar/core/logz"
 )
 
-// RequestID injects a unique request ID into the context (via [logz.WithRequestID])
+// RequestIDFrom injects a per-request ID into the context (via [logz.WithRequestID])
-// and sets the X-Request-ID response header.
+// and the X-Request-ID response header, using the ID that resolve returns for the
-// generator is called once per request — pass uuid.NewString or a custom function.
+// request.
-func RequestID(generator func() string) func(http.Handler) http.Handler {
+//
+// resolve receives the request so the application can decide the ID from it — most
+// importantly, to continue a correlation ID a client already sent, so a distributed
+// trace survives this boundary. The framework deliberately does not read a header,
+// choose a header name, or validate the value: acceptability is per-service. A
+// service that persists the ID in a typed column must reject what it cannot store
+// and mint its own; a service that only logs an opaque string need not care. Reading
+// the header here would accept, on a service's behalf, a value that service may be
+// unable to store — so resolution is the application's to own, and generation is
+// merely the fallback branch a resolver takes when there is no usable inbound ID.
+//
+// resolve is called exactly once per request and is expected to return a non-empty
+// ID. When it returns "", no ID is attached — the response header is omitted and the
+// context carries none — rather than propagating an empty value; supplying a resolver
+// that can resolve to "" (e.g. one with no generation fallback) is a caller error.
+func RequestIDFrom(resolve func(r *http.Request) string) func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			id := generator()
+			if id := resolve(r); id != "" {
-			ctx := logz.WithRequestID(r.Context(), id)
+				r = r.WithContext(logz.WithRequestID(r.Context(), id))
-			r = r.WithContext(ctx)
+				w.Header().Set("X-Request-ID", id)
-			w.Header().Set("X-Request-ID", id)
+			}
 			next.ServeHTTP(w, r)
 		})
 	}
 }
+
+// RequestID injects a freshly generated request ID into the context (via
+// [logz.WithRequestID]) and sets the X-Request-ID response header. generator is
+// called once per request — pass uuid.NewString or a custom function.
+//
+// It always generates and ignores any inbound X-Request-ID. To continue a
+// correlation ID the client supplied, use [RequestIDFrom] with a resolver that
+// reads and validates it.
+func RequestID(generator func() string) func(http.Handler) http.Handler {
+	return RequestIDFrom(func(*http.Request) string { return generator() })
+}

mw/requestid_test.go

@@ -0,0 +1,96 @@
+package mw
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"code.nochebuena.dev/einherjar/core/logz"
+)
+
+// A resolver that continues the client's X-Request-ID lands in both the context
+// and the response header.
+func TestRequestIDFrom_HonoursInbound(t *testing.T) {
+	const inbound = "client-supplied-123"
+
+	var ctxID string
+	h := RequestIDFrom(func(r *http.Request) string {
+		return r.Header.Get("X-Request-ID")
+	})(http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
+		ctxID = logz.GetRequestID(r.Context())
+	}))
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.Header.Set("X-Request-ID", inbound)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+
+	if ctxID != inbound {
+		t.Errorf("context request id = %q, want %q", ctxID, inbound)
+	}
+	if got := rec.Header().Get("X-Request-ID"); got != inbound {
+		t.Errorf("response header = %q, want %q", got, inbound)
+	}
+}
+
+// Deliberate regression: RequestID(gen) always generates and never honours an
+// inbound X-Request-ID. Callers that want to continue a client id use RequestIDFrom.
+func TestRequestID_AlwaysGenerates_IgnoresInbound(t *testing.T) {
+	const inbound = "client-supplied-123"
+	const generated = "generated-999"
+
+	var ctxID string
+	h := RequestID(func() string { return generated })(
+		http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
+			ctxID = logz.GetRequestID(r.Context())
+		}))
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.Header.Set("X-Request-ID", inbound)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+
+	if ctxID != generated {
+		t.Errorf("context request id = %q, want generated %q (inbound must be ignored)", ctxID, generated)
+	}
+	if got := rec.Header().Get("X-Request-ID"); got != generated {
+		t.Errorf("response header = %q, want %q", got, generated)
+	}
+}
+
+// The resolver runs exactly once per request.
+func TestRequestIDFrom_ResolverCalledOnce(t *testing.T) {
+	calls := 0
+	h := RequestIDFrom(func(*http.Request) string {
+		calls++
+		return "id"
+	})(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}))
+
+	h.ServeHTTP(httptest.NewRecorder(), httptest.NewRequest(http.MethodGet, "/", nil))
+
+	if calls != 1 {
+		t.Errorf("resolver called %d times, want 1", calls)
+	}
+}
+
+// An empty resolver result attaches nothing: no context id and no response header,
+// rather than a silently-empty value.
+func TestRequestIDFrom_EmptyResult_AttachesNothing(t *testing.T) {
+	var ctxID string
+	h := RequestIDFrom(func(*http.Request) string { return "" })(
+		http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
+			ctxID = logz.GetRequestID(r.Context())
+		}))
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.Header.Set("X-Request-ID", "should-be-ignored")
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+
+	if ctxID != "" {
+		t.Errorf("context request id = %q, want empty (nothing attached)", ctxID)
+	}
+	if vals := rec.Header().Values("X-Request-ID"); len(vals) != 0 {
+		t.Errorf("X-Request-ID header = %v on empty resolve; want absent", vals)
+	}
+}

server/config.go

@@ -11,6 +11,12 @@ type Config struct {
 	WriteTimeout    time.Duration `env:"EINHERJAR_SERVER_WRITE_TIMEOUT"    envDefault:"10s"`
 	IdleTimeout     time.Duration `env:"EINHERJAR_SERVER_IDLE_TIMEOUT"     envDefault:"120s"`
 	ShutdownTimeout time.Duration `env:"EINHERJAR_SERVER_SHUTDOWN_TIMEOUT" envDefault:"10s"`
+
+	// CORSOrigins is the allowed cross-origin list (comma-separated in the env var).
+	// web.New applies mw.CORS with it automatically; callers of server.New pass it to
+	// mw.CORS themselves. "*" is rejected by mw.CORS — use mw.CORSAllowAll for allow-all
+	// (development only).
+	CORSOrigins []string `env:"EINHERJAR_SERVER_CORS_ORIGINS" envSeparator:","`
 }
 
 const defaultShutdownTimeout = 10 * time.Second

server/doc.go

@@ -4,9 +4,22 @@
 // directly into [launcher.New] and exposes the full chi routing API.
 //
 // For the happy path use [web.New], which pre-wires the recommended middleware
-// stack. Use this package directly when you need explicit control over
+// stack (explicit-origin CORS included). Use this package directly when you need
-// middleware order, a custom request-ID generator, or any other deviation from
+// explicit control over middleware order, a custom request-ID generator, or
-// the defaults.
+// allow-all CORS in development.
+//
+// # CORS
+//
+// [Config.CORSOrigins] loads EINHERJAR_SERVER_CORS_ORIGINS. Gate allow-all by
+// environment — mw.CORS panics on "*", so allow-all is [mw.CORSAllowAll], never a
+// wildcard origin:
+//
+//	var corsMW func(http.Handler) http.Handler
+//	if strings.EqualFold(cfg.AppEnv, "local") {
+//	    corsMW = mw.CORSAllowAll()          // dev: any origin
+//	} else {
+//	    corsMW = mw.CORS(cfg.Server.CORSOrigins) // prod: explicit origins
+//	}
 //
 // # Basic usage
 //

web.go

@@ -10,21 +10,24 @@ import (
 	"code.nochebuena.dev/einherjar/web/server"
 )
 
-// Config aggregates configuration for the web module.
+// Config aggregates configuration for the web module. Server holds the HTTP server
-// Server holds HTTP server settings; all fields carry caarlos0/env struct tags.
+// settings, including the single source of truth for CORS: Server.CORSOrigins,
-// AllowedOrigins is programmatic-only — set it directly or via the env tag.
+// loaded from EINHERJAR_SERVER_CORS_ORIGINS. To override origins from code (without
+// the env var), set Server.CORSOrigins directly before calling New.
 type Config struct {
-	Server         server.Config
+	Server server.Config
-	AllowedOrigins []string `env:"EINHERJAR_SERVER_CORS_ORIGINS" envSeparator:","`
 }
 
 // New creates a [server.Server] with the recommended middleware stack pre-applied:
 //  1. Recover — catches panics, returns 500
 //  2. RequestID — injects UUID v7 request ID (falls back to v4)
 //  3. RequestLogger — logs method, path, status, latency
-//  4. CORS — applied only when cfg.AllowedOrigins is non-empty
+//  4. CORS — applied only when Server.CORSOrigins is non-empty (from
+//     EINHERJAR_SERVER_CORS_ORIGINS, or set in code before calling New)
 //
-// For full control over middleware composition use [server.New] directly.
+// web.New uses explicit origins only; it does NOT support allow-all. For
+// [mw.CORSAllowAll] (development) or any custom middleware order, use [server.New]
+// directly. When no origins are configured, CORS is off and a log line records it.
 func New(logger logging.Logger, cfg ...Config) server.Server {
 	var c Config
 	if len(cfg) > 0 {
@@ -36,8 +39,10 @@ func New(logger logging.Logger, cfg ...Config) server.Server {
 		mw.RequestID(newRequestID),
 		mw.RequestLogger(logger),
 	}
-	if len(c.AllowedOrigins) > 0 {
+	if len(c.Server.CORSOrigins) > 0 {
-		middleware = append(middleware, mw.CORS(c.AllowedOrigins))
+		middleware = append(middleware, mw.CORS(c.Server.CORSOrigins))
+	} else {
+		logger.Info("web.New: no CORS origins configured (EINHERJAR_SERVER_CORS_ORIGINS) — cross-origin browser requests will be blocked")
 	}
 
 	return server.New(logger, c.Server, server.WithMiddleware(middleware...))