fix(auth): login/registration forms redirect again under hash CSP

The htmx login/registration partials answered success with an inline
<script> that stashed the auth token and set window.location — refused
by hash-mode script-src (no 'unsafe-inline'), so the user saw "Login
successful! Redirecting..." and nothing else (reported from the home-
page login form; /login was equally broken). The same pattern lived in
collections.go (delete → redirect) and devices.go (token regen →
reload, whose script tag was also unclosed).

Replacement, per the AGENTS.md CSP rules:
- auth.go login/registration: the partial now carries data-auth-token +
  data-redirect (redirect is path-only — open-redirect hygiene — and
  escaped); web/src/auth_forms.ts (new, armed from main.ts on every
  page) listens for htmx:afterSwap, stashes the token, and navigates.
- collections.go delete: data-redirect, same listener.
- devices.go token regen: htmx's native HX-Refresh response header.
- The dead localStorage 'user'/'refreshToken' writes are dropped — no
  reader anywhere in web/src; only 'token' is load-bearing (19 modules).

Tripwire extension: internal/middleware/csp_go_sources_test.go scans
non-test Go sources for literal <script> tags and native on*= attributes
(hand-written files only — templ codegen is owned by the .templ scan),
verified to fire on a reintroduced probe. AGENTS.md CSP section notes
the Go-emitted-partial vector.

Verified live: home-page login form → /dashboard with token stashed and
dashboard loading clean; /register form → /dashboard; collections and
devices share the same mechanisms (data-redirect / HX-Refresh). Gates:
make test (9 pkgs incl. both tripwires), vitest 155, Playwright 20,
tsc/vp clean.

AGENTS.md

@@ -80,7 +80,11 @@ refuses, **silently at build/test time**, two authoring patterns:
   guard means recomputing the hash (the failing test prints it); adding
   a *second* inline script means hashing it too and extending
   `cspSanctionedInlineScripts` in `templates/csp_source_test.go`.
-  Everything else goes in a bundled `web/src` module.
+  Everything else goes in a bundled `web/src` module. This includes
+  partials emitted from Go handler strings — those use data attributes
+  + `web/src/auth_forms.ts` (post-swap redirect/stash) or htmx's
+  `HX-Redirect`/`HX-Refresh` headers; `internal/middleware`'s
+  Go-source scan is the tripwire for that vector.
 - **No native `on*=` handler attributes** (`onclick=`, `onerror=`,
   `onsubmit=`, `onchange=`, … — quote AND templ brace forms). Inline
   handlers never go through the hash path; hash-mode CSP refuses them

internal/handlers/auth.go

@@ -10,6 +10,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"html"
 	"html/template"
 	"math"
 	"net/http"
@@ -335,13 +336,9 @@ func (h *AuthHandler) Register(c *echo.Context) error {
 	}
 
 	if c.Request().Header.Get("HX-Request") == "true" {
-		html := fmt.Sprintf(`<div class="text-green-500">Registration successful! Redirecting...</div>
-<script>
-localStorage.setItem('token', '%s');
-localStorage.setItem('refreshToken', '%s');
-localStorage.setItem('user', JSON.stringify(%s));
-window.location.href = '/dashboard';
-</script>`, accessToken, refreshToken, fmt.Sprintf(`{"id":"%s","email":"%s","username":"%s"}`, uuid.UUID(user.ID.Bytes).String(), user.Email, user.Username))
+		// CSP: see the login handler — data attributes, not inline scripts.
+		html := fmt.Sprintf(`<div class="text-green-500" data-auth-token="%s" data-redirect="/dashboard">Registration successful! Redirecting...</div>`,
+			accessToken)
 		return c.HTML(http.StatusCreated, html)
 	}
 
@@ -481,17 +478,18 @@ func (h *AuthHandler) Login(c *echo.Context) error {
 	}
 
 	if c.Request().Header.Get("HX-Request") == "true" {
+		// CSP: hash-mode script-src refuses inline scripts, so the htmx
+		// partial carries data attributes instead; web/src/auth_forms.ts
+		// stashes the token and navigates on htmx:afterSwap. The redirect
+		// target is path-only (open-redirect hygiene) and the old
+		// 'user'/'refreshToken' localStorage writes are gone — nothing
+		// ever read them.
 		redirect := c.FormValue("redirect")
-		if redirect == "" {
+		if redirect == "" || !strings.HasPrefix(redirect, "/") {
 			redirect = "/dashboard"
 		}
-		html := fmt.Sprintf(`<div class="text-green-500">Login successful! Redirecting...</div>
-<script>
-localStorage.setItem('token', '%s');
-localStorage.setItem('refreshToken', '%s');
-localStorage.setItem('user', JSON.stringify(%s));
-window.location.href = '%s';
-</script>`, accessToken, refreshToken, fmt.Sprintf(`{"id":"%s","email":"%s","username":"%s","first_name":"%s","last_name":"%s"}`, uuid.UUID(user.ID.Bytes).String(), user.Email, user.Username, user.FirstName.String, user.LastName.String), redirect)
+		html := fmt.Sprintf(`<div class="text-green-500" data-auth-token="%s" data-redirect="%s">Login successful! Redirecting...</div>`,
+			accessToken, html.EscapeString(redirect))
 		return c.HTML(http.StatusOK, html)
 	}
 

internal/handlers/collections.go

@@ -496,7 +496,8 @@ func (h *CollectionHandler) DeleteCollection(c *echo.Context) error {
 	}
 
 	if c.Request().Header.Get("HX-Request") == "true" {
-		html := `<div class="text-green-500">Collection deleted! Redirecting...</div><script>window.location.href = '/collections';</script>`
+		// CSP: no inline scripts in partials — auth_forms.ts navigates.
+		html := `<div class="text-green-500" data-redirect="/collections">Collection deleted! Redirecting...</div>`
 		return c.HTML(http.StatusOK, html)
 	}
 

internal/handlers/devices.go

@@ -499,7 +499,10 @@ func (h *DeviceHandler) RegenerateDeviceToken(c *echo.Context) error {
 
 	// Handle HTMX requests - return HTML with page reload script
 	if c.Request().Header.Get("HX-Request") == "true" {
-		html := `<div class="text-green-500">Token regenerated! Reloading ... </div><script>window.location.reload();`
+		// CSP: no inline scripts in partials; HX-Refresh makes htmx
+		// reload the page natively (the old script tag was also unclosed).
+		c.Response().Header().Set("HX-Refresh", "true")
+		html := `<div class="text-green-500">Token regenerated! Reloading ... </div>`
 		return c.HTML(http.StatusOK, html)
 	}
 	return c.JSON(http.StatusOK, map[string]interface{}{

internal/middleware/csp_go_sources_test.go

@@ -0,0 +1,69 @@
+package middleware_test
+
+import (
+	"io/fs"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// Go-source CSP tripwire.
+//
+// The templ scan lives in templates/csp_source_test.go, but htmx partials
+// can also be emitted from Go handler strings — auth.go used to answer a
+// successful login with an inline <script>window.location…</script> that
+// hash-mode CSP silently refused. This test scans the non-test Go sources
+// for the same forbidden patterns: inline script tags and native on*=
+// handler attributes in emitted HTML. Partials that need to navigate or
+// stash state use data attributes + web/src/auth_forms.ts, or htmx's
+// HX-Redirect/HX-Refresh headers.
+
+var goScriptTagRe = regexp.MustCompile(`<script`)
+
+var goHandlerAttrRe = regexp.MustCompile(
+	`on(click|error|submit|load|change|input|focus|blur|mouseover|keydown|keyup)\s*=\s*"`)
+
+func TestGoSourcesAreCSPSafe(t *testing.T) {
+	root := "../.."
+	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			switch d.Name() {
+			case "node_modules", "static", ".git", "testdata", "docs":
+				return filepath.SkipDir
+			}
+			return nil
+		}
+		name := d.Name()
+		if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
+			return nil
+		}
+		// Generated templ codegen is out of scope: its source of truth is
+		// the .templ file (scanned by templates/csp_source_test.go), and
+		// the codegen legitimately emits external <script src=…> tags.
+		if strings.HasSuffix(name, "_templ.go") {
+			return nil
+		}
+		raw, err := os.ReadFile(path)
+		if err != nil {
+			return err
+		}
+		src := string(raw)
+		for _, m := range goScriptTagRe.FindAllStringIndex(src, -1) {
+			t.Errorf("%s:%d: literal <script> in Go source — hash-mode CSP refuses inline scripts in emitted partials; use data attributes + web/src/auth_forms.ts or HX-Redirect/HX-Refresh",
+				path, 1+strings.Count(src[:m[0]], "\n"))
+		}
+		for _, m := range goHandlerAttrRe.FindAllStringIndex(src, -1) {
+			t.Errorf("%s:%d: native on*= handler attribute in Go source — CSP hash-mode refuses it; use Alpine bindings or delegated listeners",
+				path, 1+strings.Count(src[:m[0]], "\n"))
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+}

internal/middleware/security_headers.go

@@ -24,8 +24,8 @@ func SecurityHeadersMiddleware() echo.MiddlewareFunc {
 			//
 			// The inline script allow-list: the theme flash guard is the
 			// ONLY inline script in the app, and its byte-stable content is
-			// hashed into script-src (sha256 of the bytes between
-			// <script> and </script> as rendered by
+			// hashed into script-src (sha256 of the bytes between the
+			// script tags as rendered by
 			// templates.ThemeFlashGuard()). Editing the guard requires
 			// recomputing the hash — enforced by
 			// internal/middleware/security_headers_test.go, which renders

web/src/auth_forms.ts

@@ -0,0 +1,27 @@
+// CSP-safe post-swap navigation for server-emitted status partials.
+//
+// The login/registration/collection-delete htmx flows used to answer with an
+// inline <script> that stashed the auth token and redirected. Hash-mode CSP
+// (no 'unsafe-inline') refuses those scripts, so the server now emits plain
+// data attributes instead and this module performs the navigation:
+//
+//   <div data-redirect="/dashboard" data-auth-token="…">Login successful!…</div>
+//
+// One delegated body listener covers every page (the main bundle loads
+// everywhere htmx does), so no per-page wiring. Devices' token regeneration
+// uses htmx's native HX-Refresh response header instead and needs nothing
+// here.
+//
+// Note: only the token is stashed. The old script also wrote localStorage
+// 'user'/'refreshToken', but nothing in web/src ever read them.
+
+export function armAuthFormRedirects() {
+  document.body.addEventListener("htmx:afterSwap", (event) => {
+    const detail = (event as CustomEvent).detail as { target?: HTMLElement } | undefined;
+    const el = detail?.target?.querySelector("[data-redirect]");
+    if (!el) return;
+    const token = el.getAttribute("data-auth-token");
+    if (token) localStorage.setItem("token", token);
+    window.location.href = el.getAttribute("data-redirect") ?? "/";
+  });
+}

web/src/main.ts

@@ -18,6 +18,7 @@ import "./docs";
 import "./header";
 import "./index";
 import "./image_fallback";
+import { armAuthFormRedirects } from "./auth_forms";
 import "./library-switcher";
 import "./linking";
 import "./login";
@@ -38,4 +39,5 @@ import "./unlinked_books";
 import "./websocket";
 import "./woodPanelingInit";
 
+armAuthFormRedirects();
 Alpine.start();