Drop 'unsafe-inline' from the Content-Security-Policy (closes #530)

The delete prompts on the webhook page were inline onsubmit handlers.
Each delete form now carries its question in a data-confirm attribute,
which one submit listener in static/js/app.js asks. The three style
attributes became Tailwind classes, with tailwind.css regenerated, and
the x-cloak rule moved to style.css. The policy now sends
script-src 'self' and style-src 'self'.

The browser test now answers a target's delete prompt no and then yes,
and loads the webhook list, settings and profile pages under the
policy. The README states the policy as sent.

Model: opus-5-5

internal/handlers/delivery_result_view_test.go

@@ -158,8 +158,7 @@ func TestHandleSourceLogs_RendersFailedAttempt(t *testing.T) {
 // TestHandleSourceLogs_EscapesResponseBody proves the
 // response body is treated as the untrusted remote content it
 // is. The remote chooses these bytes and the page is rendered
-// inside the operator's authenticated origin, where the
-// application's own CSP allows inline script from 'self'.
+// inside the operator's authenticated origin.
 func TestHandleSourceLogs_EscapesResponseBody(t *testing.T) {
 	t.Parallel()
 

internal/handlers/event_body.go

@@ -35,11 +35,10 @@ const eventBodyQuery = "SELECT cast(body as blob) " +
 // response is deliberately not renderable. Content-Disposition
 // makes the browser download rather than display it, and the
 // octet-stream type plus nosniff stop it being interpreted as
-// HTML or script. Without those a stored payload would execute
-// as the logged-in operator. The application's CSP does not
-// help here: script-src allows 'unsafe-inline' from 'self', so
-// a document served from this origin could run its own inline
-// script.
+// HTML or script. Without those a stored payload would be shown
+// as a page of the operator's own origin. The application's CSP
+// is a second defence behind them: it allows no inline script,
+// so such a page could not run script of its own.
 func (h *Handlers) HandleEventBodyDownload() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		webhook, ok := h.ownedWebhook(w, r)

internal/handlers/event_detail_test.go

@@ -84,7 +84,7 @@ func TestHandleEventDetail_ShowsEventWholeWithDeliveries(t *testing.T) {
 	assert.Contains(t, page, strconv.Itoa(len(body))+" bytes")
 	assert.Contains(t, page, "{\n  "pad": "xxx")
 	assert.Contains(t, page, ""tail": ""+sentinel+""\n}")
-	assert.Contains(t, page, `style="max-height: 32rem; overflow-y: auto"`)
+	assert.Contains(t, page, `break-all max-h-[32rem] overflow-y-auto"`)
 	assert.NotContains(t, page, "Showing the first")
 	assert.Contains(t, page, target.Name)
 	assert.Contains(t, page, ">failed</span>")

internal/handlers/source_detail_test.go

@@ -273,7 +273,7 @@ func TestHandleSourceDetail_FitsWideAndNarrowWindows(t *testing.T) {
 
 	assert.Contains(
 		t, body,
-		`<div class="mx-auto px-6 py-8" style="max-width: 108rem"`,
+		`<div class="max-w-[108rem] mx-auto px-6 py-8">`,
 	)
 	assert.Contains(
 		t, body,
@@ -286,8 +286,8 @@ func TestHandleSourceDetail_FitsWideAndNarrowWindows(t *testing.T) {
 // target and says what deleting it loses, that the webhook's gives its
 // number of stored events (5 received, 2 removed by retention, so 3,
 // the statistics pane's "Within retention" figure), and that an
-// entrypoint with no description is named by its URL. The template
-// writes the slashes after http: as \/, which the browser reads as /.
+// entrypoint with no description is named by its URL. Each prompt is
+// its form's data-confirm attribute, where &#10; is a line break.
 func TestHandleSourceDetail_DeletePromptsNameWhatIsLost(t *testing.T) {
 	t.Parallel()
 
@@ -325,29 +325,28 @@ func TestHandleSourceDetail_DeletePromptsNameWhatIsLost(t *testing.T) {
 	body := renderSourceDetailPage(t, h, sess, wh.ID)
 
 	assert.Contains(t, body,
-		`Delete webhook &quot;delete-me&quot;?\n\n`+
+		`data-confirm="Delete webhook &quot;delete-me&quot;?&#10;&#10;`+
 			`This deletes its stored events (3) and their deliveries. `+
-			`Any archive files it wrote are kept.`)
+			`Any archive files it wrote are kept."`)
 	assert.Contains(t, body,
-		`Delete entrypoint &quot;Stripe&quot;?\n\n`+
+		`data-confirm="Delete entrypoint &quot;Stripe&quot;?&#10;&#10;`+
 			`Senders using its URL get an error from now on, `+
-			`and the URL cannot be restored.`)
+			`and the URL cannot be restored."`)
 	assert.Contains(t, body,
-		`Delete entrypoint &quot;http:\/\/example.com/h/`+
-			unnamed.Path+`&quot;?`)
+		`data-confirm="Delete entrypoint &quot;http://example.com/h/`+
+			unnamed.Path+`&quot;?&#10;&#10;`)
 	assert.Contains(t, body,
-		`Delete target &quot;t-log&quot;?\n\n`+
+		`data-confirm="Delete target &quot;t-log&quot;?&#10;&#10;`+
 			`Nothing more is delivered to it. `+
-			`Its past deliveries stay in the event log.`)
+			`Its past deliveries stay in the event log."`)
 }
 
 // TestHandleSourceDetail_DeletePromptKeepsQuotesInName checks that a
 // webhook name with quotes, a backslash, a closing script tag and a
-// newline reaches its delete prompt escaped for the script, which the
-// browser reads back as the name typed: each quote and angle bracket
-// as a \u escape, the slash as \/, the newline as \n and the backslash
-// doubled. An unescaped newline would break the prompt's script, and
-// the form would then submit without asking.
+// newline reaches its delete prompt escaped for the attribute, which
+// the browser reads back as the name typed: each quote and angle
+// bracket as a character reference, the rest as typed. An unescaped
+// double quote would end the attribute and cut the prompt short.
 func TestHandleSourceDetail_DeletePromptKeepsQuotesInName(t *testing.T) {
 	t.Parallel()
 
@@ -373,6 +372,6 @@ func TestHandleSourceDetail_DeletePromptKeepsQuotesInName(t *testing.T) {
 	body := renderSourceDetailPage(t, h, sess, wh.ID)
 
 	assert.Contains(t, body,
-		"Delete webhook &quot;Bob\\u0027s \\u0022best\\u0022 \\\\ hook"+
-			"\\u003c\\/script\\u003e\\nline two&quot;?")
+		"Delete webhook &quot;Bob&#39;s &#34;best&#34; \\ hook"+
+			"&lt;/script&gt;\nline two&quot;?")
 }