fix: resolve lint errors and add traceparent docs

bartlomieju · claude · bartlomieju · commit dbfc15d56c54 · 2026-03-29T20:27:37.000+02:00
Move `as any` cast to a single line so the deno-lint-ignore directive
covers it, fixing ban-unused-ignore and no-explicit-any errors on CI.

Also document the new traceparent meta tag injection in the
OpenTelemetry docs page.

Co-Authored-By: Claude Opus 4.6 (1M context) &lt;noreply@anthropic.com&gt;
diff --git a/docs/latest/advanced/opentelemetry.md b/docs/latest/advanced/opentelemetry.md
@@ -127,3 +127,21 @@ deno task start
 
 Open `http://localhost:16686` to browse traces. You'll see each request broken
 down into its middleware, handler, and rendering spans.
+
+## Client-side trace correlation
+
+When an OpenTelemetry exporter is active, Fresh automatically injects a
+[W3C Trace Context](https://www.w3.org/TR/trace-context/) `<meta>` tag into the
+`<head>` of every rendered page:
+
+```html
+<head>
+  <meta name="traceparent" content="00-ab42124a3c573678d4d8b21ba52df3bf-d21f7bc17caa5aba-01">
+  <!-- ... -->
+</head>
+```
+
+This allows client-side OpenTelemetry instrumentation (such as
+[`@opentelemetry/instrumentation-document-load`](https://www.npmjs.com/package/@opentelemetry/instrumentation-document-load))
+to link browser performance traces back to the server-side span that rendered the
+page, giving you end-to-end visibility from server rendering through page load.
diff --git a/packages/fresh/src/runtime/server/preact_hooks.ts b/packages/fresh/src/runtime/server/preact_hooks.ts
@@ -290,13 +290,10 @@ options[OptionsType.DIFF] = (vnode) => {
             const spanCtx = activeSpan.spanContext();
             if (isSpanContextValid(spanCtx)) {
               const flags = (spanCtx.traceFlags & 1) ? "01" : "00";
-              items.push(
-                // deno-lint-ignore no-explicit-any
-                h("meta", {
-                  name: "traceparent",
-                  content: `00-${spanCtx.traceId}-${spanCtx.spanId}-${flags}`,
-                } as any),
-              );
+              const traceparent =
+                `00-${spanCtx.traceId}-${spanCtx.spanId}-${flags}`;
+              // deno-lint-ignore no-explicit-any
+              items.push(h("meta", { name: "traceparent", content: traceparent }) as any);
             }
           }
 
