fix(logging): redact http.path + http.route in WideEventBuilder.setHttp

Closes the WITHINGS_WEBHOOK_SECRET leak (sec-C1): the api-handler
seeds http.path and http.route from url.pathname, which carries the
shared secret for /api/withings/webhook/<secret> requests. Routing
both fields through redactSecrets() at setHttp() time keeps the
secret out of stdout, the in-memory ring buffer, and Loki egress.

src/lib/logging/__tests__/event-builder.test.ts

@@ -0,0 +1,112 @@
+import { describe, expect, it } from "vitest";
+import { WideEventBuilder } from "../event-builder";
+
+describe("WideEventBuilder.setHttp", () => {
+  it("stores plain http metadata as-is", () => {
+    const evt = new WideEventBuilder("http");
+    evt.setHttp({
+      method: "GET",
+      path: "/api/health",
+      route: "/api/health",
+      status: 200,
+    });
+    const json = evt.toJSON();
+    expect(json.http).toMatchObject({
+      method: "GET",
+      path: "/api/health",
+      route: "/api/health",
+      status: 200,
+    });
+  });
+
+  // Fix-J (v1.4.25 W21, sec-C1): WITHINGS_WEBHOOK_SECRET lands in
+  // http.path on every request without this scrub. Verify the redaction
+  // is applied at setHttp time so the secret never reaches stdout, the
+  // in-memory ring buffer, or Loki.
+  it("redacts Withings webhook secret from http.path and http.route", () => {
+    const evt = new WideEventBuilder("http");
+    evt.setHttp({
+      method: "POST",
+      path: "/api/withings/webhook/test-secret",
+      route: "/api/withings/webhook/test-secret",
+      status: 200,
+    });
+    const http = evt.toJSON().http;
+    expect(http?.path).toBe("/api/withings/webhook/[REDACTED]");
+    expect(http?.route).toBe("/api/withings/webhook/[REDACTED]");
+  });
+
+  it("preserves trailing path segments after the redacted secret", () => {
+    const evt = new WideEventBuilder("http");
+    evt.setHttp({
+      method: "GET",
+      path: "/api/withings/webhook/sup3r-secr3t/verify",
+      route: "/api/withings/webhook/[token]/verify",
+      status: 200,
+    });
+    const http = evt.toJSON().http;
+    expect(http?.path).toBe("/api/withings/webhook/[REDACTED]/verify");
+    // The Next.js route template `[token]` does not match the
+    // path-segment rule's `<segment>` shape boundary (the brackets are
+    // treated as a regular segment), so it is still redacted; either
+    // shape is acceptable since the goal is to never leak the secret.
+    expect(http?.route).toBe("/api/withings/webhook/[REDACTED]/verify");
+  });
+
+  it("does not over-redact unrelated paths", () => {
+    const evt = new WideEventBuilder("http");
+    evt.setHttp({
+      method: "GET",
+      path: "/api/measurements/123",
+      route: "/api/measurements/[id]",
+      status: 200,
+    });
+    const http = evt.toJSON().http;
+    expect(http?.path).toBe("/api/measurements/123");
+    expect(http?.route).toBe("/api/measurements/[id]");
+  });
+
+  it("still scrubs query-string secrets via the existing rule", () => {
+    const evt = new WideEventBuilder("http");
+    evt.setHttp({
+      method: "POST",
+      path: "/api/withings/webhook?secret=abc123",
+      route: "/api/withings/webhook",
+      status: 200,
+    });
+    const http = evt.toJSON().http;
+    expect(http?.path).toBe("/api/withings/webhook?secret=[REDACTED]");
+    expect(http?.route).toBe("/api/withings/webhook");
+  });
+
+  it("preserves other http fields verbatim", () => {
+    const evt = new WideEventBuilder("http");
+    evt.setHttp({
+      method: "POST",
+      path: "/api/withings/webhook/leak",
+      route: "/api/withings/webhook/leak",
+      status: 200,
+      user_agent: "WithingsClient/1.0",
+      ip: "10.0.0.1",
+      content_length: 42,
+      response_size: 17,
+    });
+    const http = evt.toJSON().http;
+    expect(http).toMatchObject({
+      method: "POST",
+      path: "/api/withings/webhook/[REDACTED]",
+      route: "/api/withings/webhook/[REDACTED]",
+      status: 200,
+      user_agent: "WithingsClient/1.0",
+      ip: "10.0.0.1",
+      content_length: 42,
+      response_size: 17,
+    });
+  });
+
+  it("handles an undefined http payload without throwing", () => {
+    const evt = new WideEventBuilder("http");
+    evt.setHttp(undefined);
+    expect(evt.toJSON().http).toBeUndefined();
+  });
+});

src/lib/logging/event-builder.ts

@@ -38,7 +38,20 @@ export class WideEventBuilder {
   }
 
   setHttp(http: WideEvent["http"]): this {
-    this.event.http = http;
+    if (http) {
+      // Fix-J (v1.4.25 W21): the Withings webhook ships its shared
+      // secret as a path segment, so `path` and `route` carry the
+      // secret unless we scrub on the way in. `redactSecrets` is the
+      // single egress-redaction surface (see redact.ts for the rules
+      // and the PATH_SECRET_PATHS registry).
+      this.event.http = {
+        ...http,
+        path: redactSecrets(http.path),
+        route: redactSecrets(http.route),
+      };
+    } else {
+      this.event.http = http;
+    }
     return this;
   }