fix: harden evidence URI validation

backend/src/workspaces/schema.ts

@@ -276,6 +276,7 @@ function isSafeEvidencePattern(value: string): boolean {
 }
 
 function parsePublicHttpUri(value: string): URL | undefined {
+  if (value.trim() !== value || /[\u0000-\u001f\u007f\\]/u.test(value)) return undefined;
   try {
     const parsed = new URL(value);
     if (
@@ -297,14 +298,20 @@ function canonicalPublicHttpUri(value: string): string | undefined {
 }
 
 function isSafeS3Uri(value: string): boolean {
+  if (value.trim() !== value || /[\u0000-\u001f\u007f\\]/u.test(value)) return false;
   try {
     const parsed = new URL(value);
+    const bucket = parsed.hostname;
+    const validBucket = /^(?=.{3,63}$)(?!-)(?!.*\.\.)(?!.*\.-)(?!.*-\.)[a-z0-9](?:[a-z0-9.-]*[a-z0-9])?$/.test(bucket)
+      && !/^\d{1,3}(?:\.\d{1,3}){3}$/.test(bucket);
     return parsed.protocol === "s3:"
-      && parsed.hostname.length > 0
+      && validBucket
+      && parsed.port === ""
       && parsed.username === ""
       && parsed.password === ""
       && parsed.search === ""
-      && parsed.hash === "";
+      && parsed.hash === ""
+      && parsed.href === value;
   } catch {
     return false;
   }
@@ -380,7 +387,8 @@ const s3EvidenceSourceSchema = z.object({
       message: "custom S3 endpoints must be explicitly trusted",
     });
   }
-  if (source.endpoint_url.startsWith("http:") && !source.allow_insecure_endpoint) {
+  const endpoint = parsePublicHttpUri(source.endpoint_url);
+  if (endpoint?.protocol === "http:" && !source.allow_insecure_endpoint) {
     context.addIssue({
       code: "custom", path: ["allow_insecure_endpoint"],
       message: "HTTP S3 endpoints require an explicit insecure opt-in",