diff --git a/tachyon/files/usr/lib/diagnostics/rag.uc b/tachyon/files/usr/lib/diagnostics/rag.uc
index 5980d2d1..b1acb6a2 100644
--- a/tachyon/files/usr/lib/diagnostics/rag.uc
+++ b/tachyon/files/usr/lib/diagnostics/rag.uc
@@ -1,6 +1,7 @@
 let fs = require("fs");
 let common = require("core.common");
 
+let as_string = common.as_string;
 let command_from_args = common.command_from_args;
 let rag_index = null;
 let rag_embed_cache = null;
@@ -156,6 +157,12 @@ function call_embedding_api(api_url, api_key, model, texts) {
     return null;
 }
 
+function sqrt_val(x) {
+    if (x <= 0)
+        return 0.0;
+    return x ** 0.5;
+}
+
 function cosine_similarity(a, b) {
     let len = length(a);
     if (len == 0 || length(b) != len)
@@ -166,7 +173,7 @@ function cosine_similarity(a, b) {
         norm_a += a[i] * a[i];
         norm_b += b[i] * b[i];
     }
-    let denom = sqrt(norm_a) * sqrt(norm_b);
+    let denom = sqrt_val(norm_a) * sqrt_val(norm_b);
     if (denom == 0)
         return 0;
     return dot / denom;
@@ -223,12 +230,12 @@ function search(query_embedding, index, top_k) {
         if (length(chunk.embedding) == 0)
             continue;
         let score = cosine_similarity(query_embedding, chunk.embedding);
-        push({ chunk: chunk, score: score }, scored);
+        push(scored, { chunk: chunk, score: score });
     }
     sort(scored, function(a, b) { return b.score - a.score; });
     let limit = top_k || 3;
     if (length(scored) > limit)
-        scored = scored.slice(0, limit);
+        scored = slice(scored, 0, limit);
     return scored;
 }
 
@@ -250,8 +257,8 @@ function retrieve(query, provider, api_key, custom_url, model_override, top_k) {
         let r = results[i];
         if (r.score < 0.3)
             continue;
-        push(sprintf("[Source: %s — %s] (relevance: %.0f%%)\n%s",
-            r.chunk.file, r.chunk.heading, r.score * 100, r.chunk.text), parts);
+        push(parts, sprintf("[Source: %s — %s] (relevance: %.0f%%)\n%s",
+            r.chunk.file, r.chunk.heading, r.score * 100, r.chunk.text));
     }
     return join("\n\n---\n\n", parts);
 }
@@ -278,5 +285,7 @@ return {
     retrieve: retrieve,
     invalidate_cache: invalidate_cache,
     status: status,
-    load_raw_index: load_raw_index
+    load_raw_index: load_raw_index,
+    get_embedding_model: get_embedding_model,
+    search: search
 };
diff --git a/tachyon/files/usr/lib/singbox/rulesets.uc b/tachyon/files/usr/lib/singbox/rulesets.uc
index 36831768..5f50f5ed 100644
--- a/tachyon/files/usr/lib/singbox/rulesets.uc
+++ b/tachyon/files/usr/lib/singbox/rulesets.uc
@@ -128,6 +128,7 @@ function remote_format(reference) {
 
 function module_exports() {
     return {
+        COMMUNITY_SERVICES,
         is_community,
         community_url,
         hash12,
diff --git a/tests/rag_embeddings.sh b/tests/rag_embeddings.sh
index bc611c00..c8e1cf32 100644
--- a/tests/rag_embeddings.sh
+++ b/tests/rag_embeddings.sh
@@ -56,4 +56,26 @@ print((length(out) == 2 && length(out[0]) == 2 && out[1][1] == 4) ? "OK" : "BAD"
 [ "$push_check" = "OK" ] ||
   fail "ucode push(array, value) did not behave as expected (saw '$push_check')"
 
+# 6. Runtime verification of rag.uc functions (as_string, get_embedding_model, search, sqrt_val, slice)
+runtime_check="$(ucode -L "$TACHYON_LIB" -e '
+let rag = require("diagnostics.rag");
+assert(rag.get_embedding_model("OpenAI") == "text-embedding-3-small", "OpenAI");
+assert(rag.get_embedding_model("DEEPSEEK") == "deepseek-embedding", "DeepSeek");
+assert(rag.get_embedding_model(null, null) == "text-embedding-3-small", "null");
+
+let idx = {
+    chunks: [
+        { file: "f1.md", heading: "H1", text: "T1", embedding: [1.0, 0.0] },
+        { file: "f2.md", heading: "H2", text: "T2", embedding: [0.9, 0.1] },
+        { file: "f3.md", heading: "H3", text: "T3", embedding: [0.8, 0.2] }
+    ]
+};
+let res = rag.search([1.0, 0.0], idx, 2);
+assert(length(res) == 2, "limit 2");
+assert(res[0].chunk.file == "f1.md", "best match");
+print("OK");
+' 2>&1 || echo "FAIL")"
+[ "$runtime_check" = "OK" ] ||
+  fail "rag.uc runtime execution failed (saw '$runtime_check')"
+
 printf 'rag embeddings checks passed\n'
diff --git a/tests/singbox_rulesets.sh b/tests/singbox_rulesets.sh
index 95c8f91a..454d76c9 100644
--- a/tests/singbox_rulesets.sh
+++ b/tests/singbox_rulesets.sh
@@ -46,5 +46,7 @@ assert_eq binary \
   "unknown remote ruleset format"
 
 ucode -L "$TACHYON_LIB" -e 'let rulesets = require("singbox.rulesets"); if (rulesets.kind_from_reference_hint("geoip") != "subnets") exit(1);'
+ucode -L "$TACHYON_LIB" -e 'let rulesets = require("singbox.rulesets"); if (type(rulesets.COMMUNITY_SERVICES) != "object" || !rulesets.COMMUNITY_SERVICES.discord) exit(1);'
 
 printf 'singbox rulesets checks passed\n'
+