diff --git a/auditor/checks/kimi_architect.ts b/auditor/checks/kimi_architect.ts
index 65bd600..fc834ec 100644
--- a/auditor/checks/kimi_architect.ts
+++ b/auditor/checks/kimi_architect.ts
@@ -27,7 +27,7 @@
 // Off by default: caller checks LH_AUDITOR_KIMI=1 before invoking.
 
 import { readFile, writeFile, mkdir, appendFile, stat } from "node:fs/promises";
-import { existsSync, readFileSync } from "node:fs";
+import { existsSync } from "node:fs";
 import { join, resolve } from "node:path";
 import type { Finding, CheckKind } from "../types.ts";
 
@@ -265,31 +265,36 @@ function parseFindings(content: string): Finding[] {
 // is appended into the evidence array so the reader can see which
 // citations were verified.
 async function computeGrounding(findings: Finding[]): Promise<{ total: number; verified: number; rate: number }> {
-  let verified = 0;
-  for (const f of findings) {
+  // readFile (async) instead of readFileSync — caught 2026-04-27 by
+  // Kimi's self-audit. Sync I/O in an async fn blocks the event loop
+  // for every cited file; doesn't matter at 10 findings, would matter
+  // at 100+.
+  const checks = await Promise.all(findings.map(async (f) => {
     const cite = f.evidence[0] ?? "";
     const m = /^(\S+?):(\d+)/.exec(cite);
-    if (!m) continue;
+    if (!m) return false;
     const [, relpath, lineStr] = m;
     const line = Number(lineStr);
-    if (!line || !relpath) continue;
+    if (!line || !relpath) return false;
     const abs = relpath.startsWith("/") ? relpath : resolve(REPO_ROOT, relpath);
     if (!existsSync(abs)) {
       f.evidence.push("[grounding: file not found]");
-      continue;
+      return false;
     }
     try {
-      const lines = readFileSync(abs, "utf8").split("\n");
+      const lines = (await readFile(abs, "utf8")).split("\n");
       if (line < 1 || line > lines.length) {
         f.evidence.push(`[grounding: line ${line} > EOF (${lines.length})]`);
-        continue;
+        return false;
       }
       f.evidence.push(`[grounding: verified at ${relpath}:${line}]`);
-      verified++;
+      return true;
     } catch (e) {
       f.evidence.push(`[grounding: read failed: ${(e as Error).message.slice(0, 80)}]`);
+      return false;
     }
-  }
+  }));
+  const verified = checks.filter(Boolean).length;
   const total = findings.length;
   return { total, verified, rate: total === 0 ? 0 : verified / total };
 }
diff --git a/crates/gateway/src/v1/kimi.rs b/crates/gateway/src/v1/kimi.rs
index ee0cf92..9ff2b7e 100644
--- a/crates/gateway/src/v1/kimi.rs
+++ b/crates/gateway/src/v1/kimi.rs
@@ -64,11 +64,17 @@ pub async fn chat(
     // upstream API sees the bare model id (e.g. "kimi-for-coding").
     let model = req.model.strip_prefix("kimi/").unwrap_or(&req.model).to_string();
 
+    // Flatten content to a plain String. api.kimi.com is text-only on
+    // the coding endpoint; the OpenAI multimodal array shape
+    // ([{type:"text",text:"..."},{type:"image_url",...}]) returns 400.
+    // Message::text() concats text-parts and drops non-text. Caught
+    // 2026-04-27 by Kimi's self-audit (kimi.rs:137 — content as raw
+    // serde_json::Value risked upstream rejection).
     let body = KimiChatBody {
         model: model.clone(),
         messages: req.messages.iter().map(|m| KimiMessage {
             role: m.role.clone(),
-            content: m.content.clone(),
+            content: serde_json::Value::String(m.text()),
         }).collect(),
         max_tokens: req.max_tokens.unwrap_or(800),
         temperature: req.temperature.unwrap_or(0.3),