diff --git a/src/shared/config.ts b/src/shared/config.ts
index 7073f58..fde4fb0 100644
--- a/src/shared/config.ts
+++ b/src/shared/config.ts
@@ -29,9 +29,11 @@ export function replaceVariables(
       // Check if this pattern actually exists in the string
       if (result.match(pattern)) {
         if (Array.isArray(replacement)) {
+          // Log the key only — never the value. user_config options can be
+          // sensitive (API keys, passwords), so the substituted value and the
+          // replacement array must not be written to the console.
           console.warn(
-            `Cannot replace ${key} with array value in string context: "${value}"`,
-            { key, replacement },
+            `Cannot replace "${key}" with an array value in string context`,
           );
         } else {
           result = result.replace(pattern, replacement);
diff --git a/src/shared/manifestVersionResolve.ts b/src/shared/manifestVersionResolve.ts
index 5bc6381..55f05a2 100644
--- a/src/shared/manifestVersionResolve.ts
+++ b/src/shared/manifestVersionResolve.ts
@@ -1,24 +1,31 @@
 import { MANIFEST_SCHEMAS } from "./constants.js";
 
 export function getManifestVersionFromRawData(manifestData: unknown) {
-  let manifestVersion: keyof typeof MANIFEST_SCHEMAS | null = null;
+  if (typeof manifestData !== "object" || !manifestData) {
+    return null;
+  }
+
+  // manifest_version is authoritative when present. If it is present but
+  // unsupported, do NOT silently fall back to the deprecated dxt_version — the
+  // manifest has declared its version, so an unsupported value is a resolution
+  // failure (null), not a reason to resolve via the deprecated field.
   if (
-    typeof manifestData === "object" &&
-    manifestData &&
     "manifest_version" in manifestData &&
-    typeof manifestData.manifest_version === "string" &&
-    Object.keys(MANIFEST_SCHEMAS).includes(manifestData.manifest_version)
+    typeof manifestData.manifest_version === "string"
   ) {
-    manifestVersion =
-      manifestData.manifest_version as keyof typeof MANIFEST_SCHEMAS;
-  } else if (
-    typeof manifestData === "object" &&
-    manifestData &&
+    return Object.keys(MANIFEST_SCHEMAS).includes(manifestData.manifest_version)
+      ? (manifestData.manifest_version as keyof typeof MANIFEST_SCHEMAS)
+      : null;
+  }
+
+  // Fall back to the deprecated dxt_version only when manifest_version is absent.
+  if (
     "dxt_version" in manifestData &&
     typeof manifestData.dxt_version === "string" &&
     Object.keys(MANIFEST_SCHEMAS).includes(manifestData.dxt_version)
   ) {
-    manifestVersion = manifestData.dxt_version as keyof typeof MANIFEST_SCHEMAS;
+    return manifestData.dxt_version as keyof typeof MANIFEST_SCHEMAS;
   }
-  return manifestVersion;
+
+  return null;
 }
diff --git a/test/config.test.ts b/test/config.test.ts
index 7e29f69..1f856fc 100644
--- a/test/config.test.ts
+++ b/test/config.test.ts
@@ -29,6 +29,28 @@ describe("replaceVariables", () => {
     consoleWarnSpy.mockRestore();
   });
 
+  it("should not log the array value when warning (no secret leakage)", () => {
+    const consoleWarnSpy = jest.spyOn(console, "warn").mockImplementation();
+    replaceVariables("token=${user_config.api_keys}", {
+      "user_config.api_keys": ["super-secret-1", "super-secret-2"],
+    });
+    expect(consoleWarnSpy).toHaveBeenCalled();
+    // The warning must reference the key but never the sensitive values.
+    // Serialize each argument (including objects) so a value logged inside an
+    // object — e.g. console.warn(msg, { replacement }) — is also inspected.
+    const logged = consoleWarnSpy.mock.calls
+      .map((call) =>
+        call
+          .map((arg) => (typeof arg === "string" ? arg : JSON.stringify(arg)))
+          .join(" "),
+      )
+      .join(" ");
+    expect(logged).toContain("user_config.api_keys");
+    expect(logged).not.toContain("super-secret-1");
+    expect(logged).not.toContain("super-secret-2");
+    consoleWarnSpy.mockRestore();
+  });
+
   it("should replace variables in objects", () => {
     const result = replaceVariables(
       { message: "Hello ${name}!" },
diff --git a/test/manifestVersionResolve.test.ts b/test/manifestVersionResolve.test.ts
new file mode 100644
index 0000000..6a2a896
--- /dev/null
+++ b/test/manifestVersionResolve.test.ts
@@ -0,0 +1,29 @@
+import { getManifestVersionFromRawData } from "../src/shared/manifestVersionResolve";
+
+describe("getManifestVersionFromRawData", () => {
+  it("resolves a supported manifest_version", () => {
+    expect(getManifestVersionFromRawData({ manifest_version: "0.3" })).toBe(
+      "0.3",
+    );
+  });
+
+  it("falls back to dxt_version when manifest_version is absent", () => {
+    expect(getManifestVersionFromRawData({ dxt_version: "0.3" })).toBe("0.3");
+  });
+
+  it("does not fall back to dxt_version when manifest_version is present but unsupported", () => {
+    // manifest_version is authoritative; an unsupported value must not silently
+    // resolve via the deprecated dxt_version field.
+    expect(
+      getManifestVersionFromRawData({
+        manifest_version: "99.0",
+        dxt_version: "0.3",
+      }),
+    ).toBeNull();
+  });
+
+  it("returns null for non-object input", () => {
+    expect(getManifestVersionFromRawData(null)).toBeNull();
+    expect(getManifestVersionFromRawData("0.3")).toBeNull();
+  });
+});