diff --git a/docs/mcp/reference.md b/docs/mcp/reference.md
index ddbdb0b2..653a8468 100644
--- a/docs/mcp/reference.md
+++ b/docs/mcp/reference.md
@@ -139,7 +139,7 @@ Set `MEMWAL_MCP_DEBUG=1` to enable verbose stderr logging.
 
 ## Default namespace
 
-Set a default memory namespace once in your client config instead of having the agent pass `namespace` on every call. The package injects it into `memwal_remember`, `memwal_recall`, `memwal_analyze`, and `memwal_restore` calls that don't already carry one.
+Set a default memory namespace once in your client config instead of having the agent pass `namespace` on every call. The package injects it into `memwal_remember`, `memwal_remember_bulk`, `memwal_recall`, `memwal_analyze`, and `memwal_restore` calls that don't already carry one.
 
 Precedence, highest first:
 
diff --git a/packages/mcp/README.md b/packages/mcp/README.md
index eabdc0ef..4a21e858 100644
--- a/packages/mcp/README.md
+++ b/packages/mcp/README.md
@@ -58,9 +58,9 @@ Enable verbose stderr logging with `MEMWAL_MCP_DEBUG=1`.
 ## Default Namespace
 
 By default the MCP tool schemas expose an optional `namespace` argument and the
-agent has to pass it on every `memwal_remember` / `memwal_recall` /
-`memwal_analyze` call (and `memwal_restore` requires it). Set a default once in
-your client config instead:
+agent has to pass it on every `memwal_remember` / `memwal_remember_bulk` /
+`memwal_recall` / `memwal_analyze` call (and `memwal_restore` requires it). Set
+a default once in your client config instead:
 
 ```json
 {
diff --git a/packages/mcp/src/bridge.ts b/packages/mcp/src/bridge.ts
index 280a6f73..06fe72e3 100644
--- a/packages/mcp/src/bridge.ts
+++ b/packages/mcp/src/bridge.ts
@@ -38,10 +38,10 @@ export interface BridgeConfig {
 }
 
 /** Memory tools that take a `namespace` argument. `memwal_remember`,
- * `memwal_recall`, and `memwal_analyze` treat it as optional; `memwal_restore`
- * requires it (its upstream schema still lists `namespace` as required, so
- * agents normally pass one — but a configured default is filled in if the
- * agent calls it without). */
+ * `memwal_remember_bulk`, `memwal_recall`, and `memwal_analyze` treat it as
+ * optional; `memwal_restore` requires it (its upstream schema still lists
+ * `namespace` as required, so agents normally pass one — but a configured
+ * default is filled in if the agent calls it without). */
 const NAMESPACE_TOOLS = new Set([
     "memwal_remember",
     "memwal_remember_bulk",
diff --git a/packages/mcp/test/default-namespace.test.mjs b/packages/mcp/test/default-namespace.test.mjs
new file mode 100644
index 00000000..cca141c8
--- /dev/null
+++ b/packages/mcp/test/default-namespace.test.mjs
@@ -0,0 +1,123 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { applyDefaultNamespace } from "../dist/bridge.js";
+
+test("applyDefaultNamespace injects configured namespace into memwal_remember_bulk", () => {
+    const msg = {
+        jsonrpc: "2.0",
+        id: 1,
+        method: "tools/call",
+        params: {
+            name: "memwal_remember_bulk",
+            arguments: {
+                facts: ["fact 1", "fact 2"],
+            },
+        },
+    };
+
+    const updated = applyDefaultNamespace(msg, "project-alpha");
+    assert.equal(updated.params.arguments.namespace, "project-alpha");
+    assert.deepEqual(updated.params.arguments.facts, ["fact 1", "fact 2"]);
+    // The call site ignores the return value — in-place mutation is the real contract.
+    assert.equal(msg.params.arguments.namespace, "project-alpha");
+});
+
+test("applyDefaultNamespace respects explicit namespace on memwal_remember_bulk", () => {
+    const msg = {
+        jsonrpc: "2.0",
+        id: 2,
+        method: "tools/call",
+        params: {
+            name: "memwal_remember_bulk",
+            arguments: {
+                facts: ["fact 1"],
+                namespace: "explicit-scope",
+            },
+        },
+    };
+
+    const updated = applyDefaultNamespace(msg, "project-alpha");
+    assert.equal(updated.params.arguments.namespace, "explicit-scope");
+});
+
+test("applyDefaultNamespace injects into all namespace-aware tools", () => {
+    const tools = [
+        "memwal_remember",
+        "memwal_remember_bulk",
+        "memwal_recall",
+        "memwal_analyze",
+        "memwal_restore",
+    ];
+
+    for (const toolName of tools) {
+        const msg = {
+            jsonrpc: "2.0",
+            id: 3,
+            method: "tools/call",
+            params: {
+                name: toolName,
+                arguments: {},
+            },
+        };
+
+        const updated = applyDefaultNamespace(msg, "shared-namespace");
+        assert.equal(
+            updated.params.arguments.namespace,
+            "shared-namespace",
+            `expected default namespace to be injected for ${toolName}`
+        );
+    }
+});
+
+test("applyDefaultNamespace does not touch unrelated tools or non-call RPC messages", () => {
+    const loginMsg = {
+        jsonrpc: "2.0",
+        id: 4,
+        method: "tools/call",
+        params: {
+            name: "memwal_login",
+            arguments: {},
+        },
+    };
+    const updatedLogin = applyDefaultNamespace(loginMsg, "test-ns");
+    assert.equal(updatedLogin.params.arguments.namespace, undefined);
+
+    const listMsg = {
+        jsonrpc: "2.0",
+        id: 5,
+        method: "tools/list",
+        params: { name: "memwal_remember_bulk", arguments: {} },
+    };
+    const updatedList = applyDefaultNamespace(listMsg, "test-ns");
+    assert.equal(updatedList.params.arguments.namespace, undefined);
+});
+
+test("applyDefaultNamespace is a no-op when no default is configured", () => {
+    const msg = {
+        jsonrpc: "2.0",
+        id: 6,
+        method: "tools/call",
+        params: { name: "memwal_remember_bulk", arguments: { facts: ["fact 1"] } },
+    };
+
+    applyDefaultNamespace(msg, undefined);
+    assert.equal(msg.params.arguments.namespace, undefined);
+});
+
+test("applyDefaultNamespace overrides a blank explicit namespace", () => {
+    for (const blank of ["", "   "]) {
+        const msg = {
+            jsonrpc: "2.0",
+            id: 7,
+            method: "tools/call",
+            params: {
+                name: "memwal_remember_bulk",
+                arguments: { facts: ["fact 1"], namespace: blank },
+            },
+        };
+
+        applyDefaultNamespace(msg, "project-alpha");
+        assert.equal(msg.params.arguments.namespace, "project-alpha");
+    }
+});