fix: auto-namespace messageMeta by pluginId in hook runner instead of plugin self-wrapping

extensions/memory-lancedb/index.ts

@@ -565,14 +565,12 @@ const memoryPlugin = {
               results.map((r) => ({ category: r.entry.category, text: r.entry.text })),
             ),
             messageMeta: {
-              "memory-lancedb": {
-                displayStripPatterns: [
-                  {
-                    regex:
-                      "<\\s*relevant[-_]memories\\b[^>]*>[\\s\\S]*?<\\s*/\\s*relevant[-_]memories\\s*>\\s*",
-                  },
-                ],
-              },
+              displayStripPatterns: [
+                {
+                  regex:
+                    "<\\s*relevant[-_]memories\\b[^>]*>[\\s\\S]*?<\\s*/\\s*relevant[-_]memories\\s*>\\s*",
+                },
+              ],
             },
           };
         } catch (err) {

src/plugins/hooks.ts

@@ -121,11 +121,12 @@ function getHooksForName<K extends PluginHookName>(
 }
 
 /**
- * Deep-merge two messageMeta bags.  Top-level keys are plugin-namespaced
- * (e.g. `"memory-lancedb"`) and each plugin's value is an object whose
- * array-valued keys are concatenated so multiple hook phases can each
- * contribute entries without overwriting each other. Scalar keys inside a
- * plugin namespace use last-wins semantics.
+ * Deep-merge two messageMeta bags.  Top-level keys are plugin IDs
+ * (auto-injected by the hook runner via {@link namespaceMessageMeta})
+ * and each plugin's value is an object whose array-valued keys are
+ * concatenated so multiple hook phases can each contribute entries
+ * without overwriting each other. Scalar keys inside a plugin
+ * namespace use last-wins semantics.
  */
 function mergeMessageMeta(
   acc: Record<string, unknown> | undefined,
@@ -170,6 +171,24 @@ function mergeMessageMeta(
   return merged;
 }
 
+/**
+ * Wrap a handler result's `messageMeta` inside a `{ [pluginId]: ... }` envelope.
+ * This is called by the hook runner **before** merging so that each plugin's
+ * meta is isolated under its own key — a plugin returning `{ displayStripPatterns: [...] }`
+ * becomes `{ "memory-lancedb": { displayStripPatterns: [...] } }` automatically.
+ * Plugins cannot write into another plugin's namespace because the runner
+ * controls the wrapping.
+ */
+function namespaceMessageMeta(
+  result: { messageMeta?: Record<string, unknown> } | undefined | null,
+  pluginId: string,
+): void {
+  if (!result?.messageMeta || Object.keys(result.messageMeta).length === 0) {
+    return;
+  }
+  result.messageMeta = { [pluginId]: result.messageMeta };
+}
+
 /**
  * Create a hook runner for a specific registry.
  */
@@ -300,6 +319,11 @@ export function createHookRunner(registry: PluginRegistry, options: HookRunnerOp
         )(event, ctx);
 
         if (handlerResult !== undefined && handlerResult !== null) {
+          // Auto-namespace messageMeta by pluginId so plugins cannot write
+          // into another plugin's namespace.  The plugin returns flat meta
+          // (e.g. { displayStripPatterns: [...] }) and we wrap it as
+          // { [pluginId]: { displayStripPatterns: [...] } }.
+          namespaceMessageMeta(handlerResult, hook.pluginId);
           if (mergeResults && result !== undefined) {
             result = mergeResults(result, handlerResult);
           } else {

src/plugins/types.ts

@@ -544,12 +544,11 @@ export type PluginHookBeforePromptBuildResult = {
   appendSystemContext?: string;
   /**
    * Generic key-value bag for plugins to attach metadata to the persisted
-   * user message. Top-level keys are namespaced by plugin ID (e.g.
-   * `"memory-lancedb"`) so each plugin's data is isolated from others.
-   *
-   * Example: memory-lancedb stores `displayStripPatterns` under its own
-   * namespace: `{ "memory-lancedb": { displayStripPatterns: [...] } }`.
-   * The UI reads only `messageMeta["memory-lancedb"]` to apply strip patterns.
+   * user message. Plugins return flat meta (e.g. `{ displayStripPatterns: [...] }`)
+   * and the hook runner automatically wraps it under the plugin's ID
+   * (e.g. `{ "memory-lancedb": { displayStripPatterns: [...] } }`).
+   * This ensures each plugin's data is isolated — a plugin cannot write
+   * into another plugin's namespace.
    */
   messageMeta?: Record<string, unknown>;
 };