From 25a3efe0ace58702264d18e4a0aeba1294f2868b Mon Sep 17 00:00:00 2001
From: Mohamed Boudra <boudra.moha@gmail.com>
Date: Mon, 2 Nov 2026 01:01:24 +0100
Subject: [PATCH] fix(server): a plugin that stops reporting an option has
 reset it

The adapter only visited keys present in a new report, so a key the plugin
dropped to return to its default kept its stored value and its rewind value.
A previously reported key that disappears is now reported as removed.
---
 .../src/server/agent/plugin-provider.test.ts  | 24 +++++++++++++++++++
 .../src/server/agent/plugin-provider.ts       |  5 ++++
 2 files changed, 29 insertions(+)

diff --git a/packages/server/src/server/agent/plugin-provider.test.ts b/packages/server/src/server/agent/plugin-provider.test.ts
index c79039a4a8..ecfcd440b6 100644
--- a/packages/server/src/server/agent/plugin-provider.test.ts
+++ b/packages/server/src/server/agent/plugin-provider.test.ts
@@ -1209,6 +1209,30 @@ describe("PluginAgentClientRegistry", () => {
       await session.close();
     });
 
+    test.runIf(shape === "controls")(
+      "reports an option the plugin stops reporting as removed, alone or with another change",
+      async () => {
+        const { session, events, changeOnItsOwn } = await openStubbornVoiceSession({});
+        changeOnItsOwn({ tokenBudget: 500 });
+
+        changeOnItsOwn({ tokenBudget: undefined });
+        changeOnItsOwn({ tokenBudget: 700 });
+        changeOnItsOwn({ tokenBudget: undefined, loud: true });
+
+        expect(eventsOfType(events, "options_changed")).toEqual([
+          { type: "options_changed", provider: "plugin-direct", patch: { token_budget: 500 } },
+          { type: "options_changed", provider: "plugin-direct", patch: { token_budget: null } },
+          { type: "options_changed", provider: "plugin-direct", patch: { token_budget: 700 } },
+          {
+            type: "options_changed",
+            provider: "plugin-direct",
+            patch: { token_budget: null, loud: true },
+          },
+        ]);
+        await session.close();
+      },
+    );
+
     test("a rejected apply reports what the plugin moved before refusing, since nothing is stored", async () => {
       const { session, events } = await openStubbornVoiceSession({}, { refuseAfterChanging: true });
 
diff --git a/packages/server/src/server/agent/plugin-provider.ts b/packages/server/src/server/agent/plugin-provider.ts
index 07181abc1c..e1560d2fa7 100644
--- a/packages/server/src/server/agent/plugin-provider.ts
+++ b/packages/server/src/server/agent/plugin-provider.ts
@@ -1675,6 +1675,11 @@ class PluginAgentSession implements AgentSession {
   private reportOptionChanges(): AgentStreamEvent[] {
     if (this.applyingOptions) return [];
     const patch = this.optionDifferences(this.knownOptions);
+    // A key the plugin reported before and no longer reports went back to its default.
+    const current = this.currentOptions();
+    for (const id of Object.keys(this.knownOptions)) {
+      if (!(id in current)) patch[id] = null;
+    }
     if (Object.keys(patch).length === 0) return [];
     this.commitOptions();
     return [{ type: "options_changed", provider: this.provider, patch }];