diff --git a/src/plugin/event.test.ts b/src/plugin/event.test.ts
index 49ed2c031..a400118e6 100644
--- a/src/plugin/event.test.ts
+++ b/src/plugin/event.test.ts
@@ -335,7 +335,7 @@ describe("createEventHandler - idle deduplication", () => {
 		expect(spawnTmuxPane).toHaveBeenCalledTimes(1)
 	})
 
-	it("dedups real-idle-after-synthetic-idle within 500ms", async () => {
+	it("does NOT dedup real-idle-after-synthetic-idle within 500ms", async () => {
 		//#given
 		const dispatchCalls: EventInput[] = []
 		const eventHandler = createIdleTrackingEventHandler(dispatchCalls)
@@ -359,9 +359,77 @@ describe("createEventHandler - idle deduplication", () => {
 		}))
 
 		//#then
-		expect(dispatchCalls).toHaveLength(1)
+		expect(dispatchCalls).toHaveLength(2)
 		expect(dispatchCalls[0]?.event.type).toBe("session.idle")
 		expect((dispatchCalls[0]?.event.properties as { sessionID?: string } | undefined)?.sessionID).toBe(sessionId)
+		expect(dispatchCalls[1]?.event.type).toBe("session.idle")
+		expect((dispatchCalls[1]?.event.properties as { sessionID?: string } | undefined)?.sessionID).toBe(sessionId)
+	})
+
+	it("keeps other session dedup state untouched when bypassing synthetic-idle for current session", async () => {
+		//#given
+		const originalDateNow = Date.now
+		let currentNow = 30_000
+		Date.now = () => currentNow
+		const dispatchedSessionIds: string[] = []
+		const eventHandler = createIdleDedupSpyEventHandler({
+			onEvent: () => {},
+			sessionNotification: async (input: EventInput) => {
+				if (input.event.type !== "session.idle") {
+					return
+				}
+				const props = input.event.properties as { sessionID?: string } | undefined
+				if (props?.sessionID) {
+					dispatchedSessionIds.push(props.sessionID)
+				}
+			},
+		})
+
+		try {
+			//#when
+			await eventHandler(asEventHandlerInput({
+				event: {
+					type: "session.status",
+					properties: {
+						sessionID: "ses_a",
+						status: { type: "idle" },
+					},
+				},
+			}))
+			await eventHandler(asEventHandlerInput({
+				event: {
+					type: "session.idle",
+					properties: {
+						sessionID: "ses_b",
+					},
+				},
+			}))
+
+			currentNow += 100
+			await eventHandler(asEventHandlerInput({
+				event: {
+					type: "session.idle",
+					properties: {
+						sessionID: "ses_a",
+					},
+				},
+			}))
+
+			currentNow += 100
+			await eventHandler(asEventHandlerInput({
+				event: {
+					type: "session.idle",
+					properties: {
+						sessionID: "ses_b",
+					},
+				},
+			}))
+
+			//#then
+			expect(dispatchedSessionIds).toEqual(["ses_a", "ses_b", "ses_a"])
+		} finally {
+			Date.now = originalDateNow
+		}
 	})
 
 	it("dedups back-to-back real session.idle events for the same sessionID within 500ms", async () => {
diff --git a/src/plugin/event.ts b/src/plugin/event.ts
index 265244f29..2b94fcadf 100644
--- a/src/plugin/event.ts
+++ b/src/plugin/event.ts
@@ -415,6 +415,12 @@ export function createEventHandler(args: {
         const emittedAt = recentSyntheticIdles.get(sessionID);
         if (emittedAt !== undefined && now - emittedAt < DEDUP_WINDOW_MS) {
           recentSyntheticIdles.delete(sessionID);
+          // Let real idle events through even when a synthetic idle fired moments earlier.
+          // OpenCode diagnostics expect a concrete session.idle event signal.
+          const lastAnyIdleAt = recentAnyIdles.get(sessionID);
+          if (lastAnyIdleAt === emittedAt) {
+            recentAnyIdles.delete(sessionID);
+          }
         }
         recentRealIdles.set(sessionID, now);
         if (!shouldDispatchIdleEvent(sessionID, now)) {