From 1192e3ccf9178a2caa563a17fa7a3d240d6f52cd Mon Sep 17 00:00:00 2001
From: Rai Butera <rai@rbutera.com>
Date: Thu, 12 Mar 2026 07:46:31 +0000
Subject: [PATCH] test: harden sentinel edge cases (empty channel, leaked
 state, non-discord external)

Pre-empt edge case regressions flagged in review:
- empty string persistedLastChannel treated as absent (no mismatch risk)
- sentinel value leaked into persistedLastChannel returns undefined (corrupted state guard)
- non-discord external channels (telegram etc.) correctly preserve persistedLastTo
---
 src/auto-reply/reply/session-delivery.test.ts | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/src/auto-reply/reply/session-delivery.test.ts b/src/auto-reply/reply/session-delivery.test.ts
index 34f063ce365..6b4caaa555e 100644
--- a/src/auto-reply/reply/session-delivery.test.ts
+++ b/src/auto-reply/reply/session-delivery.test.ts
@@ -105,6 +105,46 @@ describe("INTER_SESSION_CHANNEL sentinel routing", () => {
     ).toBe("channel:receiver-discord-channel");
   });
 
+  it("returns undefined from resolveLastToRaw when persistedLastChannel is empty string", () => {
+    // Empty string is not an external routing channel — treat same as absent.
+    // Returning stale persistedLastTo would risk a channel/to mismatch.
+    expect(
+      resolveLastToRaw({
+        originatingChannelRaw: INTER_SESSION_CHANNEL,
+        persistedLastChannel: "",
+        persistedLastTo: "channel:some-target",
+        sessionKey: "agent:navi:main",
+      }),
+    ).toBeUndefined();
+  });
+
+  it("returns undefined from resolveLastToRaw when persistedLastChannel is the sentinel itself (leaked state)", () => {
+    // Guard against corrupted persisted state where persistedLastChannel was
+    // accidentally set to "inter_session". The sentinel is not a deliverable
+    // channel and should never be treated as an established external route.
+    expect(
+      resolveLastToRaw({
+        originatingChannelRaw: INTER_SESSION_CHANNEL,
+        persistedLastChannel: INTER_SESSION_CHANNEL,
+        persistedLastTo: "channel:some-target",
+        sessionKey: "agent:navi:main",
+      }),
+    ).toBeUndefined();
+  });
+
+  it("preserves persistedLastTo for non-discord external channels (e.g. telegram)", () => {
+    // The sentinel path should work for any external channel, not just discord.
+    expect(
+      resolveLastToRaw({
+        originatingChannelRaw: INTER_SESSION_CHANNEL,
+        originatingToRaw: "channel:sender-telegram",
+        persistedLastChannel: "telegram",
+        persistedLastTo: "user:987654321",
+        sessionKey: "agent:navi:main",
+      }),
+    ).toBe("user:987654321");
+  });
+
   it("does not treat a real deliverable channel named 'inter_session' as the sentinel (Codex P2 guard)", () => {
     // isInterSessionChannel guards against plugin channel collision:
     // if a real channel plugin registers with id="inter_session", it must not