fix(tlon): restore DM partner ship extraction for proper routing

- Add extractDmPartnerShip() to extract partner from 'whom' field
- Use partner ship for routing (more reliable than essay.author)
- Explicitly ignore bot's own outbound DM events
- Log mismatch between author and partner for debugging

extensions/tlon/src/monitor/index.ts

@@ -791,6 +791,23 @@ export async function monitorTlonProvider(opts: MonitorTlonOpts = {}): Promise<v
     return normalizeShip(ship) === effectiveOwnerShip;
   }
 
+  /**
+   * Extract the DM partner ship from the 'whom' field.
+   * This is the canonical source for DM routing (more reliable than essay.author).
+   * Returns empty string if whom doesn't contain a valid patp-like value.
+   */
+  function extractDmPartnerShip(whom: unknown): string {
+    const raw =
+      typeof whom === "string"
+        ? whom
+        : whom && typeof whom === "object" && "ship" in whom && typeof whom.ship === "string"
+          ? whom.ship
+          : "";
+    const normalized = normalizeShip(raw);
+    // Keep DM routing strict: accept only patp-like values.
+    return /^~?[a-z-]+$/i.test(normalized) ? normalized : "";
+  }
+
   const processMessage = async (params: {
     messageId: string;
     senderShip: string;
@@ -1281,7 +1298,7 @@ export async function monitorTlonProvider(opts: MonitorTlonOpts = {}): Promise<v
         return;
       }
 
-      const _whom = event.whom; // DM partner ship or club ID
+      const whom = event.whom; // DM partner ship or club ID
       const messageId = event.id;
       const response = event.response;
 
@@ -1295,11 +1312,25 @@ export async function monitorTlonProvider(opts: MonitorTlonOpts = {}): Promise<v
         return;
       }
 
-      const senderShip = normalizeShip(essay.author ?? "");
+      const authorShip = normalizeShip(essay.author ?? "");
+      const partnerShip = extractDmPartnerShip(whom);
+      const senderShip = partnerShip || authorShip;
+
+      // Ignore the bot's own outbound DM events.
+      if (authorShip === botShipName) {
+        return;
+      }
       if (!senderShip || senderShip === botShipName) {
         return;
       }
 
+      // Log mismatch between author and partner for debugging
+      if (authorShip && partnerShip && authorShip !== partnerShip) {
+        runtime.log?.(
+          `[tlon] DM ship mismatch (author=${authorShip}, partner=${partnerShip}) - routing to partner`,
+        );
+      }
+
       // Resolve any cited/quoted messages first
       const citedContent = await resolveAllCites(essay.content);
       const rawText = extractMessageText(essay.content);