fix(webapp): make a repeated watch card close leave the revision alone

`settleInvestigationStateAndCloseCard()` bumped the revision before it looked at
the transcript, so a redelivered or replayed action settled the row a second time
while the append refused the duplicate card. The row then held revision 2 and the
transcript's terminal card revision 1: the live run rendered 2, a refresh rendered
1, for a tool advertised as idempotent on the action id.

The transaction now locks the investigation, checks the tenancy triple, locks the
chat, and looks for the message id before it writes anything. An action already in
the transcript returns the stored card and the current revision untouched.

Lock order stays investigation then chat, matching `persistTurn` and the sweep's
`settleInvestigationAndCloseCard`; taking the chat first here would deadlock
against them.

A missing or deleted chat was indistinguishable from an already-closed card —
both came back `closed: false` — and the settle committed anyway, which is exactly
the terminal-row-without-a-card the transaction exists to prevent. It is now
`{ ok: false, error: "chat_missing" }`, and the watch lane logs it as the race it
is rather than a fault.

apps/webapp/test/dashboardAgentWatchCardAtomicity.test.ts

@@ -5,6 +5,7 @@ import {
   getInvestigation,
   listStaleOpenInvestigations,
   settleInvestigationStateAndCloseCard,
+  softDeleteChat,
   upsertInvestigationRevision,
   type DashboardAgentDb,
   type DashboardAgentDbClient,
@@ -121,7 +122,8 @@ describe("closing a consented watch investigation's card", () => {
         investigationStateSchema.parse((await getInvestigation(agentDb, { id }))?.state).outcome
       ).toBe("inconclusive");
 
-      // The lane dedupes on the action, so a redelivered kick closes nothing twice.
+      // The lane dedupes on the action, so a redelivered kick closes nothing twice —
+      // and must not bump the revision, or the row runs ahead of the stored card.
       const again = await settleInvestigationStateAndCloseCard(agentDb, {
         id,
         chatId,
@@ -130,8 +132,65 @@ describe("closing a consented watch investigation's card", () => {
         state: forceSettledInvestigationState(openState()),
         messageId: MESSAGE_ID,
       });
-      expect(again).toMatchObject({ ok: true, closed: false });
-      expect((await transcript(chatId)).length).toBe(1);
+      expect(again).toMatchObject({ ok: true, id, revision: 1, closed: false });
+      expect((await getInvestigation(agentDb, { id }))?.revision).toBe(1);
+
+      const after = await transcript(chatId);
+      expect(after.map((message) => message.id)).toEqual([MESSAGE_ID]);
+      expect(after[0]!.parts[0]!.output.blocks[0]).toMatchObject({ id, revision: 1 });
+      // The replayed result is the card the transcript holds, not a second rendering.
+      expect((again as { card: unknown }).card).toEqual(after[0]);
+    },
+    30_000
+  );
+
+  postgresTest(
+    "settles nothing when the chat was deleted, so the sweep still selects the row",
+    async ({ prisma, postgresContainer }) => {
+      const chatId = "chat_watch_card_deleted";
+      await boot(prisma, postgresContainer.getConnectionUri(), chatId);
+      const id = await seed(chatId, openState());
+      await softDeleteChat(agentDb, { chatId, userId: USER_ID });
+
+      expect(
+        await settleInvestigationStateAndCloseCard(agentDb, {
+          id,
+          chatId,
+          projectRef: PROJECT_REF,
+          environmentRef: ENV_REF,
+          state: forceSettledInvestigationState(openState()),
+          messageId: MESSAGE_ID,
+        })
+      ).toEqual({ ok: false, error: "chat_missing" });
+
+      const row = await getInvestigation(agentDb, { id });
+      expect(row?.revision).toBe(0);
+      expect((row!.state as { outcome?: string }).outcome).toBe("in_progress");
+    },
+    30_000
+  );
+
+  postgresTest(
+    "settles nothing when the chat row was never there",
+    async ({ prisma, postgresContainer }) => {
+      const chatId = "chat_watch_card_absent";
+      await boot(prisma, postgresContainer.getConnectionUri(), "chat_watch_card_present");
+      const id = await seed(chatId, openState());
+
+      expect(
+        await settleInvestigationStateAndCloseCard(agentDb, {
+          id,
+          chatId,
+          projectRef: PROJECT_REF,
+          environmentRef: ENV_REF,
+          state: forceSettledInvestigationState(openState()),
+          messageId: MESSAGE_ID,
+        })
+      ).toEqual({ ok: false, error: "chat_missing" });
+
+      const row = await getInvestigation(agentDb, { id });
+      expect(row?.revision).toBe(0);
+      expect((row!.state as { outcome?: string }).outcome).toBe("in_progress");
     },
     30_000
   );