fix(conversations): 修复会话标识与解决后跳转

backend/migrations/000066_repair_conversation_display_ids.down.sql

@@ -0,0 +1,7 @@
+DROP INDEX IF EXISTS idx_conversations_account_display_id;
+CREATE INDEX idx_conversations_account_display_id
+    ON conversations(account_id, display_id)
+    WHERE deleted_at IS NULL;
+
+-- Repaired display IDs are intentionally retained: their previous duplicate
+-- values cannot be restored without reintroducing ambiguous conversation URLs.

backend/migrations/000066_repair_conversation_display_ids.up.sql

@@ -0,0 +1,57 @@
+-- Repair duplicate and missing account-scoped conversation display IDs before
+-- enforcing the Chatwoot routing invariant. Keep already-unique IDs stable so
+-- existing conversation URLs continue to resolve to the same records.
+WITH ranked AS (
+    SELECT
+        id,
+        account_id,
+        display_id,
+        ROW_NUMBER() OVER (
+            PARTITION BY account_id, display_id
+            ORDER BY id
+        ) AS duplicate_rank
+    FROM conversations
+    WHERE deleted_at IS NULL
+      AND display_id IS NOT NULL
+      AND display_id > 0
+),
+needs_repair AS (
+    SELECT id, account_id
+    FROM ranked
+    WHERE duplicate_rank > 1
+
+    UNION ALL
+
+    SELECT id, account_id
+    FROM conversations
+    WHERE deleted_at IS NULL
+      AND (display_id IS NULL OR display_id = 0)
+),
+account_max AS (
+    SELECT account_id, COALESCE(MAX(display_id), 0) AS max_display_id
+    FROM conversations
+    WHERE deleted_at IS NULL
+      AND display_id IS NOT NULL
+      AND display_id > 0
+    GROUP BY account_id
+),
+replacements AS (
+    SELECT
+        repair.id,
+        COALESCE(account_max.max_display_id, 0)
+            + ROW_NUMBER() OVER (
+                PARTITION BY repair.account_id
+                ORDER BY repair.id
+            ) AS display_id
+    FROM needs_repair AS repair
+    LEFT JOIN account_max ON account_max.account_id = repair.account_id
+)
+UPDATE conversations AS conversation
+SET display_id = replacements.display_id
+FROM replacements
+WHERE conversation.id = replacements.id;
+
+DROP INDEX IF EXISTS idx_conversations_account_display_id;
+CREATE UNIQUE INDEX idx_conversations_account_display_id
+    ON conversations(account_id, display_id)
+    WHERE deleted_at IS NULL;