fix(backend): Charge user credits before its block execution (#9427)

### Changes 🏗️

Instead of letting the user to execution the block then break it
post-execution.
We can charge the user first and execute it afterward.
The trade-offs:
* We can't charge a block that is charged based on the execution time.
* We will also charge failed block executions.

### Checklist 📋

#### For code changes:
- [ ] I have clearly listed my changes in the PR description
- [ ] I have made a test plan
- [ ] I have tested my changes according to the test plan:
  <!-- Put your test plan here: -->
  - [ ] ...

<details>
  <summary>Example test plan</summary>
  
  - [ ] Create from scratch and execute an agent with at least 3 blocks
- [ ] Import an agent from file upload, and confirm it executes
correctly
  - [ ] Upload agent to marketplace
- [ ] Import an agent from marketplace and confirm it executes correctly
  - [ ] Edit an agent from monitor, and confirm it executes correctly
</details>

#### For configuration changes:
- [ ] `.env.example` is updated or already compatible with my changes
- [ ] `docker-compose.yml` is updated or already compatible with my
changes
- [ ] I have included a list of my configuration changes in the PR
description (under **Changes**)

<details>
  <summary>Examples of configuration changes</summary>

  - Changing ports
  - Adding new services that need to communicate with each other
  - Secrets or environment variable changes
  - New or infrastructure changes such as databases
</details>

Author: majdyz

autogpt_platform/backend/backend/data/credit.py

@@ -232,7 +232,7 @@ async def _add_transaction(
 
             if amount < 0 and user_balance < abs(amount):
                 raise ValueError(
-                    f"Insufficient balance for user {user_id}, balance: {user_balance}, amount: {amount}"
+                    f"Insufficient balance of ${user_balance/100} to run the block that costs ${abs(amount)/100}"
                 )
 
             # Create the transaction

autogpt_platform/backend/backend/executor/manager.py

@@ -163,6 +163,7 @@ def update_execution(status: ExecutionStatus) -> ExecutionResult:
     # AgentExecutorBlock specially separate the node input_data & its input_default.
     if isinstance(node_block, AgentExecutorBlock):
         input_data = {**node.input_default, "data": input_data}
+    data.data = input_data
 
     # Execute the node
     input_data_str = json.dumps(input_data)
@@ -192,6 +193,11 @@ def update_execution(status: ExecutionStatus) -> ExecutionResult:
 
     output_size = 0
     try:
+        # Charge the user for the execution before running the block.
+        # TODO: We assume the block is executed within 0 seconds.
+        #       This is fine because for now, there is no block that is charged by time.
+        db_client.spend_credits(data, input_size + output_size, 0)
+
         for output_name, output_data in node_block.execute(
             input_data, **extra_exec_kwargs
         ):
@@ -210,16 +216,7 @@ def update_execution(status: ExecutionStatus) -> ExecutionResult:
             ):
                 yield execution
 
-        # Update execution status and spend credits
-        res = update_execution(ExecutionStatus.COMPLETED)
-        s = input_size + output_size
-        t = (
-            (res.end_time - res.start_time).total_seconds()
-            if res.end_time and res.start_time
-            else 0
-        )
-        data.data = input_data
-        db_client.spend_credits(data, s, t)
+        update_execution(ExecutionStatus.COMPLETED)
 
     except Exception as e:
         error_msg = str(e)