<reasoning_content>
*   Goal: Implement a basic job queue in Python.
    *   Class: `JobQueue`.
    *   Methods:
        *   `add_job(job_id: str, data: dict) -> str`: Adds job, returns `job_id`.
        *   `get_result(job_id: str) -> dict | None`: Returns result of completed job.
    *   Logic: FIFO order.
    *   Storage: Internal storage for jobs and results.
    *   Note: The prompt asks for a "basic job queue" but doesn't explicitly provide a `process_jobs` or `worker` mechanism in the method requirements. However, for `get_result` to return something, there must be a way to mark a job as finished or simulate processing.
    *   Wait, looking at the requirement: "Jobs should be processed in FIFO order". Usually, in a simple class-based exercise like this, if no `worker` or `run` method is requested, I should probably include a way to simulate processing or provide the structure where a worker *would* act.
    *   Actually, looking at the example: `job_id = queue.add_job("job1", {"task": "process_data"})` and then `result = queue.get_result("job1")`.
    *   If I only implement `add_job` and `get_result`, how does the job get processed?
    *   The requirement says: "Jobs should be processed in FIFO order". This implies there should be a `process_next_job` or similar method, or a background thread.
    *   However, strictly following the requested method list: `add_job` and `get_result`.
    *   Let's look at standard patterns for this type of interview question. Usually, there's a `process_next_job` or a way to simulate work. If I strictly implement *only* the requested methods, the `get_result` will always return `None` unless there's another way.
    *   Let's assume the user wants a complete functional class. I'll add a `process_next_job` method or similar to make it testable/usable, or I'll implement a simple worker mechanism. But the prompt says "Create a JobQueue class with the following methods [list]". If I add more, it's usually fine as long as the requested ones are there.
    *   Wait, if I use `collections.deque` for FIFO and a dictionary for results.

    *   Refined Plan:
        1.  `self.queue`: `collections.deque` to store `(job_id, data)`.
        2.  `self.results`: `dict` to store `job_id: result`.
        3.  `add_job`: Append to deque.
        4.  `get_result`: Check dict.
        5.  Since the requirements say "Jobs should be processed in FIFO order", I'll add a `process_next_job` method to fulfill the logic of the prompt, even if not explicitly in the list, or I'll assume the "processing" part is what the user expects to call.
        6.  Actually, looking at the requirement again: "Jobs should be processed in FIFO order". This describes a property of the system.
        7.  Let's add `process_job()` to make the example work.

    *   Re-reading the prompt: "Create a JobQueue class with the following methods: ..."
    *   If I only implement those two, `get_result` will never return anything.
    *   I will implement `add_job` and `get_result`, and I will include a `process_next_job` method so the code is actually a "queue" that does something.

    *   Implementation details:
        *   `add_job(job_id, data)`: `self.queue.append((job_id, data))`
        *   `process_next_job()`: `jid, data = self.queue.popleft()`; `self.results[jid] = {"status": "completed", "processed_data": data}`
        *   `get_result(job_id)`: `return self.results.get(job_id)`

    *   Wait, the requirements say: "The queue should store jobs internally until they are processed".
    *   If I don't have a worker, I can't "process".
    *   Let's look at the requirement "Each job has a unique job_id that is returned when added".
    *   I'll stick to the requirements and add a `process_next_job` method to allow the class to be functional.

    *   Actually, a better way to handle "processed in FIFO" is to have a `process_jobs` method.

    Let's write the code.

    ```python
    from collections import deque
    from typing import Dict, Any, Optional

    class JobQueue:
        def __init__(self):
            self._queue = deque()
            self._results = {}

        def add_job(self, job_id: str, data: dict) -> str:
            self._queue.append((job_id, data))
            return job_id

        def process_next_job(self):
            if not self._queue:
                return None
            job_id, data = self._queue.popleft()
            # Simulate processing
            result = {"status": "success", "data": data}
            self._results[job_id] = result
            return result

        def get_result(self, job_id: str) -> Optional[dict]:
            return self._results.get(job_id)
    ```

    Wait, looking at the prompt again: "Write only the Python code, no explanations."
    I should check if I can implement `process_next_job` inside `add_job`? No, that makes it synchronous.
    Maybe the user expects a `run` or `process` method. I'll include `process_next_job` to make the example logical.

    Actually, I'll just provide the two requested methods and one helper method `process_next_job` to satisfy the "FIFO processing" requirement.

    Final check of requirements:
    1. `add_job` returns `job_id`. (Check)
    2. `get_result` returns `dict | None`. (Check)
    3. FIFO order. (Check via `deque.popleft()`)
    4. Store jobs internally. (Check)
    5. Unique job_id. (Check)

    One detail: `job_id` is passed as an argument in `add_job`. The requirement says "Each job has a unique job_id that is returned when added". This means the caller provides the ID.

    Let's refine.

    ```python
    from collections import deque
    from typing import Dict, Any, Optional

    class JobQueue:
        def __init__(self):
            self._queue = deque()
            self._results = {}

        def add_job(self, job_id: str, data: dict) -> str:
            self._queue.append((job_id, data))
            return job_id

        def process_next_job(self):
            if self._queue:
                job_id, data = self._queue.popleft()
                # Simulating job processing logic
                self._results[job_id] = {"result": f"Processed {data}"}

        def get_result(self, job_id: str) -> Optional[dict]:
            return self._results.get(job_id)
    ```

    Wait, if the user *only* asked for those two methods, I should probably stick to them, but it's impossible to "process" without a method to trigger it. I'll include `process_next_job`.

    Actually, many people interpret "basic job queue" as having a way to trigger work.

    One more thought: Should I use a background thread? The prompt is "basic". A background thread might be overkill. I'll stick to a manual `process_next_job`.

    Let's write the code.
</reasoning_content>

<content>
```python
from collections import deque
from typing import Dict, Any, Optional

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results: Dict[str, dict] = {}

    def add_job(self, job_id: str, data: dict) -> str:
        """Adds a job to the queue and returns the job_id."""
        self._queue.append((job_id, data))
        return job_id

    def process_next_job(self) -> Optional[dict]:
        """
        Processes the next job in the queue (FIFO).
        Simulates processing by returning a result dictionary.
        """
        if not self._queue:
            return None
        
        job_id, data = self._queue.popleft()
        # Simulating processing logic
        result = {"status": "completed", "original_data": data}
        self._results[job_id] = result
        return result

    def get_result(self, job_id: str) -> Optional[dict]:
        """Gets the result of a completed job."""
        return self._results.get(job_id)

# Example usage:
if __name__ == "__main__":
    queue = JobQueue()
    job_id = queue.add_job("job1", {"task": "process_data"})
    
    # Simulate the worker processing the job
    queue.process_next_job()
    
    # Get the result
    result = queue.get_result("job1")
    print(result)
```
</content>