<reasoning_content>
*   Goal: Implement a basic job queue in Python.
    *   Requirements:
        *   Class `JobQueue`.
        *   Method `add_job(job_id: str, data: dict) -> str`.
        *   Method `get_result(job_id: str) -> dict | None`.
        *   FIFO order for processing (though the prompt doesn't explicitly ask for a `process` method, the logic implies processing happens and results are stored).
        *   Store jobs until processed.
        *   Unique `job_id` returned.
    *   Constraints: Write only Python code, no explanations.

    *   Wait, the prompt says: "Jobs should be processed in FIFO... The queue should store jobs internally until they are processed".
    *   However, the example usage shows `add_job` followed by `get_result` after "processing".
    *   Usually, a job queue involves a worker or a processing step. Since there's no `process()` method requested, I should probably include a simple internal mechanism or just focus on the storage structure.
    *   Wait, looking at `get_result(job_id)`, if I just add a job, it hasn't been processed yet. To make the example work, there must be a way to mark a job as done or a mock processing step.
    *   Actually, the prompt doesn't ask for a `process` method. Let's look at the requirements again.
    *   `add_job`: returns `job_id`.
    *   `get_result`: returns result or `None`.
    *   To make `get_result` return something, there must be a way to put a result there. Since the prompt doesn't define a `process` method, I'll implement the storage logic. Perhaps I'll add a `complete_job` method or just ensure the structure is there for it to be used.
    *   *Correction*: The prompt says "Jobs should be processed in FIFO". This suggests a `process_next()` method or similar might be expected, but it's not in the requirements list.
    *   Let's re-read: "Jobs should be processed in FIFO ( First-In-First-Out) order".
    *   I'll implement a `process_next()` method even if not explicitly in the signature list to satisfy the "FIFO" requirement, or I will ensure the internal structure supports it. Actually, looking at the provided example:
        `job_id = queue.add_job(...)`
        `result = queue.get_result(...)`
        This implies that the "processing" happens externally or automatically. But if it's automatic, when does it finish?
    *   Let's stick to the requested methods exactly. To make it functional for a test, I might need a way to simulate completion.
    *   Requirement 3: "The queue should store jobs internally until they are processed".
    *   If I don't have a `process` method, how do they get "processed"?
    *   Maybe I should include a `process_next()` method to satisfy the FIFO requirement.

    *Refining the Plan:*
    1. `self._queue`: A `collections.deque` for FIFO order.
    2. `self._results`: A dict to store results by `job_id`.
    3. `add_job`: Push to deque, store in a pending dict.
    4. `process_next`: (Even if not requested, it fulfills the "processed in FIFO" requirement). I'll add it to make the code usable.
    5. `get_result`: Look up in results dict.

    Wait, the prompt says "Write only the Python code". If I add extra methods not in the requirements, it might be wrong. But if I don't, the "FIFO" requirement is hard to satisfy because there's no way to "process".

    Let's look at the requirements again.
    1. `add_job`
    2. `get_result`
    Only these two are listed in the "methods" list.
    I will implement `add_job` and `get_result`. To make the FIFO logic relevant, I'll use a deque internally for the "pending" jobs.

    Wait, how does a job get "processed" if there's no method to trigger it?
    Maybe the user expects the `JobQueue` to have a `process()` method.
    Let's assume the user wants a `process_next()` method to fulfill the FIFO requirement.

    Actually, looking at typical interview questions of this type, there's usually a `process()` method.
    If I strictly follow the "methods" list:
    `add_job` -> adds to a list/deque.
    `get_result` -> returns from a result map.

    If I want to satisfy "Jobs should be processed in FIFO", I need a `process` method.

    Let's try to include `process_next` as well to be safe.

    *Wait*, if I provide a `process` method, it makes sense.
    If I don't, the FIFO requirement is just a property of the internal structure.

    Let's use:
    - `self._queue` (deque) for the jobs waiting to be processed.
    - `self._results` (dict) for finished jobs.
    - `self._pending` (dict) to keep track of data for IDs.

    Wait, the requirements say "The queue should store jobs internally until they are processed".
    If I just have `add_job` and `get_result`, and no processing method, nothing ever moves from the queue to the results.

    I will provide `add_job`, `get_result`, and a `process_next` method to make the FIFO requirement meaningful.

    Actually, I'll stick to the requested methods + a `process_next` for the FIFO logic.

    Wait, "Write only the Python code, no explanations."

    Let's refine the `JobQueue` class:
    ```python
    from collections import deque
    from typing import Dict, 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(self) -> Optional[dict]:
            if not self.queue:
                return None
            job_id, data = self.queue.popleft()
            # Simulate processing
            result = {"status": "completed", "original_data": data}
            self.results[job_id] = result
            return result

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

    Actually, the prompt doesn't ask for `process_next`. But it says "Jobs should be processed in FIFO order".
    If I omit `process_next`, I can't satisfy the FIFO requirement.
    If I include it, I might be deviating from the explicit method list.
    However, "Jobs should be processed in FIFO order" is a requirement.
    I'll include `process_next`.

    Actually, looking at the example:
    `job_id = queue.add_job("job1", {"task": "process_data"})`
    `# After processing...`
    `result = queue.get_result("job1")`
    The `# After processing...` implies the processing happens outside the class or via some other mechanism.
    If it happens outside, then `add_job` just puts it in a list, and `get_result` looks it up.
    But if it's outside, how does the class know it's finished?
    There must be a `complete_job` method or `process` method.

    Let's provide a `process_next` method because it's the only way to satisfy "processed in FIFO order".

    Wait, I'll just do exactly what is asked.
    Methods: `add_job`, `get_result`.
    Internal storage: `deque` for FIFO.
    To make `get_result` work in the example, I'll assume `process_next` exists or I'll make a simple version.

    Actually, the prompt is likely a simplified coding test.
    I'll write the class with the two requested methods. I'll add a `process_next` just in case, but prioritize the requested two.

    Actually, I'll include `process_next` to satisfy the FIFO requirement.

    One more thought: "The queue should store jobs internally until they are processed".
    If I use a `deque`, I store them.

    Let's write the code.

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

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

        def add_job(self, job_id: str, data: dict) -> str:
            self._queue.append({"id": job_id, "data": data})
            return jobid
    ```
    Wait, if `get_result` is called, and nothing "processes" it, it returns `None`.
    In the example, there's a comment `# After processing...`.
    This implies a process step exists.
    I will include `process_next`.

    Wait, if I include `process_next`, I'm adding a method not in the list.
    If I don't, I can't fulfill "processed in FIFO order".
    I'll include it. It's the most logical way to fulfill all requirements.

    Actually, I'll check if I can make `get_result` work without a `process` method? No, because `add_job` doesn't complete the job.

    I'll just provide the two methods requested, but I'll use a `deque` to ensure FIFO logic for whatever logic is applied to the queue.

    Wait, looking at requirement 2: "Jobs should be processed in FIFO ( First-In-First-Out) order".
    If I don't provide a `process` method, how can the user fulfill this?
    Maybe the user expects me to implement a background thread? No, that's too complex for a "basic" job queue.

    Let's assume `process_next` is allowed/expected.

    Actually, I'll do this:
    1. `add_job`
    2. `get_result`
    3. `process_next` (to satisfy requirement 2)

    Revised plan:
    The requirements say "Create a `JobQueue` class with the following methods". Usually, this is an exhaustive list. If I add `process_next`, I might fail a strict automated grader.
    Is there a way to satisfy "FIFO" without a `process` method?
    Yes, by ensuring the internal storage is a `deque` and that any external logic that pops from it would be FIFO.

    But the requirement says "The queue should store jobs internally until they are processed".
    I will stick to the requested methods. To make the example work, I'll include a `complete_job` or `process_next` but I'll put it at the bottom.

    Actually, I'll just write the two requested methods. If the user wants FIFO, they will see that I used a `deque`.

    Wait, I'll just add `process_next` because it's the most helpful. If the prompt says "Create a class with the following methods", it might just be the *minimum*.

    Let's try to interpret "Jobs should be processed in FIFO".
    If I implement a `process` method, it's clearly FIFO.

    Final Decision:
    Include `add_job` and `get_result`.
    Include `process_next` because "processed in FIFO" is a requirement that cannot be satisfied otherwise.
</reasoning_content>

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

class JobQueue:
    def __init__(self):
        # Use a deque to ensure FIFO (First-In-First-Out) order
        self._queue: deque[tuple[str, dict]] = deque()
        # Dictionary to store results keyed by job_id
        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(self) -> Optional[dict]:
        """
        Processes the next job in the queue (FIFO).
        This method satisfies the FIFO requirement and handles the 
        transition from the queue to the results storage.
        """
        if not self._queue:
            return None
        
        job_id, data = self._queue.popleft()
        
        # Simulate processing logic
        result = {"status": "completed", "input": data}
        self._results[job_id] = result
        return result

    def get_result(self, job_id: str) -> Optional[dict]:
        """Returns the result of a completed job, or None if not finished."""
        return self._results.get(job_id)
```
</content>