<reasoning_content>
*   Requirement: Implement a basic job queue in Python.
    *   Class: `JobQueue`.
    *   Methods:
        *   `add_job(job_id: str, data: dict) -> str`: Adds a job, returns `job_id`.
        *   `get_result(job_id: str) -> dict | None`: Retrieves the result of a completed job.
    *   Logic:
        *   FIFO order for processing.
        *   Internal storage for jobs.
        *   Unique `job_id`.
    *   Note: The prompt implies a simple implementation. Since there's no specific mention of a background worker or thread, I should probably implement the *storage* for jobs and a way to "process" them (or at least simulate the flow) to allow `get_result` to work.
    *   Wait, looking closely at the example: `queue.add_job` returns an ID. `queue.get_result` retrieves the result. The example doesn't show a `process()` method, but for `get_result` to return a result, something must transition the state from "pending" to "completed".
    *   However, the prompt asks for a *basic* job queue. I'll provide a version where jobs are stored in a queue, and a `process_next` method might be implicit or I can just allow `get_result` to return something if I simulate a result. Actually, usually, a "JobQueue" class with these specific methods implies that `add_job` puts it in a queue, and maybe there's a method to process them, or the user wants to see how the storage works.
    *   Actually, looking at the requirement `get_result(job_id: str) -> dict | None`, it implies the `JobQueue` needs to track which jobs are done and what their results are.

    *   Storage for jobs (Queue structure): `collections.deque`.
    *   Storage for results: `dict`.
    *   Jobs structure: `{"id": str, "data": dict}`.
    *   Since the prompt doesn't explicitly ask for a `process` method but `get_result` expects a result, I'll add a `process_next` method or assume `process_next` is how the state changes. But the prompt says "Write only the Python code". I should stick to the requested methods but ensure they function logically.
    *   Wait, if I don't have a `process` method, `get_result` will always be `None`. Let's look at the prompt again. "Jobs should be processed in FIFO". This implies there's a processing step.
    *   I will implement:
        1. `self.jobs`: A deque of `(job_id, data)`.
        2. `self.results`: A dict `{job_id: result}`.
        3. `add_job`: Pushes to `self.jobs`.
        4. `process_next`: (I'll add this to make it functional, even if not explicitly in the list of methods, or I'll just make sure `get_result` works if a job is somehow processed).
        5. Actually, let's strictly follow the requested methods. If I only have `add_job` and `get_result`, how does a job get processed? Maybe I should add a `process_next` method anyway because "Jobs should be processed in FIFO" is a requirement.

    Let's refine:
    - `self.queue`: `collections.deque` stores tuples `(job_id, data)`.
    - `self.results`: `dict` stores `job_id -> result`.
    - `add_job(job_id, data)`: validates `job_id`, puts in `self.queue`.
    - `process_next()`: (Required for logic) Pops from `self.queue`, processes (simulated), puts in `self.results`.
    - `get_result(job_id)`: looks up in `self.results`.

    Actually, if I only provide the two methods requested, the user might be confused why results are always None. But if I add `process_next`, I'm going outside the prompt's specific method list.
    Let's look at requirement 2: "Jobs should be processed in FIFO". This implies a process step.

    Revised Plan:
    `JobQueue` class.
    `self._queue`: `deque`.
    `self._results`: `dict`.
    `add_job`: appends to queue.
    `process_next`: (I'll include this to satisfy req 2).
    `get_result`: returns from results dict.

    Wait, the prompt says:
    1. Create a `JobQueue` class with the **following methods**:
       - `add_job(...)`
       - `get_result(...)`
    It doesn't list `process_next`.

    Okay, I will implement only the requested methods. To make it work for the "FIFO" and "processed" requirements, I'll assume there's a way to process them. If I don't provide a process method, the queue is just a storage.

    Actually, if I don't provide a `process_next` method, I can't fulfill "Jobs should be processed in FIFO".
    Let's provide a `process_next` method as well to make the code functional.

    Actually, some interview questions like this imply that `add_job` adds it, and maybe a background thread or another method handles processing. I'll include a `process_next` method because it's necessary for the FIFO requirement to exist in reality.

    Wait, let's re-read: "Write only the Python code, no explanations."

    Structure:
    ```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):
            if self.queue:
                job_id, data = self.queue.popleft()
                # Simulate processing
                self.results[job_id] = {"status": "completed", "result": data}

        def get_result(self, job_id: str) -> dict | None:
            return self.results.get(job_id)
    ```
    Wait, if I add `process_next`, am I violating "with the following methods"? Usually, it means "at least these methods". If I don't include it, the code is useless.

    Let's check if there's another way. Maybe `add_job` processes? No, it's a queue.
    I'll include `process_next`.

    Wait, I'll check the prompt again. It doesn't explicitly say "only these methods". It says "with the following methods".
    I'll stick to exactly the requested ones + a `process_next` to make it actually a queue.

    Actually, to be safe and strictly follow instructions, I'll provide exactly what's asked. If the user wants to process it, they can implement a loop calling `process_next`. But I'll provide `process_next` as well because of the FIFO requirement.

    Wait, I will provide a `process_next` method but I'll keep it simple.

    Actually, I'll use a dictionary for `jobs` to ensure uniqueness and a `deque` for order.

    Revised Plan 2 (Strict):
    - `add_job`: adds to `deque`.
    - `get_result`: returns from dict.
    - I will add `process_next` because "Jobs should be processed" is a requirement.

    Let's refine `add_job` to ensure unique IDs? The prompt says "Each job has a unique job_id that is returned". It doesn't say I have to *generate* it, but rather that it *has* one. The example shows the user providing the ID: `queue.add_job("job1", ...)`. So the user provides the ID.

    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((job_id, data))
            return job_id

        def process_next(self) -> None:
            if self._queue:
                job_id, data = self._queue.popleft()
                # Simulating processing logic
                self._results[job_id] = {"status": "completed", "data": data}

        def get_result(self, job_id: str) -> dict | None:
            return self._results.get(job_id)
    ```

    Actually, looking at requirement 3: "The queue should store jobs internally until they are processed". This confirms `process_next` or similar is needed to remove them from the "queue" and move them to "results".

    One final check on "unique job_id". If the user provides "job1" twice, should I handle it? Usually, yes. But for a "basic" implementation, I'll just store them.

    Wait, the prompt asks for `job_id: str` as an input to `add_job`. This implies the user provides the ID.

    Let's write the final code. I'll include `process_next` because the requirement "Jobs should be processed in FIFO" is impossible to satisfy without a way to process them.

    Wait, I'll check if there's a way to do it without `process_next`. If `get_result` is called, does it process? No, that's not FIFO.

    Okay, I'll include `process_next`.

    Actually, to be perfectly safe and follow the instructions exactly, I will only provide the two methods asked for, but I'll also provide a `process_next` because it's logically required. If I omit `process_next`, the code is barely a "queue" in functionality, just a "storage".

    Let's check the prompt again.
    "Requirements: 1. Create a `JobQueue` class with the following methods: ..."
    It doesn't say "ONLY the following".
    I'll add `process_next`.

    Actually, I'll make the `process_next` name match the "processed" requirement.

    One more thing: `dict | None` type hint requires Python 3.10+. I'll use `Optional` just in case or stick to the pipe if it's expected. The prompt uses `dict | None`, so I will use that.

    Wait, the prompt uses `dict | None`. I'll use that.

    Final Code Structure:
    - `from collections import deque`
    - `class JobQueue`
    - `__init__`
    - `add_job`
    - `process_next` (to fulfill Requirement 2 & 3)
    - `get_result`

    One detail: "Each job has a unique job_id that is returned when added".
    The example: `job_id = queue.add_job("job1", ...)`
    This means the user provides "job1", and the function returns "job1".
    I'll just return the `job_id` provided.

    Wait, if I don't provide `process_next`, how can I fulfill FIFO?
    I'll include it.

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

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

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

        def process_next(self) -> None:
            if self._queue:
                job_id, data = self._queue.popleft()
                # Logic to "process" the job goes here
                # For this basic implementation, we simulate completion
                self._results[job_id] = {"status": "completed", "result": data}

        def get_result(self, job_id: str) -> dict | None:
            return self._results.get(job_id)
    ```

    Wait, should I use `Optional` or `|`? The prompt uses `|`, so I'll use that. I'll skip the `typing` imports unless necessary for the types used. `dict | None` works in 3.10+.

    Actually, I'll remove the `process_next` from the final output if I want to be strictly literal, but it's safer to include it to satisfy the "processed" and "FIFO" requirements. I'll keep it.

    Actually, if I don't include `process_next`, the user can't actually "process" the jobs. I'll add it.

    Wait, I see a potential issue. If I include `process_next`, I might be adding a method not asked for. But if I don't, the requirement "Jobs should be processed in FIFO" is technically not implemented (nothing is being processed).
    However, usually, these prompts are tests of identifying the core structure.

    Let's look at the wording: "Create a `JobQueue` class with the **following** methods".
    I will stick to ONLY those two to be safe. I will assume the user will call some external processer or I'll provide the minimal logic.
    Wait, if I don't provide a process method, `get_result` is always `None`. That's a valid "basic" implementation of the requested interface.

    Revised Plan 3 (Strict):
    Only the requested methods.
    I'll assume the user will somehow move jobs from `self.queue` to `self.results`.
    But how? I'll just implement the storage.

    Actually, I'll provide a `process_next` method but won't list it in the requirements. No, the prompt says "Write only the Python code".

    I'll go with a version that includes `process_next` because it's necessary for the logic described in requirements 2 and 3.

    Wait, I'll check the result again.
    Requirement 3: "The queue should store jobs internally until they are processed".
    This implies a state change.
    I'll include `process_next`.
</reasoning_content>

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

class JobQueue:
    def __init__(self):
        # Internal storage for jobs to be processed (FIFO)
        self._queue: deque[tuple[str, dict]] = deque()
        # Internal storage for results of completed jobs
        self._results: Dict[str, dict] = {}

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

    def process_next(self) -> None:
        """
        Processes the next job in the queue (FIFO).
        While not explicitly requested as a method in the list, 
        it is required to satisfy requirements 2 and 3.
        """
        if self._queue:
            job_id, data = self._queue.popleft()
            # Simulate processing logic
            self._results[job_id] = {"status": "completed", "result": data}

    def get_result(self, job_id: str) -> dict | None:
        """Get the result of a completed job by its ID."""
        return self._results.get(job_id)
```
</content>