<reasoning_content>
The user wants a basic job queue implementation in Python.
Requirements:
1. Class `JobQueue`
2. Methods: `add_job(job_id, data)` returns `job_id`, `get_result(job_id)` returns result dict or None
3. FIFO order
4. Store jobs internally until processed
5. Unique job_id returned when added (though the example shows passing job_id in, the requirement says "Each job has a unique job_id that is returned when added". I'll stick to the signature `add_job(job_id: str, data: dict) -> str` but maybe generate one if needed, or just use the provided one. The example passes "job1", so I'll accept it.)

Wait, the example shows:
```python
job_id = queue.add_job("job1", {"task": "process_data"})
```
So `job_id` is passed in. I'll just store it.

I need to implement the queue logic. Since it's a basic implementation, I can use `collections.deque` for FIFO.
I also need to store results. A dictionary mapping `job_id` to result would work.

Let's think about how jobs are "processed". The prompt says "The queue should store jobs internally until they are processed". It doesn't specify an actual worker thread or processing logic, just the queue structure. I'll add a `process_next()` method or similar, or maybe just simulate processing by storing results in a dict. But the requirement only asks for `add_job` and `get_result`. I should probably add a way to mark jobs as processed or simulate it. Actually, I can just store the job in a deque, and when `get_result` is called, maybe process it? No, that breaks separation of concerns. I'll add a `process()` method that processes the next job and stores the result. Or maybe the user expects me to just implement the storage and FIFO order, and maybe a `process()` method isn't strictly required but makes sense. I'll stick to the required methods and add a simple `process()` or `run()` method to simulate processing, or just store jobs and results internally.

Actually, the prompt says: "Each job has a unique job_id that is returned when added". I'll generate a UUID if not provided, or just use the provided one. The signature says `job_id: str`, so I'll use it.

Let's implement:
```python
import collections

class JobQueue:
    def __init__(self):
        self.queue = collections.deque()
        self.results = {}
        
    def add_job(self, job_id: str, data: dict) -> str:
        self.queue.append((job_id, data))
        return job_id
        
    def get_result(self, job_id: str) -> dict | None:
        return self.results.get(job_id)
        
    def process_next(self) -> dict | None:
        if not self.queue:
            return None
        job_id, data = self.queue.popleft()
        # Simulate processing
        result = {"job_id": job_id, "status": "completed", "data": data}
        self.results[job_id] = result
        return result
```

Wait, the prompt says "Write only the Python code, no explanations."
I should make sure it matches exactly.
Maybe I don't need `process_next`, but the example says "# After processing...". I'll include a `process()` method to make it functional, or maybe the queue is just for storage and the user handles processing. But to be safe, I'll add a `process()` method that processes the next job and stores the result. Alternatively, I can just store jobs and let `get_result` check if it's done, but that's overcomplicating.

Actually, a simpler approach: just store jobs in a deque, and provide a `process()` method. Or maybe the queue itself doesn't need to process, just store. I'll stick to the required methods and add `process()` for completeness.

Wait, the requirement says: "Each job has a unique job_id that is returned when added". I'll generate a unique ID if not provided, but the signature has `job_id` as a parameter. I'll just use it.

Let's refine:
```python
import uuid
import collections
from typing import Dict, Optional

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

    def add_job(self, job_id: str, data: dict) -> str:
        if not job_id:
            job_id = str(uuid.uuid4())
        self._queue.append((job_id, data))
        return job_id

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

    def process_next(self) -> Optional[dict]:
        if not self._queue:
            return None
        job_id, data = self._queue.popleft()
        result = {"job_id": job_id, "status": "completed", "data": data}
        self._results[job_id] = result
        return result
```

The prompt says "Write only the Python code, no explanations."
I'll remove type hints if they cause issues, but they are fine. I'll keep it simple.
Actually, `typing` is standard. I'll just use standard Python.

One thing: `dict | None` is Python 3.10+ syntax. I'll use `Optional[dict]` or just `dict | None` as requested. The prompt uses `dict | None`, so I'll stick with that or just omit hints for the return type if needed, but I'll keep them.

Let's adjust to match exactly:
```python
import collections

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

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

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

    def process(self) -> dict | None:
        if not self._queue:
            return None
        job_id, data = self._queue.popleft()
        result = {"job_id": job_id, "status": "completed", "data": data}
        self._results[job_id] = result
        return result
```

Wait, should I generate unique job_ids automatically? The example shows passing "job1", so it's fine.
The prompt says "Each job has a unique job_id that is returned when added". This might imply I should generate it, but the signature has `job_id` as a parameter. I'll just use the provided one. If they want auto-generation, they would have said `job_id: str = None`. I'll stick to the signature.

Actually, to be safe, I'll generate a UUID if job_id is not provided, but the type hint says `job_id: str`, so it's required. I'll just use it.

I think the implementation is solid. I'll output just the code.
One minor thing: `dict | None` requires Python 3.10+. I'll use `from typing import Optional` to be safe, or just keep `dict | None` as requested. The prompt uses it, so I'll keep it.

Final code:
```python
import collections

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

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

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

    def process_next(self) -> dict | None:
        if not self._queue:
            return None
        job_id, data = self._queue.popleft()
        result = {"job_id": job_id, "status": "completed", "data": data}
        self._results[job_id] = result
        return result
```

Wait, the prompt says "Write only the Python code, no explanations."
I'll make sure it's exactly that.
I'll add a comment about processing if needed, but no.
The example shows:
```python
queue = JobQueue()
job_id = queue.add_job("job1", {"task": "process_data"})
# After processing...
result = queue.get_result("job1")
```
So `process_next` isn't strictly called in the example, but it's implied. I'll keep it.
Actually, maybe the queue should just store jobs and the user processes them externally. The prompt says "The queue should store jobs internally until they are processed". This implies the queue itself might have a processing method, or maybe it's just a storage queue. I'll stick with `process_next`.

One thing: `dict | None` syntax is fine for 3.10+. I'll use it.
I'll output the code now.
All good.
Let's double check requirements:
1. `JobQueue` class with `add_job` and `get_result` - yes
2. FIFO - `deque` handles this - yes
3. Store jobs internally until processed - yes
4. Unique job_id returned - yes
Example matches - yes

I'll produce the code. 
One minor adjustment: I'll use `typing.Optional` to be compatible with older Python versions, or just keep `dict | None` as requested. I'll stick to `dict | None`.
Actually, I'll just write it cleanly.
Done. 
Output matches request.✅
Proceeds. 
Self-Correction/Refinement during thought: 
The prompt says "Each job has a unique job_id that is returned when added". It might be better to generate a UUID if not provided, but the signature explicitly takes `job_id`. I'll keep it as is. If they want auto-generation, they'd change the signature. I'll stick to the given signature.
I'll add `import uuid` just in case, but not use it. Or I'll just use the provided ID.
Actually, to strictly follow "Each job has a unique job_id that is returned when added", I'll generate one if empty, but it's fine.
I'll output exactly the class.
Done. 
Code:
```python
import collections

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

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

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

    def process_next(self) -> dict | None:
        if not self._queue:
            return None
        job_id, data = self._queue.popleft()
        result = {"job_id": job_id, "status": "completed", "data": data}
        self._results[job_id] = result
        return result
```
This looks solid. I'll output it. 
Wait, should I include `typing` imports? Not strictly necessary. I'll keep it simple.
All requirements met.
Output matches.✅
Proceeds. 
(Self-Correction/Note during generation prep)
The prompt says `dict | None` in the method signature. I'll keep that.
I'll make sure there's no extra text.
Done. 
Output generation. 
[Done] 
```python
import collections

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

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

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

    def process_next(self) -> dict | None:
        if not self._queue:
            return None
        job_id, data = self._queue.popleft()
        result = {"job_id": job_id, "status": "completed", "data": data}
        self._results[job_id] = result
        return result
```
This matches all constraints. I will output exactly this. 
One thing: `dict | None` is Python 3.10+. It's fine.
I'll output it now. 
[Final Check]
- Class `JobQueue`? Yes.
- `add_job` returns `job_id`? Yes.
- `get_result` returns `dict | None`? Yes.
- FIFO? `deque` ensures it.
- Stores internally? Yes.
- Unique job_id? Used as provided, which is standard for queues unless auto-generated. I'll add auto-generation just in case, but the signature says `job_id: str`, so it's expected. I'll leave it.
- Example usage works? Yes.
All good. 
Output matches. 
Proceeds. 
[Output Generation] -> *Proceeds*

</reasoning_content>

<content>
```python
import collections

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

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

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

    def process_next(self) -> dict | None:
        if not self._queue:
            return None
        job_id, data = self._queue.popleft()
        result = {"job_id": job_id, "status": "completed", "data": data}
        self._results[job_id] = result
        return result
```
</content>