<reasoning_content>
The user wants a basic job queue implementation in Python.
Requirements:
- Class `JobQueue`
- Method `add_job(job_id: str, data: dict) -> str`: Adds a job, returns job_id
- Method `get_result(job_id: str) -> dict | None`: Returns result of completed job, or None
- FIFO processing order
- Stores jobs internally until processed
- Each job has a unique job_id

Wait, the requirements don't specify how jobs are processed. It just says "Jobs should be processed in FIFO order" and "The queue should store jobs internally until they are processed". This implies there might be a processing mechanism, or maybe I just need to simulate processing, or perhaps the class should have a method to process jobs? The example shows adding a job and then getting a result "after processing", but doesn't show how processing happens.

I should probably add a `process()` or `process_all()` method, or maybe the queue processes jobs automatically in the background? Since it's a "basic" job queue, I'll implement a simple synchronous processing method, or perhaps just store jobs and provide a way to mark them as complete. But the requirement says "Jobs should be processed in FIFO order", which usually implies there's a worker or a process method.

Let's re-read carefully: "The queue should store jobs internally until they are processed". This suggests I might need a `process()` method or similar. But it's not explicitly required in the method list. I'll stick to the required methods and maybe add a `_process_jobs()` or just assume the user will call a processing method, or I can make `get_result` trigger processing? No, that's not standard.

Actually, a simple implementation could just use `collections.deque` for the queue and a dictionary for results. I'll add a `process()` method that processes the next job, or `process_all()`. But the prompt says "Write only the Python code, no explanations." and lists only two methods in requirements. I'll stick to exactly what's asked, but I need to handle the "processing" part somehow. Maybe I'll add a `process()` method that takes a function, or just simulate processing by marking jobs as complete? Or maybe the queue is just a data structure that holds jobs, and the "processing" is external? The example shows `# After processing...`, implying external processing.

Wait, maybe I should just implement a simple queue that stores jobs, and provide a `process()` method that processes the next job in FIFO order using a provided function? Or maybe it's simpler: just store jobs in a deque, and `get_result` returns the result if processed, else None. I'll add a `process()` method that processes the next job. But to keep it simple and match the requirements exactly, I'll just implement the two methods, and maybe add a `_jobs` dict and a `_queue` deque. For processing, I'll assume the user will call a method like `process()` or I'll just leave it as a storage queue. Actually, many basic job queue implementations just use `queue.Queue` or `collections.deque`. I'll implement it with `collections.deque` and a dict for results.

Let's think about what "processed" means. It could mean the job's data is transformed somehow. Since no processing function is given, I'll just store the data as the result, or maybe I should add a `process()` method that pops from the queue and stores a dummy result? Or maybe the requirement implies that the queue itself should have a method to process jobs. I'll add a `process()` method that processes the next job (e.g., just marks it as completed and stores the original data as result, or maybe applies a simple transformation). Actually, it's safer to just implement the queue structure and add a `process()` method that returns the next job's result, or just store jobs and let external code process them. But the prompt says "Jobs should be processed in FIFO order", which might just mean the internal storage order is FIFO.

I'll implement:
- `__init__`: `self._queue = collections.deque()`, `self._results = {}`
- `add_job`: append to deque, store in results dict with None, return job_id
- `get_result`: return result if exists, else None
- I'll add a `process()` method that pops the first job, computes a result (maybe just returns the data or a dict with status), and stores it. But since no processing logic is specified, I'll just store the job data as the result, or maybe I'll add a `process_all()` or just leave it as is. Actually, I can make `get_result` trigger processing? No.

Wait, the example shows:
```python
queue = JobQueue()
job_id = queue.add_job("job1", {"task": "process_data"})
# After processing...
result = queue.get_result("job1")
```
This implies that somewhere between adding and getting result, the job is processed. I'll add a `process()` method that processes the next job in the queue. To make it useful, I'll assume processing just marks it as complete and returns the original data as result, or maybe I'll add a `process_job(job_id)` method. But the requirement doesn't ask for it. I'll just implement the two methods, and maybe add a `_is_processed` flag or just store results in a dict. I'll also add a `process()` method that processes the next job in FIFO order.

Actually, a simpler interpretation: The queue stores jobs. When `get_result` is called, if the job hasn't been processed, it returns None. The "processing" is external or simulated. I'll just implement the storage and FIFO order using `deque`. I'll add a `process()` method that pops from the queue and stores a result. To keep it minimal and compliant, I'll just implement exactly what's asked, plus necessary internals.

Let's draft:
```python
import collections

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

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append(job_id)
        self._jobs[job_id] = data
        self._results[job_id] = None
        return job_id

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

    def process(self):
        if self._queue:
            job_id = self._queue.popleft()
            # Simulate processing
            self._results[job_id] = {"status": "completed", "data": self._jobs[job_id]}
```

But the requirement says "Jobs should be processed in FIFO order". It doesn't explicitly require a `process()` method, but it's implied. I'll include it. Alternatively, maybe the queue should process automatically? No, that's overcomplicating.

Wait, maybe I should just use `queue.Queue` from standard library? But the requirement says "Create a JobQueue class with the following methods", so I'll implement it from scratch.

Another thought: The prompt might be from a coding test where they just want the class with those two methods, and the "processing" is just conceptual. I'll stick to the two methods plus maybe a `process()` method for completeness, or I'll just implement exactly what's asked. I'll add a `process()` method but keep it simple. Actually, I'll just implement the two methods and store jobs in a list/deque. For `get_result`, I'll return the result if it exists. I'll also add a `_processed` flag or just store results in a dict.

Let's refine:
```python
import collections

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

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append(job_id)
        self._job_data[job_id] = data
        self._results[job_id] = None
        return job_id

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

This satisfies the requirements. The "processing" part can be handled externally or via an added method. I'll add a `process()` method that processes the next job in FIFO order, as it's standard for a job queue. But the prompt says "Write only the Python code, no explanations." so I'll just provide the class.

Actually, I'll make `get_result` return `None` if not processed, and add a `process()` method that processes the next job. To be safe, I'll just implement exactly what's asked. I'll also add type hints as requested.

Wait, the prompt says: "Jobs should be processed in FIFO order". This might mean that when you call a `process()` method, it processes them in FIFO. I'll add it.

Let's consider if the prompt expects a background thread? Unlikely for "basic".

I'll implement:
```python
import collections
from typing import Optional

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

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append(job_id)
        self._jobs[job_id] = data
        self._results[job_id] = None
        return job_id

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

    def process(self) -> Optional[dict]:
        if self._queue:
            job_id = self._queue.popleft()
            result = {"status": "completed", "data": self._jobs[job_id]}
            self._results[job_id] = result
            return result
        return None
```

But the requirement only lists `add_job` and `get_result`. I'll stick to those two to be precise, but I'll add `process` if needed. Actually, many such problems just want the storage and FIFO order. I'll keep it simple.

Wait, maybe the "processing" is just conceptual, and the queue just stores jobs. I'll provide exactly what's asked.

One more thing: `dict | None` is Python 3.10+ syntax. I'll use `Optional[dict]` or keep `dict | None` as requested. The prompt uses `dict | None`, so I'll use that.

I'll write the code now. I'll make sure it's clean and matches requirements.

```python
import collections

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

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append(job_id)
        self._job_data[job_id] = data
        self._results[job_id] = None
        return job_id

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

This is minimal and meets all stated requirements. I'll add a `process()` method just in case, but the prompt doesn't ask for it. I'll stick to the two methods. Actually, the prompt says "Jobs should be processed in FIFO order", which might imply I should include a processing mechanism. I'll add a `process()` method that processes the next job, but I'll make it optional or just include it. To be safe, I'll include it.

Wait, re-reading: "The queue should store jobs internally until they are processed". This strongly implies there's a processing step. I'll add `process()` and `process_all()`. But I'll keep it simple: just `process()` that processes the next job.

Actually, I'll just implement exactly what's requested. The "processing" can be simulated or external. I'll provide the class with the two methods. If they want processing, they can call a method I add. I'll add `process()` to be thorough.

Final decision: I'll implement the class with `__init__`, `add_job`, `get_result`, and `process`. I'll use `collections.deque` for FIFO. I'll return `dict | None` as specified.

Let's write it out.
I'll make sure type hints match exactly.
```python
import collections

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

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append(job_id)
        self._jobs[job_id] = data
        self._results[job_id] = None
        return job_id

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

    def process(self) -> dict | None:
        if self._queue:
            job_id = self._queue.popleft()
            result = {"status": "completed", "data": self._jobs[job_id]}
            self._results[job_id] = result
            return result
        return None
```

This covers everything. I'll output only the code.
One minor thing: `dict | None` is valid in Python 3.10+. The prompt uses it, so I'll keep it.
I'll remove comments and extra fluff.
Ready.✅
Output matches request.✅
Proceeds. 
Self-Correction/Refinement during thought: 
The prompt says "Write only the Python code, no explanations." I will strictly follow that.
I'll make sure the class name is exactly `JobQueue`.
I'll use `typing.Optional` or `dict | None` as given. I'll stick to `dict | None`.
The code looks solid.
Output matches.✅
Proceeds. 
```python
import collections

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

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append(job_id)
        self._jobs[job_id] = data
        self._results[job_id] = None
        return job_id

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

    def process(self) -> dict | None:
        if self._queue:
            job_id = self._queue.popleft()
            result = {"status": "completed", "data": self._jobs[job_id]}
            self._results[job_id] = result
            return result
        return None
```
This satisfies all constraints. I'll output it. 
Wait, should I include `process`? The requirements only list `add_job` and `get_result`. I'll include it because of "Jobs should be processed in FIFO order". It's better to have it. If not needed, it doesn't hurt. I'll keep it.
Actually, to be strictly compliant, I'll just provide the two methods plus necessary internals. The processing can be done externally or via a simple method. I'll keep `process`.
Done. 
Output matches.✅
Proceeds. 
[Output Generation] -> *Proceeds*

</reasoning_content>

<content>
```python
import collections

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

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append(job_id)
        self._jobs[job_id] = data
        self._results[job_id] = None
        return job_id

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

    def process(self) -> dict | None:
        if self._queue:
            job_id = self._queue.popleft()
            result = {"status": "completed", "data": self._jobs[job_id]}
            self._results[job_id] = result
            return result
        return None
```
</content>