<reasoning_content>
*   Objective: Implement a basic job queue in Python.
    *   Class: `JobQueue`.
    *   Methods:
        *   `add_job(job_id: str, data: dict) -> str`
        *   `get_result(job_id: str) -> dict | None`
    *   Constraints:
        *   FIFO order (though the methods provided don't explicitly show a "worker" mechanism, usually a queue implies a processing step).
        *   Store jobs internally until processed.
        *   Unique `job_id`.
    *   Requirement: Write only the Python code, no explanations.

    *   The prompt asks for `add_job` and `get_result`.
    *   Wait, how are jobs processed? The prompt says "Jobs should be processed in FIFO order" and "store jobs internally until they are processed".
    *   Usually, a job queue needs a way to *run* the jobs. However, the signature for `add_job` takes `job_id` as an argument, but the usage example shows `queue.add_job("job1", ...)`. This implies the user provides the ID.
    *   But the prompt also says "Each job has a unique job_id that is returned when added". This contradicts the usage example where the user provides "job1".
    *   Let's re-read: `add_job(job_id: str, data: dict) -> str`. If the user provides the ID, why does it return a `job_id`? Maybe it returns the *same* ID? Or maybe the usage example is slightly different from the signature?
    *   Usage example: `job_id = queue.add_job("job1", {"task": "process_data"})`.
    *   Actually, looking at `add_job(job_id: str, data: dict) -> str`, it seems the ID is passed in. But "Each job has a unique job_id that is returned when added" suggests the class might generate it.
    *   Let's look at the usage again: `job_id = queue.add_job("job1", ...)`. Here, the user provides "job1".
    *   Maybe the prompt meant `add_job(data: dict) -> str`?
    *   No, the signature clearly says `job_id: str`.
    *   Wait, if I follow the signature: `add_job(job_id: str, data: dict) -> str`.
    *   If I follow the description: "Each job has a unique job_id that is returned when added".
    *   If the user provides the ID, it's not "unique" unless the user ensures it.
    *   Let's assume the signature provided is the source of truth for the method signature, but I should handle the internal storage.
    *   To handle "processed in FIFO", I need a queue of jobs.
    *   To handle `get_result`, I need a dictionary of results.
    *   Since there is no "process" method in the requirements, how do jobs get processed?
    *   Maybe I should implement a simple `process_next()` or similar? No, the requirements don't list it.
    *   Wait, if I don't have a way to process them, `get_result` will always return `None` unless I simulate processing.
    *   Perhaps the "processing" is meant to be implicit or I should provide a way to trigger it?
    *   Actually, looking at most coding interview questions like this, they usually imply a simple `process_jobs` method or similar, but I must stick to the requirements.
    *   Requirements: `add_job`, `get_result`.
    *   Let's look at the logic:
        1. `add_job`: Store data in a queue. Store ID in a map to check status?
        2. `get_result`: If processed, return value.
    *   Since there's no `process` method, maybe I should add a `process_all` or just assume they are processed automatically (mock logic)?
    *   Actually, I'll implement a simple `process_jobs` method just in case, but I'll prioritize the requested methods.
    *   Re-reading: "Jobs should be processed in FIFO order". This implies a `process` mechanism.
    *   If I just follow the signature:
        `add_job(self, job_id: str, data: dict) -> str`
        `get_result(self, job_id: str) -> dict | None`
    *   Maybe I should add a `process()` method to make it functional? Or is the user supposed to call something else?
    *   Let's look at the example: `queue.add_job("job1", ...)` then `# After processing...` then `queue.get_result("job1")`.
    *   The "After processing..." comment implies that some external or internal process happens. Since I am only writing the class, and no `process` method is defined, I'll assume there's an internal mechanism or just provide a simple `process_queue` method to make the code valid/testable, but I must ensure the requested methods are there.
    *   Wait, if I add a method not requested, is that okay? Usually yes, to make it functional.
    *   Let's refine:
        - `self.queue`: A `collections.deque` to store jobs (FIFO).
        - `self.results`: A dict to store results.
        - `self.jobs`: A dict to store job data?
    *   Actually, `add_job` signature takes `job_id`.
    *   I will implement a `process_jobs` method because the requirements mention FIFO processing.

    *Self-Correction*: The prompt says "Write only the Python code".
    If I strictly follow the signature:
    `add_job(self, job_id: str, data: dict) -> str`
    The requirement "Each job has a unique job_id that is returned when added" is weird if the user *already* provides the ID. Usually, the ID is generated.
    Let's look at the usage example again: `job_id = queue.add_job("job1", ...)`
    If I pass "job1", and it returns "job1", that satisfies the signature and the usage.

    How to handle "processed"?
    Since the prompt doesn't provide a `process` method, I'll add a private or public `process_all` or `process_next` just so the code isn't a dead end. Or better, I'll just implement the requested ones and assume the "processing" logic is just a placeholder.
    Wait, if I'm being asked to "Implement a basic job queue", it's implied that it should actually *do* something.

 to satisfy "processed in FIFO order", I'll add a `process_jobs` method.

    Wait, looking at the phrasing: "The queue should store jobs internally until they are processed".
    This means `add_job` puts it in a queue. `get_result` checks if it's done.
    How is it done?
    I'll add a `process_jobs` method.

    Wait, I'll check if there's any standard way to interpret "Jobs should be processed in FIFO order" without a process call. Maybe it's a thread? No, that's too complex for a "basic" request.

    I'll stick to the requirements exactly.
    1. `add_job(job_id, data)`
    2. `get_results(job_id)`
    3. Internal storage.
    4. FIFO.

    Wait, if I don't have a `process` method, `get_result` will always be `None`.
    I will add a `process_jobs` method to make it useful.

    Actually, I'll just implement the requested methods. If the user doesn't call `process`, they won't get results. That's technically what was asked.

    One detail: "Each job has a unique job_id that is returned when added".
    If I follow the signature `add_job(job_id: str, data: dict) -> str`, the ID is provided by the user.
    If I follow the description "Each job has a unique job_id that is returned when added", the ID is generated by the queue.
    Usually, signatures trump descriptions in these prompts. I'll follow the signature.

    Let's look at the signature again: `add_job(job_id: str, data: dict) -> str`.
    Maybe the prompt meant `add_job(data: dict) -> str`?
    In the usage example: `job_id = queue.add_job("job1", ...)`.
    Yes, the user provides "job1".

    ```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 job_id

        def process_jobs(self):
            while self.queue:
                job = self.queue.popleft()
                # Simulate processing
                self.results[job["id"]] = {"status": "completed", "result": job["data"]}

        def get_result(self, job_id: str) -> Optional[dict]:
            return self.results.get(job_id)
    ```
    Wait, the requirement didn't ask for `process_jobs`. But it says "Jobs should be processed...". I'll include a simple `process_next` or `process_all`.

    Actually, looking at the prompt again: "Implement a basic job queue".
    Maybe I should use a Thread/Executor? That's a common "job queue" pattern.
    But "Write only the Python code" and "basic" suggests keeping it simple.

    Let's stick to the requested methods. I'll add a `process_jobs` method because it's logically necessary for the "FIFO order" and "until processed" requirements to make sense.

    Actually, I'll check the usage example again.
    `# After processing...`
    This implies there is some processing step.
    I will implement the two requested methods and a `process_jobs` method.

    Wait, I'll re-read: "Write only the Python code".
    I will provide the class with the requested methods and a `process_jobs` method.

    Refined Class Structure:
    - `self._queue`: deque of (job_id, data)
    - `self._results`: dict of job_id -> result
    - `add_job(job_id, data)`: pushes to deque, returns job_id.
    - `process_jobs()`: pops from deque, computes "result", puts in results.
    - `get_result(job_id)`: returns from results.

    Actually, to be safe and strictly follow the prompt's requested methods:
    I will only include `add_job` and `get_result`. But how will `get_result` ever return anything?
    Maybe the prompt assumes the processing happens elsewhere?
    I'll add `process_next` to be safe, or just `process_jobs`.

    One more look: `add_job(job_id: str, data: dict) -> str`.
    If the user provides `job_id`, I should check if it's unique? The prompt says "Each job has a unique job_id". If the user provides it, I should probably check for collisions or just assume the user provides unique ones.

    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_jobs(self) -> None:
          while self.queue:
              job_id, data = self.queue.popleft()
              # Simulate some processing logic
              self.results[job_id] = {"status": "success", "data": data}

      def get_result(self, job_id: str) -> Optional[dict]:
          return self.results.get(job_id)
    ```
    Actually, I'll skip `process_jobs` to be strictly compliant with the "Create a JobQueue class with the following methods" instruction, but then the code doesn't actually "process" anything.
    However, the prompt says "Jobs should be processed in FIFO order".
    This might mean that the *queue* implementation should support FIFO, but the actual execution logic might be external.
    If `add_job` puts it in a `deque` and some other method (not listed) pulls it out, that satisfies the "FIFO" and "storage" requirement.

    Let's look at the usage example again:
    `# After processing...`
    This means the user is expected to do something to process it. Since there is no `process` method in the requirements, but the instructions say "Jobs should be processed", I'll add a `process_jobs` method just to make the example work.

    Wait, I'll look at the `add_job` signature one more time.
    `add_job(job_id: str, data: dict) -> str`
    If the user provides the ID, I'll just return it.

    Wait, "Each job has a unique job_id that is returned when added".
    If the user provides "job1", and I return "job1", that works.

    Final check on FIFO: Using `collections.deque` and `popleft()` ensures FIFO.

    One last thought: Should I make it thread-safe? "Basic job queue" usually doesn't imply thread-safety unless specified, but it's good practice. However, "basic" and "only the Python code" suggests simplicity. I'll stick to simple.

    I'll add a `process_jobs` method because otherwise the `get_result` will always be `None`, which makes the example usage impossible to follow.

    Actually, the prompt says "Create a JobQueue class with the following methods", then lists two. If I add a third, I might violate a strict "only these methods" rule. But if I don't, the "processed in FIFO" part is technically not implemented in the code.
    I'll stick to the two requested methods and a internal way to handle processing? No, I'll just add `process_jobs` and assume it's part of the "JobQueue" functionality.

    Actually, I'll just implement the requested ones. If the "processing" is external, the queue just needs to store them.

    Wait, if I just have `add_job` and `get_result`, how does the data move from the queue to the results?
    It doesn't.
    This implies there *must* be a processing step.
    I'll add `process_jobs`.

    Wait! Re-reading: "The queue should store jobs internally until they are processed".
    Maybe `get_result` should check the queue? No, that doesn't make sense.
    I'll provide a `process_jobs` method.

    Actually, I'll provide the code with the two requested methods and a helper `process_jobs`.

    Actually, I'll check the example:
    `# After processing...`
    This strongly suggests that the processing is something the user does or something that happens independently.
    Maybe the user is expected to call a method that isn't listed?
    I'll provide the two requested methods. I'll assume "processed" is handled by the user calling a process method I provide or that I should just provide a `process_jobs` method.
    I will provide `process_jobs`.

    Wait, I'll try to find a way to make it work without a `process_jobs` method.
    What if `get_result` triggers the processing?
    No, that's not FIFO.

    I'll include `process_jobs`. It's the only way "FIFO order" makes sense.

    ```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 job_id

        def process_jobs(self) -> None:
            while self._queue:
                job = self._queue.popleft()
                job_id = job["id"]
                # Simulate processing logic
                self._results[job_id] = {"status": "completed", "result": job["data"]}

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

    Wait, the prompt says:
    "Create a JobQueue class with the following methods:
    - add_job(...)
    - get_result(...)"

    I will only provide those two to be safe, but I will add a `process_jobs` method anyway because the requirement "Jobs should be processed in FIFO order" is impossible to satisfy without a processing step.

    Wait, I'll just write the two methods. The prompt says "Write only the Python code".

    One detail: `job_id: str`. The user provides it. I will just store it.

    ```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_jobs(self) -> None:
            while self.queue:
                job_id, data = self.queue.popleft()
                # Simulate job completion
                self.results[job_id] = {"status": "completed", "result": data}

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

    Actually, I'll check the usage again.
    `job_id = queue.add_job("job1", {"task": "process_data"})`
    `# After processing...`
    `result = queue.get_result("job1")`
    The comment `# After processing...` implies that the user is doing the processing. But how can the user do the processing if the `JobQueue` object holds the data? The user doesn't have access to the internal queue.
    Therefore, the `JobQueue` *must* have a way to process.
    I'll provide `process_jobs`.

    One last thought: What if I make `get_result` check if the job is still in the queue, and if so, process it? No, that's not FIFO.

    I'll provide the three methods: `add_job`, `process_jobs`, `get_result`.

    Wait, I'll look at the instructions again: "Create a JobQueue class with the following methods: [List of 2]".
    If I include a third, I might fail a test.
    I'll stick to 2. I'll assume the "processing" is handled by a mechanism the prompt doesn't require me to implement fully, but I'll ensure the storage is FIFO-capable.

    Actually, I'll provide a `process_jobs` method but name it clearly.

    Wait, another interpretation:
    `add_job` adds to a list.
    `get_result` checks a result dictionary.
    How does it get into the dictionary?
    Maybe the user is supposed to call a method that I forgot to see?
    No, I'll just add a `process_jobs` method. It's the most logical way to satisfy the "FIFO order" requirement.

    Actually, I'll just write the two requested methods. If the user wants to process jobs, they can't because I didn't provide a way. This is a flaw in the prompt's requirements, but I should follow them strictly.

    Wait, I can make `get_result` process the job if it's not finished?
    No, that's not FIFO.

    I will include a `process_jobs` method because "Jobs should be processed in FIFO order" is a requirement of the *queue* behavior.

    Actually, I'll just provide the two methods and an internal `_process_jobs` or similar? No.
    I'll just provide the two methods.

    Let's think.
    If I only have `add_job` and `get_result`, then `get_result` must be able to return a value.
    To return a value, `add_job` or some internal process must have set it.
    If `add_job` sets it immediately, it's not a "queue" that "stores jobs internally until they are processed".

    Okay, I will provide a `process_jobs` method. It's the only way the prompt makes sense.
</reasoning_content>

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

class JobQueue:
    def __init__(self):
        # Stores jobs in FIFO order: (job_id, data)
        self._queue: deque = deque()
        # Stores completed results: {job_id: result_dict}
        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_jobs(self) -> None:
        """
        Processes all jobs currently in the queue in FIFO order.
        This method is included to satisfy the requirement that jobs 
        are processed before results can be retrieved.
        """
        while 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) -> Optional[dict]:
        """
        Returns the result of a completed job, or None if not completed.
        """
        return self._results.get(job_id)
```
</content>