<reasoning_content>
Thinking Process:

1.  **Analyze the Request:**
    *   Goal: Implement a basic job queue in Python.
    *   Class: `JobQueue`.
    *   Methods:
        *   `add_job(job_id: str, data: dict) -> str`: Add job, return ID.
        *   `get_result(job_id: str) -> dict | None`: Get result of completed job.
    *   Constraints:
        *   FIFO processing.
        *   Internal storage until processed.
        *   Unique job IDs (though the example suggests passing the ID, the requirement says "return job_id" implying it might generate one or validate it. Looking at the example `job_id = queue.add_job("job1", ...)` suggests the caller provides the ID, but standard queue implementations often generate UUIDs. However, the signature `add_job(job_id: str, data: dict) -> str` implies the input ID is used, or a new one is generated. The example shows passing "job1" and assigning it to `job_id`. To be safe and flexible, I'll allow the caller to provide the ID but ensure uniqueness or just use the provided one as the key. Let's look closer: `add_job(job_id: str, data: dict) -> str`. It takes a `job_id` and returns a `str`. Usually, this means the function validates/creates the ID. Given the example `job_id = queue.add_job("job1", ...)` implies the user supplies it. I will assume the user supplies a unique ID for simplicity, or I can generate one if I want to be more robust. However, strict adherence to the signature suggests the ID is an input. But wait, if the signature is `add_job(job_id, data) -> str`, and the example passes "job1", it implies the ID is provided. I will store the job data and mark it as pending.
        *   "Jobs should be processed in FIFO order": This implies there needs to be a mechanism to *process* them. The prompt doesn't explicitly ask for a `process_jobs` method, but it says "The queue should store jobs internally until they are processed". This implies there must be a way to simulate or trigger processing to move jobs from "pending" to "completed" so `get_result` works.
        *   Since it's a basic implementation without external workers, I need a way to simulate the processing. I'll add a `process` method or a mechanism to mark jobs as done.
        *   Actually, looking at the requirements:
            1. `add_job`
            2. `get_result`
            3. FIFO order.
            4. Store internally.
            5. Example shows `add_job` then `get_result`.
            *Crucial point:* How does the job get processed? The prompt doesn't specify a `process` method, but `get_result` needs to return a result. If the job hasn't been processed, it should probably return `None` or wait. For a basic implementation, I should probably add a `process` method (or `process_all`) to simulate the worker consuming the queue.
            *Re-reading:* "Jobs should be processed... The queue should store jobs internally until they are processed".
            If I only implement `add_job` and `get_result`, how does the state change from "pending" to "completed"?
            I will add a `process` method (or similar) to advance the state, or I can make `get_result` return `None` if not processed.
            To make the example work logically:
            1. Add job.
            2. Process job (simulate work).
            3. Get result.
            I will add a private `_process` mechanism or a public `process_job` or `process_all` method to fulfill the "processed" requirement.
            Let's stick to the requested methods primarily, but to make `get_result` return something other than `None`, there must be a way to populate the result.
            I'll add a `process` method that pops from the queue and stores the result.

    *   Refining the `add_job` signature: The example shows `job_id = queue.add_job("job1", ...)`. This implies the ID is passed in. I will use the provided ID as the key.
    *   Refining `get_result`: Returns the result dict if completed, `None` otherwise.
    *   Processing mechanism: I need to simulate the work. I'll add a `process_job(job_id)` or `process_all()` method. Since the prompt didn't explicitly forbid extra methods but asked for specific ones, I should focus on the core requirements. However, without a way to mark a job as done, `get_result` is useless. I will implement a `process()` method that takes the next item in the queue and marks it as completed.

    *   Wait, the prompt asks to "Implement a basic job queue". Usually, a job queue implies a background worker. Since I can't spawn threads easily without complexity, I'll simulate the processing step.
    *   I will add a `process_next` method to move a job from pending to completed.
    *   Actually, to keep it strictly to the requested interface or minimal necessary additions:
        1. `add_job` adds to a queue (list/queue).
        2. `get_result` looks up a completed job in a result store.
        3. To make it work, I'll add a `process()` method (or `process_jobs`) that iterates through the queue and stores dummy results.
        4. Let's ensure FIFO. `collections.deque` is good for the queue.

    *   Plan:
        1. Import `deque` from `collections`.
        2. Store pending jobs in a `deque`.
        3. Store completed results in a `dict`.
        4. Implement `add_job`: Add to pending queue. Store ID.
        5. Implement `process_job` (internal or external): To satisfy "until they are processed", I need a trigger. I'll add a `process` method to simulate the worker.
        6. Implement `get_result`: Check results dict.

    *   Wait, the prompt says "Write only the Python code".
    *   I need to make sure the example usage works.
    *   Example:
        ```python
        queue = JobQueue()
        job_id = queue.add_job("job1", {"task": "process_data"})
        # After processing...
        result = queue.get_result("job1")
        ```
    *   To make `result` return something, I need to simulate the "processing" step between add and get. I will add a method `process_all` or similar to make it functional. Or I can make `get_result` block (not possible in basic sync code easily) or I assume the user calls a processing method.
    *   Best approach: Add a `process` method that executes the jobs in FIFO order and stores the result.

    *   Wait, strict reading: "Create a `JobQueue` class with the following methods: `add_job`, `get_result`". It doesn't explicitly forbid other methods, but implies those are the main ones.
    *   However, if I don't provide a way to process, the example "After processing..." is vague.
    *   I will implement a `process` method that processes the next job in the queue and returns its ID, updating the internal result storage.
    *   Actually, I'll implement a `process_all` or `process` method so the example can be completed logically.
    *   Let's check the constraints again.
    *   "Jobs should be processed in FIFO".
    *   "Queue should store jobs internally until they are processed".
    *   Okay, I will add a `process` method to simulate the worker consuming the queue.

    *   Wait, looking at the signature `add_job(job_id: str, data: dict) -> str`.
    *   If I pass "job1", I should return "job1".
    *   I will store the job data in the queue.
    *   I will store the result in a separate dictionary.

    *   Implementation details:
        *   `self._queue`: `deque` of `(job_id, data)`.
        *   `self._results`: `dict` of `job_id -> result`.
        *   `self._processing`: maybe track status.
        *   `add_job`: append to queue.
        *   `get_result`: return from `self._results`.
        *   `process`: (auxiliary) pop from queue, compute dummy result, save to results.

    *   Wait, should I make `process` part of the class? Yes, otherwise the queue never processes.
    *   I will add a `process` method to make it functional.

    *   Code 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(self):
                if self._queue:
                    job_id, data = self._queue.popleft()
                    # Simulate processing
                    self._results[job_id] = {"status": "completed", "data": data}

            def get_result(self, job_id: str) -> Optional[dict]:
                return self._results.get(job_id)
        ```
    *   Wait, the prompt example:
        ```python
        job_id = queue.add_job("job1", {"task": "process_data"})
        # After processing...
        result = queue.get_result("job1")
        ```
    *   This implies the processing happens asynchronously or via a call. Since I need to write code that works, I should probably include the processing logic. I'll add a `process_all` or just `process` method. I'll stick to `process` to simulate one job completion or `process_all` to clear the queue. `process_all` makes the example easier to complete.
    *   Let's refine `add_job`. It says "return job_id".
    *   Let's refine `get_result`. "return dict | None".

    *   One detail: "Jobs should be processed in FIFO".
    *   If I don't add a `process` method, the user doesn't know how to trigger it. I will add `process` method to the class definition.

    *   Wait, is there any constraint on *only* those two methods? "Create a `JobQueue` class with the following methods: ...". It usually means "at least these methods". Adding a `process` method is necessary for the "processed" state to change.

    *   Let's write the code.

    *   Wait, I should check if `job_id` needs to be generated. The signature `add_job(job_id: str, data: dict) -> str` implies `job_id` is input. The example passes "job1". I will use the passed ID.

    *   Wait, one edge case: Duplicate job IDs. I should probably handle that or assume uniqueness. I'll assume uniqueness based on the example, but I'll store the status to ensure it's processed only once.
    *   Also, `get_result` should return `None` if the job exists in the queue but isn't processed yet.

    *   Revised Plan:
        1. Import `deque`.
        2. Define class `JobQueue`.
        3. `__init__`: Initialize `deque` and `results_dict`.
        4. `add_job`: Add to queue, return ID.
        5. `process`: Helper to move from queue to results. (Necessary for the "processed" requirement). I'll call it `process` or `process_jobs`. Let's use `process` to process the next job.
        6. `get_result`: Return from results dict.

    *   Wait, if I add `process`, does it violate "Create a `JobQueue` class with the following methods"? Usually, it implies the public interface required. Additional helper methods are fine.
    *   However, to strictly follow the example logic:
        `queue = JobQueue()`
        `job_id = queue.add_job(...)`
        `queue.process()` # Implicitly needed
        `result = queue.get_result(...)`
    *   I'll include a `process` method.

    *   Wait, looking at the prompt again: "Write only the Python code, no explanations."
    *   I will write the class.

    *   Wait, I need to make sure I don't miss imports.
    *   I will use `typing` for type hints.

    *   Final check on constraints:
        *   `add_job(job_id: str, data: dict) -> str`
        *   `get_result(job_id: str) -> dict | None`
        *   FIFO.
        *   Store internally.
        *   Unique ID.

    *   Okay, I'll implement `process` as a method to simulate the worker consuming the queue.

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

class JobQueue:
    def __init__(self):
        self._queue = 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(self):
        if self._queue:
            job_id, data = self._queue.popleft()
            # Simulate job processing
            self._results[job_id] = {"status": "completed", "result": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id)
```
    *   Wait, should I add a `process_all` method to make it easier for the user to test? `process` processes one. `process_all` processes all.
    *   The requirement says "Jobs should be processed...".
    *   I will add a `process` method.
    *   Also, I should ensure the return type matches `dict | None` (Python 3.10+ syntax or `Optional[dict]`). I'll use `Optional[dict]` for compatibility.
    *   I'll stick to the requested methods but add `process` to make it functional, as a queue without processing is incomplete based on the "processed" requirement.
    *   Actually, I can make `get_result` return `None` if not processed.
    *   Let's ensure the code is clean.

    *   One more thing: The prompt example shows `job_id = queue.add_job("job1", ...)`.
    *   If I look strictly at "Create a JobQueue class with the following methods", I should probably not add extra public methods if not needed, but `process` is logically required for the "processed" state. I will add `process` as a public method to allow the user to trigger the processing.

    *   Wait, I can also implement `get_result` to process lazily? No, that violates FIFO processing logic usually.
    *   I will add `process` method.

    *   Wait, I should check if I need to handle the case where `job_id` is not found. `get_result` returns `None`.
    *   I will write the code now.

```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(self):
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id)
```
    *   Wait, I should check if `process` is required by the prompt requirements strictly. It lists `add_job` and `get_result`. It says "Jobs should be processed...". It doesn't explicitly list a `process` method, but for the functionality to work (state change from pending to completed), a mechanism is needed. I will include `process` as it's standard for a queue implementation where the consumer needs to pop.
    *   However, to be safest, I could make `get_result` return the result if it exists, but without `process`, it never exists.
    *   I will add `process` method.

    *   Wait, I'll check the example again.
    *   `job_id = queue.add_job("job1", {"task": "process_data"})`
    *   `# After processing...`
    *   `result = queue.get_result("job1")`
    *   The comment `# After processing...` implies the user performs processing.
    *   So I need a method to do that. I'll name it `process`.

    *   One detail: `job_id` uniqueness. The prompt says "Each job has a unique job_id that is returned when added". It implies the ID provided is unique or the system ensures it. Since the signature takes `job_id`, I will assume the caller provides a unique one.

    *   Final check on imports. `typing` is standard. `collections` is standard.
    *   I will use `Optional` for return type.
    *   I will use `deque` for FIFO.

    *   Wait, I can combine `process` into `get_result`? No, that's lazy processing, might not be desired.
    *   I will stick to explicit `process`.

    *   Wait, I should make sure I don't use features incompatible with standard Python environments (like 3.10+ type hints `|` vs `Optional`). The prompt uses `dict | None` in the text, but Python 3.9+ supports `|`. I'll use `Optional[dict]` for broader compatibility or `dict | None` if I assume 3.10. I'll use `Optional[dict]` to be safe. Actually, the prompt used `dict | None` in the text description. I'll stick to standard typing.

    *   Wait, I need to make sure I don't add unnecessary comments.

    *   Wait, one more thing. The prompt asks for "Write only the Python code".
    *   I will provide the class definition.

    *   Let's refine the `process` method. It should probably process *all* jobs or just one? "Jobs should be processed...". Usually, a worker processes one at a time. I'll implement `process` to handle one, or `process_all`. `process` is safer for a queue.
    *   I'll add `process` to process the next job.

    *   Wait, I'll check if I can make it work without `process` by having `get_result` block? No, blocking requires threading.
    *   I'll add `process`.

    *   Wait, I'll check the signature `add_job(job_id: str, data: dict) -> str`.
    *   If I return `job_id`, I should just return the input `job_id`.

    *   Okay, ready to write.

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

class JobQueue:
    def __init__(self):
        self._queue = 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(self):
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id)
```
    *   Wait, I should check if I need to handle duplicate job IDs in `add_job`. The requirement says "Each job has a unique job_id". I will assume the input is unique.
    *   The code looks solid.

    *   Wait, I'll remove the `process` method if I want to be strict about "with the following methods". But without it, `get_result` is static. I'll keep `process` because "until they are processed" implies a state transition mechanism.

    *   Wait, I'll check if I should use `Optional` or `|`. The prompt uses `dict | None`. I will use `dict | None` in type hints to match the prompt style if I can, but `Optional` is more standard in older Python. I'll use `Optional` for compatibility. Actually, I'll use `dict | None` since the prompt used it. It requires Python 3.10+. I'll use `Optional` to be safe across versions usually expected in interview settings, but the prompt used `dict | None`. I will use `Optional` to be safe.

    *   Wait, I'll check the `process` method logic. It simulates work. I'll just store the data.
    *   Okay, I will finalize the code.

    *   One more check: "Write only the Python code". No markdown blocks? Usually markdown blocks are expected for code. I will use markdown code block.
    *   Wait, "Write only the Python code" might mean no markdown ticks. But usually it means "no text explanation". I will use markdown ticks for clarity.
    *   Actually, I'll just output the code block.

    *   Wait, I need to make sure I don't import `typing` if I use `dict | None`. `dict | None` is valid in Python 3.10+. `Optional` requires import. I will use `Optional` and import `typing`.

    *   Wait, I will ensure `process` is available.
    *   Okay.

    *   Wait, I'll double check the `get_result` return type. `dict | None`.
    *   Okay.

    *   Final check on `add_job`. `job_id: str, data: dict`. Returns `str`.
    *   Okay.

    *   Wait, I should consider if `process` should be `process_all`. The example comment `# After processing...` suggests the user might want to process all. `process` processes one. `process_all` processes all. I'll add `process` as it's more granular. Or I can add `process_jobs` to clear the queue. Let's stick to `process` for one job, it's standard.
    *   Actually, to make the example work easily, `process` is sufficient.

    *   Wait, I'll remove the `Optional` import if I use `dict | None`.
    *   I will use `Optional` to be explicit.

    *   Okay, writing the code.

```python
from collections import deque
from typing import 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(self):
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id)
```
    *   Wait, I'll check if I need to handle the case where `job_id` is already in `_results`. I'll just overwrite or ignore. Overwriting is fine for "completed".
    *   I'll ensure the code is clean.

    *   Wait, one detail from the prompt: "Each job has a unique job_id that is returned when added".
    *   The example passes "job1".
    *   I will return the passed `job_id`.

    *   Okay, ready.

</reasoning_content>

<content>
```python
from collections import deque
from typing import 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(self):
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

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