G: TL;DR:
Brown sausage → remove → cook mushrooms hard → add peppers → add garlic/seasoning → return sausage → toss with noodles.

---

Here’s the logic-driven order (minimizes sogginess and flavor loss):

1. Kielbasa first

• Medium-high heat, little/no oil (it has its own fat).
• Get real browning on the slices.
• Remove and set aside.
• Reason: you want that fond (brown bits) left behind, not steamed sausage later.

---

2. Mushrooms next (alone)

• Add a bit of oil/butter if pan is dry.
• High-ish heat, don’t crowd, don’t salt immediately.
• Let them dump moisture, then re-brown.

👉 This is the step most people mess up—if you mix them early, they steam everything else.

---

3. Peppers go in

• Once mushrooms are browned, add sliced peppers.
• Now you can add a pinch of salt.
• Cook until softened but still slightly firm.

---

4. Aromatics / seasoning (optional but recommended)

• Garlic, black pepper, maybe paprika or a splash of vinegar.
• 30–60 seconds max so garlic doesn’t burn.

---

5. Return sausage

• Add kielbasa back in.
• Toss to reheat and combine flavors.

---

6. Add noodles

• Ideally slightly undercooked and a bit wet (carryover starch helps).
• Toss everything together.
• If dry: small splash of pasta water or butter.

---

Key principle

Each ingredient gets its own phase based on moisture behavior:

• Sausage = fat + browning
• Mushrooms = water dump → browning
• Peppers = soften
• Then combine

If you skip the separation, everything trends toward gray and soft instead of distinct textures.