At Senior and Staff, the behavioural rounds set your level as much as system design does. Interviewers listen for scope (how far your decisions reached), judgment (what you chose not to do) and ownership of failures. Keep 8–10 stories, each told in about two minutes, and map every one to several prompts.
| Beat | What to say | Senior (L5) | Staff (L6) |
|---|---|---|---|
| Situation | One or two lines, with the scale in numbers. | "Our team's order service…" | "Three teams depended on…" |
| Task | What you owned. Say "I", not "we". | Delivering a project | Choosing the direction, often against a default |
| Action | 2–4 decisions with the trade-off each one made. | Design and execution | Aligning people, changing how others work, cutting scope |
| Result | A number, and what happened afterwards. | Team metric moved | Org-level change that outlived your involvement |
| Reflection | What you would do differently. Interviewers often ask for it, and a ready answer scores well. | Same at both levels. Have a real answer ready. | |
A filled-in bank: three rows for a backend developer
An example, not a script. Your bank is a table like this: one row per story, one line for each beat, and a tag for every question it can answer. The facts are made up to show the shape; use your own.
| Story | Situation and task (with a number) | Action (your decisions) | Result and reflection | Questions it answers |
|---|---|---|---|---|
| Payment retries double-charged users | Checkout service, about 40k orders a day. A timeout made clients retry, and 0.3% of orders were charged twice. I owned the fix. | Added an idempotency key per order (rejected a lock: it would not survive a restart). Refunded affected users first. Wrote the incident review. | Duplicates went to zero over the next quarter. Next time I would add the key before launch, not after the incident. | A production incident you led · A mistake · A design decision with a rejected option · Ownership |
| I said no to a launch feature | Two weeks to a launch date. A PM wanted bulk export on top of the core flow. I owned the delivery plan for four engineers. | Showed the cost in days and the risk to the core flow. Proposed a smaller export, a CSV for one report. The PM agreed after one meeting. | Launched on the date with no Sev-1. Full export shipped six weeks later. I would bring the cost estimate to the PM earlier. | What you chose not to build · Disagree and commit · Deliver under a deadline · Judgment |
| Helping a junior own a service | A new engineer on my team was only fixing small bugs. Goal: have them own the notifications service in six months. | Weekly 30-minute reviews of their designs, then I stepped back from the on-call rota for that service so they had to decide. | They ran two releases alone and later trained the next hire. Reflection: I stepped back a month too late. | Growing someone · Leading without authority · Raising the bar for others |
Notice that one story answers three or four different questions, and that each row has a number and a reflection. Eight to ten rows like these cover almost any behavioural round.