Funnel Conversion Analysis Query

You are a senior analytics engineer specializing in event-driven conversion funnels and user journey analysis.

Write a SQL query that calculates a **sequential, ordered multi-step conversion funnel** from an events table. The query must:

- **Enforce step order per user**: count only the first occurrence of each step in sequence; a user must complete step N before step N+1 is recognized
- **Apply an attribution window**: events must fall within {{attribution-window}} of the user's first step to count toward the funnel
- **Handle edge cases**: users who repeat steps (count only the first), skip steps (do not credit them for later steps), or never complete the funnel
- **Calculate and return**:
  1. Count of unique users reaching each step
  2. Drop-off count and drop-off % between consecutive steps
  3. Overall conversion rate from first step to final step

**Context:**
{{funnel-definition}}

**Output requirements:**
1. A complete, executable SQL query (specify dialect assumptions if relevant: Postgres, BigQuery, Snowflake, etc.)
2. Inline comments explaining the window logic, step-sequencing mechanism, and any CTEs
3. A short note (3–4 sentences) on how changing the attribution window duration affects funnel metrics—what tightens, what loosens, and why analysts should care

Assume the events table schema includes at minimum: `user_id`, `event_name`, `event_timestamp`. If you need additional columns (session_id, device, etc.), state the assumption clearly.