fix(repository): set where_added for ttfb filter

[fergusfinn]

Summary

• set where_added = true in the max_duration_to_first_byte_ms filter branch when it introduces the first WHERE clause
• preserve the existing query builder pattern so later filters append with AND

Testing

• DATABASE_URL=postgresql:///postgres cargo test

[Copilot]

Pull request overview

This PR fixes a bug in RequestFilter::build_query where the max_duration_to_first_byte_ms filter branch pushed a WHERE clause to the SQL query but failed to set where_added = true, causing any filter applied after it to also emit WHERE instead of AND, producing invalid SQL.

Changes:

• Adds where_added = true in the else branch of the max_duration_to_first_byte_ms filter block, making it consistent with every other filter branch in build_query.

Comments suppressed due to low confidence (1)

src/repository.rs:218

• The test suite covers every other filter field (including min_duration_ms/max_duration_ms) but there are no unit tests for min_duration_to_first_byte_ms or max_duration_to_first_byte_ms. Without a dedicated test:

1. The exact bug this PR fixes (missing where_added = true) would not have been caught by the existing tests.
2. A future regression in the TTFB filter branch would similarly go undetected.

Please add tests analogous to test_duration_filters that exercise:

• max_duration_to_first_byte_ms as the sole filter (verifying it emits WHERE rather than AND).
• Both min_duration_to_first_byte_ms and max_duration_to_first_byte_ms together (verifying the first gets WHERE and the second gets AND).
• max_duration_to_first_byte_ms combined with another filter (e.g., correlation_id) to verify the AND path still works correctly.

        if let Some(max_duration_to_first_byte) = self.max_duration_to_first_byte_ms {
            if where_added {
                query.push(" AND ");
            } else {
                query.push(" WHERE ");
                where_added = true;
            }
            query.push("res.duration_to_first_byte_ms <= ");
            query.push_bind(max_duration_to_first_byte);
        }

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.