# Label Velocity

- **Command:** `lore label-flow <from-label> <to-label>`
- **Confidence:** 78%
- **Tier:** 3
- **Status:** proposed
- **Effort:** medium — self-join on resource_label_events, percentile computation

## What

For a given label pair (e.g., "needs-review" to "approved"), compute median and P90
transition times using `resource_label_events`. Shows how fast work moves through
your process labels.

Also supports: single label dwell time (how long does "in-progress" stay applied?).

## Why

Process bottlenecks become quantifiable. "Our code review takes a median of 3 days"
is actionable data for retrospectives and process improvement.

## Data Required

All exists today:
- `resource_label_events` (label_name, action, created_at, issue_id, merge_request_id)

## Implementation Sketch

```sql
-- Label A → Label B transition time
WITH add_a AS (
    SELECT issue_id, merge_request_id, MIN(created_at) as added_at
    FROM resource_label_events
    WHERE label_name = ?1 AND action = 'add'
    GROUP BY issue_id, merge_request_id
),
add_b AS (
    SELECT issue_id, merge_request_id, MIN(created_at) as added_at
    FROM resource_label_events
    WHERE label_name = ?2 AND action = 'add'
    GROUP BY issue_id, merge_request_id
)
SELECT
    (b.added_at - a.added_at) / 3600000.0 as hours_transition
FROM add_a a
JOIN add_b b ON a.issue_id = b.issue_id OR a.merge_request_id = b.merge_request_id
WHERE b.added_at > a.added_at;
```

Then compute percentiles in Rust (median, P75, P90).

## Human Output

```
Label Flow: "needs-review" → "approved"

  Transitions:  42 issues/MRs in last 90 days
  Median:       18.5 hours
  P75:          36.2 hours
  P90:          72.8 hours
  Slowest:      !234 Refactor auth (168 hours)
```

## Downsides

- Only works if teams use label-based workflows consistently
- Labels may be applied out of order or skipped
- Self-join performance could be slow with many events

## Extensions

- `lore label-flow --dwell "in-progress"` — how long does a label stay?
- `lore label-flow --all` — auto-discover common transitions from event data
- Visualization: label state machine with median transition times on edges