---
id: T01
parent: S02
milestone: M006
provides: []
requires: []
affects: []
key_files: ["backend/routers/pipeline.py"]
key_decisions: ["Used explicit string validation with 400 response rather than FastAPI Literal/Enum to stay consistent with existing endpoint param style"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "Tested all four scenarios against the live API on ub01 using video 92aacf2b-19c0-4879-89c3-236a4323a0f1 (70 events): order=asc returned ascending timestamps, order=desc returned descending, order=invalid returned HTTP 400, no order param returned desc (backward compatible)."
completed_at: 2026-03-30T11:10:42.034Z
blocker_discovered: false
---

# T01: Added `order` query parameter (asc/desc, default desc) to pipeline events endpoint with validation and dynamic ordering

> Added `order` query parameter (asc/desc, default desc) to pipeline events endpoint with validation and dynamic ordering

## What Happened
---
id: T01
parent: S02
milestone: M006
key_files:
  - backend/routers/pipeline.py
key_decisions:
  - Used explicit string validation with 400 response rather than FastAPI Literal/Enum to stay consistent with existing endpoint param style
duration: ""
verification_result: passed
completed_at: 2026-03-30T11:10:42.035Z
blocker_discovered: false
---

# T01: Added `order` query parameter (asc/desc, default desc) to pipeline events endpoint with validation and dynamic ordering

**Added `order` query parameter (asc/desc, default desc) to pipeline events endpoint with validation and dynamic ordering**

## What Happened

Modified `list_pipeline_events` in `backend/routers/pipeline.py` on ub01 to accept an `order` query parameter. Added the parameter to the function signature with `Annotated[str, Query(...)]`, defaulting to `"desc"` to preserve backward compatibility. Added explicit validation that returns HTTP 400 for invalid values. Replaced the hardcoded `.order_by(PipelineEvent.created_at.desc())` with a dynamic `order_clause` that selects `.asc()` or `.desc()` based on the parameter. Rebuilt and restarted the API container on ub01.

## Verification

Tested all four scenarios against the live API on ub01 using video 92aacf2b-19c0-4879-89c3-236a4323a0f1 (70 events): order=asc returned ascending timestamps, order=desc returned descending, order=invalid returned HTTP 400, no order param returned desc (backward compatible).

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `curl -sf 'http://ub01:8096/api/v1/admin/pipeline/events/{vid}?order=asc&limit=3'` | 0 | ✅ pass | 1200ms |
| 2 | `curl -sf 'http://ub01:8096/api/v1/admin/pipeline/events/{vid}?order=desc&limit=3'` | 0 | ✅ pass | 800ms |
| 3 | `curl -s -w '%{http_code}' 'http://ub01:8096/api/v1/admin/pipeline/events/{vid}?order=invalid'` | 0 | ✅ pass (400) | 500ms |
| 4 | `curl -sf 'http://ub01:8096/api/v1/admin/pipeline/events/{vid}?limit=3' (no order)` | 0 | ✅ pass (desc default) | 700ms |


## Deviations

None.

## Known Issues

None.

## Files Created/Modified

- `backend/routers/pipeline.py`


## Deviations
None.

## Known Issues
None.
