---
id: S02
parent: M007
milestone: M007
provides:
  - DebugPayloadViewer component for viewing LLM I/O in admin UI
  - Per-section clipboard copy for prompt/response text
  - JSON export of debug payloads
requires:
  - slice: S01
    provides: PipelineEvent model with debug text fields populated by debug mode pipeline runs
affects:
  - S04
key_files:
  - frontend/src/pages/AdminPipeline.tsx
  - frontend/src/api/public-client.ts
  - frontend/src/App.css
key_decisions:
  - Used clipboard API with execCommand fallback for non-HTTPS admin tool context
  - DebugPayloadViewer renders only when at least one debug text field is non-null
  - Field names use system_prompt_text/user_prompt_text/response_text matching the backend PipelineEvent model
patterns_established:
  - BEM-style component CSS with debug-viewer__ prefix following existing JsonViewer pattern
  - Conditional component rendering gated on non-null payload fields
observability_surfaces:
  - Debug viewer surfaces full LLM prompts and responses inline — this IS the observability tool for pipeline prompt debugging
drill_down_paths:
  - .gsd/milestones/M007/slices/S02/tasks/T01-SUMMARY.md
duration: ""
verification_result: passed
completed_at: 2026-03-30T19:10:25.752Z
blocker_discovered: false
---

# S02: Debug Payload Viewer — Inline View, Copy, and Export in Admin UI

**Added DebugPayloadViewer component to the admin pipeline page — LLM call events now show collapsible System Prompt / User Prompt / Response sections with per-section clipboard copy and full JSON export.**

## What Happened

This slice delivered the frontend viewer for LLM debug payloads captured by S01's debug mode infrastructure. A single task (T01) added three optional string fields to the PipelineEvent TypeScript interface (`system_prompt_text`, `user_prompt_text`, `response_text`), built the `DebugPayloadViewer` component with independently collapsible sections, per-section copy-to-clipboard (with `execCommand` fallback for non-HTTPS contexts), and a JSON export button that downloads all debug fields as a formatted file. The component renders inline on every `llm_call` event row in the pipeline event log, gated on at least one debug field being non-null. CSS follows the existing JsonViewer BEM pattern with `var(--color-*)` custom properties per D017. Changes were applied directly on ub01 (canonical dev directory) and deployed via Docker Compose rebuild. Browser verification confirmed all UI elements render correctly with real pipeline data.

## Verification

Container chrysopedia-web-8096 healthy and serving HTTP 200. DebugPayloadViewer component present in deployed JS bundle (grep confirmed). Browser verification: `.debug-viewer` selector visible, "LLM Debug" label rendered, collapsible section headers (System Prompt / User Prompt / Response) present in DOM with Copy buttons, JSON export button visible. Expanded System Prompt section displays full prompt text in pre-formatted block. Component renders on all 3 llm_call events in the expanded video's event list.

## Requirements Advanced

None.

## Requirements Validated

None.

## New Requirements Surfaced

None.

## Requirements Invalidated or Re-scoped

None.

## Deviations

Changes applied directly on ub01 rather than pushing through git — diverged branches prevented git pull. Service name in plan verification command was `chrysopedia-web-8096` but Docker Compose build target is `chrysopedia-web` (the `-8096` is only the container name). Unicode escape issue in export button required a second build pass.

## Known Limitations

Local dev01 copy is out of sync with ub01 — all changes live only on ub01. The plan verification command in S02-PLAN.md has shell quoting issues (unterminated quotes in the SSH command) that would always fail as written.

## Follow-ups

None.

## Files Created/Modified

- `frontend/src/pages/AdminPipeline.tsx` — Added DebugPayloadViewer component (collapsible sections, copy, export) and wired into llm_call event rows
- `frontend/src/api/public-client.ts` — Added system_prompt_text, user_prompt_text, response_text fields to PipelineEvent interface
- `frontend/src/App.css` — Added ~100 lines of debug-viewer CSS using var(--color-*) custom properties
