# Diagnostic Access Improvements

## Goal

Make it practical for an agent on a separate SSH machine to diagnose browser and
production failures without granting broad production control or asking the user
to paste console output.

## Browser Captures

Diagnostic mode (`?diag=1`) offers **Capture diagnostic**. Upload and metadata
remain authenticated. The PNG URL at `/api/debug/captures/{id}` is public by its
72-bit id, which is the explicit handoff capability a user shares with an agent.

After inspecting a user-shared capture, the agent must immediately call:

```
DELETE /api/debug/captures/{id}
```

The 24-hour expiry and 50-capture cap remain a backstop. Do not inspect capture
URLs that the user has not explicitly supplied.

## Production Diagnostics

Do not grant an agent a general production shell or Docker-group membership.
Docker access is effectively root access, and arbitrary shell access can expose
environment variables, OAuth tokens, and mounted volumes.

Instead create a dedicated `chart-debug` production account with a forced-command
SSH wrapper. It accepts only a small, read-oriented command set:

```
logs --since <duration>
status
container-state
recent-deploy
capture-read <capture-id>
capture-delete <capture-id>
```

The wrapper must reject arbitrary commands and paths. It should cap output,
redact known secret patterns, and log every request. Use a dedicated SSH key that
can be revoked without affecting deployment or normal administration.

Expected agent usage:

```
ssh chart-debug@production logs --since 20m
```

## Observability

Keep browser performance telemetry separate from production access. A future
frontend recorder should locally aggregate frame timing, long tasks, tick rate,
visible bars, and rendered line/level counts, then periodically upload compact,
authenticated summaries. Pair it with server timing for bar handling, level
rebuilds, WebSocket serialization, and the existing loop-lag measure.

This separates rendering, feed, transport, and backend pressure without logging
prices, drawing text, cursor positions, screenshots, or per-tick event history.