---
# claudbg-pfa5
title: JSON output is array-of-arrays instead of array-of-objects
status: completed
type: bug
priority: normal
created_at: 2026-03-30T04:37:05Z
updated_at: 2026-03-30T05:05:12Z
parent: claudbg-tci9
---

## Problem

`sessions list --output json` and `sessions dump --output json` serialize rows as `Vec<Vec<String>>`, producing an array of arrays with no field names:

```json
[["21fae0a8", "2024-01-01", "/path", "claude-3", "42"], ...]
```

## Expected behavior

Output should be an array of objects with named keys:

```json
[{"id": "21fae0a8", "date": "2024-01-01", "project": "/path", "model": "claude-3", "messages": 42, "subagents": 0}, ...]
```

## Affected commands

- `sessions list --output json`: keys should be `id`, `date`, `project`, `model`, `messages`, `subagents`
- `sessions dump --output json`: keys should be `seq`, `timestamp`, `type`, `role`, `content`

## Root cause

`src/commands/sessions.rs` passes `&rows: &Vec<Vec<String>>` directly to `render_json`. The fix is to build a typed struct or `serde_json::Value` map per row before serializing.

## Relevant files

- `src/commands/sessions.rs` — `list()` and `dump()` JSON output branches
- `src/output/json.rs` — generic `render_json`

## Summary of Changes

Fixed JSON output in both sessions.rs and agents.rs to produce array-of-objects instead of array-of-arrays. Each row is now mapped to a serde_json object with named keys before serializing. Keys: sessions list (id, date, project, model, messages, subagents), sessions dump (seq, timestamp, type, role, content), agents list (id, type, file, modified), agents dump (seq, timestamp, type, role, content).