Understand the JSONL log files Libretto captures during every session.
Libretto automatically records network requests and browser actions to JSONL log files during every session. Your agent reads these files directly to reverse-engineer APIs, reconstruct workflows from user behavior, and debug failures.
Log file locations
.libretto/sessions/<session>/
logs.jsonl # CLI and system events
network.jsonl # HTTP requests and responses
actions.jsonl # User and agent browser actions
network.jsonl
One JSON object per line, one entry per HTTP request/response captured while the session was open.
Key fields
| Field | Description |
|---|
ts | ISO timestamp of the request |
method | HTTP method (GET, POST, PUT, etc.) |
url | Full request URL |
status | HTTP response status code |
contentType | Response content type |
responseBody | Response body string (may be null) |
postData | Request body for POST/PUT requests |
pageId | Playwright page ID that produced the entry |
Querying examples
# All POST requests
jq 'select(.method == "POST")' .libretto/sessions/<session>/network.jsonl
# Find requests to a specific endpoint
jq 'select(.url | contains("/api/"))' .libretto/sessions/<session>/network.jsonl
# View JSON API responses
jq 'select(.contentType | contains("application/json")) | .responseBody' \
.libretto/sessions/<session>/network.jsonl
# Count requests by HTTP method
jq -r '.method' .libretto/sessions/<session>/network.jsonl | sort | uniq -c
actions.jsonl
One JSON object per line, one entry per browser interaction. Libretto records both actions you perform manually in the browser (source: "user") and actions the agent performs programmatically (source: "agent").
Key fields
| Field | Description |
|---|
ts | ISO timestamp |
source | user (manual DOM event) or agent (Playwright call) |
action | Action name: click, dblclick, fill, goto, reload, etc. |
selector | Locator used by the agent |
bestSemanticSelector | Canonical selector from the user DOM event |
nearbyText | Visible text near the event target |
coordinates | {x, y} for pointer events |
value | Typed, selected, or submitted value |
url | Navigation target for goto-style actions |
duration | Elapsed time in milliseconds (agent entries) |
success | true if the action completed, false on failure |
error | Error message when the action failed |
Agent entries describe what Playwright tried to do (selector, duration). User entries describe what DOM element was actually interacted with (bestSemanticSelector, nearbyText, coordinates).
Querying examples
# Last 20 actions
tail -n 20 .libretto/sessions/<session>/actions.jsonl | jq .
# Show only user-initiated actions
jq 'select(.source == "user")' .libretto/sessions/<session>/actions.jsonl
# Find all failed actions
jq 'select(.success == false)' .libretto/sessions/<session>/actions.jsonl
# Extract selector and action for agent entries
jq 'select(.source == "agent") | {action: .action, selector: .selector}' \
.libretto/sessions/<session>/actions.jsonl
logs.jsonl
Structured CLI and system log. Contains debug output from Libretto itself, including command execution, errors, and internal events.
# View the last 20 log entries
tail -n 20 .libretto/sessions/<session>/logs.jsonl | jq .
