session-compress

Compress an OpenClaw .jsonl session file by trimming old messages while retaining active task context and basic message structure.

When to Use

• User asks to compress, shrink, or trim a session file
• Session context is too large and causing performance issues
• Before archiving an old session but wanting to preserve task memory

Workflow

Step 1: Identify the target file

Session files are located at:

<OPENCLAW_DIR>\agents\main\sessions\*.jsonl

List files by size to find candidates:

Get-ChildItem <OPENCLAW_DIR>\agents\main\sessions\*.jsonl | Sort-Object Length -Descending | Select-Object Name, @{N='SizeMB';E={[math]::Round($_.Length/1MB,2)}}

Step 2: Dry run first

Always dry run before modifying anything:

powershell -File scripts/compress.ps1 -FilePath "<path-to-file>" -DryRun

Review: how many messages will be kept, what the output size will be.

Step 3: Compress

# In-place compress (overwrites original):
powershell -File scripts/compress.ps1 -FilePath "<path-to-file>"

# Compress to a new file (preserves original):
powershell -File scripts/compress.ps1 -FilePath "<path-to-file>" -OutputPath "<new-path>"

Compression Logic

1. Always kept: All system role messages
2. Always kept: Last 30 message turns (configurable via -KeepRecent)
3. Conditionally kept (task context keywords): messages containing keywords like next step, todo, plan, task, pending, in progress, remember, dont forget, important
4. Summarized: Culled messages are replaced with a single placeholder message — preserving the file structure so OpenClaw can still load it
5. Deduplicated: No message appears twice in the output

Parameters

What Gets Preserved

Each message in the output .jsonl retains:

• role (system / user / assistant)
• content (as array of content blocks)
• timestamp

What Gets Removed

• Older messages not in the recent window and not flagged as task-relevant
• Tool call metadata is stripped (content blocks are kept as text)

Important Notes

• Always dry run first — compression is destructive unless -OutputPath is used
• This skill is for the main agent session files only
• After compression the file remains a valid .jsonl that OpenClaw can load normally