Codex Session Image Scrubber

Purpose

Clean oversized Codex session logs by replacing embedded image/base64 payloads with small placeholders while keeping the surrounding conversation, tool calls, and text intact.

Use this when the user says a Codex chat/thread is heavy, slow, bloated, or contains pasted screenshots/images/base64 they want removed from history.

Workflow

1. Confirm the target thread/session.
   - Prefer a thread id if the user provides one.
   - If they provide a remembered phrase, locate the session with rg -l "<phrase>" ~/.codex/sessions ~/.codex/session_index.jsonl.
   - Do not edit the active file until you know which JSONL is the target.

2. Dry-run the scrubber.
   bash node ~/.codex/skills/codex-session-image-scrubber/scripts/scrub-codex-session-images.mjs --thread-id <thread-id>
   Or, with an exact file:
   bash node ~/.codex/skills/codex-session-image-scrubber/scripts/scrub-codex-session-images.mjs --file /path/to/rollout.jsonl

3. If the dry-run looks right, write the cleaned file.
   bash node ~/.codex/skills/codex-session-image-scrubber/scripts/scrub-codex-session-images.mjs --thread-id <thread-id> --write

4. Validate after writing.
   - Confirm size dropped with ls -lh <file> <backup>.
   - Confirm the JSONL still parses; the script reports parseErrors: 0.
   - Check obvious image payloads are gone:
   bash rg -n "data:image|iVBORw0KGgo|/9j/4AAQ|UklGR" <file>
   Exit code 1 with no output is the desired result.

5. Tell the user the before/after size, backup path, and whether validation passed. Suggest reopening the thread so the app reloads the lighter file.

Safety Rules

• Only remove image payloads, not text that mentions images.
• Keep <image> or </image> text markers if present; they are small and can preserve conversation structure.
• Always keep a backup outside ~/.codex/sessions; the script defaults to ~/.codex/session_backups.
• If multiple session files match a thread id, stop and pick explicitly instead of guessing.
• If the user wants the backup removed later, ask for confirmation before deleting it.

Script

The deterministic scrubber is at scripts/scrub-codex-session-images.mjs.

Useful options:

• --thread-id <id>: find a rollout JSONL under ~/.codex/sessions.
• --file <path>: scrub a specific JSONL.
• --write: perform the rewrite; without this the script is dry-run only.
• --backup-dir <path>: override the backup directory.
• --sessions-dir <path>: override the Codex sessions root.
• --min-bytes <n>: threshold for suspicious image fields; defaults to 100000.