~/.codex grew to 42 GB (28.6 GB in a single month): compaction re-embeds the full replacement_history in rollout JSONL, and archived sessions are never cleaned up #41806

What version of Codex are you running?

• Codex Desktop: 26.826.12353
• codex-cli: 0.149.1

What subscription do you have?

ChatGPT Pro

Which model were you using?

gpt-5.6-sol

What platform is your computer?

macOS (Apple Silicon, M4 Pro, arm64)

Summary

Between 2026-04-21 and 2026-08-31, ~/.codex grew to ~42 GB across multiple workspaces/sessions, with occasional subagent usage. Usage was heavily back-loaded: the first file dates to 2026-04-21, but 98.8% of the archived volume was produced in August 2026 alone (see timeline below). Almost all of it is rollout session logs:

Archived rollouts are never cleaned up, compressed, or pruned, and the per-file analysis below shows the logging itself is unbounded.

Details: archived_sessions/

• 1,145 rollout-*.jsonl files stored flat — no subdirectory layout, no sign of any retention policy.
• 82 files exceed 100 MB, totaling ~23 GB — 82% of the directory.
• Largest single file: 1.2 GB; plus 4 files around 1 GB each and several in the 300–900 MB range.
• Growth is continuous within the active period, not a one-off spike: on Aug 30 alone, 190 new files were added; on Jul 29, multiple active files in sessions/ each reached 210–270 MB.

Timeline: the volume arrived in one month

File dates span 2026-04-21 → 2026-08-31, but those are only the two extreme endpoints — there are long empty gaps in between:

So this is not slow accumulation over 4 months: it is ~28.6 GB of rollout logs produced in a single month of active use.

Root cause analysis (inside the 1.2 GB file)

The largest file contains 70,902 lines. Its size is dominated by two behaviors:

1. Every compacted event re-serializes the entire conversation history

• The file contains 139 "type":"compacted" records; those 139 lines alone occupy ~794 MB (≈66% of the file).
• Each compaction writes the full replacement_history — the complete conversation, including ~25,000 messages and 1,100+ input_image items — inline as a single JSON line. The largest single line observed is 13 MB.
• Since the history already contains all previous content, every additional compaction rewrites an ever-larger snapshot of the same data. Bytes written to disk grow roughly quadratically with the number of compactions in a long-lived session.

2. Large payloads (base64 images, big tool outputs) are never truncated

• 123 lines exceed 1 MB, dominated by screenshots (input_image, stored as full base64) and large tool outputs (e.g. big file reads), written verbatim with no size cap.
• Combined with (1), each such payload is then re-embedded in every subsequent compaction snapshot, multiplying its footprint.

Impact

• Disk fills up quickly with no user-visible warning: ~28.6 GB of archived rollout logs in one month of active use.
• The archive behaves as an append-only, unbounded store; nothing is ever reclaimed.
• Any tool that scans, copies, backs up, or migrates ~/.codex must process multi-MB single JSON lines (13 MB max observed).

Relationship to existing issues

This is an independent real-world dataset confirming the same underlying mechanisms reported in:

• Subagent spawns duplicate the full parent session history into each child rollout file (quadratic disk growth) #36557 / Codex Desktop subagent session logs grow to 145GiB from repeated compacted replacement_history #31198 / Codex Desktop 26.810: repeated compacted image snapshots grow rollout to 16.9 GB and app-server to 19.5 GB #39013 — compaction repeatedly rewrites the full replacement_history / image snapshots (those reports emphasize subagent fan-out or specific Desktop builds; here the dominant factor is repeated compaction in long-lived sessions across multiple workspaces, with only occasional subagent use).
• Local compaction v2 retains unbounded input_image payloads, causing repeated auto-compaction #33493 — compaction retains unbounded input_image payloads.
• Rollout JSONL grew to 98 GB from inline Base64 PNG payloads #40111 / Bug Report: Rollout Log Size Explosion from Unbounded Base64 Image Data #32128 — inline base64 image payloads stored verbatim in rollout JSONL.
• Archived session storage should fail fast and support deep archive/cold storage #28868 / Subagent fork sessions persist large JSONL histories indefinitely, causing severe ~/.codex disk bloat #30779 / Desktop: provide supported external/cold archive storage before local rollout history exhausts disk #37216 — archived session storage has no size bound, no fail-fast, and no cleanup/cold-archive path.

Suggested fixes

1. Don't re-embed full history on compaction. Store compaction output as a reference/delta (or deduplicate history segments by content hash) instead of serializing the entire replacement_history into every compacted record.
2. Cap or externalize large payloads. Truncate, hash, or spill base64 images and oversized tool outputs to side storage instead of inlining multi-MB blobs in the rollout stream.
3. Add a retention policy for archived_sessions/ — age/size caps, compression (e.g. zstd), and/or a supported command to prune/compact local session storage.
4. Warn the user when ~/.codex crosses a size threshold.

Workaround

None built in; the only mitigation is manually deleting old rollout-*.jsonl files, presumably at the cost of losing resume/archive history.