> ## Documentation Index > Fetch the complete documentation index at: https://docs2.openclaw.ai/llms.txt > Use this file to discover all available pages before exploring further. # Codex compaction and transcript mirror Who owns compaction on a Codex turn, and what the OpenClaw transcript mirror keeps. Part of the [Codex harness runtime](/plugins/codex-harness-runtime) guide; [Where each section moved](/plugins/codex-harness-runtime#where-each-section-moved) lists every section. ## Compaction and transcript mirror When the selected model uses the Codex harness, Codex app-server owns native token-pressure and manual thread compaction. OpenClaw separately owns its transcript mirror. When `agents.defaults.compaction.maxActiveTranscriptBytes` is set to a positive value, OpenClaw checks that mirror before ordinary and heartbeat turns. When the byte guard trips, OpenClaw requires semantic compaction through its selected host context engine before admitting the turn. This host compaction does not itself replace or rewrite Codex's canonical native thread. After host mirror compaction commits, OpenClaw may request `thread/compact/start` to synchronize an eligible native thread. This request is secondary: OpenClaw does not send it for host-isolated operations or bindings with restricted native authority, and unavailable or failed native synchronization does not roll back committed host compaction. Explicit compaction requests, such as `/compact` or a plugin-requested manual compact operation, start native Codex compaction with `thread/compact/start`. OpenClaw keeps the request and shared-client lease open until Codex emits the matching `contextCompaction` completion item and then reports the compaction turn as completed. If that terminal turn exceeds the configured compaction timeout, OpenClaw requests a native turn interrupt. The lease and per-thread compaction fence remain held until Codex reports terminal state or confirms the interrupt RPC. If Codex does not confirm within the interrupt grace period, OpenClaw retires the connection before releasing the fence. Remote connections also detach the matching thread binding so later work cannot overlap an unconfirmed remote turn. Other turns on a retired connection fail and can retry on a fresh client. Client closure, request cancellation, or a failed compaction turn returns a failed operation. Automatic native token-pressure compaction remains Codex's job. Outside the secondary synchronization described above, OpenClaw starts native compaction only for explicit manual requests. A standalone cold compact operation does not run prompt-build hooks or establish ordinary-turn configuration. It releases its subscription after the operation; the next ordinary turn verifies configuration and refreshes generic policy through the normal resume path. Warm compaction returns only the configuration ownership it actually acquired. If context-engine compaction rotates the OpenClaw session generation, the next Codex turn, compaction, or side question continues the same native thread even if the Gateway stopped immediately after committing the new generation. Only the recorded predecessor under that session key can be adopted. Native tool catalogs, connection ownership, and supervision checks still apply before the resumed thread executes. When OpenClaw projects an existing session's continuity into a fresh Codex thread, it includes saved compaction and branch summaries, even when no earlier user messages remain. Context-engine projections preserve those summary entries too. Summaries stay quoted as prior context, separate from the current request, and remain subject to the projection's size limits; oversized summaries or older context can be truncated. This handoff does not change native Codex compaction ownership. When a context engine requests Codex thread-bootstrap projection, OpenClaw projects tool-call names and ids, input shapes, and redacted tool-result content into the fresh Codex thread. It does not copy raw tool-call argument values into that projection. The mirror includes the user prompt, final assistant text, and lightweight Codex reasoning records when the app-server emits them. Reasoning retains typed `thinking` content rather than ordinary final-answer text, so OpenClaw's existing reasoning visibility and history controls apply. OpenClaw records the native compaction start and terminal status, but it does not expose a human-readable compaction summary or an auditable list of which entries Codex kept after compaction. Because Codex owns the canonical native thread, `tool_result_persist` does not rewrite Codex-native tool result records. It only applies when OpenClaw writes an OpenClaw-owned session transcript tool result.