openclaw/docs/reference/session-management-compaction.md

summary, read_when, title

summary	read_when	title
Deep dive: session store + transcripts, lifecycle, and (auto)compaction internals	You need to debug session ids, transcript JSONL, or sessions.json fields You are changing auto-compaction behavior or adding "pre-compaction" housekeeping You want to implement memory flushes or silent system turns	Session management deep dive

OpenClaw manages sessions end-to-end across these areas:

• Session routing (how inbound messages map to a sessionKey)
• Session store (sessions.json) and what it tracks
• Transcript persistence (*.jsonl) and its structure
• Transcript hygiene (provider-specific fixups before runs)
• Context limits (context window vs tracked tokens)
• Compaction (manual and auto-compaction) and where to hook pre-compaction work
• Silent housekeeping (memory writes that should not produce user-visible output)

If you want a higher-level overview first, start with:

• Session management
• Compaction
• Memory overview
• Memory search
• Session pruning
• Transcript hygiene

---

Source of truth: the Gateway

OpenClaw is designed around a single Gateway process that owns session state.

• UIs (macOS app, web Control UI, TUI) should query the Gateway for session lists and token counts.
• In remote mode, session files are on the remote host; "checking your local Mac files" won't reflect what the Gateway is using.

---

Two persistence layers

OpenClaw persists sessions in two layers:

1. Session store (sessions.json)

   • Key/value map: sessionKey -> SessionEntry
   • Small, mutable, safe to edit (or delete entries)
   • Tracks session metadata (current session id, last activity, toggles, token counters, etc.)

2. Transcript (<sessionId>.jsonl)

   • Append-only transcript with tree structure (entries have id + parentId)
   • Stores the actual conversation + tool calls + compaction summaries
   • Used to rebuild the model context for future turns
   • Compaction checkpoints are metadata over the compacted successor transcript. New compactions do not write a second .checkpoint.*.jsonl copy.

Gateway history readers should avoid materializing the whole transcript unless the surface explicitly needs arbitrary historical access. First-page history, embedded chat history, restart recovery, and token/usage checks use bounded tail reads. Full transcript scans go through the async transcript index, which is cached by file path plus mtimeMs/size and shared across concurrent readers.

---

On-disk locations

Per agent, on the Gateway host:

• Store: ~/.openclaw/agents/<agentId>/sessions/sessions.json
• Transcripts: ~/.openclaw/agents/<agentId>/sessions/<sessionId>.jsonl
  • Telegram topic sessions: .../<sessionId>-topic-<threadId>.jsonl

OpenClaw resolves these via src/config/sessions.ts.

---

Store maintenance and disk controls

Session persistence has automatic maintenance controls (session.maintenance) for sessions.json, transcript artifacts, and trajectory sidecars:

• mode: warn (default) or enforce
• pruneAfter: stale-entry age cutoff (default 30d)
• maxEntries: cap entries in sessions.json (default 500)
• resetArchiveRetention: retention for *.reset.<timestamp> transcript archives (default: same as pruneAfter; false disables cleanup)
• maxDiskBytes: optional sessions-directory budget
• highWaterBytes: optional target after cleanup (default 80% of maxDiskBytes)

Normal Gateway writes flow through a per-store session writer that serializes in-process mutations without taking a runtime file lock. Hot-path patch helpers borrow the validated mutable cache while they hold that writer slot, so large sessions.json files are not cloned or reread for every metadata update. Runtime code should prefer updateSessionStore(...) or updateSessionStoreEntry(...); direct whole-store saves are compatibility and offline-maintenance tools. When a Gateway is reachable, non-dry-run openclaw sessions cleanup and openclaw agents delete delegate store mutations to the Gateway so cleanup joins the same writer queue; --store <path> is the explicit offline repair path for direct file maintenance. maxEntries cleanup is still batched for production-sized caps, so a store may briefly exceed the configured cap before the next high-water cleanup rewrites it back down. Session store reads do not prune or cap entries during Gateway startup; use writes or openclaw sessions cleanup --enforce for cleanup. openclaw sessions cleanup --enforce still applies the configured cap immediately and prunes old unreferenced transcript, checkpoint, and trajectory artifacts even when no disk budget is configured.

Maintenance keeps durable external conversation pointers such as group sessions and thread-scoped chat sessions, but synthetic runtime entries for cron, hooks, heartbeat, ACP, and sub-agents can still be removed when they exceed the configured age, count, or disk budget.

OpenClaw no longer creates automatic sessions.json.bak.* rotation backups during Gateway writes. The legacy session.maintenance.rotateBytes key is ignored and openclaw doctor --fix removes it from older configs.

Transcript mutations use a session write lock on the transcript file. Lock acquisition waits up to session.writeLock.acquireTimeoutMs before surfacing a busy-session error; the default is 60000 ms. Raise this only when legitimate prep, cleanup, compaction, or transcript mirror work contends longer on slow machines. session.writeLock.staleMs controls when an existing lock can be reclaimed as stale; the default is 1800000 ms. session.writeLock.maxHoldMs controls the in-process watchdog release threshold; the default is 300000 ms. Emergency env overrides are OPENCLAW_SESSION_WRITE_LOCK_ACQUIRE_TIMEOUT_MS, OPENCLAW_SESSION_WRITE_LOCK_STALE_MS, and OPENCLAW_SESSION_WRITE_LOCK_MAX_HOLD_MS.

Enforcement order for disk budget cleanup (mode: "enforce"):

1. Remove oldest archived, orphan transcript, or orphan trajectory artifacts first.
2. If still above the target, evict oldest session entries and their transcript/trajectory files.
3. Keep going until usage is at or below highWaterBytes.

In mode: "warn", OpenClaw reports potential evictions but does not mutate the store/files.

Run maintenance on demand:

openclaw sessions cleanup --dry-run
openclaw sessions cleanup --enforce

---

Cron sessions and run logs

Isolated cron runs also create session entries/transcripts, and they have dedicated retention controls:

• cron.sessionRetention (default 24h) prunes old isolated cron run sessions from the session store (false disables).
• cron.runLog.maxBytes + cron.runLog.keepLines prune ~/.openclaw/cron/runs/<jobId>.jsonl files (defaults: 2_000_000 bytes and 2000 lines).

When cron force-creates a new isolated run session, it sanitizes the previous cron:<jobId> session entry before writing the new row. It carries safe preferences such as thinking/fast/verbose settings, labels, and explicit user-selected model/auth overrides. It drops ambient conversation context such as channel/group routing, send or queue policy, elevation, origin, and ACP runtime binding so a fresh isolated run cannot inherit stale delivery or runtime authority from an older run.

---

Session keys (sessionKey)

A sessionKey identifies which conversation bucket you're in (routing + isolation).

Common patterns:

• Main/direct chat (per agent): agent:<agentId>:<mainKey> (default main)
• Group: agent:<agentId>:<channel>:group:<id>
• Room/channel (Discord/Slack): agent:<agentId>:<channel>:channel:<id> or ...:room:<id>
• Cron: cron:<job.id>
• Webhook: hook:<uuid> (unless overridden)

The canonical rules are documented at /concepts/session.

---

Session ids (sessionId)

Each sessionKey points at a current sessionId (the transcript file that continues the conversation).

Rules of thumb:

• Reset (/new, /reset) creates a new sessionId for that sessionKey.
• Daily reset (default 4:00 AM local time on the gateway host) creates a new sessionId on the next message after the reset boundary.
• Idle expiry (session.reset.idleMinutes or legacy session.idleMinutes) creates a new sessionId when a message arrives after the idle window. When daily + idle are both configured, whichever expires first wins.
• System events (heartbeat, cron wakeups, exec notifications, gateway bookkeeping) may mutate the session row but do not extend daily/idle reset freshness. Reset rollover discards queued system-event notices for the previous session before the fresh prompt is built.
• Parent fork policy uses OpenClaw's active branch when creating a thread or subagent fork. If that branch is too large, OpenClaw starts the child with isolated context instead of failing or inheriting unusable history. The sizing policy is automatic; legacy session.parentForkMaxTokens config is removed by openclaw doctor --fix.

Implementation detail: the decision happens in initSessionState() in src/auto-reply/reply/session.ts.

---

Session store schema (sessions.json)

The store's value type is SessionEntry in src/config/sessions.ts.

Key fields (not exhaustive):

• sessionId: current transcript id (filename is derived from this unless sessionFile is set)
• sessionStartedAt: start timestamp for the current sessionId; daily reset freshness uses this. Legacy rows may derive it from the JSONL session header.
• lastInteractionAt: last real user/channel interaction timestamp; idle reset freshness uses this so heartbeat, cron, and exec events do not keep sessions alive. Legacy rows without this field fall back to the recovered session start time for idle freshness.
• updatedAt: last store-row mutation timestamp, used for listing, pruning, and bookkeeping. It is not the authority for daily/idle reset freshness.
• sessionFile: optional explicit transcript path override
• chatType: direct | group | room (helps UIs and send policy)
• provider, subject, room, space, displayName: metadata for group/channel labeling
• Toggles:
  • thinkingLevel, verboseLevel, reasoningLevel, elevatedLevel
  • sendPolicy (per-session override)
• Model selection:
  • providerOverride, modelOverride, authProfileOverride
• Token counters (best-effort / provider-dependent):
  • inputTokens, outputTokens, totalTokens, contextTokens
• compactionCount: how often auto-compaction completed for this session key
• memoryFlushAt: timestamp for the last pre-compaction memory flush
• memoryFlushCompactionCount: compaction count when the last flush ran

The store is safe to edit, but the Gateway is the authority: it may rewrite or rehydrate entries as sessions run.

---

Transcript structure (*.jsonl)

Transcripts are managed by openclaw/plugin-sdk/agent-sessions's SessionManager.

The file is JSONL:

• First line: session header (type: "session", includes id, cwd, timestamp, optional parentSession)
• Then: session entries with id + parentId (tree)

Notable entry types:

• message: user/assistant/toolResult messages
• custom_message: extension-injected messages that do enter model context (can be hidden from UI)
• custom: extension state that does not enter model context
• compaction: persisted compaction summary with firstKeptEntryId and tokensBefore
• branch_summary: persisted summary when navigating a tree branch

OpenClaw intentionally does not "fix up" transcripts; the Gateway uses SessionManager to read/write them.

---

Context windows vs tracked tokens

Two different concepts matter:

1. Model context window: hard cap per model (tokens visible to the model)
2. Session store counters: rolling stats written into sessions.json (used for /status and dashboards)

If you're tuning limits:

• The context window comes from the model catalog (and can be overridden via config).
• contextTokens in the store is a runtime estimate/reporting value; don't treat it as a strict guarantee.

For more, see /token-use.

---

Compaction: what it is

Compaction summarizes older conversation into a persisted compaction entry in the transcript and keeps recent messages intact.

After compaction, future turns see:

• The compaction summary
• Messages after firstKeptEntryId

AGENTS.md section reinjection after compaction is opt-in via agents.defaults.compaction.postCompactionSections; when unset or [], OpenClaw does not append AGENTS.md excerpts on top of the compaction summary.

Compaction is persistent (unlike session pruning). See /concepts/session-pruning.

Compaction chunk boundaries and tool pairing

When OpenClaw splits a long transcript into compaction chunks, it keeps assistant tool calls paired with their matching toolResult entries.

• If the token-share split lands between a tool call and its result, OpenClaw shifts the boundary to the assistant tool-call message instead of separating the pair.
• If a trailing tool-result block would otherwise push the chunk over target, OpenClaw preserves that pending tool block and keeps the unsummarized tail intact.
• Aborted/error tool-call blocks do not hold a pending split open.

---

When auto-compaction happens (OpenClaw runtime)

In the embedded OpenClaw agent, auto-compaction triggers in two cases:

1. Overflow recovery: the model returns a context overflow error (request_too_large, context length exceeded, input exceeds the maximum number of tokens, input token count exceeds the maximum number of input tokens, input is too long for the model, ollama error: context length exceeded, and similar provider-shaped variants) → compact → retry. When the provider reports the attempted token count, OpenClaw forwards that observed count into overflow recovery compaction. If the provider confirms overflow but does not expose a parseable count, OpenClaw passes a minimally over-budget synthetic count to compaction engines and diagnostics. If overflow recovery still fails, OpenClaw surfaces explicit guidance to the user and preserves the current session mapping instead of silently rotating the session key to a fresh session id. The next step is operator-controlled: retry the message, run /compact, or run /new when a fresh session is preferred.
2. Threshold maintenance: after a successful turn, when:

contextTokens > contextWindow - reserveTokens

Where:

• contextWindow is the model's context window
• reserveTokens is headroom reserved for prompts + the next model output

These are OpenClaw runtime semantics.

OpenClaw can also trigger a preflight local compaction before opening the next run when agents.defaults.compaction.maxActiveTranscriptBytes is set and the active transcript file reaches that size. This is a file-size guard for local reopen cost, not raw archival: OpenClaw still runs normal semantic compaction, and it requires truncateAfterCompaction so the compacted summary can become a new successor transcript.

For embedded OpenClaw runs, agents.defaults.compaction.midTurnPrecheck.enabled: true adds an opt-in tool-loop guard. After a tool result is appended and before the next model call, OpenClaw estimates the prompt pressure using the same preflight budget logic used at turn start. If the context no longer fits, the guard does not compact inside OpenClaw runtime's transformContext hook. It raises a structured mid-turn precheck signal, stops the current prompt submission, and lets the outer run loop use the existing recovery path: truncate oversized tool results when that is enough, or trigger the configured compaction mode and retry. The option is disabled by default and works with both default and safeguard compaction modes, including provider-backed safeguard compaction. This is independent of maxActiveTranscriptBytes: the byte-size guard runs before a turn opens, while mid-turn precheck runs later in the embedded OpenClaw tool loop after new tool results have been appended.

---

Compaction settings (reserveTokens, keepRecentTokens)

OpenClaw runtime's compaction settings live in agent settings:

{
  compaction: {
    enabled: true,
    reserveTokens: 16384,
    keepRecentTokens: 20000,
  },
}

OpenClaw also enforces a safety floor for embedded runs:

• If compaction.reserveTokens < reserveTokensFloor, OpenClaw bumps it.
• Default floor is 20000 tokens.
• Set agents.defaults.compaction.reserveTokensFloor: 0 to disable the floor.
• If it's already higher, OpenClaw leaves it alone.
• Manual /compact honors an explicit agents.defaults.compaction.keepRecentTokens and keeps OpenClaw runtime's recent-tail cut point. Without an explicit keep budget, manual compaction remains a hard checkpoint and rebuilt context starts from the new summary.
• Set agents.defaults.compaction.midTurnPrecheck.enabled: true to run the optional tool-loop precheck after new tool results and before the next model call. This is a trigger only; summary generation still uses the configured compaction path. It is independent of maxActiveTranscriptBytes, which is a turn-start active-transcript byte-size guard.
• Set agents.defaults.compaction.maxActiveTranscriptBytes to a byte value or string such as "20mb" to run local compaction before a turn when the active transcript gets large. This guard is active only when truncateAfterCompaction is also enabled. Leave it unset or set 0 to disable.
• When agents.defaults.compaction.truncateAfterCompaction is enabled, OpenClaw rotates the active transcript to a compacted successor JSONL after compaction. Branch/restore checkpoint actions use that compacted successor; legacy pre-compaction checkpoint files remain readable while referenced.

Why: leave enough headroom for multi-turn "housekeeping" (like memory writes) before compaction becomes unavoidable.

Implementation: ensureAgentCompactionReserveTokens() in src/agents/agent-settings.ts (called from src/agents/embedded-agent-runner.ts).

---

Pluggable compaction providers

Plugins can register a compaction provider via registerCompactionProvider() on the plugin API. When agents.defaults.compaction.provider is set to a registered provider id, the safeguard extension delegates summarization to that provider instead of the built-in summarizeInStages pipeline.

• provider: id of a registered compaction provider plugin. Leave unset for default LLM summarization.
• Setting a provider forces mode: "safeguard".
• Providers receive the same compaction instructions and identifier-preservation policy as the built-in path.
• The safeguard still preserves recent-turn and split-turn suffix context after provider output.
• Built-in safeguard summarization re-distills prior summaries with new messages instead of preserving the full previous summary verbatim.
• Safeguard mode enables summary quality audits by default; set qualityGuard.enabled: false to skip retry-on-malformed-output behavior.
• If the provider fails or returns an empty result, OpenClaw falls back to built-in LLM summarization automatically.
• Abort/timeout signals are re-thrown (not swallowed) to respect caller cancellation.

Source: src/plugins/compaction-provider.ts, src/agents/agent-hooks/compaction-safeguard.ts.

---

User-visible surfaces

You can observe compaction and session state via:

• /status (in any chat session)
• openclaw status (CLI)
• openclaw sessions / sessions --json
• Gateway logs (pnpm gateway:watch or openclaw logs --follow): embedded run auto-compaction start + complete
• Verbose mode: 🧹 Auto-compaction complete + compaction count

---

Silent housekeeping (NO_REPLY)

OpenClaw supports "silent" turns for background tasks where the user should not see intermediate output.

Convention:

• The assistant starts its output with the exact silent token NO_REPLY / no_reply to indicate "do not deliver a reply to the user".
• OpenClaw strips/suppresses this in the delivery layer.
• Exact silent-token suppression is case-insensitive, so NO_REPLY and no_reply both count when the whole payload is just the silent token.
• This is for true background/no-delivery turns only; it is not a shortcut for ordinary actionable user requests.

As of 2026.1.10, OpenClaw also suppresses draft/typing streaming when a partial chunk begins with NO_REPLY, so silent operations don't leak partial output mid-turn.

---

Pre-compaction "memory flush" (implemented)

Goal: before auto-compaction happens, run a silent agentic turn that writes durable state to disk (e.g. memory/YYYY-MM-DD.md in the agent workspace) so compaction can't erase critical context.

OpenClaw uses the pre-threshold flush approach:

1. Monitor session context usage.
2. When it crosses a "soft threshold" (below OpenClaw runtime's compaction threshold), run a silent "write memory now" directive to the agent.
3. Use the exact silent token NO_REPLY / no_reply so the user sees nothing.

Config (agents.defaults.compaction.memoryFlush):

• enabled (default: true)
• model (optional exact provider/model override for the flush turn, for example ollama/qwen3:8b)
• softThresholdTokens (default: 4000)
• prompt (user message for the flush turn)
• systemPrompt (extra system prompt appended for the flush turn)

Notes:

• The default prompt/system prompt include a NO_REPLY hint to suppress delivery.
• When model is set, the flush turn uses that model without inheriting the active session fallback chain, so local-only housekeeping does not silently fall back to a paid conversation model.
• The flush runs once per compaction cycle (tracked in sessions.json).
• The flush runs only for embedded OpenClaw sessions (CLI backends skip it).
• The flush is skipped when the session workspace is read-only (workspaceAccess: "ro" or "none").
• See Memory for the workspace file layout and write patterns.

OpenClaw also exposes a session_before_compact hook in the extension API, but OpenClaw's flush logic lives on the Gateway side today.

---

Troubleshooting checklist

• Session key wrong? Start with /concepts/session and confirm the sessionKey in /status.
• Store vs transcript mismatch? Confirm the Gateway host and the store path from openclaw status.
• Compaction spam? Check:
  • model context window (too small)
  • compaction settings (reserveTokens too high for the model window can cause earlier compaction)
  • tool-result bloat: enable/tune session pruning
• Silent turns leaking? Confirm the reply starts with NO_REPLY (case-insensitive exact token) and you're on a build that includes the streaming suppression fix.

Related

• Session management
• Session pruning
• Context engine