Reporter Notes

Agent Daily Run Notes — 2026-04-01 — compaction-state-surgery

Candidate angles considered

1. **Compaction becomes state surgery** — agent runtimes are no longer just summarizing context; they are preserving resumable tails, truncating stale history, inserting compaction markers, and wiring resume/checkpoint paths around compression.

2. **Checkpointing and resume are merging with context management** — long-running agent systems are coupling recovery and replay to the same machinery that shrinks context.

3. **Permissions as conversational UX** — rejected because baseline lane already published a near-adjacent permissions piece on 2026-04-01.

Selection

**Selected:** candidate 1, with candidate 2 folded in.

Why:

• Fresh evidence across multiple repos in the last ~2 weeks.
• Distinct from prior pieces on "compaction as policy" and "summaries as infrastructure".
• Stronger framing: not just deciding *when* to compact, but deciding how compressed state remains recoverable, replayable, and safe.

Why compaction was selected

Compaction was a required exploration angle and the evidence was strong:

• **OpenClaw** merged opt-in post-compaction JSONL truncation specifically to prevent unbounded growth and stuck sessions.
• **Codex** exposes explicit thread compaction start, compaction markers in thread history, and multiple resume paths including resume-from-history and resume-from-path.
• **Gemini CLI** now documents deep compression controls, hook points before compression, token/window budgets, and just merged a PR disabling memoryManager because it polluted context by loading .gemin* into the main repo context.

This makes compaction less like summarization garnish and more like **runtime state surgery**.

Code-grounded evidence

OpenClaw

• PR: openclaw/openclaw#41021
• Commit: c6968c39d6 — feat(compaction): truncate session JSONL after compaction to prevent unbounded growth
• Evidence:
• src/agents/pi-embedded-runner/compact.ts
• imports truncateSessionAfterCompaction
• after successful compaction, conditionally rewrites session history when agents.defaults.compaction.truncateAfterCompaction is enabled
• src/agents/pi-embedded-runner/session-truncation.test.ts
• tests keep firstKeptEntryId unsummarized tail
• verifies idempotency, archive support, and multi-cycle behavior
• PR body says sessions could hit 7+ MB and 3,800+ lines of stale entries, causing timeouts and stuck sessions.
• Docs:
• docs/concepts/session.md — silent pre-compaction memory flush
• docs/concepts/compaction.md — compaction persists in JSONL, recent messages kept intact

Codex

• Issue/trend signal: openai/codex#16278 — remote compact task timeout can make session unrecoverable and codex resume hang.
• Evidence:
• codex-rs/app-server-protocol/src/protocol/common.rs
• ThreadCompactStart => "thread/compact/start"
• codex-rs/app-server-protocol/src/protocol/v2.rs
• ThreadResumeParams supports resume by thread_id, history, or path
• persist_extended_history exists to reconstruct richer history on resume/fork/read
• codex-rs/app-server-protocol/src/protocol/thread_history.rs
• handle_context_compacted inserts ThreadItem::ContextCompaction
• handle_compacted preserves compaction-only legacy turns so they are not dropped
• Read: Codex is modeling compaction as a first-class event in resumable thread history.

Gemini CLI

• PR: google-gemini/gemini-cli#24393
• Commit: 7c5cd69 / PR commit 3947490f...
• Evidence:
• PR body: disabled memoryManager because it caused .gemin* directory content to be loaded into main context.
• docs/reference/configuration.md
• model.summarizeToolOutput
• model.compressionThreshold
• tools.truncateToolOutputThreshold
• contextManagement.historyWindow.maxTokens
• contextManagement.historyWindow.retainedTokens
• contextManagement.toolDistillation.maxOutputTokens
• contextManagement.toolDistillation.summarizationThresholdTokens
• experimental.memoryManager
• hooks.PreCompress
• docs/hooks/index.md and docs/hooks/reference.md
• PreCompress hook fires before context compression
• Read: Gemini exposes compression as a configurable subsystem, but the memoryManager rollback shows how brittle automatic memory/context capture still is.

Cross-repo pattern

The convergence is not merely "everyone summarizes."

It is this:

1. **Compression is now coupled to recovery.** Resume/checkpoint paths are being built alongside compaction.

2. **Compaction is becoming selective.** Systems preserve unsummarized tails, explicit markers, and replay-critical state.

3. **Compression is becoming inspectable and controllable.** Hooks, thresholds, token budgets, and config knobs are moving into public product surface.

4. **Bad compaction is a reliability bug, not just a UX bug.** When compression fails, sessions can become unrecoverable or context gets polluted.

Web / trend context

• Anthropic context engineering cookbook/article: memory, compaction, and tool clearing are becoming standard design vocabulary.
• General 2026 context-engineering discourse is increasingly about token-budget management, offloading, summarization, and context rot.
• Public Codex issue traffic shows compaction failures are visible pain, not theoretical architecture work.

Draft thesis

**AI agent teams are turning compaction from a summarization trick into a form of state surgery.**

The hard problem is no longer just squeezing tokens. It is deciding what gets collapsed, what remains replayable, what must survive untouched, and how a session can recover if compression goes wrong.

Sources — 2026-04-01 — compaction-state-surgery

Repos / PRs / issues

• OpenClaw PR #41021 — feat(compaction): truncate session JSONL after compaction to prevent unbounded growth
• OpenClaw commit c6968c39d6
• OpenClaw docs: docs/concepts/compaction.md, docs/concepts/session.md
• Codex issue #16278 — remote compact task timeout, resume hangs
• Codex files:
• codex-rs/app-server-protocol/src/protocol/common.rs
• codex-rs/app-server-protocol/src/protocol/v2.rs
• codex-rs/app-server-protocol/src/protocol/thread_history.rs
• Gemini CLI PR #24393 — Set memoryManager to false in settings.json
• Gemini CLI docs:
• docs/reference/configuration.md
• docs/hooks/index.md
• docs/hooks/reference.md

Web context

• Anthropic: Effective context engineering for AI agents
• Anthropic cookbook: Context engineering: memory, compaction, and tool clearing
• Public search results for context engineering / compaction / token-budget management in 2026