This PR is intentionally the provider-native complement to the no-stall/background-maintenance work in #65233 and the lossless-claw sidecar changes in Martian-Engineering/lossless-claw#408.

The goal is a hybrid model:

• provider-native Anthropic compaction manages the live Claude prompt
• mixed cache TTLs keep the stable prefix hot without paying 1-hour write cost for volatile conversation content
• lossless-claw remains the searchable lossless sidecar instead of rewriting the active prompt on every turn

Validation on this branch:

• pnpm test -- --run src/agents/anthropic-payload-policy.test.ts src/agents/anthropic-transport-stream.test.ts src/agents/pi-embedded-runner-extraparams.test.ts passed
• NODE_OPTIONS=--max-old-space-size=8192 pnpm exec tsc -p tsconfig.json --noEmit reports only the pre-existing unrelated Telegram AbortSignal baseline in extensions/telegram/src/bot.ts

Greptile Summary

This PR adds Anthropic-native context compaction support and a mixed cache-TTL policy: the stable system/tool prefix gets a 1h TTL on eligible endpoints (api.anthropic.com, Vertex AI) while trailing conversation messages keep plain ephemeral. Compaction blocks are round-tripped through history conversion and streaming so Anthropic's active-context compaction can run without discarding prior context.

• The GitHub Copilot transport path computes betaFeatures (including compaction betas when history contains compaction blocks), but then builds a separate copilotBetas array from scratch and sends that instead. Any session where a prior Anthropic turn produced a compaction block would cause the Copilot API to receive type: \"compaction\" messages without the required compact-2026-01-12 beta header, resulting in an API error.

Confidence Score: 4/5

Safe to merge for pure Anthropic sessions; one edge case needs attention before mixed-provider sessions with compaction history are possible.

The core implementation — mixed cache TTLs, compaction config injection, beta feature gating, and streaming round-trip — is correct and well-tested. One P2 finding (Copilot path ignoring compaction betas when history has compaction blocks) would produce an API error in a cross-provider scenario that this PR makes reachable for the first time, warranting a score of 4 rather than 5.

src/agents/anthropic-transport-stream.ts — specifically the createAnthropicTransportClient GitHub Copilot branch and the resolveAnthropicCompactionThreshold return type.

This is a comment left during a code review.
Path: src/agents/anthropic-transport-stream.ts
Line: 514-538

Comment:
**Compaction beta headers silently dropped for GitHub Copilot when history contains compaction blocks**

`betaFeatures` is computed at lines 503–509 using `hasCompactionBlocks(context.messages)`, which can return `true` if the conversation history carries compaction blocks from a previous Anthropic session. However, the Copilot branch ignores `betaFeatures` entirely and builds `copilotBetas` from scratch (only including `interleaved-thinking-2025-05-14`). If compaction blocks are present, the Copilot API receives messages with `type: "compaction"` content blocks but without `compact-2026-01-12` in the `anthropic-beta` header, which will cause an API error.

The auto-enable guard in `shouldEnableAnthropicServerCompaction` already blocks compaction from being injected for non-Anthropic providers, but `hasCompactionBlocks` independently triggers the beta requirement regardless of provider. A simple fix is to skip the compaction betas for the Copilot path, or filter compaction blocks from messages before conversion when the provider doesn't support them.

How can I resolve this? If you propose a fix, please make it concise.

---

This is a comment left during a code review.
Path: src/agents/anthropic-transport-stream.ts
Line: 427-442

Comment:
**Return type is wider than actual behaviour**

`resolveAnthropicCompactionThreshold` is declared as returning `number | undefined`, but every code path returns a `number` (either the user-supplied value, `150_000`, or the computed `contextWindow * 0.75` result). The `| undefined` in the signature doesn't match the implementation and may mislead callers into adding unnecessary nullish checks.

```suggestion
function resolveAnthropicCompactionThreshold(
  model: Pick<AnthropicTransportModel, "contextWindow">,
  requested: number | undefined,
): number {
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "Add Anthropic native compaction support" | Re-trigger Greptile}

@codex review

Latest head makes Anthropic server compaction opt-in, stops streaming compaction blocks as visible text, and strips compaction blocks from the GitHub Copilot Anthropic path.

Pass 2 fixes are up in fd20e73521.

What changed:

• clamp Anthropic native-compaction triggers to the documented 50_000 token minimum
• preserve stop_reason: "compaction"
• make Copilot compaction stripping safe for string assistant content
• normalize plain-string assistant messages into text blocks in the shared transport transform

Validation:

• pnpm test -- --run src/agents/anthropic-payload-policy.test.ts src/agents/anthropic-transport-stream.test.ts src/agents/pi-embedded-runner-extraparams.test.ts
• passed (116 focused tests)

@codex review

@codex review

Follow-up fixes are in:

• Anthropic compaction replay is now gated by actual transport capability instead of replaying on any anthropic-messages provider
• non-Anthropic transports strip compaction blocks before conversion and suppress compaction/context-management betas
• added a MiniMax regression covering the non-Anthropic replay path

Focused tests:

• pnpm test -- --run src/agents/anthropic-transport-stream.test.ts src/agents/anthropic-payload-policy.test.ts

Codex Review: Didn't find any major issues. Nice work!

Codex Review: Didn't find any major issues. Can't wait for the next one!

@codex review

Final follow-up is in:

• compaction-only Anthropic stops are now treated as paused incomplete turns instead of successful empty replies
• runner retries once automatically after a server-compaction-only stop
• focused coverage added for paused-state classification and one-shot continuation retry

Focused tests:

• pnpm test -- --run src/agents/pi-embedded-runner/run.incomplete-turn.test.ts src/agents/anthropic-transport-stream.test.ts src/agents/anthropic-payload-policy.test.ts

Codex Review: Didn't find any major issues. 🎉

@jalehman this is what I use locally for best practices/much better experience with Anthropic models. It's technically two features. The most valuable of which is the mixed cache system that Anthropic is working on to cut cost for users (1hr for durable system prompting and 5m stuff that is in/out quick task wise).

This DOES not add this feature to native compaction or touch anything outside of when you're using an anthropic model. IT also works hand in hand with LCM to still save durable memory and work as context engine but it does NOT run compaction nor damage the cache.

It saves so far testing wise about over 50%> of cache write cost in my initial testing. It can make Anthropic more "usable" for Openclaw users now off max and affordable.

due to limit in my PR's and focus toward GPT 5.4 improvements. @jalehman closing this, since you're handling just copy it yourself and or reopen when you get to it. I need the extra slot for now.