Vendor OpenClaw source as Adolf fork baseline

Adolf is a fork/vendored clone of github.com/openclaw/openclaw (v2026.6.11),
free to diverge. Tree copied sans upstream .git; upstream remote added for
future syncs. Node pinned to 24 (.nvmrc); engines already require >=22.19.
Preserves docs/ARCHITECTURE.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LeqyaxJF2nbRXJtae2kNB2

docs/concepts/session-pruning.md

@@ -0,0 +1,91 @@
+---
+summary: "Trimming old tool results to keep context lean and caching efficient"
+title: "Session pruning"
+read_when:
+  - You want to reduce context growth from tool outputs
+  - You want to understand Anthropic prompt cache optimization
+---
+
+Session pruning trims **old tool results** from the context before each LLM call. It reduces context bloat from accumulated tool outputs (exec results, file reads, search results) without rewriting normal conversation text.
+
+<Info>
+Pruning is in-memory only -- it does not modify the on-disk session transcript. Your full history is always preserved.
+</Info>
+
+## Why it matters
+
+Long sessions accumulate tool output that inflates the context window. This increases cost and can force [compaction](/concepts/compaction) sooner than necessary.
+
+Pruning is especially valuable for **Anthropic prompt caching**. After the cache TTL expires, the next request re-caches the full prompt. Pruning reduces the cache-write size, directly lowering cost.
+
+## How it works
+
+Pruning runs in `cache-ttl` mode, gated on both a time check and a context-size check:
+
+1. Wait for the cache TTL to expire (default 5 minutes when set manually; see [Smart defaults](#smart-defaults) for the Anthropic auto-default). Before the TTL elapses, pruning is skipped entirely to preserve prompt-cache reuse for nearby turns.
+2. Once the TTL has elapsed, estimate total context size against the model's context window. If the ratio is below `softTrimRatio` (default 0.3), skip pruning and keep the TTL clock running.
+3. **Soft-trim** oversized tool results above the ratio: keep the head and tail (default 1500 chars each, capped at 4000 chars combined), insert `...` in between.
+4. If the ratio is still at or above `hardClearRatio` (default 0.5) and at least `minPrunableToolChars` (default 50,000) of prunable tool content remains, **hard-clear** those results: replace their content with a placeholder (default `[Old tool result content cleared]`).
+5. Reset the TTL clock only when pruning actually changed the context, so follow-up requests reuse the fresh cache.
+
+Two safety rules apply regardless of thresholds: the most recent `keepLastAssistants` assistant turns (default 3) are never pruned, and nothing before the session's first user message is ever pruned (protects bootstrap reads like `SOUL.md`/`USER.md`).
+
+Only `toolResult` messages are eligible; normal conversation text is left alone. Use `agents.defaults.contextPruning.tools.{allow,deny}` to scope which tool names are prunable.
+
+## Legacy image cleanup
+
+OpenClaw also builds a separate idempotent replay view for sessions that persist raw image blocks or prompt-hydration media markers in history.
+
+- It preserves the **3 most recent completed turns** byte-for-byte so prompt cache prefixes for recent follow-ups stay stable. This count includes all completed turns, not just image-bearing ones, so text-only turns consume the window too.
+- In the replay view, older already-processed image blocks from `user` or `toolResult` history are replaced with `[image data removed - already processed by model]`.
+- Older textual media references such as `[media attached: ...]`, `[Image: source: ...]`, and `media://inbound/...` are replaced with `[media reference removed - already processed by model]`. Current-turn attachment markers stay intact so vision models can still hydrate fresh images.
+- The raw session transcript is not rewritten, so history viewers can still render the original message entries and their images.
+- This is separate from normal cache-TTL pruning above. It exists to stop repeated image payloads or stale media refs from busting prompt caches on later turns.
+
+## Smart defaults
+
+The bundled Anthropic plugin auto-configures pruning and heartbeat cadence the first time it resolves an Anthropic (or Claude CLI) auth profile, but only for fields you have not already set explicitly:
+
+| Auth mode                                | `contextPruning.mode` | `contextPruning.ttl` | `heartbeat.every` |
+| ---------------------------------------- | --------------------- | -------------------- | ----------------- |
+| OAuth/token (including Claude CLI reuse) | `cache-ttl`           | `1h`                 | `1h`              |
+| API key                                  | `cache-ttl`           | `1h`                 | `30m`             |
+
+If you set `agents.defaults.contextPruning.mode` or `agents.defaults.heartbeat.every` yourself, OpenClaw does not override them. This auto-default only fires for Anthropic-family auth; other providers get pruning `off` unless you configure it.
+
+## Enable or disable
+
+Pruning is off by default for non-Anthropic providers. To enable:
+
+```json5
+{
+  agents: {
+    defaults: {
+      contextPruning: { mode: "cache-ttl", ttl: "5m" },
+    },
+  },
+}
+```
+
+To disable: set `mode: "off"`.
+
+## Pruning vs compaction
+
+|            | Pruning            | Compaction              |
+| ---------- | ------------------ | ----------------------- |
+| **What**   | Trims tool results | Summarizes conversation |
+| **Saved?** | No (per-request)   | Yes (in transcript)     |
+| **Scope**  | Tool results only  | Entire conversation     |
+
+They complement each other -- pruning keeps tool output lean between compaction cycles.
+
+## Further reading
+
+- [Compaction](/concepts/compaction): summarization-based context reduction
+- [Gateway Configuration](/gateway/configuration): all pruning config knobs (`contextPruning.*`)
+
+## Related
+
+- [Session management](/concepts/session)
+- [Session tools](/concepts/session-tool)
+- [Context engine](/concepts/context-engine)