docs: add controller preview example

README.md

@@ -119,6 +119,26 @@ else:
     render(call_llm(user_input))
 ```
 
+Controller quick example:
+
+```python
+from context_compiler import create_engine, preview, state_diff, step
+
+engine = create_engine()
+
+before = engine.state
+dry_run = preview(engine, "prohibit peanuts")
+print(dry_run["would_mutate"])  # True
+planned_change = state_diff(before, dry_run["state_after"])
+print(planned_change["changed"])  # True
+
+after_preview = engine.state
+print(state_diff(before, after_preview)["changed"])  # False (preview does not mutate state)
+
+applied = step(engine, "prohibit peanuts")
+print(applied["decision"]["kind"])  # update
+```
+
 ## Installation
 
 Requirements:

examples/08_controller_preview_diff.py

@@ -0,0 +1,30 @@
+"""Example 8: controller preview + state diff + apply flow."""
+
+from _util import print_decision_summary, print_state_summary
+
+from context_compiler import create_engine, preview, state_diff, step
+
+
+def main() -> None:
+    engine = create_engine()
+
+    state_before = engine.state
+    print_state_summary(state_before, "state before preview")
+
+    print("\nPreview: prohibit peanuts")
+    preview_result = preview(engine, "prohibit peanuts")
+    print("would_mutate:", preview_result["would_mutate"])
+    print_decision_summary(preview_result["decision"])
+
+    state_after_preview = engine.state
+    diff_after_preview = state_diff(state_before, state_after_preview)
+    print("state changed after preview:", diff_after_preview["changed"])
+
+    print("\nApply: prohibit peanuts")
+    step_result = step(engine, "prohibit peanuts")
+    print_decision_summary(step_result["decision"])
+    print_state_summary(step_result["state"], "state after step")
+
+
+if __name__ == "__main__":
+    main()

examples/README.md

@@ -40,3 +40,9 @@ Shows `compile_transcript(messages)` from a fresh engine and `engine.apply_trans
 
 Demonstrates explicit single-policy correction without `reset policies`.  
 Shows `prohibit peanuts` -> `remove policy peanuts` -> `use peanuts`.
+
+## 08_controller_preview_diff.py
+
+Shows controller-layer dry-run behavior with `preview(engine, user_input)`.  
+Shows structural state inspection with `state_diff(state_before, state_after)`.  
+Shows `step(engine, user_input)` after preview to apply the same input.

examples/integrations/README.md

@@ -17,7 +17,7 @@ export OPENAI_API_KEY=...
 export PROVIDER=openai
 ```
 
-Checkpoint continuation in these integration examples requires `context-compiler>=0.6.14`.
+Checkpoint continuation in these integration examples requires `context-compiler>=0.7.0`.
 
 ### Run