fix(s08): keep the active user request visible after snip_compact

snip_compact archives the middle section of the history. Once a task
accumulates many tool calls, the current user request moves into that
archived middle, and because the context then fits under the limit,
compact_history never runs — so the model loses sight of the active
request and can drift back to an older one (reproduced in #577 by
entering the three README example prompts in one conversation).

prepare() now checks whether snip_compact archived messages and the
active request is no longer present verbatim; only then is the request
reinserted as a dedicated "Current user request" message, in the same
format compact_history and reactive_compact already use. Histories
without an archive marker and requests still visible in the kept head
or tail are left untouched.

Adds two regression tests: one drives the request into the archived
middle behind earlier turns plus a tool-call burst, the other asserts
no duplicate request message appears when nothing was archived.

Fixes #577

Author: wudilyy999

s08_context_compact/code.py

@@ -509,6 +509,20 @@ def reactive_compact(self, messages: list, active_request: str) -> list:
     def prepare(self, messages: list, active_request: str) -> list:
         messages = self.tool_result_budget(messages)
         messages = self.snip_compact(messages)
+        if active_request and any(
+            self.is_archive_marker(message) for message in messages
+        ) and not any(
+            isinstance(message.get("content"), str)
+            and message["content"] == active_request
+            for message in messages
+            if message.get("role") == "user"
+        ):
+            # snip_compact archives the middle section, which may contain the
+            # current user request once a task accumulates many tool calls.
+            # Reinsert it in the same format used by compact_history /
+            # reactive_compact so the model never loses the active task.
+            messages.insert(0, {"role": "user", "content":
+                                f"Current user request:\n{active_request}"})
         if self.estimate_chars(messages) > self.CONTEXT_CHAR_LIMIT:
             target = int(self.CONTEXT_CHAR_LIMIT * 0.8)
             messages = self.micro_compact(messages, target)

tests/test_s08_context_compact.py

@@ -136,3 +136,55 @@ def test_prepare_persists_oversized_unseen_result_before_full_compact(
     saved_line = next(line for line in content.splitlines()
                       if line.startswith("Full output: "))
     assert Path(saved_line.removeprefix("Full output: ")).read_text() == output
+
+
+def test_prepare_reinserts_active_request_archived_by_snip_compact(
+        tmp_path, monkeypatch):
+    lesson = load_lesson(monkeypatch, tmp_path)
+    request = "compare s08 and s09 context handling"
+    # Earlier conversation turns occupy the head of the history, so the
+    # active request sits before a long tool-call burst — the shape that
+    # lets snip_compact archive it into the middle section.
+    messages = [
+        {"role": "user", "content": "earlier question one"},
+        {"role": "assistant", "content": [{"type": "text", "text": "answer one"}]},
+        {"role": "user", "content": "earlier question two"},
+        {"role": "assistant", "content": [{"type": "text", "text": "answer two"}]},
+        {"role": "user", "content": request},
+        {"role": "assistant", "content": [{"type": "text", "text": "starting"}]},
+    ]
+    for index in range(26):
+        tool_id = f"tool-{index}"
+        messages.extend([
+            {"role": "assistant", "content": [
+                {"type": "tool_use", "id": tool_id, "name": "bash", "input": {}}
+            ]},
+            {"role": "user", "content": [
+                {"type": "tool_result", "tool_use_id": tool_id, "content": f"out-{index}"}
+            ]},
+        ])
+
+    prepared = lesson["COMPACTOR"].prepare(list(messages), request)
+    rendered = "\n".join(
+        message["content"] for message in prepared
+        if message.get("role") == "user"
+        and isinstance(message.get("content"), str)
+    )
+    assert "Current user request" in rendered
+    assert request in rendered
+
+
+def test_prepare_does_not_duplicate_active_request_visible_in_tail(
+        tmp_path, monkeypatch):
+    lesson = load_lesson(monkeypatch, tmp_path)
+    request = "summarize the naming pattern"
+    messages = [{"role": "user", "content": request}]
+
+    prepared = lesson["COMPACTOR"].prepare(list(messages), request)
+
+    assert len([message for message in prepared
+                if message.get("role") == "user"
+                and message.get("content") == request]) == 1
+    assert not any(isinstance(message.get("content"), str)
+                   and message["content"].startswith("Current user request")
+                   for message in prepared)