diff --git a/EvoScientist/cli/commands.py b/EvoScientist/cli/commands.py
index b94210b..6bf5741 100644
--- a/EvoScientist/cli/commands.py
+++ b/EvoScientist/cli/commands.py
@@ -90,6 +90,254 @@ def channel_setup():
         console.print("[dim]No changes made.[/dim]")
 
 
+# =============================================================================
+# Compact helper
+# =============================================================================
+
+
+class CompactResult:
+    """Structured result from compact_conversation.
+
+    Attributes:
+        status: "noop" (nothing to compact), "ok" (compacted), or "error".
+        message: Short human-readable message (used as fallback / TUI text).
+        messages_compacted: Number of messages summarized (0 for noop/error).
+        messages_kept: Number of messages unchanged.
+        tokens_before: Total tokens before compaction.
+        tokens_after: Total tokens after compaction.
+        tokens_summarized: Tokens in the summarized portion (before).
+        tokens_summary: Tokens in the summary message (after).
+        pct_decrease: Percentage decrease.
+    """
+
+    __slots__ = (
+        "status", "message",
+        "messages_compacted", "messages_kept",
+        "tokens_before", "tokens_after",
+        "tokens_summarized", "tokens_summary",
+        "pct_decrease",
+    )
+
+    def __init__(
+        self,
+        status: str,
+        message: str,
+        *,
+        messages_compacted: int = 0,
+        messages_kept: int = 0,
+        tokens_before: int = 0,
+        tokens_after: int = 0,
+        tokens_summarized: int = 0,
+        tokens_summary: int = 0,
+        pct_decrease: int = 0,
+    ):
+        self.status = status
+        self.message = message
+        self.messages_compacted = messages_compacted
+        self.messages_kept = messages_kept
+        self.tokens_before = tokens_before
+        self.tokens_after = tokens_after
+        self.tokens_summarized = tokens_summarized
+        self.tokens_summary = tokens_summary
+        self.pct_decrease = pct_decrease
+
+    def __str__(self) -> str:
+        return self.message
+
+
+def render_compact_result(result: CompactResult):  # -> rich.text.Text
+    """Render a CompactResult as styled Rich Text.
+
+    Uses the same visual language as the token usage display:
+    cyan for numbers, green for savings, dim for labels.
+    """
+    from rich.text import Text
+
+    output = Text()
+
+    if result.status == "noop":
+        output.append("○ ", style="dim")
+        output.append("Nothing to compact", style="dim")
+        if result.tokens_before > 0:
+            output.append(" — conversation is ~", style="dim")
+            output.append(f"{result.tokens_before:,}", style="cyan")
+            output.append(" tokens, within retention budget", style="dim")
+        elif result.message:
+            # Extract reason from message (e.g. "no messages")
+            output.append(f" — {result.message.split('—')[-1].strip()}" if "—" in result.message else "", style="dim")
+        return output
+
+    if result.status == "error":
+        output.append("✗ ", style="red")
+        output.append(result.message, style="red")
+        return output
+
+    # status == "ok"
+    output.append("✓ ", style="green")
+    output.append("Compacted ", style="dim")
+    output.append(f"{result.messages_compacted}", style="bold")
+    output.append(" messages", style="dim")
+    output.append("  [", style="dim")
+    output.append(f"{result.tokens_before:,}", style="cyan")
+    output.append(" → ", style="dim")
+    output.append(f"{result.tokens_after:,}", style="green")
+    output.append(" tokens", style="dim")
+    output.append(f"  ↓{result.pct_decrease}%", style="green bold")
+    output.append("]", style="dim")
+
+    # Second line: detail breakdown
+    output.append("\n  ", style="")
+    output.append("Summarized: ", style="dim")
+    output.append(f"{result.tokens_summarized:,}", style="cyan")
+    output.append(" → ", style="dim")
+    output.append(f"{result.tokens_summary:,}", style="green")
+    output.append("  │  ", style="dim")
+    output.append("Kept: ", style="dim")
+    output.append(f"{result.messages_kept}", style="cyan")
+    output.append(" messages unchanged", style="dim")
+
+    return output
+
+
+async def compact_conversation(agent: Any, thread_id: str | None) -> CompactResult:
+    """Compact the conversation by summarizing old messages.
+
+    Reads the agent's checkpointed state, creates a temporary
+    ``SummarizationMiddleware``, generates a summary, and writes
+    the compacted state back via ``aupdate_state``.
+
+    Returns a structured ``CompactResult``.
+    """
+    if not agent or not thread_id:
+        return CompactResult("noop", "Nothing to compact — start a conversation first.")
+
+    from langchain_core.messages.utils import count_tokens_approximately
+
+    config = {"configurable": {"thread_id": thread_id}}
+
+    try:
+        state_snapshot = await agent.aget_state(config)
+    except Exception as exc:
+        return CompactResult("error", f"Failed to read state: {exc}")
+
+    messages = state_snapshot.values.get("messages", [])
+    if not messages:
+        return CompactResult("noop", "Nothing to compact — no messages in conversation.")
+
+    from ..EvoScientist import _ensure_chat_model, _get_default_backend
+    from deepagents.middleware.summarization import (
+        SummarizationEvent,
+        SummarizationMiddleware,
+        compute_summarization_defaults,
+    )
+
+    try:
+        model = _ensure_chat_model()
+    except Exception as exc:
+        return CompactResult("error", f"Compaction requires a working model configuration: {exc}")
+
+    backend = _get_default_backend()
+
+    defaults = compute_summarization_defaults(model)
+    middleware = SummarizationMiddleware(
+        model=model,
+        backend=backend,
+        keep=defaults["keep"],
+        trim_tokens_to_summarize=None,
+    )
+
+    # Rebuild effective message list accounting for prior compaction
+    event = state_snapshot.values.get("_summarization_event")
+    effective = middleware._apply_event_to_messages(messages, event)
+
+    cutoff = middleware._determine_cutoff_index(effective)
+    if cutoff == 0:
+        conv_tokens = count_tokens_approximately(effective)
+        return CompactResult(
+            "noop",
+            f"Nothing to compact — conversation (~{conv_tokens:,} tokens) "
+            f"is within the retention budget.",
+            tokens_before=conv_tokens,
+        )
+
+    to_summarize, to_keep = middleware._partition_messages(effective, cutoff)
+
+    tokens_summarized = count_tokens_approximately(to_summarize)
+    tokens_kept = count_tokens_approximately(to_keep)
+    tokens_before = tokens_summarized + tokens_kept
+
+    # Skip if savings would be negligible — compacting ≤2 messages with
+    # <2% of total tokens prevents the infinite 1-message-at-a-time loop
+    # that occurs when the conversation sits just above the keep budget.
+    _MIN_COMPACT_MESSAGES = 3
+    _MIN_COMPACT_TOKEN_FRACTION = 0.02
+    if (
+        len(to_summarize) < _MIN_COMPACT_MESSAGES
+        and tokens_summarized < tokens_before * _MIN_COMPACT_TOKEN_FRACTION
+    ):
+        return CompactResult(
+            "noop",
+            f"Nothing to compact — only {len(to_summarize)} message(s) "
+            f"({tokens_summarized:,} tokens) would be summarized, "
+            f"not worth the overhead.",
+            tokens_before=tokens_before,
+        )
+
+    # Generate summary (LLM call)
+    summary = await middleware._acreate_summary(to_summarize)
+
+    # Offload old messages to backend
+    file_path: str | None = None
+    try:
+        file_path = await middleware._aoffload_to_backend(backend, to_summarize)
+    except Exception:
+        pass  # non-fatal — proceed without offloaded history
+
+    summary_msg = middleware._build_new_messages_with_path(summary, file_path)[0]
+
+    # Compute token savings
+    tokens_summary = count_tokens_approximately([summary_msg])
+    tokens_after = tokens_summary + tokens_kept
+    pct = (
+        round((tokens_before - tokens_after) / tokens_before * 100)
+        if tokens_before > 0
+        else 0
+    )
+
+    # Append savings note to summary message for model awareness
+    savings_note = (
+        f"\n\n{len(to_summarize)} messages were compacted "
+        f"({tokens_summarized:,} → {tokens_summary:,} tokens). "
+        f"Total context: {tokens_before:,} → {tokens_after:,} tokens "
+        f"({pct}% decrease), "
+        f"{len(to_keep)} messages unchanged."
+    )
+    summary_msg.content += savings_note
+
+    state_cutoff = middleware._compute_state_cutoff(event, cutoff)
+
+    new_event: SummarizationEvent = {
+        "cutoff_index": state_cutoff,
+        "summary_message": summary_msg,
+        "file_path": file_path,
+    }
+
+    await agent.aupdate_state(config, {"_summarization_event": new_event})
+
+    return CompactResult(
+        "ok",
+        f"Compacted {len(to_summarize)} messages "
+        f"({tokens_before:,} → {tokens_after:,} tokens, {pct}% decrease)",
+        messages_compacted=len(to_summarize),
+        messages_kept=len(to_keep),
+        tokens_before=tokens_before,
+        tokens_after=tokens_after,
+        tokens_summarized=tokens_summarized,
+        tokens_summary=tokens_summary,
+        pct_decrease=pct,
+    )
+
+
 # =============================================================================
 # Serve helpers
 # =============================================================================
diff --git a/EvoScientist/cli/interactive.py b/EvoScientist/cli/interactive.py
index 9328dae..b364151 100644
--- a/EvoScientist/cli/interactive.py
+++ b/EvoScientist/cli/interactive.py
@@ -112,6 +112,7 @@ _SLASH_COMMANDS = [
     ("/uninstall-skill", "Remove an installed skill"),
     ("/mcp", "Manage MCP servers"),
     ("/channel", "Configure messaging channels"),
+    ("/compact", "Compact conversation to free context"),
     ("/exit", "Quit EvoScientist"),
 ]
 
@@ -694,6 +695,16 @@ def cmd_interactive(
                                 )
                             continue
 
+                        if user_input.lower() == "/compact":
+                            from .commands import compact_conversation, render_compact_result
+                            with console.status("[cyan]Compacting conversation...[/cyan]"):
+                                result = await compact_conversation(
+                                    agent=state["agent"],
+                                    thread_id=state["thread_id"],
+                                )
+                            console.print(render_compact_result(result))
+                            continue
+
                         # Stream agent response with metadata for persistence
                         console.print()
                         meta = build_metadata(state["workspace_dir"], model)
diff --git a/EvoScientist/cli/tui_interactive.py b/EvoScientist/cli/tui_interactive.py
index 990fc70..7dc28b9 100644
--- a/EvoScientist/cli/tui_interactive.py
+++ b/EvoScientist/cli/tui_interactive.py
@@ -59,6 +59,7 @@ _TUI_SLASH_COMMANDS = [
     ("/uninstall-skill", "Remove an installed skill"),
     ("/mcp", "Manage MCP servers"),
     ("/channel", "Configure messaging channels"),
+    ("/compact", "Compact conversation to free context"),
     ("/help", "Show available commands"),
     ("/exit", "Quit EvoScientist"),
 ]
@@ -1528,6 +1529,16 @@ def run_textual_interactive(
                 self._cmd_channel(arg)
                 return
 
+            if cmd == "/compact":
+                from .commands import compact_conversation, render_compact_result
+                self._append_system("Compacting conversation...")
+                result = await compact_conversation(
+                    agent=self._agent,
+                    thread_id=self._conversation_tid,
+                )
+                self._mount_renderable(render_compact_result(result))
+                return
+
             self._append_system(f"Unknown command: {command}", style="yellow")
 
         async def _resolve_thread_id(self, prefix: str) -> str | None:
diff --git a/tests/test_compact_command.py b/tests/test_compact_command.py
new file mode 100644
index 0000000..f922d5c
--- /dev/null
+++ b/tests/test_compact_command.py
@@ -0,0 +1,310 @@
+"""Tests for the /compact command (compact_conversation helper)."""
+
+import asyncio
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+
+@pytest.fixture
+def _run():
+    """Helper to run async tests."""
+    loop = asyncio.new_event_loop()
+    yield loop.run_until_complete
+    loop.close()
+
+
+class TestCompactGuards:
+    """Guard conditions that return early without touching the middleware."""
+
+    def test_no_agent(self, _run):
+        from EvoScientist.cli.commands import compact_conversation
+
+        result = _run(compact_conversation(agent=None, thread_id="abc"))
+        assert result.status == "noop"
+        assert "Nothing to compact" in result.message
+
+    def test_no_thread_id(self, _run):
+        from EvoScientist.cli.commands import compact_conversation
+
+        result = _run(compact_conversation(agent=MagicMock(), thread_id=None))
+        assert result.status == "noop"
+        assert "Nothing to compact" in result.message
+
+    def test_empty_messages(self, _run):
+        from EvoScientist.cli.commands import compact_conversation
+
+        agent = MagicMock()
+        snapshot = SimpleNamespace(values={"messages": []})
+        agent.aget_state = AsyncMock(return_value=snapshot)
+
+        result = _run(compact_conversation(agent=agent, thread_id="tid-1"))
+        assert result.status == "noop"
+        assert "no messages" in result.message
+
+    def test_state_read_failure(self, _run):
+        from EvoScientist.cli.commands import compact_conversation
+
+        agent = MagicMock()
+        agent.aget_state = AsyncMock(side_effect=RuntimeError("DB gone"))
+
+        result = _run(compact_conversation(agent=agent, thread_id="tid-1"))
+        assert result.status == "error"
+        assert "Failed to read state" in result.message
+
+
+class TestCompactCutoffZero:
+    """When cutoff == 0, conversation is within retention budget."""
+
+    def test_nothing_to_compact_short_conversation(self, _run):
+        from EvoScientist.cli.commands import compact_conversation
+
+        agent = MagicMock()
+        msgs = [MagicMock() for _ in range(3)]
+        snapshot = SimpleNamespace(values={"messages": msgs})
+        agent.aget_state = AsyncMock(return_value=snapshot)
+
+        mock_middleware_inst = MagicMock()
+        mock_middleware_inst._apply_event_to_messages.return_value = msgs
+        mock_middleware_inst._determine_cutoff_index.return_value = 0
+
+        mock_middleware_cls = MagicMock(return_value=mock_middleware_inst)
+
+        with (
+            patch("EvoScientist.EvoScientist._ensure_chat_model", return_value=MagicMock()),
+            patch("EvoScientist.EvoScientist._get_default_backend", return_value=MagicMock()),
+            patch("deepagents.middleware.summarization.SummarizationMiddleware", mock_middleware_cls),
+            patch("deepagents.middleware.summarization.compute_summarization_defaults", return_value={"keep": ("messages", 6)}),
+            patch("langchain_core.messages.utils.count_tokens_approximately", return_value=500),
+        ):
+            result = _run(compact_conversation(agent=agent, thread_id="tid-1"))
+
+        assert result.status == "noop"
+        assert "within the retention budget" in result.message
+        assert result.tokens_before == 500
+
+
+class TestCompactNegligibleSavings:
+    """When cutoff > 0 but savings are too small to be worth it."""
+
+    def test_skip_when_few_messages_and_low_tokens(self, _run):
+        from EvoScientist.cli.commands import compact_conversation
+
+        agent = MagicMock()
+        msgs = [MagicMock() for _ in range(15)]
+        snapshot = SimpleNamespace(values={"messages": msgs, "_summarization_event": None})
+        agent.aget_state = AsyncMock(return_value=snapshot)
+
+        mock_middleware_inst = MagicMock()
+        mock_middleware_inst._apply_event_to_messages.return_value = msgs
+        mock_middleware_inst._determine_cutoff_index.return_value = 1
+        # 1 message to summarize (200 tokens), 14 to keep (22000 tokens)
+        mock_middleware_inst._partition_messages.return_value = (msgs[:1], msgs[1:])
+
+        mock_middleware_cls = MagicMock(return_value=mock_middleware_inst)
+
+        # to_summarize=200, to_keep=22000 → total=22200, 200/22200 < 2%
+        token_values = iter([200, 22000])
+
+        with (
+            patch("EvoScientist.EvoScientist._ensure_chat_model", return_value=MagicMock()),
+            patch("EvoScientist.EvoScientist._get_default_backend", return_value=MagicMock()),
+            patch("deepagents.middleware.summarization.SummarizationMiddleware", mock_middleware_cls),
+            patch("deepagents.middleware.summarization.compute_summarization_defaults", return_value={"keep": ("messages", 6)}),
+            patch("langchain_core.messages.utils.count_tokens_approximately", side_effect=lambda x: next(token_values)),
+        ):
+            result = _run(compact_conversation(agent=agent, thread_id="tid-1"))
+
+        assert result.status == "noop"
+        assert "not worth" in result.message
+        # No LLM call should have been made
+        mock_middleware_inst._acreate_summary.assert_not_called()
+
+    def test_still_compacts_when_few_messages_but_high_tokens(self, _run):
+        """2 messages but they account for >2% of tokens — should compact."""
+        from EvoScientist.cli.commands import compact_conversation
+        from langchain_core.messages import HumanMessage
+
+        agent = MagicMock()
+        msgs = [MagicMock() for _ in range(10)]
+        snapshot = SimpleNamespace(values={"messages": msgs, "_summarization_event": None})
+        agent.aget_state = AsyncMock(return_value=snapshot)
+        agent.aupdate_state = AsyncMock()
+
+        summary_msg = HumanMessage(content="Summary")
+
+        mock_middleware_inst = MagicMock()
+        mock_middleware_inst._apply_event_to_messages.return_value = msgs
+        mock_middleware_inst._determine_cutoff_index.return_value = 2
+        mock_middleware_inst._partition_messages.return_value = (msgs[:2], msgs[2:])
+        mock_middleware_inst._acreate_summary = AsyncMock(return_value="Summary")
+        mock_middleware_inst._aoffload_to_backend = AsyncMock(return_value=None)
+        mock_middleware_inst._build_new_messages_with_path.return_value = [summary_msg]
+        mock_middleware_inst._compute_state_cutoff.return_value = 2
+
+        mock_middleware_cls = MagicMock(return_value=mock_middleware_inst)
+
+        # to_summarize=5000, to_keep=15000 → total=20000, 5000/20000=25% > 2%
+        token_values = iter([5000, 15000, 500])
+
+        with (
+            patch("EvoScientist.EvoScientist._ensure_chat_model", return_value=MagicMock()),
+            patch("EvoScientist.EvoScientist._get_default_backend", return_value=MagicMock()),
+            patch("deepagents.middleware.summarization.SummarizationMiddleware", mock_middleware_cls),
+            patch("deepagents.middleware.summarization.compute_summarization_defaults", return_value={"keep": ("messages", 6)}),
+            patch("langchain_core.messages.utils.count_tokens_approximately", side_effect=lambda x: next(token_values)),
+        ):
+            result = _run(compact_conversation(agent=agent, thread_id="tid-1"))
+
+        assert result.status == "ok"
+        agent.aupdate_state.assert_awaited_once()
+
+
+class TestCompactSuccess:
+    """Normal compaction flow."""
+
+    def test_successful_compaction(self, _run):
+        from EvoScientist.cli.commands import compact_conversation
+        from langchain_core.messages import HumanMessage
+
+        agent = MagicMock()
+        msgs = [MagicMock() for _ in range(20)]
+        snapshot = SimpleNamespace(values={"messages": msgs, "_summarization_event": None})
+        agent.aget_state = AsyncMock(return_value=snapshot)
+        agent.aupdate_state = AsyncMock()
+
+        summary_msg = HumanMessage(content="Summary of conversation")
+        to_summarize = msgs[:15]
+        to_keep = msgs[15:]
+
+        mock_middleware_inst = MagicMock()
+        mock_middleware_inst._apply_event_to_messages.return_value = msgs
+        mock_middleware_inst._determine_cutoff_index.return_value = 15
+        mock_middleware_inst._partition_messages.return_value = (to_summarize, to_keep)
+        mock_middleware_inst._acreate_summary = AsyncMock(return_value="Summary text")
+        mock_middleware_inst._aoffload_to_backend = AsyncMock(return_value="/conversation_history/tid.md")
+        mock_middleware_inst._build_new_messages_with_path.return_value = [summary_msg]
+        mock_middleware_inst._compute_state_cutoff.return_value = 15
+
+        mock_middleware_cls = MagicMock(return_value=mock_middleware_inst)
+
+        # count_tokens_approximately returns different values per call
+        token_values = iter([5000, 1000, 200])
+
+        with (
+            patch("EvoScientist.EvoScientist._ensure_chat_model", return_value=MagicMock()),
+            patch("EvoScientist.EvoScientist._get_default_backend", return_value=MagicMock()),
+            patch("deepagents.middleware.summarization.SummarizationMiddleware", mock_middleware_cls),
+            patch("deepagents.middleware.summarization.compute_summarization_defaults", return_value={"keep": ("messages", 6)}),
+            patch("langchain_core.messages.utils.count_tokens_approximately", side_effect=lambda x: next(token_values)),
+        ):
+            result = _run(compact_conversation(agent=agent, thread_id="tid-1"))
+
+        assert result.status == "ok"
+        assert result.messages_compacted == 15
+        assert result.messages_kept == 5
+        assert result.tokens_before == 6000
+        assert result.tokens_after == 1200
+        assert result.pct_decrease == 80
+        agent.aupdate_state.assert_awaited_once()
+
+        # Verify the event structure passed to aupdate_state
+        call_args = agent.aupdate_state.call_args
+        event_data = call_args[0][1]
+        assert "_summarization_event" in event_data
+        assert event_data["_summarization_event"]["cutoff_index"] == 15
+
+    def test_offload_failure_non_fatal(self, _run):
+        """Offload failure should not prevent compaction."""
+        from EvoScientist.cli.commands import compact_conversation
+        from langchain_core.messages import HumanMessage
+
+        agent = MagicMock()
+        msgs = [MagicMock() for _ in range(10)]
+        snapshot = SimpleNamespace(values={"messages": msgs, "_summarization_event": None})
+        agent.aget_state = AsyncMock(return_value=snapshot)
+        agent.aupdate_state = AsyncMock()
+
+        summary_msg = HumanMessage(content="Summary")
+
+        mock_middleware_inst = MagicMock()
+        mock_middleware_inst._apply_event_to_messages.return_value = msgs
+        mock_middleware_inst._determine_cutoff_index.return_value = 7
+        mock_middleware_inst._partition_messages.return_value = (msgs[:7], msgs[7:])
+        mock_middleware_inst._acreate_summary = AsyncMock(return_value="Summary")
+        mock_middleware_inst._aoffload_to_backend = AsyncMock(side_effect=RuntimeError("write failed"))
+        mock_middleware_inst._build_new_messages_with_path.return_value = [summary_msg]
+        mock_middleware_inst._compute_state_cutoff.return_value = 7
+
+        mock_middleware_cls = MagicMock(return_value=mock_middleware_inst)
+
+        with (
+            patch("EvoScientist.EvoScientist._ensure_chat_model", return_value=MagicMock()),
+            patch("EvoScientist.EvoScientist._get_default_backend", return_value=MagicMock()),
+            patch("deepagents.middleware.summarization.SummarizationMiddleware", mock_middleware_cls),
+            patch("deepagents.middleware.summarization.compute_summarization_defaults", return_value={"keep": ("messages", 6)}),
+            patch("langchain_core.messages.utils.count_tokens_approximately", return_value=1000),
+        ):
+            result = _run(compact_conversation(agent=agent, thread_id="tid-1"))
+
+        assert result.status == "ok"
+        agent.aupdate_state.assert_awaited_once()
+
+        # file_path should be None in the event
+        event_data = agent.aupdate_state.call_args[0][1]
+        assert event_data["_summarization_event"]["file_path"] is None
+
+
+class TestRenderCompactResult:
+    """Test the Rich rendering of CompactResult."""
+
+    def test_render_noop(self):
+        from EvoScientist.cli.commands import CompactResult, render_compact_result
+
+        result = CompactResult("noop", "Nothing to compact", tokens_before=500)
+        text = render_compact_result(result)
+        plain = text.plain
+        assert "Nothing to compact" in plain
+        assert "500" in plain
+
+    def test_render_noop_no_tokens(self):
+        from EvoScientist.cli.commands import CompactResult, render_compact_result
+
+        result = CompactResult("noop", "Nothing to compact — no messages in conversation.")
+        text = render_compact_result(result)
+        assert "Nothing to compact" in text.plain
+
+    def test_render_error(self):
+        from EvoScientist.cli.commands import CompactResult, render_compact_result
+
+        result = CompactResult("error", "Failed to read state: DB gone")
+        text = render_compact_result(result)
+        assert "Failed to read state" in text.plain
+
+    def test_render_ok(self):
+        from EvoScientist.cli.commands import CompactResult, render_compact_result
+
+        result = CompactResult(
+            "ok", "Compacted",
+            messages_compacted=15,
+            messages_kept=5,
+            tokens_before=6000,
+            tokens_after=1200,
+            tokens_summarized=5000,
+            tokens_summary=200,
+            pct_decrease=80,
+        )
+        text = render_compact_result(result)
+        plain = text.plain
+        assert "15" in plain
+        assert "6,000" in plain
+        assert "1,200" in plain
+        assert "80%" in plain
+        assert "5 messages unchanged" in plain
+
+    def test_str_fallback(self):
+        from EvoScientist.cli.commands import CompactResult
+
+        result = CompactResult("ok", "hello world")
+        assert str(result) == "hello world"