diff --git a/agent/agent_init.py b/agent/agent_init.py
index ea2046763e..29c0390580 100644
--- a/agent/agent_init.py
+++ b/agent/agent_init.py
@@ -3040,6 +3040,36 @@ def init_agent(
             "Ollama num_ctx: will request %d tokens (model max from /api/show)",
             agent._ollama_num_ctx,
         )
+    # ── Recalibrate the compressor to the served window (#57275 claim 3) ──
+    # The compressor was constructed ABOVE this block from the probed model
+    # window (GGUF metadata can advertise 256K+), but every request below
+    # runs at num_ctx. A config that sets only model.ollama_num_ctx (without
+    # model.context_length) previously left the compressor targeting the
+    # probed window while the server truncated/rejected at num_ctx — the
+    # compaction trigger could sit several times ABOVE the real served
+    # window and never fire. Clamp the compressor's window to the effective
+    # num_ctx so threshold math operates on the context the server actually
+    # serves. (Overlaps #60103's silent-clamp dead zone; this is the
+    # init-order half.)
+    _cc_window = getattr(agent.context_compressor, "context_length", 0) or 0
+    if (
+        agent._ollama_num_ctx
+        and agent._ollama_num_ctx > 0
+        and _cc_window
+        and agent._ollama_num_ctx < _cc_window
+    ):
+        _ra().logger.info(
+            "Compressor window clamped to Ollama num_ctx: %d -> %d",
+            _cc_window, agent._ollama_num_ctx,
+        )
+        agent.context_compressor.update_model(
+            model=agent.model,
+            context_length=agent._ollama_num_ctx,
+            base_url=agent.base_url,
+            api_key=getattr(agent, "api_key", ""),
+            provider=agent.provider,
+            api_mode=agent.api_mode,
+        )
 
     # Codex gpt-5.x autoraise notice: show at most once per profile/config
     # state. Without the persisted marker the notice re-fires on every agent
diff --git a/tests/test_ollama_num_ctx.py b/tests/test_ollama_num_ctx.py
index 3097fbbf4e..2ad57201c2 100644
--- a/tests/test_ollama_num_ctx.py
+++ b/tests/test_ollama_num_ctx.py
@@ -130,3 +130,60 @@ class TestQueryOllamaSupportsVision:
         with patch("agent.model_metadata.detect_local_server_type", return_value="vllm"):
             result = query_ollama_supports_vision("llava", "http://localhost:8000/v1")
         assert result is None
+
+
+# ═══════════════════════════════════════════════════════════════════════
+# Level 3: init-order — compressor window must clamp to effective num_ctx
+# (#57275 residual claim 3 / #60103 init-order half)
+# ═══════════════════════════════════════════════════════════════════════
+
+
+class TestCompressorClampsToNumCtx:
+    """A config setting ONLY model.ollama_num_ctx (no model.context_length)
+    must not leave the compressor targeting the probed model window while
+    requests run at the smaller served num_ctx."""
+
+    def _build_agent(self, cfg, probed_ctx):
+        import agent.context_compressor as cc_mod
+        with (
+            patch("run_agent.get_tool_definitions", return_value=[]),
+            patch("run_agent.check_toolset_requirements", return_value={}),
+            patch("run_agent.OpenAI"),
+            patch("hermes_cli.config.load_config", return_value=cfg),
+            patch("hermes_cli.config.load_config_readonly", return_value=cfg),
+            patch(
+                "agent.model_metadata.get_model_context_length",
+                return_value=probed_ctx,
+            ),
+            patch.object(
+                cc_mod, "get_model_context_length", return_value=probed_ctx,
+            ),
+        ):
+            from run_agent import AIAgent
+            return AIAgent(
+                model="gemma3:27b",
+                api_key="ollama",
+                base_url="http://localhost:11434/v1",
+                quiet_mode=True,
+                skip_context_files=True,
+                skip_memory=True,
+            )
+
+    def test_num_ctx_only_config_clamps_compressor_window(self):
+        agent = self._build_agent(
+            {"agent": {}, "model": {"ollama_num_ctx": 65536}}, probed_ctx=262144
+        )
+        assert agent._ollama_num_ctx == 65536
+        # The compressor must target the served window, not the probed 256K —
+        # otherwise its trigger sits far above what the server accepts and
+        # compaction never fires (#57275 claim 3).
+        assert agent.context_compressor.context_length == 65536
+        assert agent.context_compressor.threshold_tokens < 65536
+
+    def test_larger_num_ctx_does_not_inflate_compressor_window(self):
+        agent = self._build_agent(
+            {"agent": {}, "model": {"ollama_num_ctx": 131072}}, probed_ctx=65536
+        )
+        # num_ctx above the resolved window must not RAISE the compressor
+        # window: the clamp is one-directional.
+        assert agent.context_compressor.context_length == 65536